system/kernel: Drop BFQ scheduler patch

We're using kernel 4.12 and the BFQ scheduler is included there as a
blk-BQ scheduler, so instead of the patch, let's just use a config where
we set BFQ to be used as the default scheduler.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

2 files changed, 4 insertions, 10171 deletions

diff --git a/modules/user/aszlig/system/bfq.patch b/modules/user/aszlig/system/bfq.patch
deleted file mode 100644
index 54f82499..00000000
--- a/modules/user/aszlig/system/bfq.patch
+++ /dev/null
@@ -1,10167 +0,0 @@
-diff --git a/Documentation/block/00-INDEX b/Documentation/block/00-INDEX
-index e55103ace382..8d55b4bbb5e2 100644
---- a/Documentation/block/00-INDEX
-+++ b/Documentation/block/00-INDEX
-@@ -1,5 +1,7 @@
- 00-INDEX
- 	- This file
-+bfq-iosched.txt
-+	- BFQ IO scheduler and its tunables
- biodoc.txt
- 	- Notes on the Generic Block Layer Rewrite in Linux 2.5
- biovecs.txt
-diff --git a/Documentation/block/bfq-iosched.txt b/Documentation/block/bfq-iosched.txt
-new file mode 100644
-index 000000000000..13b5248eba7e
---- /dev/null
-+++ b/Documentation/block/bfq-iosched.txt
-@@ -0,0 +1,530 @@
-+BFQ (Budget Fair Queueing)
-+==========================
-+
-+BFQ is a proportional-share I/O scheduler, with some extra
-+low-latency capabilities. In addition to cgroups support (blkio or io
-+controllers), BFQ's main features are:
-+- BFQ guarantees a high system and application responsiveness, and a
-+  low latency for time-sensitive applications, such as audio or video
-+  players;
-+- BFQ distributes bandwidth, and not just time, among processes or
-+  groups (switching back to time distribution when needed to keep
-+  throughput high).
-+
-+On average CPUs, the current version of BFQ can handle devices
-+performing at most ~30K IOPS; at most ~50 KIOPS on faster CPUs. As a
-+reference, 30-50 KIOPS correspond to very high bandwidths with
-+sequential I/O (e.g., 8-12 GB/s if I/O requests are 256 KB large), and
-+to 120-200 MB/s with 4KB random I/O.
-+
-+The table of contents follow. Impatients can just jump to Section 3.
-+
-+CONTENTS
-+
-+1. When may BFQ be useful?
-+ 1-1 Personal systems
-+ 1-2 Server systems
-+2. How does BFQ work?
-+3. What are BFQ's tunable?
-+4. BFQ group scheduling
-+ 4-1 Service guarantees provided
-+ 4-2 Interface
-+
-+1. When may BFQ be useful?
-+==========================
-+
-+BFQ provides the following benefits on personal and server systems.
-+
-+1-1 Personal systems
-+--------------------
-+
-+Low latency for interactive applications
-+
-+Regardless of the actual background workload, BFQ guarantees that, for
-+interactive tasks, the storage device is virtually as responsive as if
-+it was idle. For example, even if one or more of the following
-+background workloads are being executed:
-+- one or more large files are being read, written or copied,
-+- a tree of source files is being compiled,
-+- one or more virtual machines are performing I/O,
-+- a software update is in progress,
-+- indexing daemons are scanning filesystems and updating their
-+  databases,
-+starting an application or loading a file from within an application
-+takes about the same time as if the storage device was idle. As a
-+comparison, with CFQ, NOOP or DEADLINE, and in the same conditions,
-+applications experience high latencies, or even become unresponsive
-+until the background workload terminates (also on SSDs).
-+
-+Low latency for soft real-time applications
-+
-+Also soft real-time applications, such as audio and video
-+players/streamers, enjoy a low latency and a low drop rate, regardless
-+of the background I/O workload. As a consequence, these applications
-+do not suffer from almost any glitch due to the background workload.
-+
-+Higher speed for code-development tasks
-+
-+If some additional workload happens to be executed in parallel, then
-+BFQ executes the I/O-related components of typical code-development
-+tasks (compilation, checkout, merge, ...) much more quickly than CFQ,
-+NOOP or DEADLINE.
-+
-+High throughput
-+
-+On hard disks, BFQ achieves up to 30% higher throughput than CFQ, and
-+up to 150% higher throughput than DEADLINE and NOOP, with all the
-+sequential workloads considered in our tests. With random workloads,
-+and with all the workloads on flash-based devices, BFQ achieves,
-+instead, about the same throughput as the other schedulers.
-+
-+Strong fairness, bandwidth and delay guarantees
-+
-+BFQ distributes the device throughput, and not just the device time,
-+among I/O-bound applications in proportion their weights, with any
-+workload and regardless of the device parameters. From these bandwidth
-+guarantees, it is possible to compute tight per-I/O-request delay
-+guarantees by a simple formula. If not configured for strict service
-+guarantees, BFQ switches to time-based resource sharing (only) for
-+applications that would otherwise cause a throughput loss.
-+
-+1-2 Server systems
-+------------------
-+
-+Most benefits for server systems follow from the same service
-+properties as above. In particular, regardless of whether additional,
-+possibly heavy workloads are being served, BFQ guarantees:
-+
-+. audio and video-streaming with zero or very low jitter and drop
-+  rate;
-+
-+. fast retrieval of WEB pages and embedded objects;
-+
-+. real-time recording of data in live-dumping applications (e.g.,
-+  packet logging);
-+
-+. responsiveness in local and remote access to a server.
-+
-+
-+2. How does BFQ work?
-+=====================
-+
-+BFQ is a proportional-share I/O scheduler, whose general structure,
-+plus a lot of code, are borrowed from CFQ.
-+
-+- Each process doing I/O on a device is associated with a weight and a
-+  (bfq_)queue.
-+
-+- BFQ grants exclusive access to the device, for a while, to one queue
-+  (process) at a time, and implements this service model by
-+  associating every queue with a budget, measured in number of
-+  sectors.
-+
-+  - After a queue is granted access to the device, the budget of the
-+    queue is decremented, on each request dispatch, by the size of the
-+    request.
-+
-+  - The in-service queue is expired, i.e., its service is suspended,
-+    only if one of the following events occurs: 1) the queue finishes
-+    its budget, 2) the queue empties, 3) a "budget timeout" fires.
-+
-+    - The budget timeout prevents processes doing random I/O from
-+      holding the device for too long and dramatically reducing
-+      throughput.
-+
-+    - Actually, as in CFQ, a queue associated with a process issuing
-+      sync requests may not be expired immediately when it empties. In
-+      contrast, BFQ may idle the device for a short time interval,
-+      giving the process the chance to go on being served if it issues
-+      a new request in time. Device idling typically boosts the
-+      throughput on rotational devices, if processes do synchronous
-+      and sequential I/O. In addition, under BFQ, device idling is
-+      also instrumental in guaranteeing the desired throughput
-+      fraction to processes issuing sync requests (see the description
-+      of the slice_idle tunable in this document, or [1, 2], for more
-+      details).
-+
-+      - With respect to idling for service guarantees, if several
-+	processes are competing for the device at the same time, but
-+	all processes (and groups, after the following commit) have
-+	the same weight, then BFQ guarantees the expected throughput
-+	distribution without ever idling the device. Throughput is
-+	thus as high as possible in this common scenario.
-+
-+  - If low-latency mode is enabled (default configuration), BFQ
-+    executes some special heuristics to detect interactive and soft
-+    real-time applications (e.g., video or audio players/streamers),
-+    and to reduce their latency. The most important action taken to
-+    achieve this goal is to give to the queues associated with these
-+    applications more than their fair share of the device
-+    throughput. For brevity, we call just "weight-raising" the whole
-+    sets of actions taken by BFQ to privilege these queues. In
-+    particular, BFQ provides a milder form of weight-raising for
-+    interactive applications, and a stronger form for soft real-time
-+    applications.
-+
-+  - BFQ automatically deactivates idling for queues born in a burst of
-+    queue creations. In fact, these queues are usually associated with
-+    the processes of applications and services that benefit mostly
-+    from a high throughput. Examples are systemd during boot, or git
-+    grep.
-+
-+  - As CFQ, BFQ merges queues performing interleaved I/O, i.e.,
-+    performing random I/O that becomes mostly sequential if
-+    merged. Differently from CFQ, BFQ achieves this goal with a more
-+    reactive mechanism, called Early Queue Merge (EQM). EQM is so
-+    responsive in detecting interleaved I/O (cooperating processes),
-+    that it enables BFQ to achieve a high throughput, by queue
-+    merging, even for queues for which CFQ needs a different
-+    mechanism, preemption, to get a high throughput. As such EQM is a
-+    unified mechanism to achieve a high throughput with interleaved
-+    I/O.
-+
-+  - Queues are scheduled according to a variant of WF2Q+, named
-+    B-WF2Q+, and implemented using an augmented rb-tree to preserve an
-+    O(log N) overall complexity.  See [2] for more details. B-WF2Q+ is
-+    also ready for hierarchical scheduling. However, for a cleaner
-+    logical breakdown, the code that enables and completes
-+    hierarchical support is provided in the next commit, which focuses
-+    exactly on this feature.
-+
-+  - B-WF2Q+ guarantees a tight deviation with respect to an ideal,
-+    perfectly fair, and smooth service. In particular, B-WF2Q+
-+    guarantees that each queue receives a fraction of the device
-+    throughput proportional to its weight, even if the throughput
-+    fluctuates, and regardless of: the device parameters, the current
-+    workload and the budgets assigned to the queue.
-+
-+  - The last, budget-independence, property (although probably
-+    counterintuitive in the first place) is definitely beneficial, for
-+    the following reasons:
-+
-+    - First, with any proportional-share scheduler, the maximum
-+      deviation with respect to an ideal service is proportional to
-+      the maximum budget (slice) assigned to queues. As a consequence,
-+      BFQ can keep this deviation tight not only because of the
-+      accurate service of B-WF2Q+, but also because BFQ *does not*
-+      need to assign a larger budget to a queue to let the queue
-+      receive a higher fraction of the device throughput.
-+
-+    - Second, BFQ is free to choose, for every process (queue), the
-+      budget that best fits the needs of the process, or best
-+      leverages the I/O pattern of the process. In particular, BFQ
-+      updates queue budgets with a simple feedback-loop algorithm that
-+      allows a high throughput to be achieved, while still providing
-+      tight latency guarantees to time-sensitive applications. When
-+      the in-service queue expires, this algorithm computes the next
-+      budget of the queue so as to:
-+
-+      - Let large budgets be eventually assigned to the queues
-+	associated with I/O-bound applications performing sequential
-+	I/O: in fact, the longer these applications are served once
-+	got access to the device, the higher the throughput is.
-+
-+      - Let small budgets be eventually assigned to the queues
-+	associated with time-sensitive applications (which typically
-+	perform sporadic and short I/O), because, the smaller the
-+	budget assigned to a queue waiting for service is, the sooner
-+	B-WF2Q+ will serve that queue (Subsec 3.3 in [2]).
-+
-+- If several processes are competing for the device at the same time,
-+  but all processes and groups have the same weight, then BFQ
-+  guarantees the expected throughput distribution without ever idling
-+  the device. It uses preemption instead. Throughput is then much
-+  higher in this common scenario.
-+
-+- ioprio classes are served in strict priority order, i.e.,
-+  lower-priority queues are not served as long as there are
-+  higher-priority queues.  Among queues in the same class, the
-+  bandwidth is distributed in proportion to the weight of each
-+  queue. A very thin extra bandwidth is however guaranteed to
-+  the Idle class, to prevent it from starving.
-+
-+
-+3. What are BFQ's tunable?
-+==========================
-+
-+The tunables back_seek-max, back_seek_penalty, fifo_expire_async and
-+fifo_expire_sync below are the same as in CFQ. Their description is
-+just copied from that for CFQ. Some considerations in the description
-+of slice_idle are copied from CFQ too.
-+
-+per-process ioprio and weight
-+-----------------------------
-+
-+Unless the cgroups interface is used (see "4. BFQ group scheduling"),
-+weights can be assigned to processes only indirectly, through I/O
-+priorities, and according to the relation:
-+weight = (IOPRIO_BE_NR - ioprio) * 10.
-+
-+Beware that, if low-latency is set, then BFQ automatically raises the
-+weight of the queues associated with interactive and soft real-time
-+applications. Unset this tunable if you need/want to control weights.
-+
-+slice_idle
-+----------
-+
-+This parameter specifies how long BFQ should idle for next I/O
-+request, when certain sync BFQ queues become empty. By default
-+slice_idle is a non-zero value. Idling has a double purpose: boosting
-+throughput and making sure that the desired throughput distribution is
-+respected (see the description of how BFQ works, and, if needed, the
-+papers referred there).
-+
-+As for throughput, idling can be very helpful on highly seeky media
-+like single spindle SATA/SAS disks where we can cut down on overall
-+number of seeks and see improved throughput.
-+
-+Setting slice_idle to 0 will remove all the idling on queues and one
-+should see an overall improved throughput on faster storage devices
-+like multiple SATA/SAS disks in hardware RAID configuration.
-+
-+So depending on storage and workload, it might be useful to set
-+slice_idle=0.  In general for SATA/SAS disks and software RAID of
-+SATA/SAS disks keeping slice_idle enabled should be useful. For any
-+configurations where there are multiple spindles behind single LUN
-+(Host based hardware RAID controller or for storage arrays), setting
-+slice_idle=0 might end up in better throughput and acceptable
-+latencies.
-+
-+Idling is however necessary to have service guarantees enforced in
-+case of differentiated weights or differentiated I/O-request lengths.
-+To see why, suppose that a given BFQ queue A must get several I/O
-+requests served for each request served for another queue B. Idling
-+ensures that, if A makes a new I/O request slightly after becoming
-+empty, then no request of B is dispatched in the middle, and thus A
-+does not lose the possibility to get more than one request dispatched
-+before the next request of B is dispatched. Note that idling
-+guarantees the desired differentiated treatment of queues only in
-+terms of I/O-request dispatches. To guarantee that the actual service
-+order then corresponds to the dispatch order, the strict_guarantees
-+tunable must be set too.
-+
-+There is an important flipside for idling: apart from the above cases
-+where it is beneficial also for throughput, idling can severely impact
-+throughput. One important case is random workload. Because of this
-+issue, BFQ tends to avoid idling as much as possible, when it is not
-+beneficial also for throughput. As a consequence of this behavior, and
-+of further issues described for the strict_guarantees tunable,
-+short-term service guarantees may be occasionally violated. And, in
-+some cases, these guarantees may be more important than guaranteeing
-+maximum throughput. For example, in video playing/streaming, a very
-+low drop rate may be more important than maximum throughput. In these
-+cases, consider setting the strict_guarantees parameter.
-+
-+strict_guarantees
-+-----------------
-+
-+If this parameter is set (default: unset), then BFQ
-+
-+- always performs idling when the in-service queue becomes empty;
-+
-+- forces the device to serve one I/O request at a time, by dispatching a
-+  new request only if there is no outstanding request.
-+
-+In the presence of differentiated weights or I/O-request sizes, both
-+the above conditions are needed to guarantee that every BFQ queue
-+receives its allotted share of the bandwidth. The first condition is
-+needed for the reasons explained in the description of the slice_idle
-+tunable.  The second condition is needed because all modern storage
-+devices reorder internally-queued requests, which may trivially break
-+the service guarantees enforced by the I/O scheduler.
-+
-+Setting strict_guarantees may evidently affect throughput.
-+
-+back_seek_max
-+-------------
-+
-+This specifies, given in Kbytes, the maximum "distance" for backward seeking.
-+The distance is the amount of space from the current head location to the
-+sectors that are backward in terms of distance.
-+
-+This parameter allows the scheduler to anticipate requests in the "backward"
-+direction and consider them as being the "next" if they are within this
-+distance from the current head location.
-+
-+back_seek_penalty
-+-----------------
-+
-+This parameter is used to compute the cost of backward seeking. If the
-+backward distance of request is just 1/back_seek_penalty from a "front"
-+request, then the seeking cost of two requests is considered equivalent.
-+
-+So scheduler will not bias toward one or the other request (otherwise scheduler
-+will bias toward front request). Default value of back_seek_penalty is 2.
-+
-+fifo_expire_async
-+-----------------
-+
-+This parameter is used to set the timeout of asynchronous requests. Default
-+value of this is 248ms.
-+
-+fifo_expire_sync
-+----------------
-+
-+This parameter is used to set the timeout of synchronous requests. Default
-+value of this is 124ms. In case to favor synchronous requests over asynchronous
-+one, this value should be decreased relative to fifo_expire_async.
-+
-+low_latency
-+-----------
-+
-+This parameter is used to enable/disable BFQ's low latency mode. By
-+default, low latency mode is enabled. If enabled, interactive and soft
-+real-time applications are privileged and experience a lower latency,
-+as explained in more detail in the description of how BFQ works.
-+
-+DO NOT enable this mode if you need full control on bandwidth
-+distribution. In fact, if it is enabled, then BFQ automatically
-+increases the bandwidth share of privileged applications, as the main
-+means to guarantee a lower latency to them.
-+
-+timeout_sync
-+------------
-+
-+Maximum amount of device time that can be given to a task (queue) once
-+it has been selected for service. On devices with costly seeks,
-+increasing this time usually increases maximum throughput. On the
-+opposite end, increasing this time coarsens the granularity of the
-+short-term bandwidth and latency guarantees, especially if the
-+following parameter is set to zero.
-+
-+max_budget
-+----------
-+
-+Maximum amount of service, measured in sectors, that can be provided
-+to a BFQ queue once it is set in service (of course within the limits
-+of the above timeout). According to what said in the description of
-+the algorithm, larger values increase the throughput in proportion to
-+the percentage of sequential I/O requests issued. The price of larger
-+values is that they coarsen the granularity of short-term bandwidth
-+and latency guarantees.
-+
-+The default value is 0, which enables auto-tuning: BFQ sets max_budget
-+to the maximum number of sectors that can be served during
-+timeout_sync, according to the estimated peak rate.
-+
-+weights
-+-------
-+
-+Read-only parameter, used to show the weights of the currently active
-+BFQ queues.
-+
-+
-+wr_ tunables
-+------------
-+
-+BFQ exports a few parameters to control/tune the behavior of
-+low-latency heuristics.
-+
-+wr_coeff
-+
-+Factor by which the weight of a weight-raised queue is multiplied. If
-+the queue is deemed soft real-time, then the weight is further
-+multiplied by an additional, constant factor.
-+
-+wr_max_time
-+
-+Maximum duration of a weight-raising period for an interactive task
-+(ms). If set to zero (default value), then this value is computed
-+automatically, as a function of the peak rate of the device. In any
-+case, when the value of this parameter is read, it always reports the
-+current duration, regardless of whether it has been set manually or
-+computed automatically.
-+
-+wr_max_softrt_rate
-+
-+Maximum service rate below which a queue is deemed to be associated
-+with a soft real-time application, and is then weight-raised
-+accordingly (sectors/sec).
-+
-+wr_min_idle_time
-+
-+Minimum idle period after which interactive weight-raising may be
-+reactivated for a queue (in ms).
-+
-+wr_rt_max_time
-+
-+Maximum weight-raising duration for soft real-time queues (in ms). The
-+start time from which this duration is considered is automatically
-+moved forward if the queue is detected to be still soft real-time
-+before the current soft real-time weight-raising period finishes.
-+
-+wr_min_inter_arr_async
-+
-+Minimum period between I/O request arrivals after which weight-raising
-+may be reactivated for an already busy async queue (in ms).
-+
-+
-+4. Group scheduling with BFQ
-+============================
-+
-+BFQ supports both cgroups-v1 and cgroups-v2 io controllers, namely
-+blkio and io. In particular, BFQ supports weight-based proportional
-+share. To activate cgroups support, set BFQ_GROUP_IOSCHED.
-+
-+4-1 Service guarantees provided
-+-------------------------------
-+
-+With BFQ, proportional share means true proportional share of the
-+device bandwidth, according to group weights. For example, a group
-+with weight 200 gets twice the bandwidth, and not just twice the time,
-+of a group with weight 100.
-+
-+BFQ supports hierarchies (group trees) of any depth. Bandwidth is
-+distributed among groups and processes in the expected way: for each
-+group, the children of the group share the whole bandwidth of the
-+group in proportion to their weights. In particular, this implies
-+that, for each leaf group, every process of the group receives the
-+same share of the whole group bandwidth, unless the ioprio of the
-+process is modified.
-+
-+The resource-sharing guarantee for a group may partially or totally
-+switch from bandwidth to time, if providing bandwidth guarantees to
-+the group lowers the throughput too much. This switch occurs on a
-+per-process basis: if a process of a leaf group causes throughput loss
-+if served in such a way to receive its share of the bandwidth, then
-+BFQ switches back to just time-based proportional share for that
-+process.
-+
-+4-2 Interface
-+-------------
-+
-+To get proportional sharing of bandwidth with BFQ for a given device,
-+BFQ must of course be the active scheduler for that device.
-+
-+Within each group directory, the names of the files associated with
-+BFQ-specific cgroup parameters and stats begin with the "bfq."
-+prefix. So, with cgroups-v1 or cgroups-v2, the full prefix for
-+BFQ-specific files is "blkio.bfq." or "io.bfq." For example, the group
-+parameter to set the weight of a group with BFQ is blkio.bfq.weight
-+or io.bfq.weight.
-+
-+Parameters to set
-+-----------------
-+
-+For each group, there is only the following parameter to set.
-+
-+weight (namely blkio.bfq.weight or io.bfq-weight): the weight of the
-+group inside its parent. Available values: 1..10000 (default 100). The
-+linear mapping between ioprio and weights, described at the beginning
-+of the tunable section, is still valid, but all weights higher than
-+IOPRIO_BE_NR*10 are mapped to ioprio 0.
-+
-+Recall that, if low-latency is set, then BFQ automatically raises the
-+weight of the queues associated with interactive and soft real-time
-+applications. Unset this tunable if you need/want to control weights.
-+
-+
-+[1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+    Scheduler", Proceedings of the First Workshop on Mobile System
-+    Technologies (MST-2015), May 2015.
-+    http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+
-+[2] P. Valente and M. Andreolini, "Improving Application
-+    Responsiveness with the BFQ Disk I/O Scheduler", Proceedings of
-+    the 5th Annual International Systems and Storage Conference
-+    (SYSTOR '12), June 2012.
-+    Slightly extended version:
-+    http://algogroup.unimore.it/people/paolo/disk_sched/bfq-v1-suite-
-+							results.pdf
-diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
-index 58fc8684788d..99a42261677a 100644
---- a/block/Kconfig.iosched
-+++ b/block/Kconfig.iosched
-@@ -39,6 +39,25 @@ config CFQ_GROUP_IOSCHED
- 	---help---
- 	  Enable group IO scheduling in CFQ.
- 
-+config IOSCHED_BFQ
-+	tristate "BFQ I/O scheduler"
-+	default n
-+	---help---
-+	The BFQ I/O scheduler distributes bandwidth among all
-+	processes according to their weights, regardless of the
-+	device parameters and with any workload. It also guarantees
-+	a low latency to interactive and soft real-time applications.
-+	Details in Documentation/block/bfq-iosched.txt
-+
-+config BFQ_GROUP_IOSCHED
-+	bool "BFQ hierarchical scheduling support"
-+	depends on IOSCHED_BFQ && BLK_CGROUP
-+	default n
-+	---help---
-+
-+	Enable hierarchical scheduling in BFQ, using the blkio
-+	(cgroups-v1) or io (cgroups-v2) controller.
-+
- choice
- 	prompt "Default I/O scheduler"
- 	default DEFAULT_CFQ
-@@ -52,6 +71,16 @@ choice
- 	config DEFAULT_CFQ
- 		bool "CFQ" if IOSCHED_CFQ=y
- 
-+	config DEFAULT_BFQ
-+		bool "BFQ" if IOSCHED_BFQ=y
-+		help
-+		  Selects BFQ as the default I/O scheduler which will be
-+		  used by default for all block devices.
-+		  The BFQ I/O scheduler aims at distributing the bandwidth
-+		  as desired, independently of the disk parameters and with
-+		  any workload. It also tries to guarantee low latency to
-+		  interactive and soft real-time applications.
-+
- 	config DEFAULT_NOOP
- 		bool "No-op"
- 
-@@ -61,6 +90,7 @@ config DEFAULT_IOSCHED
- 	string
- 	default "deadline" if DEFAULT_DEADLINE
- 	default "cfq" if DEFAULT_CFQ
-+	default "bfq" if DEFAULT_BFQ
- 	default "noop" if DEFAULT_NOOP
- 
- config MQ_IOSCHED_DEADLINE
-diff --git a/block/Makefile b/block/Makefile
-index 081bb680789b..91869f2ef2dc 100644
---- a/block/Makefile
-+++ b/block/Makefile
-@@ -20,6 +20,7 @@ obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
- obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
- obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
- obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
-+obj-$(CONFIG_IOSCHED_BFQ)	+= bfq-iosched.o
- 
- obj-$(CONFIG_BLOCK_COMPAT)	+= compat_ioctl.o
- obj-$(CONFIG_BLK_CMDLINE_PARSER)	+= cmdline-parser.o
-diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
-new file mode 100644
-index 000000000000..39daaf405dc6
---- /dev/null
-+++ b/block/bfq-cgroup.c
-@@ -0,0 +1,1190 @@
-+/*
-+ * BFQ: CGROUPS support.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ */
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+
-+/* bfqg stats flags */
-+enum bfqg_stats_flags {
-+	BFQG_stats_waiting = 0,
-+	BFQG_stats_idling,
-+	BFQG_stats_empty,
-+};
-+
-+#define BFQG_FLAG_FNS(name)						\
-+static void bfqg_stats_mark_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags |= (1 << BFQG_stats_##name);			\
-+}									\
-+static void bfqg_stats_clear_##name(struct bfqg_stats *stats)	\
-+{									\
-+	stats->flags &= ~(1 << BFQG_stats_##name);			\
-+}									\
-+static int bfqg_stats_##name(struct bfqg_stats *stats)		\
-+{									\
-+	return (stats->flags & (1 << BFQG_stats_##name)) != 0;		\
-+}									\
-+
-+BFQG_FLAG_FNS(waiting)
-+BFQG_FLAG_FNS(idling)
-+BFQG_FLAG_FNS(empty)
-+#undef BFQG_FLAG_FNS
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
-+{
-+	unsigned long long now;
-+
-+	if (!bfqg_stats_waiting(stats))
-+		return;
-+
-+	now = sched_clock();
-+	if (time_after64(now, stats->start_group_wait_time))
-+		blkg_stat_add(&stats->group_wait_time,
-+			      now - stats->start_group_wait_time);
-+	bfqg_stats_clear_waiting(stats);
-+}
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+						 struct bfq_group *curr_bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_waiting(stats))
-+		return;
-+	if (bfqg == curr_bfqg)
-+		return;
-+	stats->start_group_wait_time = sched_clock();
-+	bfqg_stats_mark_waiting(stats);
-+}
-+
-+/* This should be called with the queue_lock held. */
-+static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
-+{
-+	unsigned long long now;
-+
-+	if (!bfqg_stats_empty(stats))
-+		return;
-+
-+	now = sched_clock();
-+	if (time_after64(now, stats->start_empty_time))
-+		blkg_stat_add(&stats->empty_time,
-+			      now - stats->start_empty_time);
-+	bfqg_stats_clear_empty(stats);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
-+{
-+	blkg_stat_add(&bfqg->stats.dequeue, 1);
-+}
-+
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (blkg_rwstat_total(&stats->queued))
-+		return;
-+
-+	/*
-+	 * group is already marked empty. This can happen if bfqq got new
-+	 * request in parent group and moved to this group while being added
-+	 * to service tree. Just ignore the event and move on.
-+	 */
-+	if (bfqg_stats_empty(stats))
-+		return;
-+
-+	stats->start_empty_time = sched_clock();
-+	bfqg_stats_mark_empty(stats);
-+}
-+
-+static void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	if (bfqg_stats_idling(stats)) {
-+		unsigned long long now = sched_clock();
-+
-+		if (time_after64(now, stats->start_idle_time))
-+			blkg_stat_add(&stats->idle_time,
-+				      now - stats->start_idle_time);
-+		bfqg_stats_clear_idling(stats);
-+	}
-+}
-+
-+static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	stats->start_idle_time = sched_clock();
-+	bfqg_stats_mark_idling(stats);
-+}
-+
-+static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+
-+	blkg_stat_add(&stats->avg_queue_size_sum,
-+		      blkg_rwstat_total(&stats->queued));
-+	blkg_stat_add(&stats->avg_queue_size_samples, 1);
-+	bfqg_stats_update_group_wait_time(stats);
-+}
-+
-+static struct blkcg_policy blkcg_policy_bfq;
-+
-+/*
-+ * blk-cgroup policy-related handlers
-+ * The following functions help in converting between blk-cgroup
-+ * internal structures and BFQ-specific structures.
-+ */
-+
-+static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
-+{
-+	return pd ? container_of(pd, struct bfq_group, pd) : NULL;
-+}
-+
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
-+{
-+	return pd_to_blkg(&bfqg->pd);
-+}
-+
-+static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
-+{
-+	struct blkg_policy_data *pd = blkg_to_pd(blkg, &blkcg_policy_bfq);
-+
-+	return pd_to_bfqg(pd);
-+}
-+
-+/*
-+ * bfq_group handlers
-+ * The following functions help in navigating the bfq_group hierarchy
-+ * by allowing to find the parent of a bfq_group or the bfq_group
-+ * associated to a bfq_queue.
-+ */
-+
-+static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
-+{
-+	struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
-+
-+	return pblkg ? blkg_to_bfqg(pblkg) : NULL;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	return group_entity ? container_of(group_entity, struct bfq_group,
-+					   entity) :
-+			      bfqq->bfqd->root_group;
-+}
-+
-+/*
-+ * The following two functions handle get and put of a bfq_group by
-+ * wrapping the related blk-cgroup hooks.
-+ */
-+
-+static void bfqg_get(struct bfq_group *bfqg)
-+{
-+	return blkg_get(bfqg_to_blkg(bfqg));
-+}
-+
-+static void bfqg_put(struct bfq_group *bfqg)
-+{
-+	return blkg_put(bfqg_to_blkg(bfqg));
-+}
-+
-+static void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+				     struct bfq_queue *bfqq,
-+				     unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, 1);
-+	bfqg_stats_end_empty_time(&bfqg->stats);
-+	if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
-+		bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
-+}
-+
-+static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.queued, op, -1);
-+}
-+
-+static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
-+{
-+	blkg_rwstat_add(&bfqg->stats.merged, op, 1);
-+}
-+
-+static void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+			uint64_t start_time, uint64_t io_start_time,
-+			unsigned int op)
-+{
-+	struct bfqg_stats *stats = &bfqg->stats;
-+	unsigned long long now = sched_clock();
-+
-+	if (time_after64(now, io_start_time))
-+		blkg_rwstat_add(&stats->service_time, op,
-+				now - io_start_time);
-+	if (time_after64(io_start_time, start_time))
-+		blkg_rwstat_add(&stats->wait_time, op,
-+				io_start_time - start_time);
-+}
-+
-+/* @stats = 0 */
-+static void bfqg_stats_reset(struct bfqg_stats *stats)
-+{
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_reset(&stats->merged);
-+	blkg_rwstat_reset(&stats->service_time);
-+	blkg_rwstat_reset(&stats->wait_time);
-+	blkg_stat_reset(&stats->time);
-+	blkg_stat_reset(&stats->avg_queue_size_sum);
-+	blkg_stat_reset(&stats->avg_queue_size_samples);
-+	blkg_stat_reset(&stats->dequeue);
-+	blkg_stat_reset(&stats->group_wait_time);
-+	blkg_stat_reset(&stats->idle_time);
-+	blkg_stat_reset(&stats->empty_time);
-+}
-+
-+/* @to += @from */
-+static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
-+{
-+	if (!to || !from)
-+		return;
-+
-+	/* queued stats shouldn't be cleared */
-+	blkg_rwstat_add_aux(&to->merged, &from->merged);
-+	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
-+	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
-+	blkg_stat_add_aux(&from->time, &from->time);
-+	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-+	blkg_stat_add_aux(&to->avg_queue_size_samples,
-+			  &from->avg_queue_size_samples);
-+	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
-+	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
-+	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
-+	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
-+}
-+
-+/*
-+ * Transfer @bfqg's stats to its parent's dead_stats so that the ancestors'
-+ * recursive stats can still account for the amount used by this bfqg after
-+ * it's gone.
-+ */
-+static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
-+{
-+	struct bfq_group *parent;
-+
-+	if (!bfqg) /* root_group */
-+		return;
-+
-+	parent = bfqg_parent(bfqg);
-+
-+	lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock);
-+
-+	if (unlikely(!parent))
-+		return;
-+
-+	bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+		bfqg_get(bfqg);
-+	}
-+	entity->parent = bfqg->my_entity; /* NULL for root group */
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfqg_stats_exit(struct bfqg_stats *stats)
-+{
-+	blkg_rwstat_exit(&stats->merged);
-+	blkg_rwstat_exit(&stats->service_time);
-+	blkg_rwstat_exit(&stats->wait_time);
-+	blkg_rwstat_exit(&stats->queued);
-+	blkg_stat_exit(&stats->time);
-+	blkg_stat_exit(&stats->avg_queue_size_sum);
-+	blkg_stat_exit(&stats->avg_queue_size_samples);
-+	blkg_stat_exit(&stats->dequeue);
-+	blkg_stat_exit(&stats->group_wait_time);
-+	blkg_stat_exit(&stats->idle_time);
-+	blkg_stat_exit(&stats->empty_time);
-+}
-+
-+static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
-+{
-+	if (blkg_rwstat_init(&stats->merged, gfp) ||
-+	    blkg_rwstat_init(&stats->service_time, gfp) ||
-+	    blkg_rwstat_init(&stats->wait_time, gfp) ||
-+	    blkg_rwstat_init(&stats->queued, gfp) ||
-+	    blkg_stat_init(&stats->time, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
-+	    blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
-+	    blkg_stat_init(&stats->dequeue, gfp) ||
-+	    blkg_stat_init(&stats->group_wait_time, gfp) ||
-+	    blkg_stat_init(&stats->idle_time, gfp) ||
-+	    blkg_stat_init(&stats->empty_time, gfp)) {
-+		bfqg_stats_exit(stats);
-+		return -ENOMEM;
-+	}
-+
-+	return 0;
-+}
-+
-+static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
-+{
-+	return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
-+}
-+
-+static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
-+{
-+	return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
-+}
-+
-+static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
-+{
-+	struct bfq_group_data *bgd;
-+
-+	bgd = kzalloc(sizeof(*bgd), gfp);
-+	if (!bgd)
-+		return NULL;
-+	return &bgd->pd;
-+}
-+
-+static void bfq_cpd_init(struct blkcg_policy_data *cpd)
-+{
-+	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
-+
-+	d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
-+		CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
-+}
-+
-+static void bfq_cpd_free(struct blkcg_policy_data *cpd)
-+{
-+	kfree(cpd_to_bfqgd(cpd));
-+}
-+
-+static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node)
-+{
-+	struct bfq_group *bfqg;
-+
-+	bfqg = kzalloc_node(sizeof(*bfqg), gfp, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	if (bfqg_stats_init(&bfqg->stats, gfp)) {
-+		kfree(bfqg);
-+		return NULL;
-+	}
-+
-+	return &bfqg->pd;
-+}
-+
-+static void bfq_pd_init(struct blkg_policy_data *pd)
-+{
-+	struct blkcg_gq *blkg;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+	struct bfq_group_data *d;
-+
-+	blkg = pd_to_blkg(pd);
-+	BUG_ON(!blkg);
-+	bfqg = blkg_to_bfqg(blkg);
-+	bfqd = blkg->q->elevator->elevator_data;
-+	entity = &bfqg->entity;
-+	d = blkcg_to_bfqgd(blkg->blkcg);
-+
-+	entity->orig_weight = entity->weight = entity->new_weight = d->weight;
-+	entity->my_sched_data = &bfqg->sched_data;
-+	bfqg->my_entity = entity; /*
-+				   * the root_group's will be set to NULL
-+				   * in bfq_init_queue()
-+				   */
-+	bfqg->bfqd = bfqd;
-+	bfqg->active_entities = 0;
-+	bfqg->rq_pos_tree = RB_ROOT;
-+}
-+
-+static void bfq_pd_free(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_exit(&bfqg->stats);
-+	return kfree(bfqg);
-+}
-+
-+static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+
-+	bfqg_stats_reset(&bfqg->stats);
-+}
-+
-+static void bfq_group_set_parent(struct bfq_group *bfqg,
-+					struct bfq_group *parent)
-+{
-+	struct bfq_entity *entity;
-+
-+	BUG_ON(!parent);
-+	BUG_ON(!bfqg);
-+	BUG_ON(bfqg == parent);
-+
-+	entity = &bfqg->entity;
-+	entity->parent = parent->my_entity;
-+	entity->sched_data = &parent->sched_data;
-+}
-+
-+static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
-+					 struct blkcg *blkcg)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	blkg = blkg_lookup(blkcg, bfqd->queue);
-+	if (likely(blkg))
-+		return blkg_to_bfqg(blkg);
-+	return NULL;
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	struct bfq_group *bfqg, *parent;
-+	struct bfq_entity *entity;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	bfqg = bfq_lookup_bfqg(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		return NULL;
-+
-+	/*
-+	 * Update chain of bfq_groups as we might be handling a leaf group
-+	 * which, along with some of its relatives, has not been hooked yet
-+	 * to the private hierarchy of BFQ.
-+	 */
-+	entity = &bfqg->entity;
-+	for_each_entity(entity) {
-+		bfqg = container_of(entity, struct bfq_group, entity);
-+		BUG_ON(!bfqg);
-+		if (bfqg != bfqd->root_group) {
-+			parent = bfqg_parent(bfqg);
-+			if (!parent)
-+				parent = bfqd->root_group;
-+			BUG_ON(!parent);
-+			bfq_group_set_parent(bfqg, parent);
-+		}
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd,
-+				  struct bfq_queue *bfqq);
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/**
-+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
-+ * @bfqd: queue descriptor.
-+ * @bfqq: the queue to move.
-+ * @bfqg: the group to move to.
-+ *
-+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
-+ * it on the new one.  Avoid putting the entity on the old group idle tree.
-+ *
-+ * Must be called under the queue lock; the cgroup owning @bfqg must
-+ * not disappear (by now this just means that we are called under
-+ * rcu_read_lock()).
-+ */
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && !RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list) && !entity->on_st);
-+	BUG_ON(bfq_bfqq_busy(bfqq) && RB_EMPTY_ROOT(&bfqq->sort_list)
-+	       && entity->on_st &&
-+	       bfqq != bfqd->in_service_queue);
-+	BUG_ON(!bfq_bfqq_busy(bfqq) && bfqq == bfqd->in_service_queue);
-+
-+	/* If bfqq is empty, then bfq_bfqq_expire also invokes
-+	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
-+	 * from data structures related to current group. Otherwise we
-+	 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
-+	 * we do below.
-+	 */
-+	if (bfqq == bfqd->in_service_queue)
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	    && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_busy(bfqq))
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+	else if (entity->on_st) {
-+		BUG_ON(&bfq_entity_service_tree(entity)->idle !=
-+		       entity->tree);
-+		bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
-+	}
-+	bfqg_put(bfqq_group(bfqq));
-+
-+	/*
-+	 * Here we use a reference to bfqg.  We don't need a refcounter
-+	 * as the cgroup reference will not be dropped, so that its
-+	 * destroy() callback will not be invoked.
-+	 */
-+	entity->parent = bfqg->my_entity;
-+	entity->sched_data = &bfqg->sched_data;
-+	bfqg_get(bfqg);
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list) && bfq_bfqq_busy(bfqq));
-+	if (bfq_bfqq_busy(bfqq)) {
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+		bfq_activate_bfqq(bfqd, bfqq);
-+	}
-+
-+	if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+	BUG_ON(entity->on_st && !bfq_bfqq_busy(bfqq)
-+	       && &bfq_entity_service_tree(entity)->idle !=
-+	       entity->tree);
-+}
-+
-+/**
-+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
-+ * @bfqd: the queue descriptor.
-+ * @bic: the bic to move.
-+ * @blkcg: the blk-cgroup to move to.
-+ *
-+ * Move bic to blkcg, assuming that bfqd->queue is locked; the caller
-+ * has to make sure that the reference to cgroup is valid across the call.
-+ *
-+ * NOTE: an alternative approach might have been to store the current
-+ * cgroup in bfqq and getting a reference to it, reducing the lookup
-+ * time here, at the price of slightly more complex code.
-+ */
-+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
-+						struct bfq_io_cq *bic,
-+						struct blkcg *blkcg)
-+{
-+	struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
-+	struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
-+	struct bfq_group *bfqg;
-+	struct bfq_entity *entity;
-+
-+	lockdep_assert_held(bfqd->queue->queue_lock);
-+
-+	bfqg = bfq_find_set_group(bfqd, blkcg);
-+
-+	if (unlikely(!bfqg))
-+		bfqg = bfqd->root_group;
-+
-+	if (async_bfqq) {
-+		entity = &async_bfqq->entity;
-+
-+		if (entity->sched_data != &bfqg->sched_data) {
-+			bic_set_bfqq(bic, NULL, 0);
-+			bfq_log_bfqq(bfqd, async_bfqq,
-+				     "bic_change_group: %p %d",
-+				     async_bfqq,
-+				     async_bfqq->ref);
-+			bfq_put_queue(async_bfqq);
-+		}
-+	}
-+
-+	if (sync_bfqq) {
-+		entity = &sync_bfqq->entity;
-+		if (entity->sched_data != &bfqg->sched_data)
-+			bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
-+	}
-+
-+	return bfqg;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_group *bfqg = NULL;
-+	uint64_t serial_nr;
-+
-+	rcu_read_lock();
-+	serial_nr = bio_blkcg(bio)->css.serial_nr;
-+
-+	/*
-+	 * Check whether blkcg has changed.  The condition may trigger
-+	 * spuriously on a newly created cic but there's no harm.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
-+		goto out;
-+
-+	bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio));
-+	bic->blkcg_serial_nr = serial_nr;
-+out:
-+	rcu_read_unlock();
-+}
-+
-+/**
-+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
-+ * @st: the service tree being flushed.
-+ */
-+static void bfq_flush_idle_tree(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *entity = st->first_idle;
-+
-+	for (; entity ; entity = st->first_idle)
-+		__bfq_deactivate_entity(entity, false);
-+}
-+
-+/**
-+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
-+ * @bfqd: the device data structure with the root group.
-+ * @entity: the entity to move.
-+ */
-+static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
-+				     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	BUG_ON(!bfqq);
-+	bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
-+}
-+
-+/**
-+ * bfq_reparent_active_entities - move to the root group all active
-+ *                                entities.
-+ * @bfqd: the device data structure with the root group.
-+ * @bfqg: the group to move from.
-+ * @st: the service tree with the entities.
-+ *
-+ * Needs queue_lock to be taken and reference to be valid over the call.
-+ */
-+static void bfq_reparent_active_entities(struct bfq_data *bfqd,
-+					 struct bfq_group *bfqg,
-+					 struct bfq_service_tree *st)
-+{
-+	struct rb_root *active = &st->active;
-+	struct bfq_entity *entity = NULL;
-+
-+	if (!RB_EMPTY_ROOT(&st->active))
-+		entity = bfq_entity_of(rb_first(active));
-+
-+	for (; entity ; entity = bfq_entity_of(rb_first(active)))
-+		bfq_reparent_leaf_entity(bfqd, entity);
-+
-+	if (bfqg->sched_data.in_service_entity)
-+		bfq_reparent_leaf_entity(bfqd,
-+			bfqg->sched_data.in_service_entity);
-+}
-+
-+/**
-+ * bfq_pd_offline - deactivate the entity associated with @pd,
-+ *		    and reparent its children entities.
-+ * @pd: descriptor of the policy going offline.
-+ *
-+ * blkio already grabs the queue_lock for us, so no need to use
-+ * RCU-based magic
-+ */
-+static void bfq_pd_offline(struct blkg_policy_data *pd)
-+{
-+	struct bfq_service_tree *st;
-+	struct bfq_group *bfqg;
-+	struct bfq_data *bfqd;
-+	struct bfq_entity *entity;
-+	int i;
-+
-+	BUG_ON(!pd);
-+	bfqg = pd_to_bfqg(pd);
-+	BUG_ON(!bfqg);
-+	bfqd = bfqg->bfqd;
-+	BUG_ON(bfqd && !bfqd->root_group);
-+
-+	entity = bfqg->my_entity;
-+
-+	if (!entity) /* root group */
-+		return;
-+
-+	/*
-+	 * Empty all service_trees belonging to this group before
-+	 * deactivating the group itself.
-+	 */
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
-+		BUG_ON(!bfqg->sched_data.service_tree);
-+		st = bfqg->sched_data.service_tree + i;
-+		/*
-+		 * The idle tree may still contain bfq_queues belonging
-+		 * to exited task because they never migrated to a different
-+		 * cgroup from the one being destroyed now.  No one else
-+		 * can access them so it's safe to act without any lock.
-+		 */
-+		bfq_flush_idle_tree(st);
-+
-+		/*
-+		 * It may happen that some queues are still active
-+		 * (busy) upon group destruction (if the corresponding
-+		 * processes have been forced to terminate). We move
-+		 * all the leaf entities corresponding to these queues
-+		 * to the root_group.
-+		 * Also, it may happen that the group has an entity
-+		 * in service, which is disconnected from the active
-+		 * tree: it must be moved, too.
-+		 * There is no need to put the sync queues, as the
-+		 * scheduler has taken no reference.
-+		 */
-+		bfq_reparent_active_entities(bfqd, bfqg, st);
-+		BUG_ON(!RB_EMPTY_ROOT(&st->active));
-+		BUG_ON(!RB_EMPTY_ROOT(&st->idle));
-+	}
-+	BUG_ON(bfqg->sched_data.next_in_service);
-+	BUG_ON(bfqg->sched_data.in_service_entity);
-+
-+	__bfq_deactivate_entity(entity, false);
-+	bfq_put_async_queues(bfqd, bfqg);
-+
-+	/*
-+	 * @blkg is going offline and will be ignored by
-+	 * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
-+	 * that they don't get lost.  If IOs complete after this point, the
-+	 * stats for them will be lost.  Oh well...
-+	 */
-+	bfqg_stats_xfer_dead(bfqg);
-+}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	struct blkcg_gq *blkg;
-+
-+	list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+		BUG_ON(!bfqg);
-+
-+		bfq_end_wr_async_queues(bfqd, bfqg);
-+	}
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static int bfq_io_show_weight(struct seq_file *sf, void *v)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	unsigned int val = 0;
-+
-+	if (bfqgd)
-+		val = bfqgd->weight;
-+
-+	seq_printf(sf, "%u\n", val);
-+
-+	return 0;
-+}
-+
-+static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
-+				    struct cftype *cftype,
-+				    u64 val)
-+{
-+	struct blkcg *blkcg = css_to_blkcg(css);
-+	struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
-+	struct blkcg_gq *blkg;
-+	int ret = -ERANGE;
-+
-+	if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
-+		return ret;
-+
-+	ret = 0;
-+	spin_lock_irq(&blkcg->lock);
-+	bfqgd->weight = (unsigned short)val;
-+	hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
-+		struct bfq_group *bfqg = blkg_to_bfqg(blkg);
-+
-+		if (!bfqg)
-+			continue;
-+		/*
-+		 * Setting the prio_changed flag of the entity
-+		 * to 1 with new_weight == weight would re-set
-+		 * the value of the weight to its ioprio mapping.
-+		 * Set the flag only if necessary.
-+		 */
-+		if ((unsigned short)val != bfqg->entity.new_weight) {
-+			bfqg->entity.new_weight = (unsigned short)val;
-+			/*
-+			 * Make sure that the above new value has been
-+			 * stored in bfqg->entity.new_weight before
-+			 * setting the prio_changed flag. In fact,
-+			 * this flag may be read asynchronously (in
-+			 * critical sections protected by a different
-+			 * lock than that held here), and finding this
-+			 * flag set may cause the execution of the code
-+			 * for updating parameters whose value may
-+			 * depend also on bfqg->entity.new_weight (in
-+			 * __bfq_entity_update_weight_prio).
-+			 * This barrier makes sure that the new value
-+			 * of bfqg->entity.new_weight is correctly
-+			 * seen in that code.
-+			 */
-+			smp_wmb();
-+			bfqg->entity.prio_changed = 1;
-+		}
-+	}
-+	spin_unlock_irq(&blkcg->lock);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
-+				 char *buf, size_t nbytes,
-+				 loff_t off)
-+{
-+	u64 weight;
-+	/* First unsigned long found in the file is used */
-+	int ret = kstrtoull(strim(buf), 0, &weight);
-+
-+	if (ret)
-+		return ret;
-+
-+	return bfq_io_set_weight_legacy(of_css(of), NULL, weight);
-+}
-+
-+static int bfqg_print_stat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
-+			  &blkcg_policy_bfq, seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
-+					  &blkcg_policy_bfq, off);
-+	return __blkg_prfill_u64(sf, pd, sum);
-+}
-+
-+static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
-+					struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
-+							   &blkcg_policy_bfq,
-+							   off);
-+	return __blkg_prfill_rwstat(sf, pd, &sum);
-+}
-+
-+static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, false);
-+	return 0;
-+}
-+
-+static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
-+			  seq_cft(sf)->private, true);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
-+			       int off)
-+{
-+	u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
-+	return 0;
-+}
-+
-+static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
-+					 struct blkg_policy_data *pd, int off)
-+{
-+	struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
-+					offsetof(struct blkcg_gq, stat_bytes));
-+	u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
-+		atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
-+
-+	return __blkg_prfill_u64(sf, pd, sum >> 9);
-+}
-+
-+static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
-+			  false);
-+	return 0;
-+}
-+
-+
-+static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
-+				      struct blkg_policy_data *pd, int off)
-+{
-+	struct bfq_group *bfqg = pd_to_bfqg(pd);
-+	u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples);
-+	u64 v = 0;
-+
-+	if (samples) {
-+		v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum);
-+		v = div64_u64(v, samples);
-+	}
-+	__blkg_prfill_u64(sf, pd, v);
-+	return 0;
-+}
-+
-+/* print avg_queue_size */
-+static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
-+{
-+	blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
-+			  bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
-+			  0, false);
-+	return 0;
-+}
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	int ret;
-+
-+	ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
-+	if (ret)
-+		return NULL;
-+
-+	return blkg_to_bfqg(bfqd->queue->root_blkg);
-+}
-+
-+static struct cftype bfq_blkcg_legacy_files[] = {
-+	{
-+		.name = "bfq.weight",
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write_u64 = bfq_io_set_weight_legacy,
-+	},
-+
-+	/* statistics, covers only the tasks in the bfqg */
-+	{
-+		.name = "bfq.time",
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.sectors",
-+		.seq_show = bfqg_print_stat_sectors,
-+	},
-+	{
-+		.name = "bfq.io_service_bytes",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes,
-+	},
-+	{
-+		.name = "bfq.io_serviced",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios,
-+	},
-+	{
-+		.name = "bfq.io_service_time",
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_wait_time",
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_merged",
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+	{
-+		.name = "bfq.io_queued",
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat,
-+	},
-+
-+	/* the same statictics which cover the bfqg and its descendants */
-+	{
-+		.name = "bfq.time_recursive",
-+		.private = offsetof(struct bfq_group, stats.time),
-+		.seq_show = bfqg_print_stat_recursive,
-+	},
-+	{
-+		.name = "bfq.sectors_recursive",
-+		.seq_show = bfqg_print_stat_sectors_recursive,
-+	},
-+	{
-+		.name = "bfq.io_service_bytes_recursive",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_bytes_recursive,
-+	},
-+	{
-+		.name = "bfq.io_serviced_recursive",
-+		.private = (unsigned long)&blkcg_policy_bfq,
-+		.seq_show = blkg_print_stat_ios_recursive,
-+	},
-+	{
-+		.name = "bfq.io_service_time_recursive",
-+		.private = offsetof(struct bfq_group, stats.service_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_wait_time_recursive",
-+		.private = offsetof(struct bfq_group, stats.wait_time),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_merged_recursive",
-+		.private = offsetof(struct bfq_group, stats.merged),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.io_queued_recursive",
-+		.private = offsetof(struct bfq_group, stats.queued),
-+		.seq_show = bfqg_print_rwstat_recursive,
-+	},
-+	{
-+		.name = "bfq.avg_queue_size",
-+		.seq_show = bfqg_print_avg_queue_size,
-+	},
-+	{
-+		.name = "bfq.group_wait_time",
-+		.private = offsetof(struct bfq_group, stats.group_wait_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.idle_time",
-+		.private = offsetof(struct bfq_group, stats.idle_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.empty_time",
-+		.private = offsetof(struct bfq_group, stats.empty_time),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{
-+		.name = "bfq.dequeue",
-+		.private = offsetof(struct bfq_group, stats.dequeue),
-+		.seq_show = bfqg_print_stat,
-+	},
-+	{ }	/* terminate */
-+};
-+
-+static struct cftype bfq_blkg_files[] = {
-+	{
-+		.name = "bfq.weight",
-+		.flags = CFTYPE_NOT_ON_ROOT,
-+		.seq_show = bfq_io_show_weight,
-+		.write = bfq_io_set_weight,
-+	},
-+	{} /* terminate */
-+};
-+
-+#else /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg,
-+			struct bfq_queue *bfqq, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void
-+bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
-+static inline void bfqg_stats_update_completion(struct bfq_group *bfqg,
-+			uint64_t start_time, uint64_t io_start_time,
-+			unsigned int op) { }
-+static inline void
-+bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
-+				     struct bfq_group *curr_bfqg) { }
-+static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { }
-+static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
-+static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
-+
-+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_group *bfqg) {}
-+
-+static void bfq_init_entity(struct bfq_entity *entity,
-+			    struct bfq_group *bfqg)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->weight = entity->new_weight;
-+	entity->orig_weight = entity->new_weight;
-+	if (bfqq) {
-+		bfqq->ioprio = bfqq->new_ioprio;
-+		bfqq->ioprio_class = bfqq->new_ioprio_class;
-+	}
-+	entity->sched_data = &bfqg->sched_data;
-+}
-+
-+static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
-+
-+static void bfq_end_wr_async(struct bfq_data *bfqd)
-+{
-+	bfq_end_wr_async_queues(bfqd, bfqd->root_group);
-+}
-+
-+static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
-+					    struct blkcg *blkcg)
-+{
-+	return bfqd->root_group;
-+}
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+static struct bfq_group *
-+bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
-+{
-+	struct bfq_group *bfqg;
-+	int i;
-+
-+	bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
-+	if (!bfqg)
-+		return NULL;
-+
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+
-+	return bfqg;
-+}
-+#endif
-diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
-new file mode 100644
-index 000000000000..fb7bb8f08b75
---- /dev/null
-+++ b/block/bfq-ioc.c
-@@ -0,0 +1,36 @@
-+/*
-+ * BFQ: I/O context handling.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
-+ */
-+
-+/**
-+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
-+ * @icq: the iocontext queue.
-+ */
-+static struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
-+{
-+	/* bic->icq is the first member, %NULL will convert to %NULL */
-+	return container_of(icq, struct bfq_io_cq, icq);
-+}
-+
-+/**
-+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
-+ * @bfqd: the lookup key.
-+ * @ioc: the io_context of the process doing I/O.
-+ *
-+ * Queue lock must be held.
-+ */
-+static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
-+					struct io_context *ioc)
-+{
-+	if (ioc)
-+		return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
-+	return NULL;
-+}
-diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
-new file mode 100644
-index 000000000000..6d1f54fb9c2b
---- /dev/null
-+++ b/block/bfq-iosched.c
-@@ -0,0 +1,5336 @@
-+/*
-+ * Budget Fair Queueing (BFQ) I/O scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ *
-+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
-+ * file.
-+ *
-+ * BFQ is a proportional-share I/O scheduler, with some extra
-+ * low-latency capabilities. BFQ also supports full hierarchical
-+ * scheduling through cgroups. Next paragraphs provide an introduction
-+ * on BFQ inner workings. Details on BFQ benefits and usage can be
-+ * found in Documentation/block/bfq-iosched.txt.
-+ *
-+ * BFQ is a proportional-share storage-I/O scheduling algorithm based
-+ * on the slice-by-slice service scheme of CFQ. But BFQ assigns
-+ * budgets, measured in number of sectors, to processes instead of
-+ * time slices. The device is not granted to the in-service process
-+ * for a given time slice, but until it has exhausted its assigned
-+ * budget. This change from the time to the service domain enables BFQ
-+ * to distribute the device throughput among processes as desired,
-+ * without any distortion due to throughput fluctuations, or to device
-+ * internal queueing. BFQ uses an ad hoc internal scheduler, called
-+ * B-WF2Q+, to schedule processes according to their budgets. More
-+ * precisely, BFQ schedules queues associated with processes. Thanks to
-+ * the accurate policy of B-WF2Q+, BFQ can afford to assign high
-+ * budgets to I/O-bound processes issuing sequential requests (to
-+ * boost the throughput), and yet guarantee a low latency to
-+ * interactive and soft real-time applications.
-+ *
-+ * BFQ is described in [1], where also a reference to the initial, more
-+ * theoretical paper on BFQ can be found. The interested reader can find
-+ * in the latter paper full details on the main algorithm, as well as
-+ * formulas of the guarantees and formal proofs of all the properties.
-+ * With respect to the version of BFQ presented in these papers, this
-+ * implementation adds a few more heuristics, such as the one that
-+ * guarantees a low latency to soft real-time applications, and a
-+ * hierarchical extension based on H-WF2Q+.
-+ *
-+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
-+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
-+ * complexity derives from the one introduced with EEVDF in [3].
-+ *
-+ * [1] P. Valente, A. Avanzini, "Evolution of the BFQ Storage I/O
-+ *   Scheduler", Proceedings of the First Workshop on Mobile System
-+ *   Technologies (MST-2015), May 2015.
-+ *   http://algogroup.unimore.it/people/paolo/disk_sched/mst-2015.pdf
-+ *
-+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
-+ *
-+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
-+ *     Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
-+ *     Oct 1997.
-+ *
-+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
-+ *
-+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
-+ *     First: A Flexible and Accurate Mechanism for Proportional Share
-+ *     Resource Allocation,'' technical report.
-+ *
-+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
-+ */
-+#include <linux/module.h>
-+#include <linux/slab.h>
-+#include <linux/blkdev.h>
-+#include <linux/cgroup.h>
-+#include <linux/elevator.h>
-+#include <linux/jiffies.h>
-+#include <linux/rbtree.h>
-+#include <linux/ioprio.h>
-+#include "blk.h"
-+#include "bfq.h"
-+
-+/* Expiration time of sync (0) and async (1) requests, in ns. */
-+static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-+
-+/* Maximum backwards seek, in KiB. */
-+static const int bfq_back_max = (16 * 1024);
-+
-+/* Penalty of a backwards seek, in number of sectors. */
-+static const int bfq_back_penalty = 2;
-+
-+/* Idling period duration, in ns. */
-+static u32 bfq_slice_idle = (NSEC_PER_SEC / 125);
-+
-+/* Minimum number of assigned budgets for which stats are safe to compute. */
-+static const int bfq_stats_min_budgets = 194;
-+
-+/* Default maximum budget values, in sectors and number of requests. */
-+static const int bfq_default_max_budget = (16 * 1024);
-+
-+/*
-+ * Async to sync throughput distribution is controlled as follows:
-+ * when an async request is served, the entity is charged the number
-+ * of sectors of the request, multiplied by the factor below
-+ */
-+static const int bfq_async_charge_factor = 10;
-+
-+/* Default timeout values, in jiffies, approximating CFQ defaults. */
-+static const int bfq_timeout = (HZ / 8);
-+
-+static struct kmem_cache *bfq_pool;
-+
-+/* Below this threshold (in ns), we consider thinktime immediate. */
-+#define BFQ_MIN_TT		(2 * NSEC_PER_MSEC)
-+
-+/* hw_tag detection: parallel requests threshold and min samples needed. */
-+#define BFQ_HW_QUEUE_THRESHOLD	4
-+#define BFQ_HW_QUEUE_SAMPLES	32
-+
-+#define BFQQ_SEEK_THR		(sector_t)(8 * 100)
-+#define BFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-+#define BFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-+#define BFQQ_SEEKY(bfqq)	(hweight32(bfqq->seek_history) > 32/8)
-+
-+/* Min number of samples required to perform peak-rate update */
-+#define BFQ_RATE_MIN_SAMPLES	32
-+/* Min observation time interval required to perform a peak-rate update (ns) */
-+#define BFQ_RATE_MIN_INTERVAL	(300*NSEC_PER_MSEC)
-+/* Target observation time interval for a peak-rate update (ns) */
-+#define BFQ_RATE_REF_INTERVAL	NSEC_PER_SEC
-+
-+/* Shift used for peak rate fixed precision calculations. */
-+#define BFQ_RATE_SHIFT		16
-+
-+/*
-+ * By default, BFQ computes the duration of the weight raising for
-+ * interactive applications automatically, using the following formula:
-+ * duration = (R / r) * T, where r is the peak rate of the device, and
-+ * R and T are two reference parameters.
-+ * In particular, R is the peak rate of the reference device (see below),
-+ * and T is a reference time: given the systems that are likely to be
-+ * installed on the reference device according to its speed class, T is
-+ * about the maximum time needed, under BFQ and while reading two files in
-+ * parallel, to load typical large applications on these systems.
-+ * In practice, the slower/faster the device at hand is, the more/less it
-+ * takes to load applications with respect to the reference device.
-+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
-+ * applications.
-+ *
-+ * BFQ uses four different reference pairs (R, T), depending on:
-+ * . whether the device is rotational or non-rotational;
-+ * . whether the device is slow, such as old or portable HDDs, as well as
-+ *   SD cards, or fast, such as newer HDDs and SSDs.
-+ *
-+ * The device's speed class is dynamically (re)detected in
-+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
-+ *
-+ * In the following definitions, R_slow[0]/R_fast[0] and
-+ * T_slow[0]/T_fast[0] are the reference values for a slow/fast
-+ * rotational device, whereas R_slow[1]/R_fast[1] and
-+ * T_slow[1]/T_fast[1] are the reference values for a slow/fast
-+ * non-rotational device. Finally, device_speed_thresh are the
-+ * thresholds used to switch between speed classes. The reference
-+ * rates are not the actual peak rates of the devices used as a
-+ * reference, but slightly lower values. The reason for using these
-+ * slightly lower values is that the peak-rate estimator tends to
-+ * yield slightly lower values than the actual peak rate (it can yield
-+ * the actual peak rate only if there is only one process doing I/O,
-+ * and the process does sequential I/O).
-+ *
-+ * Both the reference peak rates and the thresholds are measured in
-+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
-+ */
-+static int R_slow[2] = {1000, 10700};
-+static int R_fast[2] = {14000, 33000};
-+/*
-+ * To improve readability, a conversion function is used to initialize the
-+ * following arrays, which entails that they can be initialized only in a
-+ * function.
-+ */
-+static int T_slow[2];
-+static int T_fast[2];
-+static int device_speed_thresh[2];
-+
-+#define BFQ_SERVICE_TREE_INIT	((struct bfq_service_tree)		\
-+				{ RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
-+
-+#define RQ_BIC(rq)		((struct bfq_io_cq *) (rq)->elv.priv[0])
-+#define RQ_BFQQ(rq)		((rq)->elv.priv[1])
-+
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd);
-+
-+#include "bfq-ioc.c"
-+#include "bfq-sched.c"
-+#include "bfq-cgroup.c"
-+
-+#define bfq_class_idle(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-+#define bfq_class_rt(bfqq)	((bfqq)->ioprio_class == IOPRIO_CLASS_RT)
-+
-+#define bfq_sample_valid(samples)	((samples) > 80)
-+
-+/*
-+ * Scheduler run of queue, if there are requests pending and no one in the
-+ * driver that will restart queueing.
-+ */
-+static void bfq_schedule_dispatch(struct bfq_data *bfqd)
-+{
-+	if (bfqd->queued != 0) {
-+		bfq_log(bfqd, "schedule dispatch");
-+		kblockd_schedule_work(&bfqd->unplug_work);
-+	}
-+}
-+
-+/*
-+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
-+ * We choose the request that is closesr to the head right now.  Distance
-+ * behind the head is penalized and only allowed to a certain extent.
-+ */
-+static struct request *bfq_choose_req(struct bfq_data *bfqd,
-+				      struct request *rq1,
-+				      struct request *rq2,
-+				      sector_t last)
-+{
-+	sector_t s1, s2, d1 = 0, d2 = 0;
-+	unsigned long back_max;
-+#define BFQ_RQ1_WRAP	0x01 /* request 1 wraps */
-+#define BFQ_RQ2_WRAP	0x02 /* request 2 wraps */
-+	unsigned int wrap = 0; /* bit mask: requests behind the disk head? */
-+
-+	if (!rq1 || rq1 == rq2)
-+		return rq2;
-+	if (!rq2)
-+		return rq1;
-+
-+	if (rq_is_sync(rq1) && !rq_is_sync(rq2))
-+		return rq1;
-+	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
-+		return rq2;
-+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
-+		return rq1;
-+	else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
-+		return rq2;
-+
-+	s1 = blk_rq_pos(rq1);
-+	s2 = blk_rq_pos(rq2);
-+
-+	/*
-+	 * By definition, 1KiB is 2 sectors.
-+	 */
-+	back_max = bfqd->bfq_back_max * 2;
-+
-+	/*
-+	 * Strict one way elevator _except_ in the case where we allow
-+	 * short backward seeks which are biased as twice the cost of a
-+	 * similar forward seek.
-+	 */
-+	if (s1 >= last)
-+		d1 = s1 - last;
-+	else if (s1 + back_max >= last)
-+		d1 = (last - s1) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ1_WRAP;
-+
-+	if (s2 >= last)
-+		d2 = s2 - last;
-+	else if (s2 + back_max >= last)
-+		d2 = (last - s2) * bfqd->bfq_back_penalty;
-+	else
-+		wrap |= BFQ_RQ2_WRAP;
-+
-+	/* Found required data */
-+
-+	/*
-+	 * By doing switch() on the bit mask "wrap" we avoid having to
-+	 * check two variables for all permutations: --> faster!
-+	 */
-+	switch (wrap) {
-+	case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
-+		if (d1 < d2)
-+			return rq1;
-+		else if (d2 < d1)
-+			return rq2;
-+
-+		if (s1 >= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+
-+	case BFQ_RQ2_WRAP:
-+		return rq1;
-+	case BFQ_RQ1_WRAP:
-+		return rq2;
-+	case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
-+	default:
-+		/*
-+		 * Since both rqs are wrapped,
-+		 * start with the one that's further behind head
-+		 * (--> only *one* back seek required),
-+		 * since back seek takes more time than forward.
-+		 */
-+		if (s1 <= s2)
-+			return rq1;
-+		else
-+			return rq2;
-+	}
-+}
-+
-+static struct bfq_queue *
-+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
-+		     sector_t sector, struct rb_node **ret_parent,
-+		     struct rb_node ***rb_link)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *bfqq = NULL;
-+
-+	parent = NULL;
-+	p = &root->rb_node;
-+	while (*p) {
-+		struct rb_node **n;
-+
-+		parent = *p;
-+		bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+
-+		/*
-+		 * Sort strictly based on sector. Smallest to the left,
-+		 * largest to the right.
-+		 */
-+		if (sector > blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_right;
-+		else if (sector < blk_rq_pos(bfqq->next_rq))
-+			n = &(*p)->rb_left;
-+		else
-+			break;
-+		p = n;
-+		bfqq = NULL;
-+	}
-+
-+	*ret_parent = parent;
-+	if (rb_link)
-+		*rb_link = p;
-+
-+	bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
-+		(unsigned long long) sector,
-+		bfqq ? bfqq->pid : 0);
-+
-+	return bfqq;
-+}
-+
-+static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct rb_node **p, *parent;
-+	struct bfq_queue *__bfqq;
-+
-+	if (bfqq->pos_root) {
-+		rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+		bfqq->pos_root = NULL;
-+	}
-+
-+	if (bfq_class_idle(bfqq))
-+		return;
-+	if (!bfqq->next_rq)
-+		return;
-+
-+	bfqq->pos_root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
-+			blk_rq_pos(bfqq->next_rq), &parent, &p);
-+	if (!__bfqq) {
-+		rb_link_node(&bfqq->pos_node, parent, p);
-+		rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
-+	} else
-+		bfqq->pos_root = NULL;
-+}
-+
-+/*
-+ * Tell whether there are active queues or groups with differentiated weights.
-+ */
-+static bool bfq_differentiated_weights(struct bfq_data *bfqd)
-+{
-+	/*
-+	 * For weights to differ, at least one of the trees must contain
-+	 * at least two nodes.
-+	 */
-+	return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
-+		(bfqd->queue_weights_tree.rb_node->rb_left ||
-+		 bfqd->queue_weights_tree.rb_node->rb_right)
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	       ) ||
-+	       (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
-+		(bfqd->group_weights_tree.rb_node->rb_left ||
-+		 bfqd->group_weights_tree.rb_node->rb_right)
-+#endif
-+	       );
-+}
-+
-+/*
-+ * The following function returns true if every queue must receive the
-+ * same share of the throughput (this condition is used when deciding
-+ * whether idling may be disabled, see the comments in the function
-+ * bfq_bfqq_may_idle()).
-+ *
-+ * Such a scenario occurs when:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups at the same level in the groups tree have the same
-+ *    weight,
-+ * 3) all active groups at the same level in the groups tree have the same
-+ *    number of children.
-+ *
-+ * Unfortunately, keeping the necessary state for evaluating exactly the
-+ * above symmetry conditions would be quite complex and time-consuming.
-+ * Therefore this function evaluates, instead, the following stronger
-+ * sub-conditions, for which it is much easier to maintain the needed
-+ * state:
-+ * 1) all active queues have the same weight,
-+ * 2) all active groups have the same weight,
-+ * 3) all active groups have at most one active child each.
-+ * In particular, the last two conditions are always true if hierarchical
-+ * support and the cgroups interface are not enabled, thus no state needs
-+ * to be maintained in this case.
-+ */
-+static bool bfq_symmetric_scenario(struct bfq_data *bfqd)
-+{
-+	return !bfq_differentiated_weights(bfqd);
-+}
-+
-+/*
-+ * If the weight-counter tree passed as input contains no counter for
-+ * the weight of the input entity, then add that counter; otherwise just
-+ * increment the existing counter.
-+ *
-+ * Note that weight-counter trees contain few nodes in mostly symmetric
-+ * scenarios. For example, if all queues have the same weight, then the
-+ * weight-counter tree for the queues may contain at most one node.
-+ * This holds even if low_latency is on, because weight-raised queues
-+ * are not inserted in the tree.
-+ * In most scenarios, the rate at which nodes are created/destroyed
-+ * should be low too.
-+ */
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_entity *entity,
-+				 struct rb_root *root)
-+{
-+	struct rb_node **new = &(root->rb_node), *parent = NULL;
-+
-+	/*
-+	 * Do not insert if the entity is already associated with a
-+	 * counter, which happens if:
-+	 *   1) the entity is associated with a queue,
-+	 *   2) a request arrival has caused the queue to become both
-+	 *      non-weight-raised, and hence change its weight, and
-+	 *      backlogged; in this respect, each of the two events
-+	 *      causes an invocation of this function,
-+	 *   3) this is the invocation of this function caused by the
-+	 *      second event. This second invocation is actually useless,
-+	 *      and we handle this fact by exiting immediately. More
-+	 *      efficient or clearer solutions might possibly be adopted.
-+	 */
-+	if (entity->weight_counter)
-+		return;
-+
-+	while (*new) {
-+		struct bfq_weight_counter *__counter = container_of(*new,
-+						struct bfq_weight_counter,
-+						weights_node);
-+		parent = *new;
-+
-+		if (entity->weight == __counter->weight) {
-+			entity->weight_counter = __counter;
-+			goto inc_counter;
-+		}
-+		if (entity->weight < __counter->weight)
-+			new = &((*new)->rb_left);
-+		else
-+			new = &((*new)->rb_right);
-+	}
-+
-+	entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
-+					 GFP_ATOMIC);
-+
-+	/*
-+	 * In the unlucky event of an allocation failure, we just
-+	 * exit. This will cause the weight of entity to not be
-+	 * considered in bfq_differentiated_weights, which, in its
-+	 * turn, causes the scenario to be deemed wrongly symmetric in
-+	 * case entity's weight would have been the only weight making
-+	 * the scenario asymmetric. On the bright side, no unbalance
-+	 * will however occur when entity becomes inactive again (the
-+	 * invocation of this function is triggered by an activation
-+	 * of entity). In fact, bfq_weights_tree_remove does nothing
-+	 * if !entity->weight_counter.
-+	 */
-+	if (unlikely(!entity->weight_counter))
-+		return;
-+
-+	entity->weight_counter->weight = entity->weight;
-+	rb_link_node(&entity->weight_counter->weights_node, parent, new);
-+	rb_insert_color(&entity->weight_counter->weights_node, root);
-+
-+inc_counter:
-+	entity->weight_counter->num_active++;
-+}
-+
-+/*
-+ * Decrement the weight counter associated with the entity, and, if the
-+ * counter reaches 0, remove the counter from the tree.
-+ * See the comments to the function bfq_weights_tree_add() for considerations
-+ * about overhead.
-+ */
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_entity *entity,
-+				    struct rb_root *root)
-+{
-+	if (!entity->weight_counter)
-+		return;
-+
-+	BUG_ON(RB_EMPTY_ROOT(root));
-+	BUG_ON(entity->weight_counter->weight != entity->weight);
-+
-+	BUG_ON(!entity->weight_counter->num_active);
-+	entity->weight_counter->num_active--;
-+	if (entity->weight_counter->num_active > 0)
-+		goto reset_entity_pointer;
-+
-+	rb_erase(&entity->weight_counter->weights_node, root);
-+	kfree(entity->weight_counter);
-+
-+reset_entity_pointer:
-+	entity->weight_counter = NULL;
-+}
-+
-+/*
-+ * Return expired entry, or NULL to just start from scratch in rbtree.
-+ */
-+static struct request *bfq_check_fifo(struct bfq_queue *bfqq,
-+				      struct request *last)
-+{
-+	struct request *rq;
-+
-+	if (bfq_bfqq_fifo_expire(bfqq))
-+		return NULL;
-+
-+	bfq_mark_bfqq_fifo_expire(bfqq);
-+
-+	rq = rq_entry_fifo(bfqq->fifo.next);
-+
-+	if (rq == last || ktime_get_ns() < rq->fifo_time)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "check_fifo: returned %p", rq);
-+	BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
-+	return rq;
-+}
-+
-+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq,
-+					struct request *last)
-+{
-+	struct rb_node *rbnext = rb_next(&last->rb_node);
-+	struct rb_node *rbprev = rb_prev(&last->rb_node);
-+	struct request *next, *prev = NULL;
-+
-+	BUG_ON(list_empty(&bfqq->fifo));
-+
-+	/* Follow expired path, else get first next available. */
-+	next = bfq_check_fifo(bfqq, last);
-+	if (next) {
-+		BUG_ON(next == last);
-+		return next;
-+	}
-+
-+	BUG_ON(RB_EMPTY_NODE(&last->rb_node));
-+
-+	if (rbprev)
-+		prev = rb_entry_rq(rbprev);
-+
-+	if (rbnext)
-+		next = rb_entry_rq(rbnext);
-+	else {
-+		rbnext = rb_first(&bfqq->sort_list);
-+		if (rbnext && rbnext != &last->rb_node)
-+			next = rb_entry_rq(rbnext);
-+	}
-+
-+	return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
-+}
-+
-+/* see the definition of bfq_async_charge_factor for details */
-+static unsigned long bfq_serv_to_charge(struct request *rq,
-+					struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_sync(bfqq) || bfqq->wr_coeff > 1)
-+		return blk_rq_sectors(rq);
-+
-+	/*
-+	 * If there are no weight-raised queues, then amplify service
-+	 * by just the async charge factor; otherwise amplify service
-+	 * by twice the async charge factor, to further reduce latency
-+	 * for weight-raised queues.
-+	 */
-+	if (bfqq->bfqd->wr_busy_queues == 0)
-+		return blk_rq_sectors(rq) * bfq_async_charge_factor;
-+
-+	return blk_rq_sectors(rq) * 2 * bfq_async_charge_factor;
-+}
-+
-+/**
-+ * bfq_updated_next_req - update the queue after a new next_rq selection.
-+ * @bfqd: the device data the queue belongs to.
-+ * @bfqq: the queue to update.
-+ *
-+ * If the first request of a queue changes we make sure that the queue
-+ * has enough budget to serve at least its first request (if the
-+ * request has grown).  We do this because if the queue has not enough
-+ * budget for its first request, it has to go through two dispatch
-+ * rounds to actually get it dispatched.
-+ */
-+static void bfq_updated_next_req(struct bfq_data *bfqd,
-+				 struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct request *next_rq = bfqq->next_rq;
-+	unsigned long new_budget;
-+
-+	if (!next_rq)
-+		return;
-+
-+	if (bfqq == bfqd->in_service_queue)
-+		/*
-+		 * In order not to break guarantees, budgets cannot be
-+		 * changed after an entity has been selected.
-+		 */
-+		return;
-+
-+	BUG_ON(entity->tree != &st->active);
-+	BUG_ON(entity == entity->sched_data->in_service_entity);
-+
-+	new_budget = max_t(unsigned long, bfqq->max_budget,
-+			   bfq_serv_to_charge(next_rq, bfqq));
-+	if (entity->budget != new_budget) {
-+		entity->budget = new_budget;
-+		bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
-+					 new_budget);
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+	}
-+}
-+
-+static unsigned int bfq_wr_duration(struct bfq_data *bfqd)
-+{
-+	u64 dur;
-+
-+	if (bfqd->bfq_wr_max_time > 0)
-+		return bfqd->bfq_wr_max_time;
-+
-+	dur = bfqd->RT_prod;
-+	do_div(dur, bfqd->peak_rate);
-+
-+	/*
-+	 * Limit duration between 3 and 13 seconds. Tests show that
-+	 * higher values than 13 seconds often yield the opposite of
-+	 * the desired result, i.e., worsen responsiveness by letting
-+	 * non-interactive and non-soft-real-time applications
-+	 * preserve weight raising for a too long time interval.
-+	 *
-+	 * On the other end, lower values than 3 seconds make it
-+	 * difficult for most interactive tasks to complete their jobs
-+	 * before weight-raising finishes.
-+	 */
-+	if (dur > msecs_to_jiffies(13000))
-+		dur = msecs_to_jiffies(13000);
-+	else if (dur < msecs_to_jiffies(3000))
-+		dur = msecs_to_jiffies(3000);
-+
-+	return dur;
-+}
-+
-+static void
-+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
-+{
-+	if (bic->saved_idle_window)
-+		bfq_mark_bfqq_idle_window(bfqq);
-+	else
-+		bfq_clear_bfqq_idle_window(bfqq);
-+
-+	if (bic->saved_IO_bound)
-+		bfq_mark_bfqq_IO_bound(bfqq);
-+	else
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	bfqq->wr_coeff = bic->saved_wr_coeff;
-+	bfqq->wr_start_at_switch_to_srt = bic->saved_wr_start_at_switch_to_srt;
-+	BUG_ON(time_is_after_jiffies(bfqq->wr_start_at_switch_to_srt));
-+	bfqq->last_wr_start_finish = bic->saved_last_wr_start_finish;
-+	bfqq->wr_cur_max_time = bic->saved_wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+	if (bfqq->wr_coeff > 1 && (bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_before_jiffies(bfqq->last_wr_start_finish +
-+				   bfqq->wr_cur_max_time))) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "resume state: switching off wr (%lu + %lu < %lu)",
-+			     bfqq->last_wr_start_finish, bfqq->wr_cur_max_time,
-+			     jiffies);
-+
-+		bfqq->wr_coeff = 1;
-+	}
-+	/* make sure weight will be updated, however we got here */
-+	bfqq->entity.prio_changed = 1;
-+}
-+
-+static int bfqq_process_refs(struct bfq_queue *bfqq)
-+{
-+	int process_refs, io_refs;
-+
-+	lockdep_assert_held(bfqq->bfqd->queue->queue_lock);
-+
-+	io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
-+	process_refs = bfqq->ref - io_refs - bfqq->entity.on_st;
-+	BUG_ON(process_refs < 0);
-+	return process_refs;
-+}
-+
-+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
-+static void bfq_reset_burst_list(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *item;
-+	struct hlist_node *n;
-+
-+	hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node)
-+		hlist_del_init(&item->burst_list_node);
-+	hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+	bfqd->burst_size = 1;
-+	bfqd->burst_parent_entity = bfqq->entity.parent;
-+}
-+
-+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
-+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/* Increment burst size to take into account also bfqq */
-+	bfqd->burst_size++;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_to_burst %d", bfqd->burst_size);
-+
-+	BUG_ON(bfqd->burst_size > bfqd->bfq_large_burst_thresh);
-+
-+	if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
-+		struct bfq_queue *pos, *bfqq_item;
-+		struct hlist_node *n;
-+
-+		/*
-+		 * Enough queues have been activated shortly after each
-+		 * other to consider this burst as large.
-+		 */
-+		bfqd->large_burst = true;
-+		bfq_log_bfqq(bfqd, bfqq, "add_to_burst: large burst started");
-+
-+		/*
-+		 * We can now mark all queues in the burst list as
-+		 * belonging to a large burst.
-+		 */
-+		hlist_for_each_entry(bfqq_item, &bfqd->burst_list,
-+				     burst_list_node) {
-+			bfq_mark_bfqq_in_large_burst(bfqq_item);
-+			bfq_log_bfqq(bfqd, bfqq_item, "marked in large burst");
-+		}
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		bfq_log_bfqq(bfqd, bfqq, "marked in large burst");
-+
-+		/*
-+		 * From now on, and until the current burst finishes, any
-+		 * new queue being activated shortly after the last queue
-+		 * was inserted in the burst can be immediately marked as
-+		 * belonging to a large burst. So the burst list is not
-+		 * needed any more. Remove it.
-+		 */
-+		hlist_for_each_entry_safe(pos, n, &bfqd->burst_list,
-+					  burst_list_node)
-+			hlist_del_init(&pos->burst_list_node);
-+	} else /*
-+		* Burst not yet large: add bfqq to the burst list. Do
-+		* not increment the ref counter for bfqq, because bfqq
-+		* is removed from the burst list before freeing bfqq
-+		* in put_queue.
-+		*/
-+		hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
-+}
-+
-+/*
-+ * If many queues belonging to the same group happen to be created
-+ * shortly after each other, then the processes associated with these
-+ * queues have typically a common goal. In particular, bursts of queue
-+ * creations are usually caused by services or applications that spawn
-+ * many parallel threads/processes. Examples are systemd during boot,
-+ * or git grep. To help these processes get their job done as soon as
-+ * possible, it is usually better to not grant either weight-raising
-+ * or device idling to their queues.
-+ *
-+ * In this comment we describe, firstly, the reasons why this fact
-+ * holds, and, secondly, the next function, which implements the main
-+ * steps needed to properly mark these queues so that they can then be
-+ * treated in a different way.
-+ *
-+ * The above services or applications benefit mostly from a high
-+ * throughput: the quicker the requests of the activated queues are
-+ * cumulatively served, the sooner the target job of these queues gets
-+ * completed. As a consequence, weight-raising any of these queues,
-+ * which also implies idling the device for it, is almost always
-+ * counterproductive. In most cases it just lowers throughput.
-+ *
-+ * On the other hand, a burst of queue creations may be caused also by
-+ * the start of an application that does not consist of a lot of
-+ * parallel I/O-bound threads. In fact, with a complex application,
-+ * several short processes may need to be executed to start-up the
-+ * application. In this respect, to start an application as quickly as
-+ * possible, the best thing to do is in any case to privilege the I/O
-+ * related to the application with respect to all other
-+ * I/O. Therefore, the best strategy to start as quickly as possible
-+ * an application that causes a burst of queue creations is to
-+ * weight-raise all the queues created during the burst. This is the
-+ * exact opposite of the best strategy for the other type of bursts.
-+ *
-+ * In the end, to take the best action for each of the two cases, the
-+ * two types of bursts need to be distinguished. Fortunately, this
-+ * seems relatively easy, by looking at the sizes of the bursts. In
-+ * particular, we found a threshold such that only bursts with a
-+ * larger size than that threshold are apparently caused by
-+ * services or commands such as systemd or git grep. For brevity,
-+ * hereafter we call just 'large' these bursts. BFQ *does not*
-+ * weight-raise queues whose creation occurs in a large burst. In
-+ * addition, for each of these queues BFQ performs or does not perform
-+ * idling depending on which choice boosts the throughput more. The
-+ * exact choice depends on the device and request pattern at
-+ * hand.
-+ *
-+ * Unfortunately, false positives may occur while an interactive task
-+ * is starting (e.g., an application is being started). The
-+ * consequence is that the queues associated with the task do not
-+ * enjoy weight raising as expected. Fortunately these false positives
-+ * are very rare. They typically occur if some service happens to
-+ * start doing I/O exactly when the interactive task starts.
-+ *
-+ * Turning back to the next function, it implements all the steps
-+ * needed to detect the occurrence of a large burst and to properly
-+ * mark all the queues belonging to it (so that they can then be
-+ * treated in a different way). This goal is achieved by maintaining a
-+ * "burst list" that holds, temporarily, the queues that belong to the
-+ * burst in progress. The list is then used to mark these queues as
-+ * belonging to a large burst if the burst does become large. The main
-+ * steps are the following.
-+ *
-+ * . when the very first queue is created, the queue is inserted into the
-+ *   list (as it could be the first queue in a possible burst)
-+ *
-+ * . if the current burst has not yet become large, and a queue Q that does
-+ *   not yet belong to the burst is activated shortly after the last time
-+ *   at which a new queue entered the burst list, then the function appends
-+ *   Q to the burst list
-+ *
-+ * . if, as a consequence of the previous step, the burst size reaches
-+ *   the large-burst threshold, then
-+ *
-+ *     . all the queues in the burst list are marked as belonging to a
-+ *       large burst
-+ *
-+ *     . the burst list is deleted; in fact, the burst list already served
-+ *       its purpose (keeping temporarily track of the queues in a burst,
-+ *       so as to be able to mark them as belonging to a large burst in the
-+ *       previous sub-step), and now is not needed any more
-+ *
-+ *     . the device enters a large-burst mode
-+ *
-+ * . if a queue Q that does not belong to the burst is created while
-+ *   the device is in large-burst mode and shortly after the last time
-+ *   at which a queue either entered the burst list or was marked as
-+ *   belonging to the current large burst, then Q is immediately marked
-+ *   as belonging to a large burst.
-+ *
-+ * . if a queue Q that does not belong to the burst is created a while
-+ *   later, i.e., not shortly after, than the last time at which a queue
-+ *   either entered the burst list or was marked as belonging to the
-+ *   current large burst, then the current burst is deemed as finished and:
-+ *
-+ *        . the large-burst mode is reset if set
-+ *
-+ *        . the burst list is emptied
-+ *
-+ *        . Q is inserted in the burst list, as Q may be the first queue
-+ *          in a possible new burst (then the burst list contains just Q
-+ *          after this step).
-+ */
-+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq is already in the burst list or is part of a large
-+	 * burst, or finally has just been split, then there is
-+	 * nothing else to do.
-+	 */
-+	if (!hlist_unhashed(&bfqq->burst_list_node) ||
-+	    bfq_bfqq_in_large_burst(bfqq) ||
-+	    time_is_after_eq_jiffies(bfqq->split_time +
-+				     msecs_to_jiffies(10)))
-+		return;
-+
-+	/*
-+	 * If bfqq's creation happens late enough, or bfqq belongs to
-+	 * a different group than the burst group, then the current
-+	 * burst is finished, and related data structures must be
-+	 * reset.
-+	 *
-+	 * In this respect, consider the special case where bfqq is
-+	 * the very first queue created after BFQ is selected for this
-+	 * device. In this case, last_ins_in_burst and
-+	 * burst_parent_entity are not yet significant when we get
-+	 * here. But it is easy to verify that, whether or not the
-+	 * following condition is true, bfqq will end up being
-+	 * inserted into the burst list. In particular the list will
-+	 * happen to contain only bfqq. And this is exactly what has
-+	 * to happen, as bfqq may be the first queue of the first
-+	 * burst.
-+	 */
-+	if (time_is_before_jiffies(bfqd->last_ins_in_burst +
-+	    bfqd->bfq_burst_interval) ||
-+	    bfqq->entity.parent != bfqd->burst_parent_entity) {
-+		bfqd->large_burst = false;
-+		bfq_reset_burst_list(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"handle_burst: late activation or different group");
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then bfqq is being activated shortly after the
-+	 * last queue. So, if the current burst is also large, we can mark
-+	 * bfqq as belonging to this large burst immediately.
-+	 */
-+	if (bfqd->large_burst) {
-+		bfq_log_bfqq(bfqd, bfqq, "handle_burst: marked in burst");
-+		bfq_mark_bfqq_in_large_burst(bfqq);
-+		goto end;
-+	}
-+
-+	/*
-+	 * If we get here, then a large-burst state has not yet been
-+	 * reached, but bfqq is being activated shortly after the last
-+	 * queue. Then we add bfqq to the burst.
-+	 */
-+	bfq_add_to_burst(bfqd, bfqq);
-+end:
-+	/*
-+	 * At this point, bfqq either has been added to the current
-+	 * burst or has caused the current burst to terminate and a
-+	 * possible new burst to start. In particular, in the second
-+	 * case, bfqq has become the first queue in the possible new
-+	 * burst.  In both cases last_ins_in_burst needs to be moved
-+	 * forward.
-+	 */
-+	bfqd->last_ins_in_burst = jiffies;
-+
-+}
-+
-+static int bfq_bfqq_budget_left(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	return entity->budget - entity->service;
-+}
-+
-+/*
-+ * If enough samples have been computed, return the current max budget
-+ * stored in bfqd, which is dynamically updated according to the
-+ * estimated disk peak rate; otherwise return the default max budget
-+ */
-+static int bfq_max_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget;
-+	else
-+		return bfqd->bfq_max_budget;
-+}
-+
-+/*
-+ * Return min budget, which is a fraction of the current or default
-+ * max budget (trying with 1/32)
-+ */
-+static int bfq_min_budget(struct bfq_data *bfqd)
-+{
-+	if (bfqd->budgets_assigned < bfq_stats_min_budgets)
-+		return bfq_default_max_budget / 32;
-+	else
-+		return bfqd->bfq_max_budget / 32;
-+}
-+
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason);
-+
-+/*
-+ * The next function, invoked after the input queue bfqq switches from
-+ * idle to busy, updates the budget of bfqq. The function also tells
-+ * whether the in-service queue should be expired, by returning
-+ * true. The purpose of expiring the in-service queue is to give bfqq
-+ * the chance to possibly preempt the in-service queue, and the reason
-+ * for preempting the in-service queue is to achieve one of the two
-+ * goals below.
-+ *
-+ * 1. Guarantee to bfqq its reserved bandwidth even if bfqq has
-+ * expired because it has remained idle. In particular, bfqq may have
-+ * expired for one of the following two reasons:
-+ *
-+ * - BFQ_BFQQ_NO_MORE_REQUEST bfqq did not enjoy any device idling and
-+ *   did not make it to issue a new request before its last request
-+ *   was served;
-+ *
-+ * - BFQ_BFQQ_TOO_IDLE bfqq did enjoy device idling, but did not issue
-+ *   a new request before the expiration of the idling-time.
-+ *
-+ * Even if bfqq has expired for one of the above reasons, the process
-+ * associated with the queue may be however issuing requests greedily,
-+ * and thus be sensitive to the bandwidth it receives (bfqq may have
-+ * remained idle for other reasons: CPU high load, bfqq not enjoying
-+ * idling, I/O throttling somewhere in the path from the process to
-+ * the I/O scheduler, ...). But if, after every expiration for one of
-+ * the above two reasons, bfqq has to wait for the service of at least
-+ * one full budget of another queue before being served again, then
-+ * bfqq is likely to get a much lower bandwidth or resource time than
-+ * its reserved ones. To address this issue, two countermeasures need
-+ * to be taken.
-+ *
-+ * First, the budget and the timestamps of bfqq need to be updated in
-+ * a special way on bfqq reactivation: they need to be updated as if
-+ * bfqq did not remain idle and did not expire. In fact, if they are
-+ * computed as if bfqq expired and remained idle until reactivation,
-+ * then the process associated with bfqq is treated as if, instead of
-+ * being greedy, it stopped issuing requests when bfqq remained idle,
-+ * and restarts issuing requests only on this reactivation. In other
-+ * words, the scheduler does not help the process recover the "service
-+ * hole" between bfqq expiration and reactivation. As a consequence,
-+ * the process receives a lower bandwidth than its reserved one. In
-+ * contrast, to recover this hole, the budget must be updated as if
-+ * bfqq was not expired at all before this reactivation, i.e., it must
-+ * be set to the value of the remaining budget when bfqq was
-+ * expired. Along the same line, timestamps need to be assigned the
-+ * value they had the last time bfqq was selected for service, i.e.,
-+ * before last expiration. Thus timestamps need to be back-shifted
-+ * with respect to their normal computation (see [1] for more details
-+ * on this tricky aspect).
-+ *
-+ * Secondly, to allow the process to recover the hole, the in-service
-+ * queue must be expired too, to give bfqq the chance to preempt it
-+ * immediately. In fact, if bfqq has to wait for a full budget of the
-+ * in-service queue to be completed, then it may become impossible to
-+ * let the process recover the hole, even if the back-shifted
-+ * timestamps of bfqq are lower than those of the in-service queue. If
-+ * this happens for most or all of the holes, then the process may not
-+ * receive its reserved bandwidth. In this respect, it is worth noting
-+ * that, being the service of outstanding requests unpreemptible, a
-+ * little fraction of the holes may however be unrecoverable, thereby
-+ * causing a little loss of bandwidth.
-+ *
-+ * The last important point is detecting whether bfqq does need this
-+ * bandwidth recovery. In this respect, the next function deems the
-+ * process associated with bfqq greedy, and thus allows it to recover
-+ * the hole, if: 1) the process is waiting for the arrival of a new
-+ * request (which implies that bfqq expired for one of the above two
-+ * reasons), and 2) such a request has arrived soon. The first
-+ * condition is controlled through the flag non_blocking_wait_rq,
-+ * while the second through the flag arrived_in_time. If both
-+ * conditions hold, then the function computes the budget in the
-+ * above-described special way, and signals that the in-service queue
-+ * should be expired. Timestamp back-shifting is done later in
-+ * __bfq_activate_entity.
-+ *
-+ * 2. Reduce latency. Even if timestamps are not backshifted to let
-+ * the process associated with bfqq recover a service hole, bfqq may
-+ * however happen to have, after being (re)activated, a lower finish
-+ * timestamp than the in-service queue.  That is, the next budget of
-+ * bfqq may have to be completed before the one of the in-service
-+ * queue. If this is the case, then preempting the in-service queue
-+ * allows this goal to be achieved, apart from the unpreemptible,
-+ * outstanding requests mentioned above.
-+ *
-+ * Unfortunately, regardless of which of the above two goals one wants
-+ * to achieve, service trees need first to be updated to know whether
-+ * the in-service queue must be preempted. To have service trees
-+ * correctly updated, the in-service queue must be expired and
-+ * rescheduled, and bfqq must be scheduled too. This is one of the
-+ * most costly operations (in future versions, the scheduling
-+ * mechanism may be re-designed in such a way to make it possible to
-+ * know whether preemption is needed without needing to update service
-+ * trees). In addition, queue preemptions almost always cause random
-+ * I/O, and thus loss of throughput. Because of these facts, the next
-+ * function adopts the following simple scheme to avoid both costly
-+ * operations and too frequent preemptions: it requests the expiration
-+ * of the in-service queue (unconditionally) only for queues that need
-+ * to recover a hole, or that either are weight-raised or deserve to
-+ * be weight-raised.
-+ */
-+static bool bfq_bfqq_update_budg_for_activation(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq,
-+						bool arrived_in_time,
-+						bool wr_or_deserves_wr)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfq_bfqq_non_blocking_wait_rq(bfqq) && arrived_in_time) {
-+		/*
-+		 * We do not clear the flag non_blocking_wait_rq here, as
-+		 * the latter is used in bfq_activate_bfqq to signal
-+		 * that timestamps need to be back-shifted (and is
-+		 * cleared right after).
-+		 */
-+
-+		/*
-+		 * In next assignment we rely on that either
-+		 * entity->service or entity->budget are not updated
-+		 * on expiration if bfqq is empty (see
-+		 * __bfq_bfqq_recalc_budget). Thus both quantities
-+		 * remain unchanged after such an expiration, and the
-+		 * following statement therefore assigns to
-+		 * entity->budget the remaining budget on such an
-+		 * expiration. For clarity, entity->service is not
-+		 * updated on expiration in any case, and, in normal
-+		 * operation, is reset only when bfqq is selected for
-+		 * service (see bfq_get_next_queue).
-+		 */
-+		BUG_ON(bfqq->max_budget < 0);
-+		entity->budget = min_t(unsigned long,
-+				       bfq_bfqq_budget_left(bfqq),
-+				       bfqq->max_budget);
-+
-+		BUG_ON(entity->budget < 0);
-+		return true;
-+	}
-+
-+	BUG_ON(bfqq->max_budget < 0);
-+	entity->budget = max_t(unsigned long, bfqq->max_budget,
-+			       bfq_serv_to_charge(bfqq->next_rq, bfqq));
-+	BUG_ON(entity->budget < 0);
-+
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	return wr_or_deserves_wr;
-+}
-+
-+static void bfq_update_bfqq_wr_on_rq_arrival(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     unsigned int old_wr_coeff,
-+					     bool wr_or_deserves_wr,
-+					     bool interactive,
-+					     bool in_burst,
-+					     bool soft_rt)
-+{
-+	if (old_wr_coeff == 1 && wr_or_deserves_wr) {
-+		/* start a weight-raising period */
-+		if (interactive) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else {
-+			bfqq->wr_start_at_switch_to_srt = jiffies;
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+				BFQ_SOFTRT_WEIGHT_FACTOR;
-+			bfqq->wr_cur_max_time =
-+				bfqd->bfq_wr_rt_max_time;
-+		}
-+		/*
-+		 * If needed, further reduce budget to make sure it is
-+		 * close to bfqq's backlog, so as to reduce the
-+		 * scheduling-error component due to a too large
-+		 * budget. Do not care about throughput consequences,
-+		 * but only about latency. Finally, do not assign a
-+		 * too small budget either, to avoid increasing
-+		 * latency by causing too frequent expirations.
-+		 */
-+		bfqq->entity.budget = min_t(unsigned long,
-+					    bfqq->entity.budget,
-+					    2 * bfq_min_budget(bfqd));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "wrais starting at %lu, rais_max_time %u",
-+			     jiffies,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	} else if (old_wr_coeff > 1) {
-+		if (interactive) { /* update wr coeff and duration */
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+		} else if (in_burst) {
-+			bfqq->wr_coeff = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "wrais ending at %lu, rais_max_time %u",
-+				     jiffies,
-+				     jiffies_to_msecs(bfqq->
-+						      wr_cur_max_time));
-+		} else if (soft_rt) {
-+			/*
-+			 * The application is now or still meeting the
-+			 * requirements for being deemed soft rt.  We
-+			 * can then correctly and safely (re)charge
-+			 * the weight-raising duration for the
-+			 * application with the weight-raising
-+			 * duration for soft rt applications.
-+			 *
-+			 * In particular, doing this recharge now, i.e.,
-+			 * before the weight-raising period for the
-+			 * application finishes, reduces the probability
-+			 * of the following negative scenario:
-+			 * 1) the weight of a soft rt application is
-+			 *    raised at startup (as for any newly
-+			 *    created application),
-+			 * 2) since the application is not interactive,
-+			 *    at a certain time weight-raising is
-+			 *    stopped for the application,
-+			 * 3) at that time the application happens to
-+			 *    still have pending requests, and hence
-+			 *    is destined to not have a chance to be
-+			 *    deemed soft rt before these requests are
-+			 *    completed (see the comments to the
-+			 *    function bfq_bfqq_softrt_next_start()
-+			 *    for details on soft rt detection),
-+			 * 4) these pending requests experience a high
-+			 *    latency because the application is not
-+			 *    weight-raised while they are pending.
-+			 */
-+			if (bfqq->wr_cur_max_time !=
-+				bfqd->bfq_wr_rt_max_time) {
-+				bfqq->wr_start_at_switch_to_srt =
-+					bfqq->last_wr_start_finish;
-+                BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+				bfqq->wr_cur_max_time =
-+					bfqd->bfq_wr_rt_max_time;
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff *
-+					BFQ_SOFTRT_WEIGHT_FACTOR;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "switching to soft_rt wr");
-+			} else
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"moving forward soft_rt wr duration");
-+			bfqq->last_wr_start_finish = jiffies;
-+		}
-+	}
-+}
-+
-+static bool bfq_bfqq_idle_for_long_time(struct bfq_data *bfqd,
-+					struct bfq_queue *bfqq)
-+{
-+	return bfqq->dispatched == 0 &&
-+		time_is_before_jiffies(
-+			bfqq->budget_timeout +
-+			bfqd->bfq_wr_min_idle_time);
-+}
-+
-+static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
-+					     struct bfq_queue *bfqq,
-+					     int old_wr_coeff,
-+					     struct request *rq,
-+					     bool *interactive)
-+{
-+	bool soft_rt, in_burst,	wr_or_deserves_wr,
-+		bfqq_wants_to_preempt,
-+		idle_for_long_time = bfq_bfqq_idle_for_long_time(bfqd, bfqq),
-+		/*
-+		 * See the comments on
-+		 * bfq_bfqq_update_budg_for_activation for
-+		 * details on the usage of the next variable.
-+		 */
-+		arrived_in_time =  ktime_get_ns() <=
-+			RQ_BIC(rq)->ttime.last_end_request +
-+			bfqd->bfq_slice_idle * 3;
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request non-busy: "
-+		     "jiffies %lu, in_time %d, idle_long %d busyw %d "
-+		     "wr_coeff %u",
-+		     jiffies, arrived_in_time,
-+		     idle_for_long_time,
-+		     bfq_bfqq_non_blocking_wait_rq(bfqq),
-+		     old_wr_coeff);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	bfqg_stats_update_io_add(bfqq_group(RQ_BFQQ(rq)), bfqq, rq->cmd_flags);
-+
-+	/*
-+	 * bfqq deserves to be weight-raised if:
-+	 * - it is sync,
-+	 * - it does not belong to a large burst,
-+	 * - it has been idle for enough time or is soft real-time,
-+	 * - is linked to a bfq_io_cq (it is not shared in any sense)
-+	 */
-+	in_burst = bfq_bfqq_in_large_burst(bfqq);
-+	soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
-+		!in_burst &&
-+		time_is_before_jiffies(bfqq->soft_rt_next_start);
-+	*interactive =
-+		!in_burst &&
-+		idle_for_long_time;
-+	wr_or_deserves_wr = bfqd->low_latency &&
-+		(bfqq->wr_coeff > 1 ||
-+		 (bfq_bfqq_sync(bfqq) &&
-+		  bfqq->bic && (*interactive || soft_rt)));
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "bfq_add_request: "
-+		     "in_burst %d, "
-+		     "soft_rt %d (next %lu), inter %d, bic %p",
-+		     bfq_bfqq_in_large_burst(bfqq), soft_rt,
-+		     bfqq->soft_rt_next_start,
-+		     *interactive,
-+		     bfqq->bic);
-+
-+	/*
-+	 * Using the last flag, update budget and check whether bfqq
-+	 * may want to preempt the in-service queue.
-+	 */
-+	bfqq_wants_to_preempt =
-+		bfq_bfqq_update_budg_for_activation(bfqd, bfqq,
-+						    arrived_in_time,
-+						    wr_or_deserves_wr);
-+
-+	/*
-+	 * If bfqq happened to be activated in a burst, but has been
-+	 * idle for much more than an interactive queue, then we
-+	 * assume that, in the overall I/O initiated in the burst, the
-+	 * I/O associated with bfqq is finished. So bfqq does not need
-+	 * to be treated as a queue belonging to a burst
-+	 * anymore. Accordingly, we reset bfqq's in_large_burst flag
-+	 * if set, and remove bfqq from the burst list if it's
-+	 * there. We do not decrement burst_size, because the fact
-+	 * that bfqq does not need to belong to the burst list any
-+	 * more does not invalidate the fact that bfqq was created in
-+	 * a burst.
-+	 */
-+	if (likely(!bfq_bfqq_just_created(bfqq)) &&
-+	    idle_for_long_time &&
-+	    time_is_before_jiffies(
-+		    bfqq->budget_timeout +
-+		    msecs_to_jiffies(10000))) {
-+		hlist_del_init(&bfqq->burst_list_node);
-+		bfq_clear_bfqq_in_large_burst(bfqq);
-+	}
-+
-+	bfq_clear_bfqq_just_created(bfqq);
-+
-+	if (!bfq_bfqq_IO_bound(bfqq)) {
-+		if (arrived_in_time) {
-+			bfqq->requests_within_timer++;
-+			if (bfqq->requests_within_timer >=
-+			    bfqd->bfq_requests_within_timer)
-+				bfq_mark_bfqq_IO_bound(bfqq);
-+		} else
-+			bfqq->requests_within_timer = 0;
-+		bfq_log_bfqq(bfqd, bfqq, "requests in time %d",
-+			     bfqq->requests_within_timer);
-+	}
-+
-+	if (bfqd->low_latency) {
-+		if (unlikely(time_is_after_jiffies(bfqq->split_time)))
-+			/* wraparound */
-+			bfqq->split_time =
-+				jiffies - bfqd->bfq_wr_min_idle_time - 1;
-+
-+		if (time_is_before_jiffies(bfqq->split_time +
-+					   bfqd->bfq_wr_min_idle_time)) {
-+			bfq_update_bfqq_wr_on_rq_arrival(bfqd, bfqq,
-+							 old_wr_coeff,
-+							 wr_or_deserves_wr,
-+							 *interactive,
-+							 in_burst,
-+							 soft_rt);
-+
-+			if (old_wr_coeff != bfqq->wr_coeff)
-+				bfqq->entity.prio_changed = 1;
-+		}
-+	}
-+
-+	bfqq->last_idle_bklogged = jiffies;
-+	bfqq->service_from_backlogged = 0;
-+	bfq_clear_bfqq_softrt_update(bfqq);
-+
-+	bfq_add_bfqq_busy(bfqd, bfqq);
-+
-+	/*
-+	 * Expire in-service queue only if preemption may be needed
-+	 * for guarantees. In this respect, the function
-+	 * next_queue_may_preempt just checks a simple, necessary
-+	 * condition, and not a sufficient condition based on
-+	 * timestamps. In fact, for the latter condition to be
-+	 * evaluated, timestamps would need first to be updated, and
-+	 * this operation is quite costly (see the comments on the
-+	 * function bfq_bfqq_update_budg_for_activation).
-+	 */
-+	if (bfqd->in_service_queue && bfqq_wants_to_preempt &&
-+	    bfqd->in_service_queue->wr_coeff < bfqq->wr_coeff &&
-+	    next_queue_may_preempt(bfqd)) {
-+		struct bfq_queue *in_serv =
-+			bfqd->in_service_queue;
-+		BUG_ON(in_serv == bfqq);
-+
-+		bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
-+				false, BFQ_BFQQ_PREEMPTED);
-+	}
-+}
-+
-+static void bfq_add_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	struct request *next_rq, *prev;
-+	unsigned int old_wr_coeff = bfqq->wr_coeff;
-+	bool interactive = false;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add_request: size %u %s",
-+		     blk_rq_sectors(rq), rq_is_sync(rq) ? "S" : "A");
-+
-+	if (bfqq->wr_coeff > 1) /* queue is being weight-raised */
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+	bfqq->queued[rq_is_sync(rq)]++;
-+	bfqd->queued++;
-+
-+	elv_rb_add(&bfqq->sort_list, rq);
-+
-+	/*
-+	 * Check if this request is a better next-to-serve candidate.
-+	 */
-+	prev = bfqq->next_rq;
-+	next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
-+	BUG_ON(!next_rq);
-+	bfqq->next_rq = next_rq;
-+
-+	/*
-+	 * Adjust priority tree position, if next_rq changes.
-+	 */
-+	if (prev != bfqq->next_rq)
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+
-+	if (!bfq_bfqq_busy(bfqq)) /* switching to busy ... */
-+		bfq_bfqq_handle_idle_busy_switch(bfqd, bfqq, old_wr_coeff,
-+						 rq, &interactive);
-+	else {
-+		if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
-+		    time_is_before_jiffies(
-+				bfqq->last_wr_start_finish +
-+				bfqd->bfq_wr_min_inter_arr_async)) {
-+			bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+			bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+
-+			bfqd->wr_busy_queues++;
-+			bfqq->entity.prio_changed = 1;
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "non-idle wrais starting, "
-+				     "wr_max_time %u wr_busy %d",
-+				     jiffies_to_msecs(bfqq->wr_cur_max_time),
-+				     bfqd->wr_busy_queues);
-+		}
-+		if (prev != bfqq->next_rq)
-+			bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * Assign jiffies to last_wr_start_finish in the following
-+	 * cases:
-+	 *
-+	 * . if bfqq is not going to be weight-raised, because, for
-+	 *   non weight-raised queues, last_wr_start_finish stores the
-+	 *   arrival time of the last request; as of now, this piece
-+	 *   of information is used only for deciding whether to
-+	 *   weight-raise async queues
-+	 *
-+	 * . if bfqq is not weight-raised, because, if bfqq is now
-+	 *   switching to weight-raised, then last_wr_start_finish
-+	 *   stores the time when weight-raising starts
-+	 *
-+	 * . if bfqq is interactive, because, regardless of whether
-+	 *   bfqq is currently weight-raised, the weight-raising
-+	 *   period must start or restart (this case is considered
-+	 *   separately because it is not detected by the above
-+	 *   conditions, if bfqq is already weight-raised)
-+	 *
-+	 * last_wr_start_finish has to be updated also if bfqq is soft
-+	 * real-time, because the weight-raising period is constantly
-+	 * restarted on idle-to-busy transitions for these queues, but
-+	 * this is already done in bfq_bfqq_handle_idle_busy_switch if
-+	 * needed.
-+	 */
-+	if (bfqd->low_latency &&
-+		(old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
-+		bfqq->last_wr_start_finish = jiffies;
-+}
-+
-+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
-+					  struct bio *bio)
-+{
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return NULL;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
-+	if (bfqq)
-+		return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio));
-+
-+	return NULL;
-+}
-+
-+static sector_t get_sdist(sector_t last_pos, struct request *rq)
-+{
-+	sector_t sdist = 0;
-+
-+	if (last_pos) {
-+		if (last_pos < blk_rq_pos(rq))
-+			sdist = blk_rq_pos(rq) - last_pos;
-+		else
-+			sdist = last_pos - blk_rq_pos(rq);
-+	}
-+
-+	return sdist;
-+}
-+
-+static void bfq_activate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bfqd->rq_in_driver++;
-+}
-+
-+static void bfq_deactivate_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+
-+	BUG_ON(bfqd->rq_in_driver == 0);
-+	bfqd->rq_in_driver--;
-+}
-+
-+static void bfq_remove_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	const int sync = rq_is_sync(rq);
-+
-+	BUG_ON(bfqq->entity.service > bfqq->entity.budget &&
-+	       bfqq == bfqd->in_service_queue);
-+
-+	if (bfqq->next_rq == rq) {
-+		bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
-+		bfq_updated_next_req(bfqd, bfqq);
-+	}
-+
-+	if (rq->queuelist.prev != &rq->queuelist)
-+		list_del_init(&rq->queuelist);
-+	BUG_ON(bfqq->queued[sync] == 0);
-+	bfqq->queued[sync]--;
-+	bfqd->queued--;
-+	elv_rb_del(&bfqq->sort_list, rq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		bfqq->next_rq = NULL;
-+
-+		BUG_ON(bfqq->entity.budget < 0);
-+
-+		if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) {
-+			BUG_ON(bfqq->ref < 2); /* referred by rq and on tree */
-+			bfq_del_bfqq_busy(bfqd, bfqq, false);
-+			/*
-+			 * bfqq emptied. In normal operation, when
-+			 * bfqq is empty, bfqq->entity.service and
-+			 * bfqq->entity.budget must contain,
-+			 * respectively, the service received and the
-+			 * budget used last time bfqq emptied. These
-+			 * facts do not hold in this case, as at least
-+			 * this last removal occurred while bfqq is
-+			 * not in service. To avoid inconsistencies,
-+			 * reset both bfqq->entity.service and
-+			 * bfqq->entity.budget, if bfqq has still a
-+			 * process that may issue I/O requests to it.
-+			 */
-+			bfqq->entity.budget = bfqq->entity.service = 0;
-+		}
-+
-+		/*
-+		 * Remove queue from request-position tree as it is empty.
-+		 */
-+		if (bfqq->pos_root) {
-+			rb_erase(&bfqq->pos_node, bfqq->pos_root);
-+			bfqq->pos_root = NULL;
-+		}
-+	}
-+
-+	if (rq->cmd_flags & REQ_META) {
-+		BUG_ON(bfqq->meta_pending == 0);
-+		bfqq->meta_pending--;
-+	}
-+	bfqg_stats_update_io_remove(bfqq_group(bfqq), rq->cmd_flags);
-+}
-+
-+static enum elv_merge bfq_merge(struct request_queue *q, struct request **req,
-+				struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct request *__rq;
-+
-+	__rq = bfq_find_rq_fmerge(bfqd, bio);
-+	if (__rq && elv_bio_merge_ok(__rq, bio)) {
-+		*req = __rq;
-+		return ELEVATOR_FRONT_MERGE;
-+	}
-+
-+	return ELEVATOR_NO_MERGE;
-+}
-+
-+static void bfq_merged_request(struct request_queue *q, struct request *req,
-+			       enum elv_merge type)
-+{
-+	if (type == ELEVATOR_FRONT_MERGE &&
-+	    rb_prev(&req->rb_node) &&
-+	    blk_rq_pos(req) <
-+	    blk_rq_pos(container_of(rb_prev(&req->rb_node),
-+				    struct request, rb_node))) {
-+		struct bfq_queue *bfqq = RQ_BFQQ(req);
-+		struct bfq_data *bfqd = bfqq->bfqd;
-+		struct request *prev, *next_rq;
-+
-+		/* Reposition request in its sort_list */
-+		elv_rb_del(&bfqq->sort_list, req);
-+		elv_rb_add(&bfqq->sort_list, req);
-+		/* Choose next request to be served for bfqq */
-+		prev = bfqq->next_rq;
-+		next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
-+					 bfqd->last_position);
-+		BUG_ON(!next_rq);
-+		bfqq->next_rq = next_rq;
-+		/*
-+		 * If next_rq changes, update both the queue's budget to
-+		 * fit the new request and the queue's position in its
-+		 * rq_pos_tree.
-+		 */
-+		if (prev != bfqq->next_rq) {
-+			bfq_updated_next_req(bfqd, bfqq);
-+			bfq_pos_tree_add_move(bfqd, bfqq);
-+		}
-+	}
-+}
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static void bfq_bio_merged(struct request_queue *q, struct request *req,
-+			   struct bio *bio)
-+{
-+	bfqg_stats_update_io_merged(bfqq_group(RQ_BFQQ(req)), bio->bi_opf);
-+}
-+#endif
-+
-+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
-+				struct request *next)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next);
-+
-+	/*
-+	 * If next and rq belong to the same bfq_queue and next is older
-+	 * than rq, then reposition rq in the fifo (by substituting next
-+	 * with rq). Otherwise, if next and rq belong to different
-+	 * bfq_queues, never reposition rq: in fact, we would have to
-+	 * reposition it with respect to next's position in its own fifo,
-+	 * which would most certainly be too expensive with respect to
-+	 * the benefits.
-+	 */
-+	if (bfqq == next_bfqq &&
-+	    !list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
-+	    next->fifo_time < rq->fifo_time) {
-+		list_del_init(&rq->queuelist);
-+		list_replace_init(&next->queuelist, &rq->queuelist);
-+		rq->fifo_time = next->fifo_time;
-+	}
-+
-+	if (bfqq->next_rq == next)
-+		bfqq->next_rq = rq;
-+
-+	bfq_remove_request(next);
-+	bfqg_stats_update_io_merged(bfqq_group(bfqq), next->cmd_flags);
-+}
-+
-+/* Must be called with bfqq != NULL */
-+static void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
-+{
-+	BUG_ON(!bfqq);
-+
-+	if (bfq_bfqq_busy(bfqq))
-+		bfqq->bfqd->wr_busy_queues--;
-+	bfqq->wr_coeff = 1;
-+	bfqq->wr_cur_max_time = 0;
-+	bfqq->last_wr_start_finish = jiffies;
-+	/*
-+	 * Trigger a weight change on the next invocation of
-+	 * __bfq_entity_update_weight_prio.
-+	 */
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "end_wr: wrais ending at %lu, rais_max_time %u",
-+		     bfqq->last_wr_start_finish,
-+		     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "end_wr: wr_busy %d",
-+		     bfqq->bfqd->wr_busy_queues);
-+}
-+
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			if (bfqg->async_bfqq[i][j])
-+				bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
-+	if (bfqg->async_idle_bfqq)
-+		bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_end_wr(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
-+		bfq_bfqq_end_wr(bfqq);
-+	bfq_end_wr_async(bfqd);
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+}
-+
-+static sector_t bfq_io_struct_pos(void *io_struct, bool request)
-+{
-+	if (request)
-+		return blk_rq_pos(io_struct);
-+	else
-+		return ((struct bio *)io_struct)->bi_iter.bi_sector;
-+}
-+
-+static int bfq_rq_close_to_sector(void *io_struct, bool request,
-+				  sector_t sector)
-+{
-+	return abs(bfq_io_struct_pos(io_struct, request) - sector) <=
-+	       BFQQ_CLOSE_THR;
-+}
-+
-+static struct bfq_queue *bfqq_find_close(struct bfq_data *bfqd,
-+					 struct bfq_queue *bfqq,
-+					 sector_t sector)
-+{
-+	struct rb_root *root = &bfq_bfqq_to_bfqg(bfqq)->rq_pos_tree;
-+	struct rb_node *parent, *node;
-+	struct bfq_queue *__bfqq;
-+
-+	if (RB_EMPTY_ROOT(root))
-+		return NULL;
-+
-+	/*
-+	 * First, if we find a request starting at the end of the last
-+	 * request, choose it.
-+	 */
-+	__bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
-+	if (__bfqq)
-+		return __bfqq;
-+
-+	/*
-+	 * If the exact sector wasn't found, the parent of the NULL leaf
-+	 * will contain the closest sector (rq_pos_tree sorted by
-+	 * next_request position).
-+	 */
-+	__bfqq = rb_entry(parent, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	if (blk_rq_pos(__bfqq->next_rq) < sector)
-+		node = rb_next(&__bfqq->pos_node);
-+	else
-+		node = rb_prev(&__bfqq->pos_node);
-+	if (!node)
-+		return NULL;
-+
-+	__bfqq = rb_entry(node, struct bfq_queue, pos_node);
-+	if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
-+		return __bfqq;
-+
-+	return NULL;
-+}
-+
-+static struct bfq_queue *bfq_find_close_cooperator(struct bfq_data *bfqd,
-+						   struct bfq_queue *cur_bfqq,
-+						   sector_t sector)
-+{
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * We shall notice if some of the queues are cooperating,
-+	 * e.g., working closely on the same area of the device. In
-+	 * that case, we can group them together and: 1) don't waste
-+	 * time idling, and 2) serve the union of their requests in
-+	 * the best possible order for throughput.
-+	 */
-+	bfqq = bfqq_find_close(bfqd, cur_bfqq, sector);
-+	if (!bfqq || bfqq == cur_bfqq)
-+		return NULL;
-+
-+	return bfqq;
-+}
-+
-+static struct bfq_queue *
-+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	int process_refs, new_process_refs;
-+	struct bfq_queue *__bfqq;
-+
-+	/*
-+	 * If there are no process references on the new_bfqq, then it is
-+	 * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
-+	 * may have dropped their last reference (not just their last process
-+	 * reference).
-+	 */
-+	if (!bfqq_process_refs(new_bfqq))
-+		return NULL;
-+
-+	/* Avoid a circular list and skip interim queue merges. */
-+	while ((__bfqq = new_bfqq->new_bfqq)) {
-+		if (__bfqq == bfqq)
-+			return NULL;
-+		new_bfqq = __bfqq;
-+	}
-+
-+	process_refs = bfqq_process_refs(bfqq);
-+	new_process_refs = bfqq_process_refs(new_bfqq);
-+	/*
-+	 * If the process for the bfqq has gone away, there is no
-+	 * sense in merging the queues.
-+	 */
-+	if (process_refs == 0 || new_process_refs == 0)
-+		return NULL;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
-+		new_bfqq->pid);
-+
-+	/*
-+	 * Merging is just a redirection: the requests of the process
-+	 * owning one of the two queues are redirected to the other queue.
-+	 * The latter queue, in its turn, is set as shared if this is the
-+	 * first time that the requests of some process are redirected to
-+	 * it.
-+	 *
-+	 * We redirect bfqq to new_bfqq and not the opposite, because we
-+	 * are in the context of the process owning bfqq, hence we have
-+	 * the io_cq of this process. So we can immediately configure this
-+	 * io_cq to redirect the requests of the process to new_bfqq.
-+	 *
-+	 * NOTE, even if new_bfqq coincides with the in-service queue, the
-+	 * io_cq of new_bfqq is not available, because, if the in-service
-+	 * queue is shared, bfqd->in_service_bic may not point to the
-+	 * io_cq of the in-service queue.
-+	 * Redirecting the requests of the process owning bfqq to the
-+	 * currently in-service queue is in any case the best option, as
-+	 * we feed the in-service queue with new requests close to the
-+	 * last request served and, by doing so, hopefully increase the
-+	 * throughput.
-+	 */
-+	bfqq->new_bfqq = new_bfqq;
-+	new_bfqq->ref += process_refs;
-+	return new_bfqq;
-+}
-+
-+static bool bfq_may_be_close_cooperator(struct bfq_queue *bfqq,
-+					struct bfq_queue *new_bfqq)
-+{
-+	if (bfq_class_idle(bfqq) || bfq_class_idle(new_bfqq) ||
-+	    (bfqq->ioprio_class != new_bfqq->ioprio_class))
-+		return false;
-+
-+	/*
-+	 * If either of the queues has already been detected as seeky,
-+	 * then merging it with the other queue is unlikely to lead to
-+	 * sequential I/O.
-+	 */
-+	if (BFQQ_SEEKY(bfqq) || BFQQ_SEEKY(new_bfqq))
-+		return false;
-+
-+	/*
-+	 * Interleaved I/O is known to be done by (some) applications
-+	 * only for reads, so it does not make sense to merge async
-+	 * queues.
-+	 */
-+	if (!bfq_bfqq_sync(bfqq) || !bfq_bfqq_sync(new_bfqq))
-+		return false;
-+
-+	return true;
-+}
-+
-+/*
-+ * If this function returns true, then bfqq cannot be merged. The idea
-+ * is that true cooperation happens very early after processes start
-+ * to do I/O. Usually, late cooperations are just accidental false
-+ * positives. In case bfqq is weight-raised, such false positives
-+ * would evidently degrade latency guarantees for bfqq.
-+ */
-+static bool wr_from_too_long(struct bfq_queue *bfqq)
-+{
-+	return bfqq->wr_coeff > 1 &&
-+		time_is_before_jiffies(bfqq->last_wr_start_finish +
-+				       msecs_to_jiffies(100));
-+}
-+
-+/*
-+ * Attempt to schedule a merge of bfqq with the currently in-service
-+ * queue or with a close queue among the scheduled queues.  Return
-+ * NULL if no merge was scheduled, a pointer to the shared bfq_queue
-+ * structure otherwise.
-+ *
-+ * The OOM queue is not allowed to participate to cooperation: in fact, since
-+ * the requests temporarily redirected to the OOM queue could be redirected
-+ * again to dedicated queues at any time, the state needed to correctly
-+ * handle merging with the OOM queue would be quite complex and expensive
-+ * to maintain. Besides, in such a critical condition as an out of memory,
-+ * the benefits of queue merging may be little relevant, or even negligible.
-+ *
-+ * Weight-raised queues can be merged only if their weight-raising
-+ * period has just started. In fact cooperating processes are usually
-+ * started together. Thus, with this filter we avoid false positives
-+ * that would jeopardize low-latency guarantees.
-+ *
-+ * WARNING: queue merging may impair fairness among non-weight raised
-+ * queues, for at least two reasons: 1) the original weight of a
-+ * merged queue may change during the merged state, 2) even being the
-+ * weight the same, a merged queue may be bloated with many more
-+ * requests than the ones produced by its originally-associated
-+ * process.
-+ */
-+static struct bfq_queue *
-+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		     void *io_struct, bool request)
-+{
-+	struct bfq_queue *in_service_bfqq, *new_bfqq;
-+
-+	if (bfqq->new_bfqq)
-+		return bfqq->new_bfqq;
-+
-+	if (io_struct && wr_from_too_long(bfqq) &&
-+	    likely(bfqq != &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have looked for coop, but bfq%d wr",
-+			bfqq->pid);
-+
-+	if (!io_struct ||
-+	    wr_from_too_long(bfqq) ||
-+	    unlikely(bfqq == &bfqd->oom_bfqq))
-+		return NULL;
-+
-+	/* If there is only one backlogged queue, don't search. */
-+	if (bfqd->busy_queues == 1)
-+		return NULL;
-+
-+	in_service_bfqq = bfqd->in_service_queue;
-+
-+	if (in_service_bfqq && in_service_bfqq != bfqq &&
-+	    bfqd->in_service_bic && wr_from_too_long(in_service_bfqq)
-+	    && likely(in_service_bfqq == &bfqd->oom_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+		"would have tried merge with in-service-queue, but wr");
-+
-+	if (!in_service_bfqq || in_service_bfqq == bfqq ||
-+	    !bfqd->in_service_bic || wr_from_too_long(in_service_bfqq) ||
-+	    unlikely(in_service_bfqq == &bfqd->oom_bfqq))
-+		goto check_scheduled;
-+
-+	if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
-+	    bfqq->entity.parent == in_service_bfqq->entity.parent &&
-+	    bfq_may_be_close_cooperator(bfqq, in_service_bfqq)) {
-+		new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
-+		if (new_bfqq)
-+			return new_bfqq;
-+	}
-+	/*
-+	 * Check whether there is a cooperator among currently scheduled
-+	 * queues. The only thing we need is that the bio/request is not
-+	 * NULL, as we need it to establish whether a cooperator exists.
-+	 */
-+check_scheduled:
-+	new_bfqq = bfq_find_close_cooperator(bfqd, bfqq,
-+			bfq_io_struct_pos(io_struct, request));
-+
-+	BUG_ON(new_bfqq && bfqq->entity.parent != new_bfqq->entity.parent);
-+
-+	if (new_bfqq && wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "would have merged with bfq%d, but wr",
-+			     new_bfqq->pid);
-+
-+	if (new_bfqq && !wr_from_too_long(new_bfqq) &&
-+	    likely(new_bfqq != &bfqd->oom_bfqq) &&
-+	    bfq_may_be_close_cooperator(bfqq, new_bfqq))
-+		return bfq_setup_merge(bfqq, new_bfqq);
-+
-+	return NULL;
-+}
-+
-+static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
-+{
-+	struct bfq_io_cq *bic = bfqq->bic;
-+
-+	/*
-+	 * If !bfqq->bic, the queue is already shared or its requests
-+	 * have already been redirected to a shared queue; both idle window
-+	 * and weight raising state have already been saved. Do nothing.
-+	 */
-+	if (!bic)
-+		return;
-+
-+	bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
-+	bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
-+	bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
-+	bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
-+	bic->saved_wr_coeff = bfqq->wr_coeff;
-+	bic->saved_wr_start_at_switch_to_srt = bfqq->wr_start_at_switch_to_srt;
-+	bic->saved_last_wr_start_finish = bfqq->last_wr_start_finish;
-+	bic->saved_wr_cur_max_time = bfqq->wr_cur_max_time;
-+	BUG_ON(time_is_after_jiffies(bfqq->last_wr_start_finish));
-+}
-+
-+static void bfq_get_bic_reference(struct bfq_queue *bfqq)
-+{
-+	/*
-+	 * If bfqq->bic has a non-NULL value, the bic to which it belongs
-+	 * is about to begin using a shared bfq_queue.
-+	 */
-+	if (bfqq->bic)
-+		atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
-+}
-+
-+static void
-+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
-+		struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
-+		     (unsigned long) new_bfqq->pid);
-+	/* Save weight raising and idle window of the merged queues */
-+	bfq_bfqq_save_state(bfqq);
-+	bfq_bfqq_save_state(new_bfqq);
-+	if (bfq_bfqq_IO_bound(bfqq))
-+		bfq_mark_bfqq_IO_bound(new_bfqq);
-+	bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	/*
-+	 * If bfqq is weight-raised, then let new_bfqq inherit
-+	 * weight-raising. To reduce false positives, neglect the case
-+	 * where bfqq has just been created, but has not yet made it
-+	 * to be weight-raised (which may happen because EQM may merge
-+	 * bfqq even before bfq_add_request is executed for the first
-+	 * time for bfqq). Handling this case would however be very
-+	 * easy, thanks to the flag just_created.
-+	 */
-+	if (new_bfqq->wr_coeff == 1 && bfqq->wr_coeff > 1) {
-+		new_bfqq->wr_coeff = bfqq->wr_coeff;
-+		new_bfqq->wr_cur_max_time = bfqq->wr_cur_max_time;
-+		new_bfqq->last_wr_start_finish = bfqq->last_wr_start_finish;
-+		new_bfqq->wr_start_at_switch_to_srt =
-+			bfqq->wr_start_at_switch_to_srt;
-+		if (bfq_bfqq_busy(new_bfqq))
-+			bfqd->wr_busy_queues++;
-+		new_bfqq->entity.prio_changed = 1;
-+		bfq_log_bfqq(bfqd, new_bfqq,
-+			     "wr start after merge with %d, rais_max_time %u",
-+			     bfqq->pid,
-+			     jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	if (bfqq->wr_coeff > 1) { /* bfqq has given its wr to new_bfqq */
-+		bfqq->wr_coeff = 1;
-+		bfqq->entity.prio_changed = 1;
-+		if (bfq_bfqq_busy(bfqq))
-+			bfqd->wr_busy_queues--;
-+	}
-+
-+	bfq_log_bfqq(bfqd, new_bfqq, "merge_bfqqs: wr_busy %d",
-+		     bfqd->wr_busy_queues);
-+
-+	/*
-+	 * Grab a reference to the bic, to prevent it from being destroyed
-+	 * before being possibly touched by a bfq_split_bfqq().
-+	 */
-+	bfq_get_bic_reference(bfqq);
-+	bfq_get_bic_reference(new_bfqq);
-+	/*
-+	 * Merge queues (that is, let bic redirect its requests to new_bfqq)
-+	 */
-+	bic_set_bfqq(bic, new_bfqq, 1);
-+	bfq_mark_bfqq_coop(new_bfqq);
-+	/*
-+	 * new_bfqq now belongs to at least two bics (it is a shared queue):
-+	 * set new_bfqq->bic to NULL. bfqq either:
-+	 * - does not belong to any bic any more, and hence bfqq->bic must
-+	 *   be set to NULL, or
-+	 * - is a queue whose owning bics have already been redirected to a
-+	 *   different queue, hence the queue is destined to not belong to
-+	 *   any bic soon and bfqq->bic is already NULL (therefore the next
-+	 *   assignment causes no harm).
-+	 */
-+	new_bfqq->bic = NULL;
-+	bfqq->bic = NULL;
-+	/* release process reference to bfqq */
-+	bfq_put_queue(bfqq);
-+}
-+
-+static int bfq_allow_bio_merge(struct request_queue *q, struct request *rq,
-+			       struct bio *bio)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	bool is_sync = op_is_sync(bio->bi_opf);
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq, *new_bfqq;
-+
-+	/*
-+	 * Disallow merge of a sync bio into an async request.
-+	 */
-+	if (is_sync && !rq_is_sync(rq))
-+		return false;
-+
-+	/*
-+	 * Lookup the bfqq that this bio will be queued with. Allow
-+	 * merge only if rq is queued there.
-+	 * Queue lock is held here.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, current->io_context);
-+	if (!bic)
-+		return false;
-+
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	/*
-+	 * We take advantage of this function to perform an early merge
-+	 * of the queues of possible cooperating processes.
-+	 */
-+	if (bfqq) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
-+		if (new_bfqq) {
-+			bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
-+			/*
-+			 * If we get here, the bio will be queued in the
-+			 * shared queue, i.e., new_bfqq, so use new_bfqq
-+			 * to decide whether bio and rq can be merged.
-+			 */
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	return bfqq == RQ_BFQQ(rq);
-+}
-+
-+static int bfq_allow_rq_merge(struct request_queue *q, struct request *rq,
-+			      struct request *next)
-+{
-+	return RQ_BFQQ(rq) == RQ_BFQQ(next);
-+}
-+
-+/*
-+ * Set the maximum time for the in-service queue to consume its
-+ * budget. This prevents seeky processes from lowering the throughput.
-+ * In practice, a time-slice service scheme is used with seeky
-+ * processes.
-+ */
-+static void bfq_set_budget_timeout(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq)
-+{
-+	unsigned int timeout_coeff;
-+
-+	if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
-+		timeout_coeff = 1;
-+	else
-+		timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
-+
-+	bfqd->last_budget_start = ktime_get();
-+
-+	bfqq->budget_timeout = jiffies +
-+		bfqd->bfq_timeout * timeout_coeff;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
-+		jiffies_to_msecs(bfqd->bfq_timeout * timeout_coeff));
-+}
-+
-+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
-+				       struct bfq_queue *bfqq)
-+{
-+	if (bfqq) {
-+		bfqg_stats_update_avg_queue_size(bfqq_group(bfqq));
-+		bfq_mark_bfqq_must_alloc(bfqq);
-+		bfq_clear_bfqq_fifo_expire(bfqq);
-+
-+		bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
-+
-+		BUG_ON(bfqq == bfqd->in_service_queue);
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (time_is_before_jiffies(bfqq->last_wr_start_finish) &&
-+		    bfqq->wr_coeff > 1 &&
-+		    bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		    time_is_before_jiffies(bfqq->budget_timeout)) {
-+			/*
-+			 * For soft real-time queues, move the start
-+			 * of the weight-raising period forward by the
-+			 * time the queue has not received any
-+			 * service. Otherwise, a relatively long
-+			 * service delay is likely to cause the
-+			 * weight-raising period of the queue to end,
-+			 * because of the short duration of the
-+			 * weight-raising period of a soft real-time
-+			 * queue.  It is worth noting that this move
-+			 * is not so dangerous for the other queues,
-+			 * because soft real-time queues are not
-+			 * greedy.
-+			 *
-+			 * To not add a further variable, we use the
-+			 * overloaded field budget_timeout to
-+			 * determine for how long the queue has not
-+			 * received service, i.e., how much time has
-+			 * elapsed since the queue expired. However,
-+			 * this is a little imprecise, because
-+			 * budget_timeout is set to jiffies if bfqq
-+			 * not only expires, but also remains with no
-+			 * request.
-+			 */
-+			if (time_after(bfqq->budget_timeout,
-+				       bfqq->last_wr_start_finish))
-+				bfqq->last_wr_start_finish +=
-+					jiffies - bfqq->budget_timeout;
-+			else
-+				bfqq->last_wr_start_finish = jiffies;
-+
-+			if (time_is_after_jiffies(bfqq->last_wr_start_finish)) {
-+			       pr_crit(
-+			       "BFQ WARNING:last %lu budget %lu jiffies %lu",
-+			       bfqq->last_wr_start_finish,
-+			       bfqq->budget_timeout,
-+			       jiffies);
-+			       pr_crit("diff %lu", jiffies -
-+				       max_t(unsigned long,
-+					     bfqq->last_wr_start_finish,
-+					     bfqq->budget_timeout));
-+			       bfqq->last_wr_start_finish = jiffies;
-+			}
-+		}
-+
-+		bfq_set_budget_timeout(bfqd, bfqq);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "set_in_service_queue, cur-budget = %d",
-+			     bfqq->entity.budget);
-+	} else
-+		bfq_log(bfqd, "set_in_service_queue: NULL");
-+
-+	bfqd->in_service_queue = bfqq;
-+}
-+
-+/*
-+ * Get and set a new queue for service.
-+ */
-+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
-+
-+	__bfq_set_in_service_queue(bfqd, bfqq);
-+	return bfqq;
-+}
-+
-+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq = bfqd->in_service_queue;
-+	struct bfq_io_cq *bic;
-+	u32 sl;
-+
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	/* Processes have exited, don't wait. */
-+	bic = bfqd->in_service_bic;
-+	if (!bic || atomic_read(&bic->icq.ioc->active_ref) == 0)
-+		return;
-+
-+	bfq_mark_bfqq_wait_request(bfqq);
-+
-+	/*
-+	 * We don't want to idle for seeks, but we do want to allow
-+	 * fair distribution of slice time for a process doing back-to-back
-+	 * seeks. So allow a little bit of time for him to submit a new rq.
-+	 *
-+	 * To prevent processes with (partly) seeky workloads from
-+	 * being too ill-treated, grant them a small fraction of the
-+	 * assigned budget before reducing the waiting time to
-+	 * BFQ_MIN_TT. This happened to help reduce latency.
-+	 */
-+	sl = bfqd->bfq_slice_idle;
-+	/*
-+	 * Unless the queue is being weight-raised or the scenario is
-+	 * asymmetric, grant only minimum idle time if the queue
-+	 * is seeky. A long idling is preserved for a weight-raised
-+	 * queue, or, more in general, in an asymemtric scenario,
-+	 * because a long idling is needed for guaranteeing to a queue
-+	 * its reserved share of the throughput (in particular, it is
-+	 * needed if the queue has a higher weight than some other
-+	 * queue).
-+	 */
-+	if (BFQQ_SEEKY(bfqq) && bfqq->wr_coeff == 1 &&
-+	    bfq_symmetric_scenario(bfqd))
-+		sl = min_t(u32, sl, BFQ_MIN_TT);
-+
-+	bfqd->last_idling_start = ktime_get();
-+	hrtimer_start(&bfqd->idle_slice_timer, ns_to_ktime(sl),
-+		      HRTIMER_MODE_REL);
-+	bfqg_stats_set_start_idle_time(bfqq_group(bfqq));
-+	bfq_log(bfqd, "arm idle: %ld/%ld ms",
-+		sl / NSEC_PER_MSEC, bfqd->bfq_slice_idle / NSEC_PER_MSEC);
-+}
-+
-+/*
-+ * In autotuning mode, max_budget is dynamically recomputed as the
-+ * amount of sectors transferred in timeout at the estimated peak
-+ * rate. This enables BFQ to utilize a full timeslice with a full
-+ * budget, even if the in-service queue is served at peak rate. And
-+ * this maximises throughput with sequential workloads.
-+ */
-+static unsigned long bfq_calc_max_budget(struct bfq_data *bfqd)
-+{
-+	return (u64)bfqd->peak_rate * USEC_PER_MSEC *
-+		jiffies_to_msecs(bfqd->bfq_timeout)>>BFQ_RATE_SHIFT;
-+}
-+
-+/*
-+ * Update parameters related to throughput and responsiveness, as a
-+ * function of the estimated peak rate. See comments on
-+ * bfq_calc_max_budget(), and on T_slow and T_fast arrays.
-+ */
-+static void update_thr_responsiveness_params(struct bfq_data *bfqd)
-+{
-+	int dev_type = blk_queue_nonrot(bfqd->queue);
-+
-+	if (bfqd->bfq_user_max_budget == 0) {
-+		bfqd->bfq_max_budget =
-+			bfq_calc_max_budget(bfqd);
-+		BUG_ON(bfqd->bfq_max_budget < 0);
-+		bfq_log(bfqd, "new max_budget = %d",
-+			bfqd->bfq_max_budget);
-+	}
-+
-+	if (bfqd->device_speed == BFQ_BFQD_FAST &&
-+	    bfqd->peak_rate < device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_SLOW;
-+		bfqd->RT_prod = R_slow[dev_type] *
-+			T_slow[dev_type];
-+	} else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
-+		   bfqd->peak_rate > device_speed_thresh[dev_type]) {
-+		bfqd->device_speed = BFQ_BFQD_FAST;
-+		bfqd->RT_prod = R_fast[dev_type] *
-+			T_fast[dev_type];
-+	}
-+
-+	bfq_log(bfqd,
-+"dev_type %s dev_speed_class = %s (%llu sects/sec), thresh %llu setcs/sec",
-+		dev_type == 0 ? "ROT" : "NONROT",
-+		bfqd->device_speed == BFQ_BFQD_FAST ? "FAST" : "SLOW",
-+		bfqd->device_speed == BFQ_BFQD_FAST ?
-+		(USEC_PER_SEC*(u64)R_fast[dev_type])>>BFQ_RATE_SHIFT :
-+		(USEC_PER_SEC*(u64)R_slow[dev_type])>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)device_speed_thresh[dev_type])>>
-+		BFQ_RATE_SHIFT);
-+}
-+
-+static void bfq_reset_rate_computation(struct bfq_data *bfqd, struct request *rq)
-+{
-+	if (rq != NULL) { /* new rq dispatch now, reset accordingly */
-+		bfqd->last_dispatch = bfqd->first_dispatch = ktime_get_ns() ;
-+		bfqd->peak_rate_samples = 1;
-+		bfqd->sequential_samples = 0;
-+		bfqd->tot_sectors_dispatched = bfqd->last_rq_max_size =
-+			blk_rq_sectors(rq);
-+	} else /* no new rq dispatched, just reset the number of samples */
-+		bfqd->peak_rate_samples = 0; /* full re-init on next disp. */
-+
-+	bfq_log(bfqd,
-+		"reset_rate_computation at end, sample %u/%u tot_sects %llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched);
-+}
-+
-+static void bfq_update_rate_reset(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u32 rate, weight, divisor;
-+
-+	/*
-+	 * For the convergence property to hold (see comments on
-+	 * bfq_update_peak_rate()) and for the assessment to be
-+	 * reliable, a minimum number of samples must be present, and
-+	 * a minimum amount of time must have elapsed. If not so, do
-+	 * not compute new rate. Just reset parameters, to get ready
-+	 * for a new evaluation attempt.
-+	 */
-+	if (bfqd->peak_rate_samples < BFQ_RATE_MIN_SAMPLES ||
-+	    bfqd->delta_from_first < BFQ_RATE_MIN_INTERVAL) {
-+		bfq_log(bfqd,
-+	"update_rate_reset: only resetting, delta_first %lluus samples %d",
-+			bfqd->delta_from_first>>10, bfqd->peak_rate_samples);
-+		goto reset_computation;
-+	}
-+
-+	/*
-+	 * If a new request completion has occurred after last
-+	 * dispatch, then, to approximate the rate at which requests
-+	 * have been served by the device, it is more precise to
-+	 * extend the observation interval to the last completion.
-+	 */
-+	bfqd->delta_from_first =
-+		max_t(u64, bfqd->delta_from_first,
-+		      bfqd->last_completion - bfqd->first_dispatch);
-+
-+	BUG_ON(bfqd->delta_from_first == 0);
-+	/*
-+	 * Rate computed in sects/usec, and not sects/nsec, for
-+	 * precision issues.
-+	 */
-+	rate = div64_ul(bfqd->tot_sectors_dispatched<<BFQ_RATE_SHIFT,
-+			div_u64(bfqd->delta_from_first, NSEC_PER_USEC));
-+
-+	bfq_log(bfqd,
-+"update_rate_reset: tot_sects %llu delta_first %lluus rate %llu sects/s (%d)",
-+		bfqd->tot_sectors_dispatched, bfqd->delta_from_first>>10,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		rate > 20<<BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * Peak rate not updated if:
-+	 * - the percentage of sequential dispatches is below 3/4 of the
-+	 *   total, and rate is below the current estimated peak rate
-+	 * - rate is unreasonably high (> 20M sectors/sec)
-+	 */
-+	if ((bfqd->sequential_samples < (3 * bfqd->peak_rate_samples)>>2 &&
-+	     rate <= bfqd->peak_rate) ||
-+		rate > 20<<BFQ_RATE_SHIFT) {
-+		bfq_log(bfqd,
-+		"update_rate_reset: goto reset, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+		goto reset_computation;
-+	} else {
-+		bfq_log(bfqd,
-+		"update_rate_reset: do update, samples %u/%u rate/peak %llu/%llu",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT),
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	}
-+
-+	/*
-+	 * We have to update the peak rate, at last! To this purpose,
-+	 * we use a low-pass filter. We compute the smoothing constant
-+	 * of the filter as a function of the 'weight' of the new
-+	 * measured rate.
-+	 *
-+	 * As can be seen in next formulas, we define this weight as a
-+	 * quantity proportional to how sequential the workload is,
-+	 * and to how long the observation time interval is.
-+	 *
-+	 * The weight runs from 0 to 8. The maximum value of the
-+	 * weight, 8, yields the minimum value for the smoothing
-+	 * constant. At this minimum value for the smoothing constant,
-+	 * the measured rate contributes for half of the next value of
-+	 * the estimated peak rate.
-+	 *
-+	 * So, the first step is to compute the weight as a function
-+	 * of how sequential the workload is. Note that the weight
-+	 * cannot reach 9, because bfqd->sequential_samples cannot
-+	 * become equal to bfqd->peak_rate_samples, which, in its
-+	 * turn, holds true because bfqd->sequential_samples is not
-+	 * incremented for the first sample.
-+	 */
-+	weight = (9 * bfqd->sequential_samples) / bfqd->peak_rate_samples;
-+
-+	/*
-+	 * Second step: further refine the weight as a function of the
-+	 * duration of the observation interval.
-+	 */
-+	weight = min_t(u32, 8,
-+		       div_u64(weight * bfqd->delta_from_first,
-+			       BFQ_RATE_REF_INTERVAL));
-+
-+	/*
-+	 * Divisor ranging from 10, for minimum weight, to 2, for
-+	 * maximum weight.
-+	 */
-+	divisor = 10 - weight;
-+	BUG_ON(divisor == 0);
-+
-+	/*
-+	 * Finally, update peak rate:
-+	 *
-+	 * peak_rate = peak_rate * (divisor-1) / divisor  +  rate / divisor
-+	 */
-+	bfqd->peak_rate *= divisor-1;
-+	bfqd->peak_rate /= divisor;
-+	rate /= divisor; /* smoothing constant alpha = 1/divisor */
-+
-+	bfq_log(bfqd,
-+		"update_rate_reset: divisor %d tmp_peak_rate %llu tmp_rate %u",
-+		divisor,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT),
-+		(u32)((USEC_PER_SEC*(u64)rate)>>BFQ_RATE_SHIFT));
-+
-+	BUG_ON(bfqd->peak_rate == 0);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+	bfqd->peak_rate += rate;
-+	update_thr_responsiveness_params(bfqd);
-+	BUG_ON(bfqd->peak_rate > 20<<BFQ_RATE_SHIFT);
-+
-+reset_computation:
-+	bfq_reset_rate_computation(bfqd, rq);
-+}
-+
-+/*
-+ * Update the read/write peak rate (the main quantity used for
-+ * auto-tuning, see update_thr_responsiveness_params()).
-+ *
-+ * It is not trivial to estimate the peak rate (correctly): because of
-+ * the presence of sw and hw queues between the scheduler and the
-+ * device components that finally serve I/O requests, it is hard to
-+ * say exactly when a given dispatched request is served inside the
-+ * device, and for how long. As a consequence, it is hard to know
-+ * precisely at what rate a given set of requests is actually served
-+ * by the device.
-+ *
-+ * On the opposite end, the dispatch time of any request is trivially
-+ * available, and, from this piece of information, the "dispatch rate"
-+ * of requests can be immediately computed. So, the idea in the next
-+ * function is to use what is known, namely request dispatch times
-+ * (plus, when useful, request completion times), to estimate what is
-+ * unknown, namely in-device request service rate.
-+ *
-+ * The main issue is that, because of the above facts, the rate at
-+ * which a certain set of requests is dispatched over a certain time
-+ * interval can vary greatly with respect to the rate at which the
-+ * same requests are then served. But, since the size of any
-+ * intermediate queue is limited, and the service scheme is lossless
-+ * (no request is silently dropped), the following obvious convergence
-+ * property holds: the number of requests dispatched MUST become
-+ * closer and closer to the number of requests completed as the
-+ * observation interval grows. This is the key property used in
-+ * the next function to estimate the peak service rate as a function
-+ * of the observed dispatch rate. The function assumes to be invoked
-+ * on every request dispatch.
-+ */
-+static void bfq_update_peak_rate(struct bfq_data *bfqd, struct request *rq)
-+{
-+	u64 now_ns = ktime_get_ns();
-+
-+	if (bfqd->peak_rate_samples == 0) { /* first dispatch */
-+		bfq_log(bfqd,
-+		"update_peak_rate: goto reset, samples %d",
-+				bfqd->peak_rate_samples) ;
-+		bfq_reset_rate_computation(bfqd, rq);
-+		goto update_last_values; /* will add one sample */
-+	}
-+
-+	/*
-+	 * Device idle for very long: the observation interval lasting
-+	 * up to this dispatch cannot be a valid observation interval
-+	 * for computing a new peak rate (similarly to the late-
-+	 * completion event in bfq_completed_request()). Go to
-+	 * update_rate_and_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - start a new observation interval with this dispatch
-+	 */
-+	if (now_ns - bfqd->last_dispatch > 100*NSEC_PER_MSEC &&
-+	    bfqd->rq_in_driver == 0) {
-+		bfq_log(bfqd,
-+"update_peak_rate: jumping to updating&resetting delta_last %lluus samples %d",
-+			(now_ns - bfqd->last_dispatch)>>10,
-+			bfqd->peak_rate_samples) ;
-+		goto update_rate_and_reset;
-+	}
-+
-+	/* Update sampling information */
-+	bfqd->peak_rate_samples++;
-+
-+	if ((bfqd->rq_in_driver > 0 ||
-+		now_ns - bfqd->last_completion < BFQ_MIN_TT)
-+	     && get_sdist(bfqd->last_position, rq) < BFQQ_SEEK_THR)
-+		bfqd->sequential_samples++;
-+
-+	bfqd->tot_sectors_dispatched += blk_rq_sectors(rq);
-+
-+	/* Reset max observed rq size every 32 dispatches */
-+	if (likely(bfqd->peak_rate_samples % 32))
-+		bfqd->last_rq_max_size =
-+			max_t(u32, blk_rq_sectors(rq), bfqd->last_rq_max_size);
-+	else
-+		bfqd->last_rq_max_size = blk_rq_sectors(rq);
-+
-+	bfqd->delta_from_first = now_ns - bfqd->first_dispatch;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: added samples %u/%u tot_sects %llu delta_first %lluus",
-+		bfqd->peak_rate_samples, bfqd->sequential_samples,
-+		bfqd->tot_sectors_dispatched,
-+		bfqd->delta_from_first>>10);
-+
-+	/* Target observation interval not yet reached, go on sampling */
-+	if (bfqd->delta_from_first < BFQ_RATE_REF_INTERVAL)
-+		goto update_last_values;
-+
-+update_rate_and_reset:
-+	bfq_update_rate_reset(bfqd, rq);
-+update_last_values:
-+	bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+	bfqd->last_dispatch = now_ns;
-+
-+	bfq_log(bfqd,
-+	"update_peak_rate: delta_first %lluus last_pos %llu peak_rate %llu",
-+		(now_ns - bfqd->first_dispatch)>>10,
-+		(unsigned long long) bfqd->last_position,
-+		((USEC_PER_SEC*(u64)bfqd->peak_rate)>>BFQ_RATE_SHIFT));
-+	bfq_log(bfqd,
-+	"update_peak_rate: samples at end %d", bfqd->peak_rate_samples);
-+}
-+
-+/*
-+ * Move request from internal lists to the dispatch list of the request queue
-+ */
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	/*
-+	 * For consistency, the next instruction should have been executed
-+	 * after removing the request from the queue and dispatching it.
-+	 * We execute instead this instruction before bfq_remove_request()
-+	 * (and hence introduce a temporary inconsistency), for efficiency.
-+	 * In fact, in a forced_dispatch, this prevents two counters related
-+	 * to bfqq->dispatched to risk to be uselessly decremented if bfqq
-+	 * is not in service, and then to be incremented again after
-+	 * incrementing bfqq->dispatched.
-+	 */
-+	bfqq->dispatched++;
-+	bfq_update_peak_rate(q->elevator->elevator_data, rq);
-+
-+	bfq_remove_request(rq);
-+	elv_dispatch_sort(q, rq);
-+}
-+
-+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * If this bfqq is shared between multiple processes, check
-+	 * to make sure that those processes are still issuing I/Os
-+	 * within the mean seek distance. If not, it may be time to
-+	 * break the queues apart again.
-+	 */
-+	if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
-+		bfq_mark_bfqq_split_coop(bfqq);
-+
-+	if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		if (bfqq->dispatched == 0)
-+			/*
-+			 * Overloading budget_timeout field to store
-+			 * the time at which the queue remains with no
-+			 * backlog and no outstanding request; used by
-+			 * the weight-raising mechanism.
-+			 */
-+			bfqq->budget_timeout = jiffies;
-+
-+		bfq_del_bfqq_busy(bfqd, bfqq, true);
-+	} else {
-+		bfq_requeue_bfqq(bfqd, bfqq);
-+		/*
-+		 * Resort priority tree of potential close cooperators.
-+		 */
-+		bfq_pos_tree_add_move(bfqd, bfqq);
-+	}
-+
-+	/*
-+	 * All in-service entities must have been properly deactivated
-+	 * or requeued before executing the next function, which
-+	 * resets all in-service entites as no more in service.
-+	 */
-+	__bfq_bfqd_reset_in_service(bfqd);
-+}
-+
-+/**
-+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
-+ * @bfqd: device data.
-+ * @bfqq: queue to update.
-+ * @reason: reason for expiration.
-+ *
-+ * Handle the feedback on @bfqq budget at queue expiration.
-+ * See the body for detailed comments.
-+ */
-+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
-+				     struct bfq_queue *bfqq,
-+				     enum bfqq_expiration reason)
-+{
-+	struct request *next_rq;
-+	int budget, min_budget;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	min_budget = bfq_min_budget(bfqd);
-+
-+	if (bfqq->wr_coeff == 1)
-+		budget = bfqq->max_budget;
-+	else /*
-+	      * Use a constant, low budget for weight-raised queues,
-+	      * to help achieve a low latency. Keep it slightly higher
-+	      * than the minimum possible budget, to cause a little
-+	      * bit fewer expirations.
-+	      */
-+		budget = 2 * min_budget;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %d, budg left %d",
-+		bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %d, min budg %d",
-+		budget, bfq_min_budget(bfqd));
-+	bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
-+		bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
-+
-+	if (bfq_bfqq_sync(bfqq) && bfqq->wr_coeff == 1) {
-+		switch (reason) {
-+		/*
-+		 * Caveat: in all the following cases we trade latency
-+		 * for throughput.
-+		 */
-+		case BFQ_BFQQ_TOO_IDLE:
-+			/*
-+			 * This is the only case where we may reduce
-+			 * the budget: if there is no request of the
-+			 * process still waiting for completion, then
-+			 * we assume (tentatively) that the timer has
-+			 * expired because the batch of requests of
-+			 * the process could have been served with a
-+			 * smaller budget.  Hence, betting that
-+			 * process will behave in the same way when it
-+			 * becomes backlogged again, we reduce its
-+			 * next budget.  As long as we guess right,
-+			 * this budget cut reduces the latency
-+			 * experienced by the process.
-+			 *
-+			 * However, if there are still outstanding
-+			 * requests, then the process may have not yet
-+			 * issued its next request just because it is
-+			 * still waiting for the completion of some of
-+			 * the still outstanding ones.  So in this
-+			 * subcase we do not reduce its budget, on the
-+			 * contrary we increase it to possibly boost
-+			 * the throughput, as discussed in the
-+			 * comments to the BUDGET_TIMEOUT case.
-+			 */
-+			if (bfqq->dispatched > 0) /* still outstanding reqs */
-+				budget = min(budget * 2, bfqd->bfq_max_budget);
-+			else {
-+				if (budget > 5 * min_budget)
-+					budget -= 4 * min_budget;
-+				else
-+					budget = min_budget;
-+			}
-+			break;
-+		case BFQ_BFQQ_BUDGET_TIMEOUT:
-+			/*
-+			 * We double the budget here because it gives
-+			 * the chance to boost the throughput if this
-+			 * is not a seeky process (and has bumped into
-+			 * this timeout because of, e.g., ZBR).
-+			 */
-+			budget = min(budget * 2, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_BUDGET_EXHAUSTED:
-+			/*
-+			 * The process still has backlog, and did not
-+			 * let either the budget timeout or the disk
-+			 * idling timeout expire. Hence it is not
-+			 * seeky, has a short thinktime and may be
-+			 * happy with a higher budget too. So
-+			 * definitely increase the budget of this good
-+			 * candidate to boost the disk throughput.
-+			 */
-+			budget = min(budget * 4, bfqd->bfq_max_budget);
-+			break;
-+		case BFQ_BFQQ_NO_MORE_REQUESTS:
-+			/*
-+			 * For queues that expire for this reason, it
-+			 * is particularly important to keep the
-+			 * budget close to the actual service they
-+			 * need. Doing so reduces the timestamp
-+			 * misalignment problem described in the
-+			 * comments in the body of
-+			 * __bfq_activate_entity. In fact, suppose
-+			 * that a queue systematically expires for
-+			 * BFQ_BFQQ_NO_MORE_REQUESTS and presents a
-+			 * new request in time to enjoy timestamp
-+			 * back-shifting. The larger the budget of the
-+			 * queue is with respect to the service the
-+			 * queue actually requests in each service
-+			 * slot, the more times the queue can be
-+			 * reactivated with the same virtual finish
-+			 * time. It follows that, even if this finish
-+			 * time is pushed to the system virtual time
-+			 * to reduce the consequent timestamp
-+			 * misalignment, the queue unjustly enjoys for
-+			 * many re-activations a lower finish time
-+			 * than all newly activated queues.
-+			 *
-+			 * The service needed by bfqq is measured
-+			 * quite precisely by bfqq->entity.service.
-+			 * Since bfqq does not enjoy device idling,
-+			 * bfqq->entity.service is equal to the number
-+			 * of sectors that the process associated with
-+			 * bfqq requested to read/write before waiting
-+			 * for request completions, or blocking for
-+			 * other reasons.
-+			 */
-+			budget = max_t(int, bfqq->entity.service, min_budget);
-+			break;
-+		default:
-+			return;
-+		}
-+	} else if (!bfq_bfqq_sync(bfqq))
-+		/*
-+		 * Async queues get always the maximum possible
-+		 * budget, as for them we do not care about latency
-+		 * (in addition, their ability to dispatch is limited
-+		 * by the charging factor).
-+		 */
-+		budget = bfqd->bfq_max_budget;
-+
-+	bfqq->max_budget = budget;
-+
-+	if (bfqd->budgets_assigned >= bfq_stats_min_budgets &&
-+	    !bfqd->bfq_user_max_budget)
-+		bfqq->max_budget = min(bfqq->max_budget, bfqd->bfq_max_budget);
-+
-+	/*
-+	 * If there is still backlog, then assign a new budget, making
-+	 * sure that it is large enough for the next request.  Since
-+	 * the finish time of bfqq must be kept in sync with the
-+	 * budget, be sure to call __bfq_bfqq_expire() *after* this
-+	 * update.
-+	 *
-+	 * If there is no backlog, then no need to update the budget;
-+	 * it will be updated on the arrival of a new request.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	if (next_rq) {
-+		BUG_ON(reason == BFQ_BFQQ_TOO_IDLE ||
-+		       reason == BFQ_BFQQ_NO_MORE_REQUESTS);
-+		bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
-+					    bfq_serv_to_charge(next_rq, bfqq));
-+		BUG_ON(!bfq_bfqq_busy(bfqq));
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %d",
-+			next_rq ? blk_rq_sectors(next_rq) : 0,
-+			bfqq->entity.budget);
-+}
-+
-+/*
-+ * Return true if the process associated with bfqq is "slow". The slow
-+ * flag is used, in addition to the budget timeout, to reduce the
-+ * amount of service provided to seeky processes, and thus reduce
-+ * their chances to lower the throughput. More details in the comments
-+ * on the function bfq_bfqq_expire().
-+ *
-+ * An important observation is in order: as discussed in the comments
-+ * on the function bfq_update_peak_rate(), with devices with internal
-+ * queues, it is hard if ever possible to know when and for how long
-+ * an I/O request is processed by the device (apart from the trivial
-+ * I/O pattern where a new request is dispatched only after the
-+ * previous one has been completed). This makes it hard to evaluate
-+ * the real rate at which the I/O requests of each bfq_queue are
-+ * served.  In fact, for an I/O scheduler like BFQ, serving a
-+ * bfq_queue means just dispatching its requests during its service
-+ * slot (i.e., until the budget of the queue is exhausted, or the
-+ * queue remains idle, or, finally, a timeout fires). But, during the
-+ * service slot of a bfq_queue, around 100 ms at most, the device may
-+ * be even still processing requests of bfq_queues served in previous
-+ * service slots. On the opposite end, the requests of the in-service
-+ * bfq_queue may be completed after the service slot of the queue
-+ * finishes.
-+ *
-+ * Anyway, unless more sophisticated solutions are used
-+ * (where possible), the sum of the sizes of the requests dispatched
-+ * during the service slot of a bfq_queue is probably the only
-+ * approximation available for the service received by the bfq_queue
-+ * during its service slot. And this sum is the quantity used in this
-+ * function to evaluate the I/O speed of a process.
-+ */
-+static bool bfq_bfqq_is_slow(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 bool compensate, enum bfqq_expiration reason,
-+				 unsigned long *delta_ms)
-+{
-+	ktime_t delta_ktime;
-+	u32 delta_usecs;
-+	bool slow = BFQQ_SEEKY(bfqq); /* if delta too short, use seekyness */
-+
-+	if (!bfq_bfqq_sync(bfqq))
-+		return false;
-+
-+	if (compensate)
-+		delta_ktime = bfqd->last_idling_start;
-+	else
-+		delta_ktime = ktime_get();
-+	delta_ktime = ktime_sub(delta_ktime, bfqd->last_budget_start);
-+	delta_usecs = ktime_to_us(delta_ktime);
-+
-+	/* don't use too short time intervals */
-+	if (delta_usecs < 1000) {
-+		if (blk_queue_nonrot(bfqd->queue))
-+			 /*
-+			  * give same worst-case guarantees as idling
-+			  * for seeky
-+			  */
-+			*delta_ms = BFQ_MIN_TT / NSEC_PER_MSEC;
-+		else /* charge at least one seek */
-+			*delta_ms = bfq_slice_idle / NSEC_PER_MSEC;
-+
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: too short %u", delta_usecs);
-+
-+		return slow;
-+	}
-+
-+	*delta_ms = delta_usecs / USEC_PER_MSEC;
-+
-+	/*
-+	 * Use only long (> 20ms) intervals to filter out excessive
-+	 * spikes in service rate estimation.
-+	 */
-+	if (delta_usecs > 20000) {
-+		/*
-+		 * Caveat for rotational devices: processes doing I/O
-+		 * in the slower disk zones tend to be slow(er) even
-+		 * if not seeky. In this respect, the estimated peak
-+		 * rate is likely to be an average over the disk
-+		 * surface. Accordingly, to not be too harsh with
-+		 * unlucky processes, a process is deemed slow only if
-+		 * its rate has been lower than half of the estimated
-+		 * peak rate.
-+		 */
-+		slow = bfqq->entity.service < bfqd->bfq_max_budget / 2;
-+		bfq_log(bfqd, "bfq_bfqq_is_slow: relative rate %d/%d",
-+			bfqq->entity.service, bfqd->bfq_max_budget);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "bfq_bfqq_is_slow: slow %d", slow);
-+
-+	return slow;
-+}
-+
-+/*
-+ * To be deemed as soft real-time, an application must meet two
-+ * requirements. First, the application must not require an average
-+ * bandwidth higher than the approximate bandwidth required to playback or
-+ * record a compressed high-definition video.
-+ * The next function is invoked on the completion of the last request of a
-+ * batch, to compute the next-start time instant, soft_rt_next_start, such
-+ * that, if the next request of the application does not arrive before
-+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
-+ *
-+ * The second requirement is that the request pattern of the application is
-+ * isochronous, i.e., that, after issuing a request or a batch of requests,
-+ * the application stops issuing new requests until all its pending requests
-+ * have been completed. After that, the application may issue a new batch,
-+ * and so on.
-+ * For this reason the next function is invoked to compute
-+ * soft_rt_next_start only for applications that meet this requirement,
-+ * whereas soft_rt_next_start is set to infinity for applications that do
-+ * not.
-+ *
-+ * Unfortunately, even a greedy application may happen to behave in an
-+ * isochronous way if the CPU load is high. In fact, the application may
-+ * stop issuing requests while the CPUs are busy serving other processes,
-+ * then restart, then stop again for a while, and so on. In addition, if
-+ * the disk achieves a low enough throughput with the request pattern
-+ * issued by the application (e.g., because the request pattern is random
-+ * and/or the device is slow), then the application may meet the above
-+ * bandwidth requirement too. To prevent such a greedy application to be
-+ * deemed as soft real-time, a further rule is used in the computation of
-+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
-+ * time plus the maximum time for which the arrival of a request is waited
-+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
-+ * This filters out greedy applications, as the latter issue instead their
-+ * next request as soon as possible after the last one has been completed
-+ * (in contrast, when a batch of requests is completed, a soft real-time
-+ * application spends some time processing data).
-+ *
-+ * Unfortunately, the last filter may easily generate false positives if
-+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
-+ * or both the following cases occur:
-+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
-+ *    than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
-+ *    HZ=100.
-+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
-+ *    for a while, then suddenly 'jump' by several units to recover the lost
-+ *    increments. This seems to happen, e.g., inside virtual machines.
-+ * To address this issue, we do not use as a reference time interval just
-+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
-+ * particular we add the minimum number of jiffies for which the filter
-+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
-+ * machines.
-+ */
-+static unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
-+						struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqd, bfqq,
-+"softrt_next_start: service_blkg %lu soft_rate %u sects/sec interval %u",
-+		     bfqq->service_from_backlogged,
-+		     bfqd->bfq_wr_max_softrt_rate,
-+		     jiffies_to_msecs(HZ * bfqq->service_from_backlogged /
-+				      bfqd->bfq_wr_max_softrt_rate));
-+
-+	return max(bfqq->last_idle_bklogged +
-+		   HZ * bfqq->service_from_backlogged /
-+		   bfqd->bfq_wr_max_softrt_rate,
-+		   jiffies + nsecs_to_jiffies(bfqq->bfqd->bfq_slice_idle) + 4);
-+}
-+
-+/*
-+ * Return the farthest future time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_greatest_from_now(void)
-+{
-+	return jiffies + MAX_JIFFY_OFFSET;
-+}
-+
-+/*
-+ * Return the farthest past time instant according to jiffies
-+ * macros.
-+ */
-+static unsigned long bfq_smallest_from_now(void)
-+{
-+	return jiffies - MAX_JIFFY_OFFSET;
-+}
-+
-+/**
-+ * bfq_bfqq_expire - expire a queue.
-+ * @bfqd: device owning the queue.
-+ * @bfqq: the queue to expire.
-+ * @compensate: if true, compensate for the time spent idling.
-+ * @reason: the reason causing the expiration.
-+ *
-+ * If the process associated with bfqq does slow I/O (e.g., because it
-+ * issues random requests), we charge bfqq with the time it has been
-+ * in service instead of the service it has received (see
-+ * bfq_bfqq_charge_time for details on how this goal is achieved). As
-+ * a consequence, bfqq will typically get higher timestamps upon
-+ * reactivation, and hence it will be rescheduled as if it had
-+ * received more service than what it has actually received. In the
-+ * end, bfqq receives less service in proportion to how slowly its
-+ * associated process consumes its budgets (and hence how seriously it
-+ * tends to lower the throughput). In addition, this time-charging
-+ * strategy guarantees time fairness among slow processes. In
-+ * contrast, if the process associated with bfqq is not slow, we
-+ * charge bfqq exactly with the service it has received.
-+ *
-+ * Charging time to the first type of queues and the exact service to
-+ * the other has the effect of using the WF2Q+ policy to schedule the
-+ * former on a timeslice basis, without violating service domain
-+ * guarantees among the latter.
-+ */
-+static void bfq_bfqq_expire(struct bfq_data *bfqd,
-+			    struct bfq_queue *bfqq,
-+			    bool compensate,
-+			    enum bfqq_expiration reason)
-+{
-+	bool slow;
-+	unsigned long delta = 0;
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int ref;
-+
-+	BUG_ON(bfqq != bfqd->in_service_queue);
-+
-+	/*
-+	 * Check whether the process is slow (see bfq_bfqq_is_slow).
-+	 */
-+	slow = bfq_bfqq_is_slow(bfqd, bfqq, compensate, reason, &delta);
-+
-+	/*
-+	 * Increase service_from_backlogged before next statement,
-+	 * because the possible next invocation of
-+	 * bfq_bfqq_charge_time would likely inflate
-+	 * entity->service. In contrast, service_from_backlogged must
-+	 * contain real service, to enable the soft real-time
-+	 * heuristic to correctly compute the bandwidth consumed by
-+	 * bfqq.
-+	 */
-+	bfqq->service_from_backlogged += entity->service;
-+
-+	/*
-+	 * As above explained, charge slow (typically seeky) and
-+	 * timed-out queues with the time and not the service
-+	 * received, to favor sequential workloads.
-+	 *
-+	 * Processes doing I/O in the slower disk zones will tend to
-+	 * be slow(er) even if not seeky. Therefore, since the
-+	 * estimated peak rate is actually an average over the disk
-+	 * surface, these processes may timeout just for bad luck. To
-+	 * avoid punishing them, do not charge time to processes that
-+	 * succeeded in consuming at least 2/3 of their budget. This
-+	 * allows BFQ to preserve enough elasticity to still perform
-+	 * bandwidth, and not time, distribution with little unlucky
-+	 * or quasi-sequential processes.
-+	 */
-+	if (bfqq->wr_coeff == 1 &&
-+	    (slow ||
-+	     (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	      bfq_bfqq_budget_left(bfqq) >=  entity->budget / 3)))
-+		bfq_bfqq_charge_time(bfqd, bfqq, delta);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	if (reason == BFQ_BFQQ_TOO_IDLE &&
-+	    entity->service <= 2 * entity->budget / 10)
-+		bfq_clear_bfqq_IO_bound(bfqq);
-+
-+	if (bfqd->low_latency && bfqq->wr_coeff == 1)
-+		bfqq->last_wr_start_finish = jiffies;
-+
-+	if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list)) {
-+		/*
-+		 * If we get here, and there are no outstanding
-+		 * requests, then the request pattern is isochronous
-+		 * (see the comments on the function
-+		 * bfq_bfqq_softrt_next_start()). Thus we can compute
-+		 * soft_rt_next_start. If, instead, the queue still
-+		 * has outstanding requests, then we have to wait for
-+		 * the completion of all the outstanding requests to
-+		 * discover whether the request pattern is actually
-+		 * isochronous.
-+		 */
-+		BUG_ON(bfqd->busy_queues < 1);
-+		if (bfqq->dispatched == 0) {
-+			bfqq->soft_rt_next_start =
-+				bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+			bfq_log_bfqq(bfqd, bfqq, "new soft_rt_next %lu",
-+				     bfqq->soft_rt_next_start);
-+		} else {
-+			/*
-+			 * The application is still waiting for the
-+			 * completion of one or more requests:
-+			 * prevent it from possibly being incorrectly
-+			 * deemed as soft real-time by setting its
-+			 * soft_rt_next_start to infinity. In fact,
-+			 * without this assignment, the application
-+			 * would be incorrectly deemed as soft
-+			 * real-time if:
-+			 * 1) it issued a new request before the
-+			 *    completion of all its in-flight
-+			 *    requests, and
-+			 * 2) at that time, its soft_rt_next_start
-+			 *    happened to be in the past.
-+			 */
-+			bfqq->soft_rt_next_start =
-+				bfq_greatest_from_now();
-+			/*
-+			 * Schedule an update of soft_rt_next_start to when
-+			 * the task may be discovered to be isochronous.
-+			 */
-+			bfq_mark_bfqq_softrt_update(bfqq);
-+		}
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		"expire (%d, slow %d, num_disp %d, idle_win %d, weight %d)",
-+		     reason, slow, bfqq->dispatched,
-+		     bfq_bfqq_idle_window(bfqq), entity->weight);
-+
-+	/*
-+	 * Increase, decrease or leave budget unchanged according to
-+	 * reason.
-+	 */
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+	__bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	ref = bfqq->ref;
-+	__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	BUG_ON(ref > 1 &&
-+	       !bfq_bfqq_busy(bfqq) && reason == BFQ_BFQQ_BUDGET_EXHAUSTED &&
-+		!bfq_class_idle(bfqq));
-+
-+	/* mark bfqq as waiting a request only if a bic still points to it */
-+	if (ref > 1 && !bfq_bfqq_busy(bfqq) &&
-+	    reason != BFQ_BFQQ_BUDGET_TIMEOUT &&
-+	    reason != BFQ_BFQQ_BUDGET_EXHAUSTED)
-+		bfq_mark_bfqq_non_blocking_wait_rq(bfqq);
-+}
-+
-+/*
-+ * Budget timeout is not implemented through a dedicated timer, but
-+ * just checked on request arrivals and completions, as well as on
-+ * idle timer expirations.
-+ */
-+static bool bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
-+{
-+	return time_is_before_eq_jiffies(bfqq->budget_timeout);
-+}
-+
-+/*
-+ * If we expire a queue that is actively waiting (i.e., with the
-+ * device idled) for the arrival of a new request, then we may incur
-+ * the timestamp misalignment problem described in the body of the
-+ * function __bfq_activate_entity. Hence we return true only if this
-+ * condition does not hold, or if the queue is slow enough to deserve
-+ * only to be kicked off for preserving a high throughput.
-+ */
-+static bool bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		"may_budget_timeout: wait_request %d left %d timeout %d",
-+		bfq_bfqq_wait_request(bfqq),
-+			bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3,
-+		bfq_bfqq_budget_timeout(bfqq));
-+
-+	return (!bfq_bfqq_wait_request(bfqq) ||
-+		bfq_bfqq_budget_left(bfqq) >=  bfqq->entity.budget / 3)
-+		&&
-+		bfq_bfqq_budget_timeout(bfqq);
-+}
-+
-+/*
-+ * For a queue that becomes empty, device idling is allowed only if
-+ * this function returns true for that queue. As a consequence, since
-+ * device idling plays a critical role for both throughput boosting
-+ * and service guarantees, the return value of this function plays a
-+ * critical role as well.
-+ *
-+ * In a nutshell, this function returns true only if idling is
-+ * beneficial for throughput or, even if detrimental for throughput,
-+ * idling is however necessary to preserve service guarantees (low
-+ * latency, desired throughput distribution, ...). In particular, on
-+ * NCQ-capable devices, this function tries to return false, so as to
-+ * help keep the drives' internal queues full, whenever this helps the
-+ * device boost the throughput without causing any service-guarantee
-+ * issue.
-+ *
-+ * In more detail, the return value of this function is obtained by,
-+ * first, computing a number of boolean variables that take into
-+ * account throughput and service-guarantee issues, and, then,
-+ * combining these variables in a logical expression. Most of the
-+ * issues taken into account are not trivial. We discuss these issues
-+ * while introducing the variables.
-+ */
-+static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	bool idling_boosts_thr, idling_boosts_thr_without_issues,
-+		idling_needed_for_service_guarantees,
-+		asymmetric_scenario;
-+
-+	if (bfqd->strict_guarantees)
-+		return true;
-+
-+	/*
-+	 * The next variable takes into account the cases where idling
-+	 * boosts the throughput.
-+	 *
-+	 * The value of the variable is computed considering, first, that
-+	 * idling is virtually always beneficial for the throughput if:
-+	 * (a) the device is not NCQ-capable, or
-+	 * (b) regardless of the presence of NCQ, the device is rotational
-+	 *     and the request pattern for bfqq is I/O-bound and sequential.
-+	 *
-+	 * Secondly, and in contrast to the above item (b), idling an
-+	 * NCQ-capable flash-based device would not boost the
-+	 * throughput even with sequential I/O; rather it would lower
-+	 * the throughput in proportion to how fast the device
-+	 * is. Accordingly, the next variable is true if any of the
-+	 * above conditions (a) and (b) is true, and, in particular,
-+	 * happens to be false if bfqd is an NCQ-capable flash-based
-+	 * device.
-+	 */
-+	idling_boosts_thr = !bfqd->hw_tag ||
-+		(!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
-+		 bfq_bfqq_idle_window(bfqq));
-+
-+	/*
-+	 * The value of the next variable,
-+	 * idling_boosts_thr_without_issues, is equal to that of
-+	 * idling_boosts_thr, unless a special case holds. In this
-+	 * special case, described below, idling may cause problems to
-+	 * weight-raised queues.
-+	 *
-+	 * When the request pool is saturated (e.g., in the presence
-+	 * of write hogs), if the processes associated with
-+	 * non-weight-raised queues ask for requests at a lower rate,
-+	 * then processes associated with weight-raised queues have a
-+	 * higher probability to get a request from the pool
-+	 * immediately (or at least soon) when they need one. Thus
-+	 * they have a higher probability to actually get a fraction
-+	 * of the device throughput proportional to their high
-+	 * weight. This is especially true with NCQ-capable drives,
-+	 * which enqueue several requests in advance, and further
-+	 * reorder internally-queued requests.
-+	 *
-+	 * For this reason, we force to false the value of
-+	 * idling_boosts_thr_without_issues if there are weight-raised
-+	 * busy queues. In this case, and if bfqq is not weight-raised,
-+	 * this guarantees that the device is not idled for bfqq (if,
-+	 * instead, bfqq is weight-raised, then idling will be
-+	 * guaranteed by another variable, see below). Combined with
-+	 * the timestamping rules of BFQ (see [1] for details), this
-+	 * behavior causes bfqq, and hence any sync non-weight-raised
-+	 * queue, to get a lower number of requests served, and thus
-+	 * to ask for a lower number of requests from the request
-+	 * pool, before the busy weight-raised queues get served
-+	 * again. This often mitigates starvation problems in the
-+	 * presence of heavy write workloads and NCQ, thereby
-+	 * guaranteeing a higher application and system responsiveness
-+	 * in these hostile scenarios.
-+	 */
-+	idling_boosts_thr_without_issues = idling_boosts_thr &&
-+		bfqd->wr_busy_queues == 0;
-+
-+	/*
-+	 * There is then a case where idling must be performed not
-+	 * for throughput concerns, but to preserve service
-+	 * guarantees.
-+	 *
-+	 * To introduce this case, we can note that allowing the drive
-+	 * to enqueue more than one request at a time, and hence
-+	 * delegating de facto final scheduling decisions to the
-+	 * drive's internal scheduler, entails loss of control on the
-+	 * actual request service order. In particular, the critical
-+	 * situation is when requests from different processes happen
-+	 * to be present, at the same time, in the internal queue(s)
-+	 * of the drive. In such a situation, the drive, by deciding
-+	 * the service order of the internally-queued requests, does
-+	 * determine also the actual throughput distribution among
-+	 * these processes. But the drive typically has no notion or
-+	 * concern about per-process throughput distribution, and
-+	 * makes its decisions only on a per-request basis. Therefore,
-+	 * the service distribution enforced by the drive's internal
-+	 * scheduler is likely to coincide with the desired
-+	 * device-throughput distribution only in a completely
-+	 * symmetric scenario where:
-+	 * (i)  each of these processes must get the same throughput as
-+	 *      the others;
-+	 * (ii) all these processes have the same I/O pattern
-+	 *      (either sequential or random).
-+	 * In fact, in such a scenario, the drive will tend to treat
-+	 * the requests of each of these processes in about the same
-+	 * way as the requests of the others, and thus to provide
-+	 * each of these processes with about the same throughput
-+	 * (which is exactly the desired throughput distribution). In
-+	 * contrast, in any asymmetric scenario, device idling is
-+	 * certainly needed to guarantee that bfqq receives its
-+	 * assigned fraction of the device throughput (see [1] for
-+	 * details).
-+	 *
-+	 * We address this issue by controlling, actually, only the
-+	 * symmetry sub-condition (i), i.e., provided that
-+	 * sub-condition (i) holds, idling is not performed,
-+	 * regardless of whether sub-condition (ii) holds. In other
-+	 * words, only if sub-condition (i) holds, then idling is
-+	 * allowed, and the device tends to be prevented from queueing
-+	 * many requests, possibly of several processes. The reason
-+	 * for not controlling also sub-condition (ii) is that we
-+	 * exploit preemption to preserve guarantees in case of
-+	 * symmetric scenarios, even if (ii) does not hold, as
-+	 * explained in the next two paragraphs.
-+	 *
-+	 * Even if a queue, say Q, is expired when it remains idle, Q
-+	 * can still preempt the new in-service queue if the next
-+	 * request of Q arrives soon (see the comments on
-+	 * bfq_bfqq_update_budg_for_activation). If all queues and
-+	 * groups have the same weight, this form of preemption,
-+	 * combined with the hole-recovery heuristic described in the
-+	 * comments on function bfq_bfqq_update_budg_for_activation,
-+	 * are enough to preserve a correct bandwidth distribution in
-+	 * the mid term, even without idling. In fact, even if not
-+	 * idling allows the internal queues of the device to contain
-+	 * many requests, and thus to reorder requests, we can rather
-+	 * safely assume that the internal scheduler still preserves a
-+	 * minimum of mid-term fairness. The motivation for using
-+	 * preemption instead of idling is that, by not idling,
-+	 * service guarantees are preserved without minimally
-+	 * sacrificing throughput. In other words, both a high
-+	 * throughput and its desired distribution are obtained.
-+	 *
-+	 * More precisely, this preemption-based, idleless approach
-+	 * provides fairness in terms of IOPS, and not sectors per
-+	 * second. This can be seen with a simple example. Suppose
-+	 * that there are two queues with the same weight, but that
-+	 * the first queue receives requests of 8 sectors, while the
-+	 * second queue receives requests of 1024 sectors. In
-+	 * addition, suppose that each of the two queues contains at
-+	 * most one request at a time, which implies that each queue
-+	 * always remains idle after it is served. Finally, after
-+	 * remaining idle, each queue receives very quickly a new
-+	 * request. It follows that the two queues are served
-+	 * alternatively, preempting each other if needed. This
-+	 * implies that, although both queues have the same weight,
-+	 * the queue with large requests receives a service that is
-+	 * 1024/8 times as high as the service received by the other
-+	 * queue.
-+	 *
-+	 * On the other hand, device idling is performed, and thus
-+	 * pure sector-domain guarantees are provided, for the
-+	 * following queues, which are likely to need stronger
-+	 * throughput guarantees: weight-raised queues, and queues
-+	 * with a higher weight than other queues. When such queues
-+	 * are active, sub-condition (i) is false, which triggers
-+	 * device idling.
-+	 *
-+	 * According to the above considerations, the next variable is
-+	 * true (only) if sub-condition (i) holds. To compute the
-+	 * value of this variable, we not only use the return value of
-+	 * the function bfq_symmetric_scenario(), but also check
-+	 * whether bfqq is being weight-raised, because
-+	 * bfq_symmetric_scenario() does not take into account also
-+	 * weight-raised queues (see comments on
-+	 * bfq_weights_tree_add()).
-+	 *
-+	 * As a side note, it is worth considering that the above
-+	 * device-idling countermeasures may however fail in the
-+	 * following unlucky scenario: if idling is (correctly)
-+	 * disabled in a time period during which all symmetry
-+	 * sub-conditions hold, and hence the device is allowed to
-+	 * enqueue many requests, but at some later point in time some
-+	 * sub-condition stops to hold, then it may become impossible
-+	 * to let requests be served in the desired order until all
-+	 * the requests already queued in the device have been served.
-+	 */
-+	asymmetric_scenario = bfqq->wr_coeff > 1 ||
-+		!bfq_symmetric_scenario(bfqd);
-+
-+	/*
-+	 * Finally, there is a case where maximizing throughput is the
-+	 * best choice even if it may cause unfairness toward
-+	 * bfqq. Such a case is when bfqq became active in a burst of
-+	 * queue activations. Queues that became active during a large
-+	 * burst benefit only from throughput, as discussed in the
-+	 * comments on bfq_handle_burst. Thus, if bfqq became active
-+	 * in a burst and not idling the device maximizes throughput,
-+	 * then the device must no be idled, because not idling the
-+	 * device provides bfqq and all other queues in the burst with
-+	 * maximum benefit. Combining this and the above case, we can
-+	 * now establish when idling is actually needed to preserve
-+	 * service guarantees.
-+	 */
-+	idling_needed_for_service_guarantees =
-+		asymmetric_scenario && !bfq_bfqq_in_large_burst(bfqq);
-+
-+	/*
-+	 * We have now all the components we need to compute the return
-+	 * value of the function, which is true only if both the following
-+	 * conditions hold:
-+	 * 1) bfqq is sync, because idling make sense only for sync queues;
-+	 * 2) idling either boosts the throughput (without issues), or
-+	 *    is necessary to preserve service guarantees.
-+	 */
-+	bfq_log_bfqq(bfqd, bfqq, "may_idle: sync %d idling_boosts_thr %d",
-+		     bfq_bfqq_sync(bfqq), idling_boosts_thr);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "may_idle: wr_busy %d boosts %d IO-bound %d guar %d",
-+		     bfqd->wr_busy_queues,
-+		     idling_boosts_thr_without_issues,
-+		     bfq_bfqq_IO_bound(bfqq),
-+		     idling_needed_for_service_guarantees);
-+
-+	return bfq_bfqq_sync(bfqq) &&
-+		(idling_boosts_thr_without_issues ||
-+		 idling_needed_for_service_guarantees);
-+}
-+
-+/*
-+ * If the in-service queue is empty but the function bfq_bfqq_may_idle
-+ * returns true, then:
-+ * 1) the queue must remain in service and cannot be expired, and
-+ * 2) the device must be idled to wait for the possible arrival of a new
-+ *    request for the queue.
-+ * See the comments on the function bfq_bfqq_may_idle for the reasons
-+ * why performing device idling is the best choice to boost the throughput
-+ * and preserve service guarantees when bfq_bfqq_may_idle itself
-+ * returns true.
-+ */
-+static bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
-+{
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+
-+	return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
-+	       bfq_bfqq_may_idle(bfqq);
-+}
-+
-+/*
-+ * Select a queue for service.  If we have a current queue in service,
-+ * check whether to continue servicing it, or retrieve and set a new one.
-+ */
-+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq;
-+	struct request *next_rq;
-+	enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (!bfqq)
-+		goto new_queue;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
-+
-+	if (bfq_may_expire_for_budg_timeout(bfqq) &&
-+	    !hrtimer_active(&bfqd->idle_slice_timer) &&
-+	    !bfq_bfqq_must_idle(bfqq))
-+		goto expire;
-+
-+check_queue:
-+	/*
-+	 * This loop is rarely executed more than once. Even when it
-+	 * happens, it is much more convenient to re-execute this loop
-+	 * than to return NULL and trigger a new dispatch to get a
-+	 * request served.
-+	 */
-+	next_rq = bfqq->next_rq;
-+	/*
-+	 * If bfqq has requests queued and it has enough budget left to
-+	 * serve them, keep the queue, otherwise expire it.
-+	 */
-+	if (next_rq) {
-+		BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+		if (bfq_serv_to_charge(next_rq, bfqq) >
-+			bfq_bfqq_budget_left(bfqq)) {
-+			/*
-+			 * Expire the queue for budget exhaustion,
-+			 * which makes sure that the next budget is
-+			 * enough to serve the next request, even if
-+			 * it comes from the fifo expired path.
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
-+			goto expire;
-+		} else {
-+			/*
-+			 * The idle timer may be pending because we may
-+			 * not disable disk idling even when a new request
-+			 * arrives.
-+			 */
-+			if (bfq_bfqq_wait_request(bfqq)) {
-+				BUG_ON(!hrtimer_active(&bfqd->idle_slice_timer));
-+				/*
-+				 * If we get here: 1) at least a new request
-+				 * has arrived but we have not disabled the
-+				 * timer because the request was too small,
-+				 * 2) then the block layer has unplugged
-+				 * the device, causing the dispatch to be
-+				 * invoked.
-+				 *
-+				 * Since the device is unplugged, now the
-+				 * requests are probably large enough to
-+				 * provide a reasonable throughput.
-+				 * So we disable idling.
-+				 */
-+				bfq_clear_bfqq_wait_request(bfqq);
-+				hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+				bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+			}
-+			goto keep_queue;
-+		}
-+	}
-+
-+	/*
-+	 * No requests pending. However, if the in-service queue is idling
-+	 * for a new request, or has requests waiting for a completion and
-+	 * may idle after their completion, then keep it anyway.
-+	 */
-+	if (hrtimer_active(&bfqd->idle_slice_timer) ||
-+	    (bfqq->dispatched != 0 && bfq_bfqq_may_idle(bfqq))) {
-+		bfqq = NULL;
-+		goto keep_queue;
-+	}
-+
-+	reason = BFQ_BFQQ_NO_MORE_REQUESTS;
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, reason);
-+new_queue:
-+	bfqq = bfq_set_in_service_queue(bfqd);
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: checking new queue");
-+		goto check_queue;
-+	}
-+keep_queue:
-+	if (bfqq)
-+		bfq_log_bfqq(bfqd, bfqq, "select_queue: returned this queue");
-+	else
-+		bfq_log(bfqd, "select_queue: no queue returned");
-+
-+	return bfqq;
-+}
-+
-+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
-+		BUG_ON(bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time &&
-+		       time_is_after_jiffies(bfqq->last_wr_start_finish));
-+
-+		bfq_log_bfqq(bfqd, bfqq,
-+			"raising period dur %u/%u msec, old coeff %u, w %d(%d)",
-+			jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
-+			jiffies_to_msecs(bfqq->wr_cur_max_time),
-+			bfqq->wr_coeff,
-+			bfqq->entity.weight, bfqq->entity.orig_weight);
-+
-+		BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
-+		       entity->orig_weight * bfqq->wr_coeff);
-+		if (entity->prio_changed)
-+			bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
-+
-+		/*
-+		 * If the queue was activated in a burst, or too much
-+		 * time has elapsed from the beginning of this
-+		 * weight-raising period, then end weight raising.
-+		 */
-+		if (bfq_bfqq_in_large_burst(bfqq))
-+			bfq_bfqq_end_wr(bfqq);
-+		else if (time_is_before_jiffies(bfqq->last_wr_start_finish +
-+					   bfqq->wr_cur_max_time)) {
-+			if (bfqq->wr_cur_max_time != bfqd->bfq_wr_rt_max_time ||
-+			time_is_before_jiffies(bfqq->wr_start_at_switch_to_srt +
-+					bfq_wr_duration(bfqd)))
-+				bfq_bfqq_end_wr(bfqq);
-+			else {
-+				/* switch back to interactive wr */
-+				bfqq->wr_coeff = bfqd->bfq_wr_coeff;
-+				bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
-+				bfqq->last_wr_start_finish =
-+					bfqq->wr_start_at_switch_to_srt;
-+				BUG_ON(time_is_after_jiffies(
-+					       bfqq->last_wr_start_finish));
-+				bfqq->entity.prio_changed = 1;
-+				bfq_log_bfqq(bfqd, bfqq,
-+					"back to interactive wr");
-+			}
-+		}
-+	}
-+	/* Update weight both if it must be raised and if it must be lowered */
-+	if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
-+		__bfq_entity_update_weight_prio(
-+			bfq_entity_service_tree(entity),
-+			entity);
-+}
-+
-+/*
-+ * Dispatch one request from bfqq, moving it to the request queue
-+ * dispatch list.
-+ */
-+static int bfq_dispatch_request(struct bfq_data *bfqd,
-+				struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+	struct request *rq = bfqq->next_rq;
-+	unsigned long service_to_charge;
-+
-+	BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
-+	BUG_ON(!rq);
-+	service_to_charge = bfq_serv_to_charge(rq, bfqq);
-+
-+	BUG_ON(service_to_charge > bfq_bfqq_budget_left(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_bfqq_served(bfqq, service_to_charge);
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	bfq_dispatch_insert(bfqd->queue, rq);
-+
-+	/*
-+	 * If weight raising has to terminate for bfqq, then next
-+	 * function causes an immediate update of bfqq's weight,
-+	 * without waiting for next activation. As a consequence, on
-+	 * expiration, bfqq will be timestamped as if has never been
-+	 * weight-raised during this service slot, even if it has
-+	 * received part or even most of the service as a
-+	 * weight-raised queue. This inflates bfqq's timestamps, which
-+	 * is beneficial, as bfqq is then more willing to leave the
-+	 * device immediately to possible other weight-raised queues.
-+	 */
-+	bfq_update_wr_data(bfqd, bfqq);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+			"dispatched %u sec req (%llu), budg left %d",
-+			blk_rq_sectors(rq),
-+			(unsigned long long) blk_rq_pos(rq),
-+			bfq_bfqq_budget_left(bfqq));
-+
-+	dispatched++;
-+
-+	if (!bfqd->in_service_bic) {
-+		atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
-+		bfqd->in_service_bic = RQ_BIC(rq);
-+	}
-+
-+	if (bfqd->busy_queues > 1 && bfq_class_idle(bfqq))
-+		goto expire;
-+
-+	return dispatched;
-+
-+expire:
-+	bfq_bfqq_expire(bfqd, bfqq, false, BFQ_BFQQ_BUDGET_EXHAUSTED);
-+	return dispatched;
-+}
-+
-+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
-+{
-+	int dispatched = 0;
-+
-+	while (bfqq->next_rq) {
-+		bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
-+		dispatched++;
-+	}
-+
-+	BUG_ON(!list_empty(&bfqq->fifo));
-+	return dispatched;
-+}
-+
-+/*
-+ * Drain our current requests.
-+ * Used for barriers and when switching io schedulers on-the-fly.
-+ */
-+static int bfq_forced_dispatch(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *bfqq, *n;
-+	struct bfq_service_tree *st;
-+	int dispatched = 0;
-+
-+	bfqq = bfqd->in_service_queue;
-+	if (bfqq)
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+
-+	/*
-+	 * Loop through classes, and be careful to leave the scheduler
-+	 * in a consistent state, as feedback mechanisms and vtime
-+	 * updates cannot be disabled during the process.
-+	 */
-+	list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
-+		st = bfq_entity_service_tree(&bfqq->entity);
-+
-+		dispatched += __bfq_forced_dispatch_bfqq(bfqq);
-+
-+		bfqq->max_budget = bfq_max_budget(bfqd);
-+		bfq_forget_idle(st);
-+	}
-+
-+	BUG_ON(bfqd->busy_queues != 0);
-+
-+	return dispatched;
-+}
-+
-+static int bfq_dispatch_requests(struct request_queue *q, int force)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq;
-+
-+	bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
-+
-+	if (bfqd->busy_queues == 0)
-+		return 0;
-+
-+	if (unlikely(force))
-+		return bfq_forced_dispatch(bfqd);
-+
-+	/*
-+	 * Force device to serve one request at a time if
-+	 * strict_guarantees is true. Forcing this service scheme is
-+	 * currently the ONLY way to guarantee that the request
-+	 * service order enforced by the scheduler is respected by a
-+	 * queueing device. Otherwise the device is free even to make
-+	 * some unlucky request wait for as long as the device
-+	 * wishes.
-+	 *
-+	 * Of course, serving one request at at time may cause loss of
-+	 * throughput.
-+	 */
-+	if (bfqd->strict_guarantees && bfqd->rq_in_driver > 0)
-+		return 0;
-+
-+	bfqq = bfq_select_queue(bfqd);
-+	if (!bfqq)
-+		return 0;
-+
-+	BUG_ON(bfqq->entity.budget < bfqq->entity.service);
-+
-+	BUG_ON(bfq_bfqq_wait_request(bfqq));
-+
-+	if (!bfq_dispatch_request(bfqd, bfqq))
-+		return 0;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "dispatched %s request",
-+			bfq_bfqq_sync(bfqq) ? "sync" : "async");
-+
-+	BUG_ON(bfqq->next_rq == NULL &&
-+	       bfqq->entity.budget < bfqq->entity.service);
-+	return 1;
-+}
-+
-+/*
-+ * Task holds one reference to the queue, dropped when task exits.  Each rq
-+ * in-flight on this queue also holds a reference, dropped when rq is freed.
-+ *
-+ * Queue lock must be held here. Recall not to use bfqq after calling
-+ * this function on it.
-+ */
-+static void bfq_put_queue(struct bfq_queue *bfqq)
-+{
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	struct bfq_group *bfqg = bfqq_group(bfqq);
-+#endif
-+
-+	BUG_ON(bfqq->ref <= 0);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p %d", bfqq, bfqq->ref);
-+	bfqq->ref--;
-+	if (bfqq->ref)
-+		return;
-+
-+	BUG_ON(rb_first(&bfqq->sort_list));
-+	BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
-+	BUG_ON(bfqq->entity.tree);
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+
-+	if (bfq_bfqq_sync(bfqq))
-+		/*
-+		 * The fact that this queue is being destroyed does not
-+		 * invalidate the fact that this queue may have been
-+		 * activated during the current burst. As a consequence,
-+		 * although the queue does not exist anymore, and hence
-+		 * needs to be removed from the burst list if there,
-+		 * the burst size has not to be decremented.
-+		 */
-+		hlist_del_init(&bfqq->burst_list_node);
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "put_queue: %p freed", bfqq);
-+
-+	kmem_cache_free(bfq_pool, bfqq);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	bfqg_put(bfqg);
-+#endif
-+}
-+
-+static void bfq_put_cooperator(struct bfq_queue *bfqq)
-+{
-+	struct bfq_queue *__bfqq, *next;
-+
-+	/*
-+	 * If this queue was scheduled to merge with another queue, be
-+	 * sure to drop the reference taken on that queue (and others in
-+	 * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
-+	 */
-+	__bfqq = bfqq->new_bfqq;
-+	while (__bfqq) {
-+		if (__bfqq == bfqq)
-+			break;
-+		next = __bfqq->new_bfqq;
-+		bfq_put_queue(__bfqq);
-+		__bfqq = next;
-+	}
-+}
-+
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	if (bfqq == bfqd->in_service_queue) {
-+		__bfq_bfqq_expire(bfqd, bfqq);
-+		bfq_schedule_dispatch(bfqd);
-+	}
-+
-+	bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, bfqq->ref);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq); /* release process reference */
-+}
-+
-+static void bfq_init_icq(struct io_cq *icq)
-+{
-+	icq_to_bic(icq)->ttime.last_end_request = ktime_get_ns() - (1ULL<<32);
-+}
-+
-+static void bfq_exit_icq(struct io_cq *icq)
-+{
-+	struct bfq_io_cq *bic = icq_to_bic(icq);
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+
-+	if (bic_to_bfqq(bic, false)) {
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, false));
-+		bic_set_bfqq(bic, NULL, false);
-+	}
-+
-+	if (bic_to_bfqq(bic, true)) {
-+		/*
-+		 * If the bic is using a shared queue, put the reference
-+		 * taken on the io_context when the bic started using a
-+		 * shared bfq_queue.
-+		 */
-+		if (bfq_bfqq_coop(bic_to_bfqq(bic, true)))
-+			put_io_context(icq->ioc);
-+		bfq_exit_bfqq(bfqd, bic_to_bfqq(bic, true));
-+		bic_set_bfqq(bic, NULL, true);
-+	}
-+}
-+
-+/*
-+ * Update the entity prio values; note that the new values will not
-+ * be used until the next (re)activation.
-+ */
-+static void bfq_set_next_ioprio_data(struct bfq_queue *bfqq,
-+				     struct bfq_io_cq *bic)
-+{
-+	struct task_struct *tsk = current;
-+	int ioprio_class;
-+
-+	ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	switch (ioprio_class) {
-+	default:
-+		dev_err(bfqq->bfqd->queue->backing_dev_info->dev,
-+			"bfq: bad prio class %d\n", ioprio_class);
-+	case IOPRIO_CLASS_NONE:
-+		/*
-+		 * No prio set, inherit CPU scheduling settings.
-+		 */
-+		bfqq->new_ioprio = task_nice_ioprio(tsk);
-+		bfqq->new_ioprio_class = task_nice_ioclass(tsk);
-+		break;
-+	case IOPRIO_CLASS_RT:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_RT;
-+		break;
-+	case IOPRIO_CLASS_BE:
-+		bfqq->new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_BE;
-+		break;
-+	case IOPRIO_CLASS_IDLE:
-+		bfqq->new_ioprio_class = IOPRIO_CLASS_IDLE;
-+		bfqq->new_ioprio = 7;
-+		bfq_clear_bfqq_idle_window(bfqq);
-+		break;
-+	}
-+
-+	if (bfqq->new_ioprio >= IOPRIO_BE_NR) {
-+		pr_crit("bfq_set_next_ioprio_data: new_ioprio %d\n",
-+			bfqq->new_ioprio);
-+		BUG();
-+	}
-+
-+	bfqq->entity.new_weight = bfq_ioprio_to_weight(bfqq->new_ioprio);
-+	bfqq->entity.prio_changed = 1;
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "set_next_ioprio_data: bic_class %d prio %d class %d",
-+		     ioprio_class, bfqq->new_ioprio, bfqq->new_ioprio_class);
-+}
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio)
-+{
-+	struct bfq_data *bfqd = bic_to_bfqd(bic);
-+	struct bfq_queue *bfqq;
-+	unsigned long uninitialized_var(flags);
-+	int ioprio = bic->icq.ioc->ioprio;
-+
-+	/*
-+	 * This condition may trigger on a newly created bic, be sure to
-+	 * drop the lock before returning.
-+	 */
-+	if (unlikely(!bfqd) || likely(bic->ioprio == ioprio))
-+		return;
-+
-+	bic->ioprio = ioprio;
-+
-+	bfqq = bic_to_bfqq(bic, false);
-+	if (bfqq) {
-+		/* release process reference on this queue */
-+		bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, BLK_RW_ASYNC, bic);
-+		bic_set_bfqq(bic, bfqq, false);
-+		bfq_log_bfqq(bfqd, bfqq,
-+			     "check_ioprio_change: bfqq %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+
-+	bfqq = bic_to_bfqq(bic, true);
-+	if (bfqq)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+}
-+
-+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			  struct bfq_io_cq *bic, pid_t pid, int is_sync)
-+{
-+	RB_CLEAR_NODE(&bfqq->entity.rb_node);
-+	INIT_LIST_HEAD(&bfqq->fifo);
-+	INIT_HLIST_NODE(&bfqq->burst_list_node);
-+	BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+	bfqq->ref = 0;
-+	bfqq->bfqd = bfqd;
-+
-+	if (bic)
-+		bfq_set_next_ioprio_data(bfqq, bic);
-+
-+	if (is_sync) {
-+		if (!bfq_class_idle(bfqq))
-+			bfq_mark_bfqq_idle_window(bfqq);
-+		bfq_mark_bfqq_sync(bfqq);
-+		bfq_mark_bfqq_just_created(bfqq);
-+	} else
-+		bfq_clear_bfqq_sync(bfqq);
-+	bfq_mark_bfqq_IO_bound(bfqq);
-+
-+	/* Tentative initial value to trade off between thr and lat */
-+	bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
-+	bfqq->pid = pid;
-+
-+	bfqq->wr_coeff = 1;
-+	bfqq->last_wr_start_finish = jiffies;
-+	bfqq->wr_start_at_switch_to_srt = bfq_smallest_from_now();
-+	bfqq->budget_timeout = bfq_smallest_from_now();
-+	bfqq->split_time = bfq_smallest_from_now();
-+
-+	/*
-+	 * Set to the value for which bfqq will not be deemed as
-+	 * soft rt when it becomes backlogged.
-+	 */
-+	bfqq->soft_rt_next_start = bfq_greatest_from_now();
-+
-+	/* first request is almost certainly seeky */
-+	bfqq->seek_history = 1;
-+}
-+
-+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
-+					       struct bfq_group *bfqg,
-+					       int ioprio_class, int ioprio)
-+{
-+	switch (ioprio_class) {
-+	case IOPRIO_CLASS_RT:
-+		return &bfqg->async_bfqq[0][ioprio];
-+	case IOPRIO_CLASS_NONE:
-+		ioprio = IOPRIO_NORM;
-+		/* fall through */
-+	case IOPRIO_CLASS_BE:
-+		return &bfqg->async_bfqq[1][ioprio];
-+	case IOPRIO_CLASS_IDLE:
-+		return &bfqg->async_idle_bfqq;
-+	default:
-+		BUG();
-+	}
-+}
-+
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic)
-+{
-+	const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio);
-+	const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio);
-+	struct bfq_queue **async_bfqq = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_group *bfqg;
-+
-+	rcu_read_lock();
-+
-+	bfqg = bfq_find_set_group(bfqd, bio_blkcg(bio));
-+	if (!bfqg) {
-+		bfqq = &bfqd->oom_bfqq;
-+		goto out;
-+	}
-+
-+	if (!is_sync) {
-+		async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
-+						  ioprio);
-+		bfqq = *async_bfqq;
-+		if (bfqq)
-+			goto out;
-+	}
-+
-+	bfqq = kmem_cache_alloc_node(bfq_pool,
-+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
-+				     bfqd->queue->node);
-+
-+	if (bfqq) {
-+		bfq_init_bfqq(bfqd, bfqq, bic, current->pid,
-+			      is_sync);
-+		bfq_init_entity(&bfqq->entity, bfqg);
-+		bfq_log_bfqq(bfqd, bfqq, "allocated");
-+	} else {
-+		bfqq = &bfqd->oom_bfqq;
-+		bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
-+		goto out;
-+	}
-+
-+	/*
-+	 * Pin the queue now that it's allocated, scheduler exit will
-+	 * prune it.
-+	 */
-+	if (async_bfqq) {
-+		bfqq->ref++; /*
-+			      * Extra group reference, w.r.t. sync
-+			      * queue. This extra reference is removed
-+			      * only if bfqq->bfqg disappears, to
-+			      * guarantee that this queue is not freed
-+			      * until its group goes away.
-+			      */
-+		bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
-+			     bfqq, bfqq->ref);
-+		*async_bfqq = bfqq;
-+	}
-+
-+out:
-+	bfqq->ref++; /* get a process reference to this queue */
-+	bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, bfqq->ref);
-+	rcu_read_unlock();
-+	return bfqq;
-+}
-+
-+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
-+				    struct bfq_io_cq *bic)
-+{
-+	struct bfq_ttime *ttime = &bic->ttime;
-+	u64 elapsed = ktime_get_ns() - bic->ttime.last_end_request;
-+
-+	elapsed = min_t(u64, elapsed, 2 * bfqd->bfq_slice_idle);
-+
-+	ttime->ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
-+	ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
-+	ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
-+				     ttime->ttime_samples);
-+}
-+
-+static void
-+bfq_update_io_seektime(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+		       struct request *rq)
-+{
-+	bfqq->seek_history <<= 1;
-+	bfqq->seek_history |=
-+		get_sdist(bfqq->last_request_pos, rq) > BFQQ_SEEK_THR &&
-+		(!blk_queue_nonrot(bfqd->queue) ||
-+		 blk_rq_sectors(rq) < BFQQ_SECT_THR_NONROT);
-+}
-+
-+/*
-+ * Disable idle window if the process thinks too long or seeks so much that
-+ * it doesn't matter.
-+ */
-+static void bfq_update_idle_window(struct bfq_data *bfqd,
-+				   struct bfq_queue *bfqq,
-+				   struct bfq_io_cq *bic)
-+{
-+	int enable_idle;
-+
-+	/* Don't idle for async or idle io prio class. */
-+	if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
-+		return;
-+
-+	/* Idle window just restored, statistics are meaningless. */
-+	if (time_is_after_eq_jiffies(bfqq->split_time +
-+				     bfqd->bfq_wr_min_idle_time))
-+		return;
-+
-+	enable_idle = bfq_bfqq_idle_window(bfqq);
-+
-+	if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
-+	    bfqd->bfq_slice_idle == 0 ||
-+		(bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
-+			bfqq->wr_coeff == 1))
-+		enable_idle = 0;
-+	else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
-+		if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
-+			bfqq->wr_coeff == 1)
-+			enable_idle = 0;
-+		else
-+			enable_idle = 1;
-+	}
-+	bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
-+		enable_idle);
-+
-+	if (enable_idle)
-+		bfq_mark_bfqq_idle_window(bfqq);
-+	else
-+		bfq_clear_bfqq_idle_window(bfqq);
-+}
-+
-+/*
-+ * Called when a new fs request (rq) is added to bfqq.  Check if there's
-+ * something we should do about it.
-+ */
-+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			    struct request *rq)
-+{
-+	struct bfq_io_cq *bic = RQ_BIC(rq);
-+
-+	if (rq->cmd_flags & REQ_META)
-+		bfqq->meta_pending++;
-+
-+	bfq_update_io_thinktime(bfqd, bic);
-+	bfq_update_io_seektime(bfqd, bfqq, rq);
-+	if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
-+	    !BFQQ_SEEKY(bfqq))
-+		bfq_update_idle_window(bfqd, bfqq, bic);
-+
-+	bfq_log_bfqq(bfqd, bfqq,
-+		     "rq_enqueued: idle_window=%d (seeky %d)",
-+		     bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq));
-+
-+	bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
-+
-+	if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
-+		bool small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
-+				 blk_rq_sectors(rq) < 32;
-+		bool budget_timeout = bfq_bfqq_budget_timeout(bfqq);
-+
-+		/*
-+		 * There is just this request queued: if the request
-+		 * is small and the queue is not to be expired, then
-+		 * just exit.
-+		 *
-+		 * In this way, if the device is being idled to wait
-+		 * for a new request from the in-service queue, we
-+		 * avoid unplugging the device and committing the
-+		 * device to serve just a small request. On the
-+		 * contrary, we wait for the block layer to decide
-+		 * when to unplug the device: hopefully, new requests
-+		 * will be merged to this one quickly, then the device
-+		 * will be unplugged and larger requests will be
-+		 * dispatched.
-+		 */
-+		if (small_req && !budget_timeout)
-+			return;
-+
-+		/*
-+		 * A large enough request arrived, or the queue is to
-+		 * be expired: in both cases disk idling is to be
-+		 * stopped, so clear wait_request flag and reset
-+		 * timer.
-+		 */
-+		bfq_clear_bfqq_wait_request(bfqq);
-+		hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+		bfqg_stats_update_idle_time(bfqq_group(bfqq));
-+
-+		/*
-+		 * The queue is not empty, because a new request just
-+		 * arrived. Hence we can safely expire the queue, in
-+		 * case of budget timeout, without risking that the
-+		 * timestamps of the queue are not updated correctly.
-+		 * See [1] for more details.
-+		 */
-+		if (budget_timeout)
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+
-+		/*
-+		 * Let the request rip immediately, or let a new queue be
-+		 * selected if bfqq has just been expired.
-+		 */
-+		__blk_run_queue(bfqd->queue);
-+	}
-+}
-+
-+static void bfq_insert_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+
-+	/*
-+	 * An unplug may trigger a requeue of a request from the device
-+	 * driver: make sure we are in process context while trying to
-+	 * merge two bfq_queues.
-+	 */
-+	if (!in_interrupt()) {
-+		new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
-+		if (new_bfqq) {
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
-+				new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
-+			/*
-+			 * Release the request's reference to the old bfqq
-+			 * and make sure one is taken to the shared queue.
-+			 */
-+			new_bfqq->allocated[rq_data_dir(rq)]++;
-+			bfqq->allocated[rq_data_dir(rq)]--;
-+			new_bfqq->ref++;
-+			bfq_clear_bfqq_just_created(bfqq);
-+			if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
-+				bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
-+						bfqq, new_bfqq);
-+			/*
-+			 * rq is about to be enqueued into new_bfqq,
-+			 * release rq reference on bfqq
-+			 */
-+			bfq_put_queue(bfqq);
-+			rq->elv.priv[1] = new_bfqq;
-+			bfqq = new_bfqq;
-+		}
-+	}
-+
-+	bfq_add_request(rq);
-+
-+	rq->fifo_time = ktime_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
-+	list_add_tail(&rq->queuelist, &bfqq->fifo);
-+
-+	bfq_rq_enqueued(bfqd, bfqq, rq);
-+}
-+
-+static void bfq_update_hw_tag(struct bfq_data *bfqd)
-+{
-+	bfqd->max_rq_in_driver = max_t(int, bfqd->max_rq_in_driver,
-+				       bfqd->rq_in_driver);
-+
-+	if (bfqd->hw_tag == 1)
-+		return;
-+
-+	/*
-+	 * This sample is valid if the number of outstanding requests
-+	 * is large enough to allow a queueing behavior.  Note that the
-+	 * sum is not exact, as it's not taking into account deactivated
-+	 * requests.
-+	 */
-+	if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
-+		return;
-+
-+	if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
-+		return;
-+
-+	bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
-+	bfqd->max_rq_in_driver = 0;
-+	bfqd->hw_tag_samples = 0;
-+}
-+
-+static void bfq_completed_request(struct request_queue *q, struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+	struct bfq_data *bfqd = bfqq->bfqd;
-+	u64 now_ns;
-+	u32 delta_us;
-+
-+	bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left",
-+		     blk_rq_sectors(rq));
-+
-+	assert_spin_locked(bfqd->queue->queue_lock);
-+	bfq_update_hw_tag(bfqd);
-+
-+	BUG_ON(!bfqd->rq_in_driver);
-+	BUG_ON(!bfqq->dispatched);
-+	bfqd->rq_in_driver--;
-+	bfqq->dispatched--;
-+	bfqg_stats_update_completion(bfqq_group(bfqq),
-+				     rq_start_time_ns(rq),
-+				     rq_io_start_time_ns(rq),
-+				     rq->cmd_flags);
-+
-+	if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
-+		BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+		/*
-+		 * Set budget_timeout (which we overload to store the
-+		 * time at which the queue remains with no backlog and
-+		 * no outstanding request; used by the weight-raising
-+		 * mechanism).
-+		 */
-+		bfqq->budget_timeout = jiffies;
-+
-+		bfq_weights_tree_remove(bfqd, &bfqq->entity,
-+					&bfqd->queue_weights_tree);
-+	}
-+
-+	now_ns = ktime_get_ns();
-+
-+	RQ_BIC(rq)->ttime.last_end_request = now_ns;
-+
-+	/*
-+	 * Using us instead of ns, to get a reasonable precision in
-+	 * computing rate in next check.
-+	 */
-+	delta_us = div_u64(now_ns - bfqd->last_completion, NSEC_PER_USEC);
-+
-+	bfq_log(bfqd, "rq_completed: delta %uus/%luus max_size %u rate %llu/%llu",
-+		delta_us, BFQ_MIN_TT/NSEC_PER_USEC, bfqd->last_rq_max_size,
-+		(USEC_PER_SEC*
-+		(u64)((bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us))
-+			>>BFQ_RATE_SHIFT,
-+		(USEC_PER_SEC*(u64)(1UL<<(BFQ_RATE_SHIFT-10)))>>BFQ_RATE_SHIFT);
-+
-+	/*
-+	 * If the request took rather long to complete, and, according
-+	 * to the maximum request size recorded, this completion latency
-+	 * implies that the request was certainly served at a very low
-+	 * rate (less than 1M sectors/sec), then the whole observation
-+	 * interval that lasts up to this time instant cannot be a
-+	 * valid time interval for computing a new peak rate.  Invoke
-+	 * bfq_update_rate_reset to have the following three steps
-+	 * taken:
-+	 * - close the observation interval at the last (previous)
-+	 *   request dispatch or completion
-+	 * - compute rate, if possible, for that observation interval
-+	 * - reset to zero samples, which will trigger a proper
-+	 *   re-initialization of the observation interval on next
-+	 *   dispatch
-+	 */
-+	if (delta_us > BFQ_MIN_TT/NSEC_PER_USEC &&
-+	   (bfqd->last_rq_max_size<<BFQ_RATE_SHIFT)/delta_us <
-+			1UL<<(BFQ_RATE_SHIFT - 10))
-+		bfq_update_rate_reset(bfqd, NULL);
-+	bfqd->last_completion = now_ns;
-+
-+	/*
-+	 * If we are waiting to discover whether the request pattern
-+	 * of the task associated with the queue is actually
-+	 * isochronous, and both requisites for this condition to hold
-+	 * are now satisfied, then compute soft_rt_next_start (see the
-+	 * comments on the function bfq_bfqq_softrt_next_start()). We
-+	 * schedule this delayed check when bfqq expires, if it still
-+	 * has in-flight requests.
-+	 */
-+	if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
-+	    RB_EMPTY_ROOT(&bfqq->sort_list))
-+		bfqq->soft_rt_next_start =
-+			bfq_bfqq_softrt_next_start(bfqd, bfqq);
-+
-+	/*
-+	 * If this is the in-service queue, check if it needs to be expired,
-+	 * or if we want to idle in case it has no pending requests.
-+	 */
-+	if (bfqd->in_service_queue == bfqq) {
-+		if (bfqq->dispatched == 0 && bfq_bfqq_must_idle(bfqq)) {
-+			bfq_arm_slice_timer(bfqd);
-+			goto out;
-+		} else if (bfq_may_expire_for_budg_timeout(bfqq))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_BUDGET_TIMEOUT);
-+		else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
-+			 (bfqq->dispatched == 0 ||
-+			  !bfq_bfqq_may_idle(bfqq)))
-+			bfq_bfqq_expire(bfqd, bfqq, false,
-+					BFQ_BFQQ_NO_MORE_REQUESTS);
-+	}
-+
-+	if (!bfqd->rq_in_driver)
-+		bfq_schedule_dispatch(bfqd);
-+
-+out:
-+	return;
-+}
-+
-+static int __bfq_may_queue(struct bfq_queue *bfqq)
-+{
-+	if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
-+		bfq_clear_bfqq_must_alloc(bfqq);
-+		return ELV_MQUEUE_MUST;
-+	}
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+static int bfq_may_queue(struct request_queue *q, unsigned int op)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct task_struct *tsk = current;
-+	struct bfq_io_cq *bic;
-+	struct bfq_queue *bfqq;
-+
-+	/*
-+	 * Don't force setup of a queue from here, as a call to may_queue
-+	 * does not necessarily imply that a request actually will be
-+	 * queued. So just lookup a possibly existing queue, or return
-+	 * 'may queue' if that fails.
-+	 */
-+	bic = bfq_bic_lookup(bfqd, tsk->io_context);
-+	if (!bic)
-+		return ELV_MQUEUE_MAY;
-+
-+	bfqq = bic_to_bfqq(bic, op_is_sync(op));
-+	if (bfqq)
-+		return __bfq_may_queue(bfqq);
-+
-+	return ELV_MQUEUE_MAY;
-+}
-+
-+/*
-+ * Queue lock held here.
-+ */
-+static void bfq_put_request(struct request *rq)
-+{
-+	struct bfq_queue *bfqq = RQ_BFQQ(rq);
-+
-+	if (bfqq) {
-+		const int rw = rq_data_dir(rq);
-+
-+		BUG_ON(!bfqq->allocated[rw]);
-+		bfqq->allocated[rw]--;
-+
-+		rq->elv.priv[0] = NULL;
-+		rq->elv.priv[1] = NULL;
-+
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/*
-+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
-+ * was the last process referring to that bfqq.
-+ */
-+static struct bfq_queue *
-+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
-+{
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
-+
-+	put_io_context(bic->icq.ioc);
-+
-+	if (bfqq_process_refs(bfqq) == 1) {
-+		bfqq->pid = current->pid;
-+		bfq_clear_bfqq_coop(bfqq);
-+		bfq_clear_bfqq_split_coop(bfqq);
-+		return bfqq;
-+	}
-+
-+	bic_set_bfqq(bic, NULL, 1);
-+
-+	bfq_put_cooperator(bfqq);
-+
-+	bfq_put_queue(bfqq);
-+	return NULL;
-+}
-+
-+/*
-+ * Allocate bfq data structures associated with this request.
-+ */
-+static int bfq_set_request(struct request_queue *q, struct request *rq,
-+			   struct bio *bio, gfp_t gfp_mask)
-+{
-+	struct bfq_data *bfqd = q->elevator->elevator_data;
-+	struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
-+	const int rw = rq_data_dir(rq);
-+	const int is_sync = rq_is_sync(rq);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	bool split = false;
-+
-+	spin_lock_irqsave(q->queue_lock, flags);
-+	bfq_check_ioprio_change(bic, bio);
-+
-+	if (!bic)
-+		goto queue_fail;
-+
-+	bfq_bic_update_cgroup(bic, bio);
-+
-+new_queue:
-+	bfqq = bic_to_bfqq(bic, is_sync);
-+	if (!bfqq || bfqq == &bfqd->oom_bfqq) {
-+		if (bfqq)
-+			bfq_put_queue(bfqq);
-+		bfqq = bfq_get_queue(bfqd, bio, is_sync, bic);
-+		BUG_ON(!hlist_unhashed(&bfqq->burst_list_node));
-+
-+		bic_set_bfqq(bic, bfqq, is_sync);
-+		if (split && is_sync) {
-+			bfq_log_bfqq(bfqd, bfqq,
-+				     "set_request: was_in_list %d "
-+				     "was_in_large_burst %d "
-+				     "large burst in progress %d",
-+				     bic->was_in_burst_list,
-+				     bic->saved_in_large_burst,
-+				     bfqd->large_burst);
-+
-+			if ((bic->was_in_burst_list && bfqd->large_burst) ||
-+			    bic->saved_in_large_burst) {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: marking in "
-+					     "large burst");
-+				bfq_mark_bfqq_in_large_burst(bfqq);
-+			} else {
-+				bfq_log_bfqq(bfqd, bfqq,
-+					     "set_request: clearing in "
-+					     "large burst");
-+				bfq_clear_bfqq_in_large_burst(bfqq);
-+				if (bic->was_in_burst_list)
-+					hlist_add_head(&bfqq->burst_list_node,
-+						       &bfqd->burst_list);
-+			}
-+			bfqq->split_time = jiffies;
-+		}
-+	} else {
-+		/* If the queue was seeky for too long, break it apart. */
-+		if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
-+			bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
-+
-+			/* Update bic before losing reference to bfqq */
-+			if (bfq_bfqq_in_large_burst(bfqq))
-+				bic->saved_in_large_burst = true;
-+
-+			bfqq = bfq_split_bfqq(bic, bfqq);
-+			split = true;
-+			if (!bfqq)
-+				goto new_queue;
-+		}
-+	}
-+
-+	bfqq->allocated[rw]++;
-+	bfqq->ref++;
-+	bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, bfqq->ref);
-+
-+	rq->elv.priv[0] = bic;
-+	rq->elv.priv[1] = bfqq;
-+
-+	/*
-+	 * If a bfq_queue has only one process reference, it is owned
-+	 * by only one bfq_io_cq: we can set the bic field of the
-+	 * bfq_queue to the address of that structure. Also, if the
-+	 * queue has just been split, mark a flag so that the
-+	 * information is available to the other scheduler hooks.
-+	 */
-+	if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
-+		bfqq->bic = bic;
-+		if (split) {
-+			/*
-+			 * If the queue has just been split from a shared
-+			 * queue, restore the idle window and the possible
-+			 * weight raising period.
-+			 */
-+			bfq_bfqq_resume_state(bfqq, bic);
-+		}
-+	}
-+
-+	if (unlikely(bfq_bfqq_just_created(bfqq)))
-+		bfq_handle_burst(bfqd, bfqq);
-+
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 0;
-+
-+queue_fail:
-+	bfq_schedule_dispatch(bfqd);
-+	spin_unlock_irqrestore(q->queue_lock, flags);
-+
-+	return 1;
-+}
-+
-+static void bfq_kick_queue(struct work_struct *work)
-+{
-+	struct bfq_data *bfqd =
-+		container_of(work, struct bfq_data, unplug_work);
-+	struct request_queue *q = bfqd->queue;
-+
-+	spin_lock_irq(q->queue_lock);
-+	__blk_run_queue(q);
-+	spin_unlock_irq(q->queue_lock);
-+}
-+
-+/*
-+ * Handler of the expiration of the timer running if the in-service queue
-+ * is idling inside its time slice.
-+ */
-+static enum hrtimer_restart bfq_idle_slice_timer(struct hrtimer *timer)
-+{
-+	struct bfq_data *bfqd = container_of(timer, struct bfq_data,
-+					     idle_slice_timer);
-+	struct bfq_queue *bfqq;
-+	unsigned long flags;
-+	enum bfqq_expiration reason;
-+
-+	spin_lock_irqsave(bfqd->queue->queue_lock, flags);
-+
-+	bfqq = bfqd->in_service_queue;
-+	/*
-+	 * Theoretical race here: the in-service queue can be NULL or
-+	 * different from the queue that was idling if the timer handler
-+	 * spins on the queue_lock and a new request arrives for the
-+	 * current queue and there is a full dispatch cycle that changes
-+	 * the in-service queue.  This can hardly happen, but in the worst
-+	 * case we just expire a queue too early.
-+	 */
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
-+		bfq_clear_bfqq_wait_request(bfqq);
-+
-+		if (bfq_bfqq_budget_timeout(bfqq))
-+			/*
-+			 * Also here the queue can be safely expired
-+			 * for budget timeout without wasting
-+			 * guarantees
-+			 */
-+			reason = BFQ_BFQQ_BUDGET_TIMEOUT;
-+		else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
-+			/*
-+			 * The queue may not be empty upon timer expiration,
-+			 * because we may not disable the timer when the
-+			 * first request of the in-service queue arrives
-+			 * during disk idling.
-+			 */
-+			reason = BFQ_BFQQ_TOO_IDLE;
-+		else
-+			goto schedule_dispatch;
-+
-+		bfq_bfqq_expire(bfqd, bfqq, true, reason);
-+	}
-+
-+schedule_dispatch:
-+	bfq_schedule_dispatch(bfqd);
-+
-+	spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
-+	return HRTIMER_NORESTART;
-+}
-+
-+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
-+{
-+	hrtimer_cancel(&bfqd->idle_slice_timer);
-+	cancel_work_sync(&bfqd->unplug_work);
-+}
-+
-+static void __bfq_put_async_bfqq(struct bfq_data *bfqd,
-+				 struct bfq_queue **bfqq_ptr)
-+{
-+	struct bfq_group *root_group = bfqd->root_group;
-+	struct bfq_queue *bfqq = *bfqq_ptr;
-+
-+	bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
-+	if (bfqq) {
-+		bfq_bfqq_move(bfqd, bfqq, root_group);
-+		bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+		*bfqq_ptr = NULL;
-+	}
-+}
-+
-+/*
-+ * Release all the bfqg references to its async queues.  If we are
-+ * deallocating the group these queues may still contain requests, so
-+ * we reparent them to the root cgroup (i.e., the only one that will
-+ * exist for sure until all the requests on a device are gone).
-+ */
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
-+{
-+	int i, j;
-+
-+	for (i = 0; i < 2; i++)
-+		for (j = 0; j < IOPRIO_BE_NR; j++)
-+			__bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
-+
-+	__bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
-+}
-+
-+static void bfq_exit_queue(struct elevator_queue *e)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	struct request_queue *q = bfqd->queue;
-+	struct bfq_queue *bfqq, *n;
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	spin_lock_irq(q->queue_lock);
-+
-+	BUG_ON(bfqd->in_service_queue);
-+	list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
-+		bfq_deactivate_bfqq(bfqd, bfqq, false, false);
-+
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfq_shutdown_timer_wq(bfqd);
-+
-+	BUG_ON(hrtimer_active(&bfqd->idle_slice_timer));
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	blkcg_deactivate_policy(q, &blkcg_policy_bfq);
-+#else
-+	bfq_put_async_queues(bfqd, bfqd->root_group);
-+	kfree(bfqd->root_group);
-+#endif
-+
-+	kfree(bfqd);
-+}
-+
-+static void bfq_init_root_group(struct bfq_group *root_group,
-+				struct bfq_data *bfqd)
-+{
-+	int i;
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	root_group->entity.parent = NULL;
-+	root_group->my_entity = NULL;
-+	root_group->bfqd = bfqd;
-+#endif
-+	root_group->rq_pos_tree = RB_ROOT;
-+	for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
-+		root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
-+	root_group->sched_data.bfq_class_idle_last_service = jiffies;
-+}
-+
-+static int bfq_init_queue(struct request_queue *q, struct elevator_type *e)
-+{
-+	struct bfq_data *bfqd;
-+	struct elevator_queue *eq;
-+
-+	eq = elevator_alloc(q, e);
-+	if (!eq)
-+		return -ENOMEM;
-+
-+	bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
-+	if (!bfqd) {
-+		kobject_put(&eq->kobj);
-+		return -ENOMEM;
-+	}
-+	eq->elevator_data = bfqd;
-+
-+	/*
-+	 * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
-+	 * Grab a permanent reference to it, so that the normal code flow
-+	 * will not attempt to free it.
-+	 */
-+	bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, NULL, 1, 0);
-+	bfqd->oom_bfqq.ref++;
-+	bfqd->oom_bfqq.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
-+	bfqd->oom_bfqq.new_ioprio_class = IOPRIO_CLASS_BE;
-+	bfqd->oom_bfqq.entity.new_weight =
-+		bfq_ioprio_to_weight(bfqd->oom_bfqq.new_ioprio);
-+
-+	/* oom_bfqq does not participate to bursts */
-+	bfq_clear_bfqq_just_created(&bfqd->oom_bfqq);
-+	/*
-+	 * Trigger weight initialization, according to ioprio, at the
-+	 * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
-+	 * class won't be changed any more.
-+	 */
-+	bfqd->oom_bfqq.entity.prio_changed = 1;
-+
-+	bfqd->queue = q;
-+
-+	spin_lock_irq(q->queue_lock);
-+	q->elevator = eq;
-+	spin_unlock_irq(q->queue_lock);
-+
-+	bfqd->root_group = bfq_create_group_hierarchy(bfqd, q->node);
-+	if (!bfqd->root_group)
-+		goto out_free;
-+	bfq_init_root_group(bfqd->root_group, bfqd);
-+	bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
-+
-+	hrtimer_init(&bfqd->idle_slice_timer, CLOCK_MONOTONIC,
-+		     HRTIMER_MODE_REL);
-+	bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
-+
-+	bfqd->queue_weights_tree = RB_ROOT;
-+	bfqd->group_weights_tree = RB_ROOT;
-+
-+	INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
-+
-+	INIT_LIST_HEAD(&bfqd->active_list);
-+	INIT_LIST_HEAD(&bfqd->idle_list);
-+	INIT_HLIST_HEAD(&bfqd->burst_list);
-+
-+	bfqd->hw_tag = -1;
-+
-+	bfqd->bfq_max_budget = bfq_default_max_budget;
-+
-+	bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
-+	bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
-+	bfqd->bfq_back_max = bfq_back_max;
-+	bfqd->bfq_back_penalty = bfq_back_penalty;
-+	bfqd->bfq_slice_idle = bfq_slice_idle;
-+	bfqd->bfq_timeout = bfq_timeout;
-+
-+	bfqd->bfq_requests_within_timer = 120;
-+
-+	bfqd->bfq_large_burst_thresh = 8;
-+	bfqd->bfq_burst_interval = msecs_to_jiffies(180);
-+
-+	bfqd->low_latency = true;
-+
-+	/*
-+	 * Trade-off between responsiveness and fairness.
-+	 */
-+	bfqd->bfq_wr_coeff = 30;
-+	bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
-+	bfqd->bfq_wr_max_time = 0;
-+	bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
-+	bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
-+	bfqd->bfq_wr_max_softrt_rate = 7000; /*
-+					      * Approximate rate required
-+					      * to playback or record a
-+					      * high-definition compressed
-+					      * video.
-+					      */
-+	bfqd->wr_busy_queues = 0;
-+
-+	/*
-+	 * Begin by assuming, optimistically, that the device is a
-+	 * high-speed one, and that its peak rate is equal to 2/3 of
-+	 * the highest reference rate.
-+	 */
-+	bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
-+			T_fast[blk_queue_nonrot(bfqd->queue)];
-+	bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)] * 2 / 3;
-+	bfqd->device_speed = BFQ_BFQD_FAST;
-+
-+	return 0;
-+
-+out_free:
-+	kfree(bfqd);
-+	kobject_put(&eq->kobj);
-+	return -ENOMEM;
-+}
-+
-+static void bfq_slab_kill(void)
-+{
-+	kmem_cache_destroy(bfq_pool);
-+}
-+
-+static int __init bfq_slab_setup(void)
-+{
-+	bfq_pool = KMEM_CACHE(bfq_queue, 0);
-+	if (!bfq_pool)
-+		return -ENOMEM;
-+	return 0;
-+}
-+
-+static ssize_t bfq_var_show(unsigned int var, char *page)
-+{
-+	return sprintf(page, "%u\n", var);
-+}
-+
-+static ssize_t bfq_var_store(unsigned long *var, const char *page,
-+			     size_t count)
-+{
-+	unsigned long new_val;
-+	int ret = kstrtoul(page, 10, &new_val);
-+
-+	if (ret == 0)
-+		*var = new_val;
-+
-+	return count;
-+}
-+
-+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+
-+	return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
-+		       jiffies_to_msecs(bfqd->bfq_wr_max_time) :
-+		       jiffies_to_msecs(bfq_wr_duration(bfqd)));
-+}
-+
-+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
-+{
-+	struct bfq_queue *bfqq;
-+	struct bfq_data *bfqd = e->elevator_data;
-+	ssize_t num_char = 0;
-+
-+	num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
-+			    bfqd->queued);
-+
-+	spin_lock_irq(bfqd->queue->queue_lock);
-+
-+	num_char += sprintf(page + num_char, "Active:\n");
-+	list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, nr_queued %d %d, ",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    bfqq->queued[0],
-+				    bfqq->queued[1]);
-+		num_char += sprintf(page + num_char,
-+				    "dur %d/%u\n",
-+				    jiffies_to_msecs(
-+					    jiffies -
-+					    bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	num_char += sprintf(page + num_char, "Idle:\n");
-+	list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
-+		num_char += sprintf(page + num_char,
-+				    "pid%d: weight %hu, dur %d/%u\n",
-+				    bfqq->pid,
-+				    bfqq->entity.weight,
-+				    jiffies_to_msecs(jiffies -
-+						     bfqq->last_wr_start_finish),
-+				    jiffies_to_msecs(bfqq->wr_cur_max_time));
-+	}
-+
-+	spin_unlock_irq(bfqd->queue->queue_lock);
-+
-+	return num_char;
-+}
-+
-+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	if (__CONV == 1)						\
-+		__data = jiffies_to_msecs(__data);			\
-+	else if (__CONV == 2)						\
-+		__data = div_u64(__data, NSEC_PER_MSEC);		\
-+	return bfq_var_show(__data, (page));				\
-+}
-+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 2);
-+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 2);
-+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
-+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
-+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 2);
-+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
-+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout, 1);
-+SHOW_FUNCTION(bfq_strict_guarantees_show, bfqd->strict_guarantees, 0);
-+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
-+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
-+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
-+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
-+	1);
-+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
-+#undef SHOW_FUNCTION
-+
-+#define USEC_SHOW_FUNCTION(__FUNC, __VAR)				\
-+static ssize_t __FUNC(struct elevator_queue *e, char *page)		\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	u64 __data = __VAR;						\
-+	__data = div_u64(__data, NSEC_PER_USEC);			\
-+	return bfq_var_show(__data, (page));				\
-+}
-+USEC_SHOW_FUNCTION(bfq_slice_idle_us_show, bfqd->bfq_slice_idle);
-+#undef USEC_SHOW_FUNCTION
-+
-+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)			\
-+static ssize_t								\
-+__FUNC(struct elevator_queue *e, const char *page, size_t count)	\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	if (__CONV == 1)						\
-+		*(__PTR) = msecs_to_jiffies(__data);			\
-+	else if (__CONV == 2)						\
-+		*(__PTR) = (u64)__data * NSEC_PER_MSEC;			\
-+	else								\
-+		*(__PTR) = __data;					\
-+	return ret;							\
-+}
-+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
-+		INT_MAX, 2);
-+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
-+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
-+		INT_MAX, 0);
-+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 2);
-+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
-+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
-+		1);
-+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
-+		INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
-+		&bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
-+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
-+		INT_MAX, 0);
-+#undef STORE_FUNCTION
-+
-+#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)			\
-+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)\
-+{									\
-+	struct bfq_data *bfqd = e->elevator_data;			\
-+	unsigned long uninitialized_var(__data);			\
-+	int ret = bfq_var_store(&__data, (page), count);		\
-+	if (__data < (MIN))						\
-+		__data = (MIN);						\
-+	else if (__data > (MAX))					\
-+		__data = (MAX);						\
-+	*(__PTR) = (u64)__data * NSEC_PER_USEC;				\
-+	return ret;							\
-+}
-+USEC_STORE_FUNCTION(bfq_slice_idle_us_store, &bfqd->bfq_slice_idle, 0,
-+		    UINT_MAX);
-+#undef USEC_STORE_FUNCTION
-+
-+/* do nothing for the moment */
-+static ssize_t bfq_weights_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	return count;
-+}
-+
-+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
-+				    const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+	else {
-+		if (__data > INT_MAX)
-+			__data = INT_MAX;
-+		bfqd->bfq_max_budget = __data;
-+	}
-+
-+	bfqd->bfq_user_max_budget = __data;
-+
-+	return ret;
-+}
-+
-+/*
-+ * Leaving this name to preserve name compatibility with cfq
-+ * parameters, but this timeout is used for both sync and async.
-+ */
-+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
-+				      const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data < 1)
-+		__data = 1;
-+	else if (__data > INT_MAX)
-+		__data = INT_MAX;
-+
-+	bfqd->bfq_timeout = msecs_to_jiffies(__data);
-+	if (bfqd->bfq_user_max_budget == 0)
-+		bfqd->bfq_max_budget = bfq_calc_max_budget(bfqd);
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_strict_guarantees_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (!bfqd->strict_guarantees && __data == 1
-+	    && bfqd->bfq_slice_idle < 8 * NSEC_PER_MSEC)
-+		bfqd->bfq_slice_idle = 8 * NSEC_PER_MSEC;
-+
-+	bfqd->strict_guarantees = __data;
-+
-+	return ret;
-+}
-+
-+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
-+				     const char *page, size_t count)
-+{
-+	struct bfq_data *bfqd = e->elevator_data;
-+	unsigned long uninitialized_var(__data);
-+	int ret = bfq_var_store(&__data, (page), count);
-+
-+	if (__data > 1)
-+		__data = 1;
-+	if (__data == 0 && bfqd->low_latency != 0)
-+		bfq_end_wr(bfqd);
-+	bfqd->low_latency = __data;
-+
-+	return ret;
-+}
-+
-+#define BFQ_ATTR(name) \
-+	__ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
-+
-+static struct elv_fs_entry bfq_attrs[] = {
-+	BFQ_ATTR(fifo_expire_sync),
-+	BFQ_ATTR(fifo_expire_async),
-+	BFQ_ATTR(back_seek_max),
-+	BFQ_ATTR(back_seek_penalty),
-+	BFQ_ATTR(slice_idle),
-+	BFQ_ATTR(slice_idle_us),
-+	BFQ_ATTR(max_budget),
-+	BFQ_ATTR(timeout_sync),
-+	BFQ_ATTR(strict_guarantees),
-+	BFQ_ATTR(low_latency),
-+	BFQ_ATTR(wr_coeff),
-+	BFQ_ATTR(wr_max_time),
-+	BFQ_ATTR(wr_rt_max_time),
-+	BFQ_ATTR(wr_min_idle_time),
-+	BFQ_ATTR(wr_min_inter_arr_async),
-+	BFQ_ATTR(wr_max_softrt_rate),
-+	BFQ_ATTR(weights),
-+	__ATTR_NULL
-+};
-+
-+static struct elevator_type iosched_bfq = {
-+	.ops.sq = {
-+		.elevator_merge_fn =		bfq_merge,
-+		.elevator_merged_fn =		bfq_merged_request,
-+		.elevator_merge_req_fn =	bfq_merged_requests,
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		.elevator_bio_merged_fn =	bfq_bio_merged,
-+#endif
-+		.elevator_allow_bio_merge_fn =	bfq_allow_bio_merge,
-+		.elevator_allow_rq_merge_fn =	bfq_allow_rq_merge,
-+		.elevator_dispatch_fn =		bfq_dispatch_requests,
-+		.elevator_add_req_fn =		bfq_insert_request,
-+		.elevator_activate_req_fn =	bfq_activate_request,
-+		.elevator_deactivate_req_fn =	bfq_deactivate_request,
-+		.elevator_completed_req_fn =	bfq_completed_request,
-+		.elevator_former_req_fn =	elv_rb_former_request,
-+		.elevator_latter_req_fn =	elv_rb_latter_request,
-+		.elevator_init_icq_fn =		bfq_init_icq,
-+		.elevator_exit_icq_fn =		bfq_exit_icq,
-+		.elevator_set_req_fn =		bfq_set_request,
-+		.elevator_put_req_fn =		bfq_put_request,
-+		.elevator_may_queue_fn =	bfq_may_queue,
-+		.elevator_init_fn =		bfq_init_queue,
-+		.elevator_exit_fn =		bfq_exit_queue,
-+	},
-+	.icq_size =		sizeof(struct bfq_io_cq),
-+	.icq_align =		__alignof__(struct bfq_io_cq),
-+	.elevator_attrs =	bfq_attrs,
-+	.elevator_name =	"bfq",
-+	.elevator_owner =	THIS_MODULE,
-+};
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static struct blkcg_policy blkcg_policy_bfq = {
-+	.dfl_cftypes		= bfq_blkg_files,
-+	.legacy_cftypes		= bfq_blkcg_legacy_files,
-+
-+	.cpd_alloc_fn		= bfq_cpd_alloc,
-+	.cpd_init_fn		= bfq_cpd_init,
-+	.cpd_bind_fn	        = bfq_cpd_init,
-+	.cpd_free_fn		= bfq_cpd_free,
-+
-+	.pd_alloc_fn		= bfq_pd_alloc,
-+	.pd_init_fn		= bfq_pd_init,
-+	.pd_offline_fn		= bfq_pd_offline,
-+	.pd_free_fn		= bfq_pd_free,
-+	.pd_reset_stats_fn	= bfq_pd_reset_stats,
-+};
-+#endif
-+
-+static int __init bfq_init(void)
-+{
-+	int ret;
-+	char msg[60] = "BFQ I/O-scheduler: v8r10-rc1";
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	ret = blkcg_policy_register(&blkcg_policy_bfq);
-+	if (ret)
-+		return ret;
-+#endif
-+
-+	ret = -ENOMEM;
-+	if (bfq_slab_setup())
-+		goto err_pol_unreg;
-+
-+	/*
-+	 * Times to load large popular applications for the typical
-+	 * systems installed on the reference devices (see the
-+	 * comments before the definitions of the next two
-+	 * arrays). Actually, we use slightly slower values, as the
-+	 * estimated peak rate tends to be smaller than the actual
-+	 * peak rate.  The reason for this last fact is that estimates
-+	 * are computed over much shorter time intervals than the long
-+	 * intervals typically used for benchmarking. Why? First, to
-+	 * adapt more quickly to variations. Second, because an I/O
-+	 * scheduler cannot rely on a peak-rate-evaluation workload to
-+	 * be run for a long time.
-+	 */
-+	T_slow[0] = msecs_to_jiffies(3500); /* actually 4 sec */
-+	T_slow[1] = msecs_to_jiffies(6000); /* actually 6.5 sec */
-+	T_fast[0] = msecs_to_jiffies(7000); /* actually 8 sec */
-+	T_fast[1] = msecs_to_jiffies(2500); /* actually 3 sec */
-+
-+	/*
-+	 * Thresholds that determine the switch between speed classes
-+	 * (see the comments before the definition of the array
-+	 * device_speed_thresh). These thresholds are biased towards
-+	 * transitions to the fast class. This is safer than the
-+	 * opposite bias. In fact, a wrong transition to the slow
-+	 * class results in short weight-raising periods, because the
-+	 * speed of the device then tends to be higher that the
-+	 * reference peak rate. On the opposite end, a wrong
-+	 * transition to the fast class tends to increase
-+	 * weight-raising periods, because of the opposite reason.
-+	 */
-+	device_speed_thresh[0] = (4 * R_slow[0]) / 3;
-+	device_speed_thresh[1] = (4 * R_slow[1]) / 3;
-+
-+	ret = elv_register(&iosched_bfq);
-+	if (ret)
-+		goto err_pol_unreg;
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	strcat(msg, " (with cgroups support)");
-+#endif
-+	pr_info("%s", msg);
-+
-+	return 0;
-+
-+err_pol_unreg:
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	return ret;
-+}
-+
-+static void __exit bfq_exit(void)
-+{
-+	elv_unregister(&iosched_bfq);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	blkcg_policy_unregister(&blkcg_policy_bfq);
-+#endif
-+	bfq_slab_kill();
-+}
-+
-+module_init(bfq_init);
-+module_exit(bfq_exit);
-+
-+MODULE_AUTHOR("Arianna Avanzini, Fabio Checconi, Paolo Valente");
-+MODULE_LICENSE("GPL");
-diff --git a/block/bfq-sched.c b/block/bfq-sched.c
-new file mode 100644
-index 000000000000..6ab75b6bfd96
---- /dev/null
-+++ b/block/bfq-sched.c
-@@ -0,0 +1,2014 @@
-+/*
-+ * BFQ: Hierarchical B-WF2Q+ scheduler.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2016 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+
-+/**
-+ * bfq_gt - compare two timestamps.
-+ * @a: first ts.
-+ * @b: second ts.
-+ *
-+ * Return @a > @b, dealing with wrapping correctly.
-+ */
-+static int bfq_gt(u64 a, u64 b)
-+{
-+	return (s64)(a - b) > 0;
-+}
-+
-+static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree)
-+{
-+	struct rb_node *node = tree->rb_node;
-+
-+	return rb_entry(node, struct bfq_entity, rb_node);
-+}
-+
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd);
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service);
-+
-+/**
-+ * bfq_update_next_in_service - update sd->next_in_service
-+ * @sd: sched_data for which to perform the update.
-+ * @new_entity: if not NULL, pointer to the entity whose activation,
-+ *		requeueing or repositionig triggered the invocation of
-+ *		this function.
-+ *
-+ * This function is called to update sd->next_in_service, which, in
-+ * its turn, may change as a consequence of the insertion or
-+ * extraction of an entity into/from one of the active trees of
-+ * sd. These insertions/extractions occur as a consequence of
-+ * activations/deactivations of entities, with some activations being
-+ * 'true' activations, and other activations being requeueings (i.e.,
-+ * implementing the second, requeueing phase of the mechanism used to
-+ * reposition an entity in its active tree; see comments on
-+ * __bfq_activate_entity and __bfq_requeue_entity for details). In
-+ * both the last two activation sub-cases, new_entity points to the
-+ * just activated or requeued entity.
-+ *
-+ * Returns true if sd->next_in_service changes in such a way that
-+ * entity->parent may become the next_in_service for its parent
-+ * entity.
-+ */
-+static bool bfq_update_next_in_service(struct bfq_sched_data *sd,
-+				       struct bfq_entity *new_entity)
-+{
-+	struct bfq_entity *next_in_service = sd->next_in_service;
-+	struct bfq_queue *bfqq;
-+	bool parent_sched_may_change = false;
-+
-+	/*
-+	 * If this update is triggered by the activation, requeueing
-+	 * or repositiong of an entity that does not coincide with
-+	 * sd->next_in_service, then a full lookup in the active tree
-+	 * can be avoided. In fact, it is enough to check whether the
-+	 * just-modified entity has a higher priority than
-+	 * sd->next_in_service, or, even if it has the same priority
-+	 * as sd->next_in_service, is eligible and has a lower virtual
-+	 * finish time than sd->next_in_service. If this compound
-+	 * condition holds, then the new entity becomes the new
-+	 * next_in_service. Otherwise no change is needed.
-+	 */
-+	if (new_entity && new_entity != sd->next_in_service) {
-+		/*
-+		 * Flag used to decide whether to replace
-+		 * sd->next_in_service with new_entity. Tentatively
-+		 * set to true, and left as true if
-+		 * sd->next_in_service is NULL.
-+		 */
-+		bool replace_next = true;
-+
-+		/*
-+		 * If there is already a next_in_service candidate
-+		 * entity, then compare class priorities or timestamps
-+		 * to decide whether to replace sd->service_tree with
-+		 * new_entity.
-+		 */
-+		if (next_in_service) {
-+			unsigned int new_entity_class_idx =
-+				bfq_class_idx(new_entity);
-+			struct bfq_service_tree *st =
-+				sd->service_tree + new_entity_class_idx;
-+
-+			/*
-+			 * For efficiency, evaluate the most likely
-+			 * sub-condition first.
-+			 */
-+			replace_next =
-+				(new_entity_class_idx ==
-+				 bfq_class_idx(next_in_service)
-+				 &&
-+				 !bfq_gt(new_entity->start, st->vtime)
-+				 &&
-+				 bfq_gt(next_in_service->finish,
-+					new_entity->finish))
-+				||
-+				new_entity_class_idx <
-+				bfq_class_idx(next_in_service);
-+		}
-+
-+		if (replace_next)
-+			next_in_service = new_entity;
-+	} else /* invoked because of a deactivation: lookup needed */
-+		next_in_service = bfq_lookup_next_entity(sd);
-+
-+	if (next_in_service) {
-+		parent_sched_may_change = !sd->next_in_service ||
-+			bfq_update_parent_budget(next_in_service);
-+	} else
-+		parent_sched_may_change = sd->next_in_service;
-+
-+	sd->next_in_service = next_in_service;
-+
-+	if (!next_in_service)
-+		return parent_sched_may_change;
-+
-+	bfqq = bfq_entity_to_bfqq(next_in_service);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "update_next_in_service: chosen this queue");
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(next_in_service,
-+				     struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "update_next_in_service: chosen this entity");
-+	}
-+#endif
-+	return parent_sched_may_change;
-+}
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+/* both next loops stop at one of the child entities of the root group */
-+#define for_each_entity(entity)				\
-+	for (; entity ; entity = entity->parent)
-+
-+/*
-+ * For each iteration, compute parent in advance, so as to be safe if
-+ * entity is deallocated during the iteration. Such a deallocation may
-+ * happen as a consequence of a bfq_put_queue that frees the bfq_queue
-+ * containing entity.
-+ */
-+#define for_each_entity_safe(entity, parent)				\
-+	for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
-+
-+/*
-+ * Returns true if this budget changes may let next_in_service->parent
-+ * become the next_in_service entity for its parent entity.
-+ */
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	struct bfq_entity *bfqg_entity;
-+	struct bfq_group *bfqg;
-+	struct bfq_sched_data *group_sd;
-+	bool ret = false;
-+
-+	BUG_ON(!next_in_service);
-+
-+	group_sd = next_in_service->sched_data;
-+
-+	bfqg = container_of(group_sd, struct bfq_group, sched_data);
-+	/*
-+	 * bfq_group's my_entity field is not NULL only if the group
-+	 * is not the root group. We must not touch the root entity
-+	 * as it must never become an in-service entity.
-+	 */
-+	bfqg_entity = bfqg->my_entity;
-+	if (bfqg_entity) {
-+		if (bfqg_entity->budget > next_in_service->budget)
-+			ret = true;
-+		bfqg_entity->budget = next_in_service->budget;
-+	}
-+
-+	return ret;
-+}
-+
-+/*
-+ * This function tells whether entity stops being a candidate for next
-+ * service, according to the following logic.
-+ *
-+ * This function is invoked for an entity that is about to be set in
-+ * service. If such an entity is a queue, then the entity is no longer
-+ * a candidate for next service (i.e, a candidate entity to serve
-+ * after the in-service entity is expired). The function then returns
-+ * true.
-+ *
-+ * In contrast, the entity could stil be a candidate for next service
-+ * if it is not a queue, and has more than one child. In fact, even if
-+ * one of its children is about to be set in service, other children
-+ * may still be the next to serve. As a consequence, a non-queue
-+ * entity is not a candidate for next-service only if it has only one
-+ * child. And only if this condition holds, then the function returns
-+ * true for a non-queue entity.
-+ */
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	struct bfq_group *bfqg;
-+
-+	if (bfq_entity_to_bfqq(entity))
-+		return true;
-+
-+	bfqg = container_of(entity, struct bfq_group, entity);
-+
-+	BUG_ON(bfqg == ((struct bfq_data *)(bfqg->bfqd))->root_group);
-+	BUG_ON(bfqg->active_entities == 0);
-+	if (bfqg->active_entities == 1)
-+		return true;
-+
-+	return false;
-+}
-+
-+#else /* CONFIG_BFQ_GROUP_IOSCHED */
-+#define for_each_entity(entity)	\
-+	for (; entity ; entity = NULL)
-+
-+#define for_each_entity_safe(entity, parent) \
-+	for (parent = NULL; entity ; entity = parent)
-+
-+static bool bfq_update_parent_budget(struct bfq_entity *next_in_service)
-+{
-+	return false;
-+}
-+
-+static bool bfq_no_longer_next_in_service(struct bfq_entity *entity)
-+{
-+	return true;
-+}
-+
-+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+/*
-+ * Shift for timestamp calculations.  This actually limits the maximum
-+ * service allowed in one timestamp delta (small shift values increase it),
-+ * the maximum total weight that can be used for the queues in the system
-+ * (big shift values increase it), and the period of virtual time
-+ * wraparounds.
-+ */
-+#define WFQ_SERVICE_SHIFT	22
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = NULL;
-+
-+	BUG_ON(!entity);
-+
-+	if (!entity->my_sched_data)
-+		bfqq = container_of(entity, struct bfq_queue, entity);
-+
-+	return bfqq;
-+}
-+
-+
-+/**
-+ * bfq_delta - map service into the virtual time domain.
-+ * @service: amount of service.
-+ * @weight: scale factor (weight of an entity or weight sum).
-+ */
-+static u64 bfq_delta(unsigned long service, unsigned long weight)
-+{
-+	u64 d = (u64)service << WFQ_SERVICE_SHIFT;
-+
-+	do_div(d, weight);
-+	return d;
-+}
-+
-+/**
-+ * bfq_calc_finish - assign the finish time to an entity.
-+ * @entity: the entity to act upon.
-+ * @service: the service to be charged to the entity.
-+ */
-+static void bfq_calc_finish(struct bfq_entity *entity, unsigned long service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned long long start, finish, delta;
-+
-+	BUG_ON(entity->weight == 0);
-+
-+	entity->finish = entity->start +
-+		bfq_delta(service, entity->weight);
-+
-+	start = ((entity->start>>10)*1000)>>12;
-+	finish = ((entity->finish>>10)*1000)>>12;
-+	delta = ((bfq_delta(service, entity->weight)>>10)*1000)>>12;
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"calc_finish: serv %lu, w %d",
-+			service, entity->weight);
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"calc_finish: start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"calc_finish group: serv %lu, w %d",
-+			     service, entity->weight);
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"calc_finish group: start %llu, finish %llu, delta %llu",
-+			start, finish, delta);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_entity_of - get an entity from a node.
-+ * @node: the node field of the entity.
-+ *
-+ * Convert a node pointer to the relative entity.  This is used only
-+ * to simplify the logic of some functions and not as the generic
-+ * conversion mechanism because, e.g., in the tree walking functions,
-+ * the check for a %NULL value would be redundant.
-+ */
-+static struct bfq_entity *bfq_entity_of(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = NULL;
-+
-+	if (node)
-+		entity = rb_entry(node, struct bfq_entity, rb_node);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_extract - remove an entity from a tree.
-+ * @root: the tree root.
-+ * @entity: the entity to remove.
-+ */
-+static void bfq_extract(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	BUG_ON(entity->tree != root);
-+
-+	entity->tree = NULL;
-+	rb_erase(&entity->rb_node, root);
-+}
-+
-+/**
-+ * bfq_idle_extract - extract an entity from the idle tree.
-+ * @st: the service tree of the owning @entity.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_idle_extract(struct bfq_service_tree *st,
-+			     struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *next;
-+
-+	BUG_ON(entity->tree != &st->idle);
-+
-+	if (entity == st->first_idle) {
-+		next = rb_next(&entity->rb_node);
-+		st->first_idle = bfq_entity_of(next);
-+	}
-+
-+	if (entity == st->last_idle) {
-+		next = rb_prev(&entity->rb_node);
-+		st->last_idle = bfq_entity_of(next);
-+	}
-+
-+	bfq_extract(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+}
-+
-+/**
-+ * bfq_insert - generic tree insertion.
-+ * @root: tree root.
-+ * @entity: entity to insert.
-+ *
-+ * This is used for the idle and the active tree, since they are both
-+ * ordered by finish time.
-+ */
-+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
-+{
-+	struct bfq_entity *entry;
-+	struct rb_node **node = &root->rb_node;
-+	struct rb_node *parent = NULL;
-+
-+	BUG_ON(entity->tree);
-+
-+	while (*node) {
-+		parent = *node;
-+		entry = rb_entry(parent, struct bfq_entity, rb_node);
-+
-+		if (bfq_gt(entry->finish, entity->finish))
-+			node = &parent->rb_left;
-+		else
-+			node = &parent->rb_right;
-+	}
-+
-+	rb_link_node(&entity->rb_node, parent, node);
-+	rb_insert_color(&entity->rb_node, root);
-+
-+	entity->tree = root;
-+}
-+
-+/**
-+ * bfq_update_min - update the min_start field of a entity.
-+ * @entity: the entity to update.
-+ * @node: one of its children.
-+ *
-+ * This function is called when @entity may store an invalid value for
-+ * min_start due to updates to the active tree.  The function  assumes
-+ * that the subtree rooted at @node (which may be its left or its right
-+ * child) has a valid min_start value.
-+ */
-+static void bfq_update_min(struct bfq_entity *entity, struct rb_node *node)
-+{
-+	struct bfq_entity *child;
-+
-+	if (node) {
-+		child = rb_entry(node, struct bfq_entity, rb_node);
-+		if (bfq_gt(entity->min_start, child->min_start))
-+			entity->min_start = child->min_start;
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_node - recalculate min_start.
-+ * @node: the node to update.
-+ *
-+ * @node may have changed position or one of its children may have moved,
-+ * this function updates its min_start value.  The left and right subtrees
-+ * are assumed to hold a correct min_start value.
-+ */
-+static void bfq_update_active_node(struct rb_node *node)
-+{
-+	struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	entity->min_start = entity->start;
-+	bfq_update_min(entity, node->rb_right);
-+	bfq_update_min(entity, node->rb_left);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "update_active_node: new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "update_active_node: new min_start %llu",
-+			     ((entity->min_start>>10)*1000)>>12);
-+#endif
-+	}
-+}
-+
-+/**
-+ * bfq_update_active_tree - update min_start for the whole active tree.
-+ * @node: the starting node.
-+ *
-+ * @node must be the deepest modified node after an update.  This function
-+ * updates its min_start using the values held by its children, assuming
-+ * that they did not change, and then updates all the nodes that may have
-+ * changed in the path to the root.  The only nodes that may have changed
-+ * are the ones in the path or their siblings.
-+ */
-+static void bfq_update_active_tree(struct rb_node *node)
-+{
-+	struct rb_node *parent;
-+
-+up:
-+	bfq_update_active_node(node);
-+
-+	parent = rb_parent(node);
-+	if (!parent)
-+		return;
-+
-+	if (node == parent->rb_left && parent->rb_right)
-+		bfq_update_active_node(parent->rb_right);
-+	else if (parent->rb_left)
-+		bfq_update_active_node(parent->rb_left);
-+
-+	node = parent;
-+	goto up;
-+}
-+
-+static void bfq_weights_tree_add(struct bfq_data *bfqd,
-+				 struct bfq_entity *entity,
-+				 struct rb_root *root);
-+
-+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
-+				    struct bfq_entity *entity,
-+				    struct rb_root *root);
-+
-+
-+/**
-+ * bfq_active_insert - insert an entity in the active tree of its
-+ *                     group/device.
-+ * @st: the service tree of the entity.
-+ * @entity: the entity being inserted.
-+ *
-+ * The active tree is ordered by finish time, but an extra key is kept
-+ * per each node, containing the minimum value for the start times of
-+ * its children (and the node itself), so it's possible to search for
-+ * the eligible node with the lowest finish time in logarithmic time.
-+ */
-+static void bfq_active_insert(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node = &entity->rb_node;
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	bfq_insert(&st->active, entity);
-+
-+	if (node->rb_left)
-+		node = node->rb_left;
-+	else if (node->rb_right)
-+		node = node->rb_right;
-+
-+	bfq_update_active_tree(node);
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else { /* bfq_group */
-+		BUG_ON(!bfqd);
-+		bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
-+	}
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		bfqg->active_entities++;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
-+ * @ioprio: the ioprio value to convert.
-+ */
-+static unsigned short bfq_ioprio_to_weight(int ioprio)
-+{
-+	BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
-+	return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF;
-+}
-+
-+/**
-+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
-+ * @weight: the weight value to convert.
-+ *
-+ * To preserve as much as possible the old only-ioprio user interface,
-+ * 0 is used as an escape ioprio value for weights (numerically) equal or
-+ * larger than IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF.
-+ */
-+static unsigned short bfq_weight_to_ioprio(int weight)
-+{
-+	BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
-+	return IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight < 0 ?
-+		0 : IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight;
-+}
-+
-+static void bfq_get_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	if (bfqq) {
-+		bfqq->ref++;
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
-+			     bfqq, bfqq->ref);
-+	}
-+}
-+
-+/**
-+ * bfq_find_deepest - find the deepest node that an extraction can modify.
-+ * @node: the node being removed.
-+ *
-+ * Do the first step of an extraction in an rb tree, looking for the
-+ * node that will replace @node, and returning the deepest node that
-+ * the following modifications to the tree can touch.  If @node is the
-+ * last node in the tree return %NULL.
-+ */
-+static struct rb_node *bfq_find_deepest(struct rb_node *node)
-+{
-+	struct rb_node *deepest;
-+
-+	if (!node->rb_right && !node->rb_left)
-+		deepest = rb_parent(node);
-+	else if (!node->rb_right)
-+		deepest = node->rb_left;
-+	else if (!node->rb_left)
-+		deepest = node->rb_right;
-+	else {
-+		deepest = rb_next(node);
-+		if (deepest->rb_right)
-+			deepest = deepest->rb_right;
-+		else if (rb_parent(deepest) != node)
-+			deepest = rb_parent(deepest);
-+	}
-+
-+	return deepest;
-+}
-+
-+/**
-+ * bfq_active_extract - remove an entity from the active tree.
-+ * @st: the service_tree containing the tree.
-+ * @entity: the entity being removed.
-+ */
-+static void bfq_active_extract(struct bfq_service_tree *st,
-+			       struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct rb_node *node;
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	struct bfq_sched_data *sd = NULL;
-+	struct bfq_group *bfqg = NULL;
-+	struct bfq_data *bfqd = NULL;
-+#endif
-+
-+	node = bfq_find_deepest(&entity->rb_node);
-+	bfq_extract(&st->active, entity);
-+
-+	if (node)
-+		bfq_update_active_tree(node);
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	sd = entity->sched_data;
-+	bfqg = container_of(sd, struct bfq_group, sched_data);
-+	BUG_ON(!bfqg);
-+	bfqd = (struct bfq_data *)bfqg->bfqd;
-+#endif
-+	if (bfqq)
-+		list_del(&bfqq->bfqq_list);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else { /* bfq_group */
-+		BUG_ON(!bfqd);
-+		bfq_weights_tree_remove(bfqd, entity,
-+					&bfqd->group_weights_tree);
-+	}
-+	if (bfqg != bfqd->root_group) {
-+		BUG_ON(!bfqg);
-+		BUG_ON(!bfqd);
-+		BUG_ON(!bfqg->active_entities);
-+		bfqg->active_entities--;
-+	}
-+#endif
-+}
-+
-+/**
-+ * bfq_idle_insert - insert an entity into the idle tree.
-+ * @st: the service tree containing the tree.
-+ * @entity: the entity to insert.
-+ */
-+static void bfq_idle_insert(struct bfq_service_tree *st,
-+			    struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (!first_idle || bfq_gt(first_idle->finish, entity->finish))
-+		st->first_idle = entity;
-+	if (!last_idle || bfq_gt(entity->finish, last_idle->finish))
-+		st->last_idle = entity;
-+
-+	bfq_insert(&st->idle, entity);
-+
-+	if (bfqq)
-+		list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
-+}
-+
-+/**
-+ * bfq_forget_entity - do not consider entity any longer for scheduling
-+ * @st: the service tree.
-+ * @entity: the entity being removed.
-+ * @is_in_service: true if entity is currently the in-service entity.
-+ *
-+ * Forget everything about @entity. In addition, if entity represents
-+ * a queue, and the latter is not in service, then release the service
-+ * reference to the queue (the one taken through bfq_get_entity). In
-+ * fact, in this case, there is really no more service reference to
-+ * the queue, as the latter is also outside any service tree. If,
-+ * instead, the queue is in service, then __bfq_bfqd_reset_in_service
-+ * will take care of putting the reference when the queue finally
-+ * stops being served.
-+ */
-+static void bfq_forget_entity(struct bfq_service_tree *st,
-+			      struct bfq_entity *entity,
-+			      bool is_in_service)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!entity->on_st);
-+
-+	entity->on_st = false;
-+	st->wsum -= entity->weight;
-+	if (bfqq && !is_in_service) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity (before): %p %d",
-+			     bfqq, bfqq->ref);
-+		bfq_put_queue(bfqq);
-+	}
-+}
-+
-+/**
-+ * bfq_put_idle_entity - release the idle tree ref of an entity.
-+ * @st: service tree for the entity.
-+ * @entity: the entity being released.
-+ */
-+static void bfq_put_idle_entity(struct bfq_service_tree *st,
-+				struct bfq_entity *entity)
-+{
-+	bfq_idle_extract(st, entity);
-+	bfq_forget_entity(st, entity,
-+			  entity == entity->sched_data->in_service_entity);
-+}
-+
-+/**
-+ * bfq_forget_idle - update the idle tree if necessary.
-+ * @st: the service tree to act upon.
-+ *
-+ * To preserve the global O(log N) complexity we only remove one entry here;
-+ * as the idle tree will not grow indefinitely this can be done safely.
-+ */
-+static void bfq_forget_idle(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *first_idle = st->first_idle;
-+	struct bfq_entity *last_idle = st->last_idle;
-+
-+	if (RB_EMPTY_ROOT(&st->active) && last_idle &&
-+	    !bfq_gt(last_idle->finish, st->vtime)) {
-+		/*
-+		 * Forget the whole idle tree, increasing the vtime past
-+		 * the last finish time of idle entities.
-+		 */
-+		st->vtime = last_idle->finish;
-+	}
-+
-+	if (first_idle && !bfq_gt(first_idle->finish, st->vtime))
-+		bfq_put_idle_entity(st, first_idle);
-+}
-+
-+static struct bfq_service_tree *
-+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
-+			 struct bfq_entity *entity)
-+{
-+	struct bfq_service_tree *new_st = old_st;
-+
-+	if (entity->prio_changed) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+		unsigned int prev_weight, new_weight;
-+		struct bfq_data *bfqd = NULL;
-+		struct rb_root *root;
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		struct bfq_sched_data *sd;
-+		struct bfq_group *bfqg;
-+#endif
-+
-+		if (bfqq)
-+			bfqd = bfqq->bfqd;
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		else {
-+			sd = entity->my_sched_data;
-+			bfqg = container_of(sd, struct bfq_group, sched_data);
-+			BUG_ON(!bfqg);
-+			bfqd = (struct bfq_data *)bfqg->bfqd;
-+			BUG_ON(!bfqd);
-+		}
-+#endif
-+
-+		BUG_ON(old_st->wsum < entity->weight);
-+		old_st->wsum -= entity->weight;
-+
-+		if (entity->new_weight != entity->orig_weight) {
-+			if (entity->new_weight < BFQ_MIN_WEIGHT ||
-+			    entity->new_weight > BFQ_MAX_WEIGHT) {
-+				pr_crit("update_weight_prio: new_weight %d\n",
-+					entity->new_weight);
-+				if (entity->new_weight < BFQ_MIN_WEIGHT)
-+					entity->new_weight = BFQ_MIN_WEIGHT;
-+				else
-+					entity->new_weight = BFQ_MAX_WEIGHT;
-+			}
-+			entity->orig_weight = entity->new_weight;
-+			if (bfqq)
-+				bfqq->ioprio =
-+				  bfq_weight_to_ioprio(entity->orig_weight);
-+		}
-+
-+		if (bfqq)
-+			bfqq->ioprio_class = bfqq->new_ioprio_class;
-+		entity->prio_changed = 0;
-+
-+		/*
-+		 * NOTE: here we may be changing the weight too early,
-+		 * this will cause unfairness.  The correct approach
-+		 * would have required additional complexity to defer
-+		 * weight changes to the proper time instants (i.e.,
-+		 * when entity->finish <= old_st->vtime).
-+		 */
-+		new_st = bfq_entity_service_tree(entity);
-+
-+		prev_weight = entity->weight;
-+		new_weight = entity->orig_weight *
-+			     (bfqq ? bfqq->wr_coeff : 1);
-+		/*
-+		 * If the weight of the entity changes, remove the entity
-+		 * from its old weight counter (if there is a counter
-+		 * associated with the entity), and add it to the counter
-+		 * associated with its new weight.
-+		 */
-+		if (prev_weight != new_weight) {
-+			if (bfqq)
-+				bfq_log_bfqq(bfqq->bfqd, bfqq,
-+					     "weight changed %d %d(%d %d)",
-+					     prev_weight, new_weight,
-+					     entity->orig_weight,
-+					     bfqq->wr_coeff);
-+
-+			root = bfqq ? &bfqd->queue_weights_tree :
-+				      &bfqd->group_weights_tree;
-+			bfq_weights_tree_remove(bfqd, entity, root);
-+		}
-+		entity->weight = new_weight;
-+		/*
-+		 * Add the entity to its weights tree only if it is
-+		 * not associated with a weight-raised queue.
-+		 */
-+		if (prev_weight != new_weight &&
-+		    (bfqq ? bfqq->wr_coeff == 1 : 1))
-+			/* If we get here, root has been initialized. */
-+			bfq_weights_tree_add(bfqd, entity, root);
-+
-+		new_st->wsum += entity->weight;
-+
-+		if (new_st != old_st)
-+			entity->start = new_st->vtime;
-+	}
-+
-+	return new_st;
-+}
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg);
-+#endif
-+
-+/**
-+ * bfq_bfqq_served - update the scheduler status after selection for
-+ *                   service.
-+ * @bfqq: the queue being served.
-+ * @served: bytes to transfer.
-+ *
-+ * NOTE: this can be optimized, as the timestamps of upper level entities
-+ * are synchronized every time a new bfqq is selected for service.  By now,
-+ * we keep it to better check consistency.
-+ */
-+static void bfq_bfqq_served(struct bfq_queue *bfqq, int served)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st;
-+
-+	for_each_entity(entity) {
-+		st = bfq_entity_service_tree(entity);
-+
-+		entity->service += served;
-+
-+		BUG_ON(st->wsum == 0);
-+
-+		st->vtime += bfq_delta(served, st->wsum);
-+		bfq_forget_idle(st);
-+	}
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	bfqg_stats_set_start_empty_time(bfqq_group(bfqq));
-+#endif
-+	st = bfq_entity_service_tree(&bfqq->entity);
-+	bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs, vtime %llu on %p",
-+		     served,  ((st->vtime>>10)*1000)>>12, st);
-+}
-+
-+/**
-+ * bfq_bfqq_charge_time - charge an amount of service equivalent to the length
-+ *			  of the time interval during which bfqq has been in
-+ *			  service.
-+ * @bfqd: the device
-+ * @bfqq: the queue that needs a service update.
-+ * @time_ms: the amount of time during which the queue has received service
-+ *
-+ * If a queue does not consume its budget fast enough, then providing
-+ * the queue with service fairness may impair throughput, more or less
-+ * severely. For this reason, queues that consume their budget slowly
-+ * are provided with time fairness instead of service fairness. This
-+ * goal is achieved through the BFQ scheduling engine, even if such an
-+ * engine works in the service, and not in the time domain. The trick
-+ * is charging these queues with an inflated amount of service, equal
-+ * to the amount of service that they would have received during their
-+ * service slot if they had been fast, i.e., if their requests had
-+ * been dispatched at a rate equal to the estimated peak rate.
-+ *
-+ * It is worth noting that time fairness can cause important
-+ * distortions in terms of bandwidth distribution, on devices with
-+ * internal queueing. The reason is that I/O requests dispatched
-+ * during the service slot of a queue may be served after that service
-+ * slot is finished, and may have a total processing time loosely
-+ * correlated with the duration of the service slot. This is
-+ * especially true for short service slots.
-+ */
-+static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				 unsigned long time_ms)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	int tot_serv_to_charge = entity->service;
-+	unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout);
-+
-+	if (time_ms > 0 && time_ms < timeout_ms)
-+		tot_serv_to_charge =
-+			(bfqd->bfq_max_budget * time_ms) / timeout_ms;
-+
-+	if (tot_serv_to_charge < entity->service)
-+		tot_serv_to_charge = entity->service;
-+
-+	bfq_log_bfqq(bfqq->bfqd, bfqq,
-+		     "charge_time: %lu/%u ms, %d/%d/%d sectors",
-+		     time_ms, timeout_ms, entity->service,
-+		     tot_serv_to_charge, entity->budget);
-+
-+	/* Increase budget to avoid inconsistencies */
-+	if (tot_serv_to_charge > entity->budget)
-+		entity->budget = tot_serv_to_charge;
-+
-+	bfq_bfqq_served(bfqq,
-+			max_t(int, 0, tot_serv_to_charge - entity->service));
-+}
-+
-+static void bfq_update_fin_time_enqueue(struct bfq_entity *entity,
-+					struct bfq_service_tree *st,
-+					bool backshifted)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	struct bfq_sched_data *sd = entity->sched_data;
-+
-+	st = __bfq_entity_update_weight_prio(st, entity);
-+	bfq_calc_finish(entity, entity->budget);
-+
-+	/*
-+	 * If some queues enjoy backshifting for a while, then their
-+	 * (virtual) finish timestamps may happen to become lower and
-+	 * lower than the system virtual time.  In particular, if
-+	 * these queues often happen to be idle for short time
-+	 * periods, and during such time periods other queues with
-+	 * higher timestamps happen to be busy, then the backshifted
-+	 * timestamps of the former queues can become much lower than
-+	 * the system virtual time. In fact, to serve the queues with
-+	 * higher timestamps while the ones with lower timestamps are
-+	 * idle, the system virtual time may be pushed-up to much
-+	 * higher values than the finish timestamps of the idle
-+	 * queues. As a consequence, the finish timestamps of all new
-+	 * or newly activated queues may end up being much larger than
-+	 * those of lucky queues with backshifted timestamps. The
-+	 * latter queues may then monopolize the device for a lot of
-+	 * time. This would simply break service guarantees.
-+	 *
-+	 * To reduce this problem, push up a little bit the
-+	 * backshifted timestamps of the queue associated with this
-+	 * entity (only a queue can happen to have the backshifted
-+	 * flag set): just enough to let the finish timestamp of the
-+	 * queue be equal to the current value of the system virtual
-+	 * time. This may introduce a little unfairness among queues
-+	 * with backshifted timestamps, but it does not break
-+	 * worst-case fairness guarantees.
-+	 *
-+	 * As a special case, if bfqq is weight-raised, push up
-+	 * timestamps much less, to keep very low the probability that
-+	 * this push up causes the backshifted finish timestamps of
-+	 * weight-raised queues to become higher than the backshifted
-+	 * finish timestamps of non weight-raised queues.
-+	 */
-+	if (backshifted && bfq_gt(st->vtime, entity->finish)) {
-+		unsigned long delta = st->vtime - entity->finish;
-+
-+		if (bfqq)
-+			delta /= bfqq->wr_coeff;
-+
-+		entity->start += delta;
-+		entity->finish += delta;
-+
-+		if (bfqq) {
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "__activate_entity: new queue finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		} else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "__activate_entity: new group finish %llu",
-+				     ((entity->finish>>10)*1000)>>12);
-+#endif
-+		}
-+	}
-+
-+	bfq_active_insert(st, entity);
-+
-+	if (bfqq) {
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			"__activate_entity: queue %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	} else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			"__activate_entity: group %seligible in st %p",
-+			     entity->start <= st->vtime ? "" : "non ", st);
-+#endif
-+	}
-+	BUG_ON(RB_EMPTY_ROOT(&st->active));
-+	BUG_ON(&st->active != &sd->service_tree->active &&
-+	       &st->active != &(sd->service_tree+1)->active &&
-+	       &st->active != &(sd->service_tree+2)->active);
-+}
-+
-+/**
-+ * __bfq_activate_entity - handle activation of entity.
-+ * @entity: the entity being activated.
-+ * @non_blocking_wait_rq: true if entity was waiting for a request
-+ *
-+ * Called for a 'true' activation, i.e., if entity is not active and
-+ * one of its children receives a new request.
-+ *
-+ * Basically, this function updates the timestamps of entity and
-+ * inserts entity into its active tree, ater possible extracting it
-+ * from its idle tree.
-+ */
-+static void __bfq_activate_entity(struct bfq_entity *entity,
-+				  bool non_blocking_wait_rq)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	bool backshifted = false;
-+	unsigned long long min_vstart;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	/* See comments on bfq_fqq_update_budg_for_activation */
-+	if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) {
-+		backshifted = true;
-+		min_vstart = entity->finish;
-+	} else
-+		min_vstart = st->vtime;
-+
-+	if (entity->tree == &st->idle) {
-+		/*
-+		 * Must be on the idle tree, bfq_idle_extract() will
-+		 * check for that.
-+		 */
-+		bfq_idle_extract(st, entity);
-+		entity->start = bfq_gt(min_vstart, entity->finish) ?
-+			min_vstart : entity->finish;
-+	} else {
-+		/*
-+		 * The finish time of the entity may be invalid, and
-+		 * it is in the past for sure, otherwise the queue
-+		 * would have been on the idle tree.
-+		 */
-+		entity->start = min_vstart;
-+		st->wsum += entity->weight;
-+		/*
-+		 * entity is about to be inserted into a service tree,
-+		 * and then set in service: get a reference to make
-+		 * sure entity does not disappear until it is no
-+		 * longer in service or scheduled for service.
-+		 */
-+		bfq_get_entity(entity);
-+
-+		BUG_ON(entity->on_st && bfqq);
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		if (entity->on_st && !bfqq) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd,
-+				     bfqg,
-+				     "activate bug, class %d in_service %p",
-+				     bfq_class_idx(entity), sd->in_service_entity);
-+		}
-+#endif
-+		BUG_ON(entity->on_st && !bfqq);
-+		entity->on_st = true;
-+	}
-+
-+	bfq_update_fin_time_enqueue(entity, st, backshifted);
-+}
-+
-+/**
-+ * __bfq_requeue_entity - handle requeueing or repositioning of an entity.
-+ * @entity: the entity being requeued or repositioned.
-+ *
-+ * Requeueing is needed if this entity stops being served, which
-+ * happens if a leaf descendant entity has expired. On the other hand,
-+ * repositioning is needed if the next_inservice_entity for the child
-+ * entity has changed. See the comments inside the function for
-+ * details.
-+ *
-+ * Basically, this function: 1) removes entity from its active tree if
-+ * present there, 2) updates the timestamps of entity and 3) inserts
-+ * entity back into its active tree (in the new, right position for
-+ * the new values of the timestamps).
-+ */
-+static void __bfq_requeue_entity(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+
-+	BUG_ON(entity != sd->in_service_entity &&
-+	       entity->tree != &st->active);
-+
-+	if (entity == sd->in_service_entity) {
-+		/*
-+		 * We are requeueing the current in-service entity,
-+		 * which may have to be done for one of the following
-+		 * reasons:
-+		 * - entity represents the in-service queue, and the
-+		 *   in-service queue is being requeued after an
-+		 *   expiration;
-+		 * - entity represents a group, and its budget has
-+		 *   changed because one of its child entities has
-+		 *   just been either activated or requeued for some
-+		 *   reason; the timestamps of the entity need then to
-+		 *   be updated, and the entity needs to be enqueued
-+		 *   or repositioned accordingly.
-+		 *
-+		 * In particular, before requeueing, the start time of
-+		 * the entity must be moved forward to account for the
-+		 * service that the entity has received while in
-+		 * service. This is done by the next instructions. The
-+		 * finish time will then be updated according to this
-+		 * new value of the start time, and to the budget of
-+		 * the entity.
-+		 */
-+		bfq_calc_finish(entity, entity->service);
-+		entity->start = entity->finish;
-+		BUG_ON(entity->tree && entity->tree != &st->active);
-+		/*
-+		 * In addition, if the entity had more than one child
-+		 * when set in service, then was not extracted from
-+		 * the active tree. This implies that the position of
-+		 * the entity in the active tree may need to be
-+		 * changed now, because we have just updated the start
-+		 * time of the entity, and we will update its finish
-+		 * time in a moment (the requeueing is then, more
-+		 * precisely, a repositioning in this case). To
-+		 * implement this repositioning, we: 1) dequeue the
-+		 * entity here, 2) update the finish time and
-+		 * requeue the entity according to the new
-+		 * timestamps below.
-+		 */
-+		if (entity->tree)
-+			bfq_active_extract(st, entity);
-+	} else { /* The entity is already active, and not in service */
-+		/*
-+		 * In this case, this function gets called only if the
-+		 * next_in_service entity below this entity has
-+		 * changed, and this change has caused the budget of
-+		 * this entity to change, which, finally implies that
-+		 * the finish time of this entity must be
-+		 * updated. Such an update may cause the scheduling,
-+		 * i.e., the position in the active tree, of this
-+		 * entity to change. We handle this change by: 1)
-+		 * dequeueing the entity here, 2) updating the finish
-+		 * time and requeueing the entity according to the new
-+		 * timestamps below. This is the same approach as the
-+		 * non-extracted-entity sub-case above.
-+		 */
-+		bfq_active_extract(st, entity);
-+	}
-+
-+	bfq_update_fin_time_enqueue(entity, st, false);
-+}
-+
-+static void __bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					  struct bfq_sched_data *sd,
-+					  bool non_blocking_wait_rq)
-+{
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	if (sd->in_service_entity == entity || entity->tree == &st->active)
-+		 /*
-+		  * in service or already queued on the active tree,
-+		  * requeue or reposition
-+		  */
-+		__bfq_requeue_entity(entity);
-+	else
-+		/*
-+		 * Not in service and not queued on its active tree:
-+		 * the activity is idle and this is a true activation.
-+		 */
-+		__bfq_activate_entity(entity, non_blocking_wait_rq);
-+}
-+
-+
-+/**
-+ * bfq_activate_entity - activate or requeue an entity representing a bfq_queue,
-+ *			 and activate, requeue or reposition all ancestors
-+ *			 for which such an update becomes necessary.
-+ * @entity: the entity to activate.
-+ * @non_blocking_wait_rq: true if this entity was waiting for a request
-+ * @requeue: true if this is a requeue, which implies that bfqq is
-+ *	     being expired; thus ALL its ancestors stop being served and must
-+ *	     therefore be requeued
-+ */
-+static void bfq_activate_requeue_entity(struct bfq_entity *entity,
-+					bool non_blocking_wait_rq,
-+					bool requeue)
-+{
-+	struct bfq_sched_data *sd;
-+
-+	for_each_entity(entity) {
-+		BUG_ON(!entity);
-+		sd = entity->sched_data;
-+		__bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq);
-+
-+		BUG_ON(RB_EMPTY_ROOT(&sd->service_tree->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+1)->active) &&
-+		       RB_EMPTY_ROOT(&(sd->service_tree+2)->active));
-+
-+		if (!bfq_update_next_in_service(sd, entity) && !requeue) {
-+			BUG_ON(!sd->next_in_service);
-+			break;
-+		}
-+		BUG_ON(!sd->next_in_service);
-+	}
-+}
-+
-+/**
-+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
-+ * @entity: the entity to deactivate.
-+ * @ins_into_idle_tree: if false, the entity will not be put into the
-+ *			idle tree.
-+ *
-+ * Deactivates an entity, independently from its previous state.  Must
-+ * be invoked only if entity is on a service tree. Extracts the entity
-+ * from that tree, and if necessary and allowed, puts it on the idle
-+ * tree.
-+ */
-+static bool __bfq_deactivate_entity(struct bfq_entity *entity,
-+				    bool ins_into_idle_tree)
-+{
-+	struct bfq_sched_data *sd = entity->sched_data;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+	bool is_in_service = entity == sd->in_service_entity;
-+
-+	if (!entity->on_st) { /* entity never activated, or already inactive */
-+		BUG_ON(entity == entity->sched_data->in_service_entity);
-+		return false;
-+	}
-+
-+	BUG_ON(is_in_service && entity->tree && entity->tree != &st->active);
-+
-+	if (is_in_service)
-+		bfq_calc_finish(entity, entity->service);
-+
-+	if (entity->tree == &st->active)
-+		bfq_active_extract(st, entity);
-+	else if (!is_in_service && entity->tree == &st->idle)
-+		bfq_idle_extract(st, entity);
-+	else if (entity->tree)
-+		BUG();
-+
-+	if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime))
-+		bfq_forget_entity(st, entity, is_in_service);
-+	else
-+		bfq_idle_insert(st, entity);
-+
-+	return true;
-+}
-+
-+/**
-+ * bfq_deactivate_entity - deactivate an entity representing a bfq_queue.
-+ * @entity: the entity to deactivate.
-+ * @ins_into_idle_tree: true if the entity can be put on the idle tree
-+ */
-+static void bfq_deactivate_entity(struct bfq_entity *entity,
-+				  bool ins_into_idle_tree,
-+				  bool expiration)
-+{
-+	struct bfq_sched_data *sd;
-+	struct bfq_entity *parent = NULL;
-+
-+	for_each_entity_safe(entity, parent) {
-+		sd = entity->sched_data;
-+
-+		BUG_ON(sd == NULL); /*
-+				     * It would mean that this is the
-+				     * root group.
-+				     */
-+
-+		BUG_ON(expiration && entity != sd->in_service_entity);
-+
-+		BUG_ON(entity != sd->in_service_entity &&
-+		       entity->tree ==
-+		       &bfq_entity_service_tree(entity)->active &&
-+		       !sd->next_in_service);
-+
-+		if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) {
-+			/*
-+			 * entity is not in any tree any more, so
-+			 * this deactivation is a no-op, and there is
-+			 * nothing to change for upper-level entities
-+			 * (in case of expiration, this can never
-+			 * happen).
-+			 */
-+			BUG_ON(expiration); /*
-+					     * entity cannot be already out of
-+					     * any tree
-+					     */
-+			return;
-+		}
-+
-+		if (sd->next_in_service == entity)
-+			/*
-+			 * entity was the next_in_service entity,
-+			 * then, since entity has just been
-+			 * deactivated, a new one must be found.
-+			 */
-+			bfq_update_next_in_service(sd, NULL);
-+
-+		if (sd->next_in_service) {
-+			/*
-+			 * The parent entity is still backlogged,
-+			 * because next_in_service is not NULL. So, no
-+			 * further upwards deactivation must be
-+			 * performed.  Yet, next_in_service has
-+			 * changed.  Then the schedule does need to be
-+			 * updated upwards.
-+			 */
-+			BUG_ON(sd->next_in_service == entity);
-+			break;
-+		}
-+
-+		/*
-+		 * If we get here, then the parent is no more
-+		 * backlogged and we need to propagate the
-+		 * deactivation upwards. Thus let the loop go on.
-+		 */
-+
-+		/*
-+		 * Also let parent be queued into the idle tree on
-+		 * deactivation, to preserve service guarantees, and
-+		 * assuming that who invoked this function does not
-+		 * need parent entities too to be removed completely.
-+		 */
-+		ins_into_idle_tree = true;
-+	}
-+
-+	/*
-+	 * If the deactivation loop is fully executed, then there are
-+	 * no more entities to touch and next loop is not executed at
-+	 * all. Otherwise, requeue remaining entities if they are
-+	 * about to stop receiving service, or reposition them if this
-+	 * is not the case.
-+	 */
-+	entity = parent;
-+	for_each_entity(entity) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+		/*
-+		 * Invoke __bfq_requeue_entity on entity, even if
-+		 * already active, to requeue/reposition it in the
-+		 * active tree (because sd->next_in_service has
-+		 * changed)
-+		 */
-+		__bfq_requeue_entity(entity);
-+
-+		sd = entity->sched_data;
-+		BUG_ON(expiration && sd->in_service_entity != entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "invoking udpdate_next for this queue");
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity,
-+					     struct bfq_group, entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "invoking udpdate_next for this entity");
-+		}
-+#endif
-+		if (!bfq_update_next_in_service(sd, entity) &&
-+		    !expiration)
-+			/*
-+			 * next_in_service unchanged or not causing
-+			 * any change in entity->parent->sd, and no
-+			 * requeueing needed for expiration: stop
-+			 * here.
-+			 */
-+			break;
-+	}
-+}
-+
-+/**
-+ * bfq_calc_vtime_jump - compute the value to which the vtime should jump,
-+ *                       if needed, to have at least one entity eligible.
-+ * @st: the service tree to act upon.
-+ *
-+ * Assumes that st is not empty.
-+ */
-+static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st)
-+{
-+	struct bfq_entity *root_entity = bfq_root_active_entity(&st->active);
-+
-+	if (bfq_gt(root_entity->min_start, st->vtime)) {
-+		struct bfq_queue *bfqq = bfq_entity_to_bfqq(root_entity);
-+
-+		if (bfqq)
-+			bfq_log_bfqq(bfqq->bfqd, bfqq,
-+				     "calc_vtime_jump: new value %llu",
-+				     root_entity->min_start);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(root_entity, struct bfq_group,
-+					     entity);
-+
-+			bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+				     "calc_vtime_jump: new value %llu",
-+				     root_entity->min_start);
-+		}
-+#endif
-+		return root_entity->min_start;
-+	}
-+	return st->vtime;
-+}
-+
-+static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value)
-+{
-+	if (new_value > st->vtime) {
-+		st->vtime = new_value;
-+		bfq_forget_idle(st);
-+	}
-+}
-+
-+/**
-+ * bfq_first_active_entity - find the eligible entity with
-+ *                           the smallest finish time
-+ * @st: the service tree to select from.
-+ * @vtime: the system virtual to use as a reference for eligibility
-+ *
-+ * This function searches the first schedulable entity, starting from the
-+ * root of the tree and going on the left every time on this side there is
-+ * a subtree with at least one eligible (start >= vtime) entity. The path on
-+ * the right is followed only if a) the left subtree contains no eligible
-+ * entities and b) no eligible entity has been found yet.
-+ */
-+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st,
-+						  u64 vtime)
-+{
-+	struct bfq_entity *entry, *first = NULL;
-+	struct rb_node *node = st->active.rb_node;
-+
-+	while (node) {
-+		entry = rb_entry(node, struct bfq_entity, rb_node);
-+left:
-+		if (!bfq_gt(entry->start, vtime))
-+			first = entry;
-+
-+		BUG_ON(bfq_gt(entry->min_start, vtime));
-+
-+		if (node->rb_left) {
-+			entry = rb_entry(node->rb_left,
-+					 struct bfq_entity, rb_node);
-+			if (!bfq_gt(entry->min_start, vtime)) {
-+				node = node->rb_left;
-+				goto left;
-+			}
-+		}
-+		if (first)
-+			break;
-+		node = node->rb_right;
-+	}
-+
-+	BUG_ON(!first && !RB_EMPTY_ROOT(&st->active));
-+	return first;
-+}
-+
-+/**
-+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
-+ * @st: the service tree.
-+ *
-+ * If there is no in-service entity for the sched_data st belongs to,
-+ * then return the entity that will be set in service if:
-+ * 1) the parent entity this st belongs to is set in service;
-+ * 2) no entity belonging to such parent entity undergoes a state change
-+ * that would influence the timestamps of the entity (e.g., becomes idle,
-+ * becomes backlogged, changes its budget, ...).
-+ *
-+ * In this first case, update the virtual time in @st too (see the
-+ * comments on this update inside the function).
-+ *
-+ * In constrast, if there is an in-service entity, then return the
-+ * entity that would be set in service if not only the above
-+ * conditions, but also the next one held true: the currently
-+ * in-service entity, on expiration,
-+ * 1) gets a finish time equal to the current one, or
-+ * 2) is not eligible any more, or
-+ * 3) is idle.
-+ */
-+static struct bfq_entity *
-+__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service
-+#if 0
-+			 , bool force
-+#endif
-+	)
-+{
-+	struct bfq_entity *entity
-+#if 0
-+		, *new_next_in_service = NULL
-+#endif
-+		;
-+	u64 new_vtime;
-+	struct bfq_queue *bfqq;
-+
-+	if (RB_EMPTY_ROOT(&st->active))
-+		return NULL;
-+
-+	/*
-+	 * Get the value of the system virtual time for which at
-+	 * least one entity is eligible.
-+	 */
-+	new_vtime = bfq_calc_vtime_jump(st);
-+
-+	/*
-+	 * If there is no in-service entity for the sched_data this
-+	 * active tree belongs to, then push the system virtual time
-+	 * up to the value that guarantees that at least one entity is
-+	 * eligible. If, instead, there is an in-service entity, then
-+	 * do not make any such update, because there is already an
-+	 * eligible entity, namely the in-service one (even if the
-+	 * entity is not on st, because it was extracted when set in
-+	 * service).
-+	 */
-+	if (!in_service)
-+		bfq_update_vtime(st, new_vtime);
-+
-+	entity = bfq_first_active_entity(st, new_vtime);
-+	BUG_ON(bfq_gt(entity->start, new_vtime));
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "__lookup_next: start %llu vtime %llu st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "__lookup_next: start %llu vtime %llu st %p",
-+			     ((entity->start>>10)*1000)>>12,
-+			     ((new_vtime>>10)*1000)>>12, st);
-+	}
-+#endif
-+
-+	BUG_ON(!entity);
-+
-+	return entity;
-+}
-+
-+/**
-+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
-+ * @sd: the sched_data.
-+ *
-+ * This function is invoked when there has been a change in the trees
-+ * for sd, and we need know what is the new next entity after this
-+ * change.
-+ */
-+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd)
-+{
-+	struct bfq_service_tree *st = sd->service_tree;
-+	struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1);
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_queue *bfqq;
-+	int class_idx = 0;
-+
-+	BUG_ON(!sd);
-+	BUG_ON(!st);
-+	/*
-+	 * Choose from idle class, if needed to guarantee a minimum
-+	 * bandwidth to this class (and if there is some active entity
-+	 * in idle class). This should also mitigate
-+	 * priority-inversion problems in case a low priority task is
-+	 * holding file system resources.
-+	 */
-+	if (time_is_before_jiffies(sd->bfq_class_idle_last_service +
-+				   BFQ_CL_IDLE_TIMEOUT)) {
-+		if (!RB_EMPTY_ROOT(&idle_class_st->active))
-+			class_idx = BFQ_IOPRIO_CLASSES - 1;
-+		/* About to be served if backlogged, or not yet backlogged */
-+		sd->bfq_class_idle_last_service = jiffies;
-+	}
-+
-+	/*
-+	 * Find the next entity to serve for the highest-priority
-+	 * class, unless the idle class needs to be served.
-+	 */
-+	for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) {
-+		entity = __bfq_lookup_next_entity(st + class_idx,
-+						  sd->in_service_entity);
-+
-+		if (entity)
-+			break;
-+	}
-+
-+	BUG_ON(!entity &&
-+	       (!RB_EMPTY_ROOT(&st->active) || !RB_EMPTY_ROOT(&(st+1)->active) ||
-+		!RB_EMPTY_ROOT(&(st+2)->active)));
-+
-+	if (!entity)
-+		return NULL;
-+
-+	/* Log some information */
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq, "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "chosen from st %p %d",
-+			     st + class_idx, class_idx);
-+	}
-+#endif
-+
-+	return entity;
-+}
-+
-+static bool next_queue_may_preempt(struct bfq_data *bfqd)
-+{
-+	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
-+
-+	return sd->next_in_service != sd->in_service_entity;
-+}
-+
-+/*
-+ * Get next queue for service.
-+ */
-+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
-+{
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_sched_data *sd;
-+	struct bfq_queue *bfqq;
-+
-+	BUG_ON(bfqd->in_service_queue);
-+
-+	if (bfqd->busy_queues == 0)
-+		return NULL;
-+
-+	/*
-+	 * Traverse the path from the root to the leaf entity to
-+	 * serve. Set in service all the entities visited along the
-+	 * way.
-+	 */
-+	sd = &bfqd->root_group->sched_data;
-+	for (; sd ; sd = entity->my_sched_data) {
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		if (entity) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+				     "get_next_queue: lookup in this group");
-+			if (!sd->next_in_service)
-+				pr_crit("get_next_queue: lookup in this group");
-+		} else {
-+			bfq_log_bfqg(bfqd, bfqd->root_group,
-+				     "get_next_queue: lookup in root group");
-+			if (!sd->next_in_service)
-+				pr_crit("get_next_queue: lookup in root group");
-+		}
-+#endif
-+
-+		BUG_ON(!sd->next_in_service);
-+
-+		/*
-+		 * WARNING. We are about to set the in-service entity
-+		 * to sd->next_in_service, i.e., to the (cached) value
-+		 * returned by bfq_lookup_next_entity(sd) the last
-+		 * time it was invoked, i.e., the last time when the
-+		 * service order in sd changed as a consequence of the
-+		 * activation or deactivation of an entity. In this
-+		 * respect, if we execute bfq_lookup_next_entity(sd)
-+		 * in this very moment, it may, although with low
-+		 * probability, yield a different entity than that
-+		 * pointed to by sd->next_in_service. This rare event
-+		 * happens in case there was no CLASS_IDLE entity to
-+		 * serve for sd when bfq_lookup_next_entity(sd) was
-+		 * invoked for the last time, while there is now one
-+		 * such entity.
-+		 *
-+		 * If the above event happens, then the scheduling of
-+		 * such entity in CLASS_IDLE is postponed until the
-+		 * service of the sd->next_in_service entity
-+		 * finishes. In fact, when the latter is expired,
-+		 * bfq_lookup_next_entity(sd) gets called again,
-+		 * exactly to update sd->next_in_service.
-+		 */
-+
-+		/* Make next_in_service entity become in_service_entity */
-+		entity = sd->next_in_service;
-+		sd->in_service_entity = entity;
-+
-+		/*
-+		 * Reset the accumulator of the amount of service that
-+		 * the entity is about to receive.
-+		 */
-+		entity->service = 0;
-+
-+		/*
-+		 * If entity is no longer a candidate for next
-+		 * service, then we extract it from its active tree,
-+		 * for the following reason. To further boost the
-+		 * throughput in some special case, BFQ needs to know
-+		 * which is the next candidate entity to serve, while
-+		 * there is already an entity in service. In this
-+		 * respect, to make it easy to compute/update the next
-+		 * candidate entity to serve after the current
-+		 * candidate has been set in service, there is a case
-+		 * where it is necessary to extract the current
-+		 * candidate from its service tree. Such a case is
-+		 * when the entity just set in service cannot be also
-+		 * a candidate for next service. Details about when
-+		 * this conditions holds are reported in the comments
-+		 * on the function bfq_no_longer_next_in_service()
-+		 * invoked below.
-+		 */
-+		if (bfq_no_longer_next_in_service(entity))
-+			bfq_active_extract(bfq_entity_service_tree(entity),
-+					   entity);
-+
-+		/*
-+		 * For the same reason why we may have just extracted
-+		 * entity from its active tree, we may need to update
-+		 * next_in_service for the sched_data of entity too,
-+		 * regardless of whether entity has been extracted.
-+		 * In fact, even if entity has not been extracted, a
-+		 * descendant entity may get extracted. Such an event
-+		 * would cause a change in next_in_service for the
-+		 * level of the descendant entity, and thus possibly
-+		 * back to upper levels.
-+		 *
-+		 * We cannot perform the resulting needed update
-+		 * before the end of this loop, because, to know which
-+		 * is the correct next-to-serve candidate entity for
-+		 * each level, we need first to find the leaf entity
-+		 * to set in service. In fact, only after we know
-+		 * which is the next-to-serve leaf entity, we can
-+		 * discover whether the parent entity of the leaf
-+		 * entity becomes the next-to-serve, and so on.
-+		 */
-+
-+		/* Log some information */
-+		bfqq = bfq_entity_to_bfqq(entity);
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+			     "get_next_queue: this queue, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+			     "get_next_queue: this entity, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+		}
-+#endif
-+
-+	}
-+
-+	BUG_ON(!entity);
-+	bfqq = bfq_entity_to_bfqq(entity);
-+	BUG_ON(!bfqq);
-+
-+	/*
-+	 * We can finally update all next-to-serve entities along the
-+	 * path from the leaf entity just set in service to the root.
-+	 */
-+	for_each_entity(entity) {
-+		struct bfq_sched_data *sd = entity->sched_data;
-+
-+		if(!bfq_update_next_in_service(sd, NULL))
-+			break;
-+	}
-+
-+	return bfqq;
-+}
-+
-+static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
-+{
-+	struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue;
-+	struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity;
-+	struct bfq_entity *entity = in_serv_entity;
-+
-+	if (bfqd->in_service_bic) {
-+		put_io_context(bfqd->in_service_bic->icq.ioc);
-+		bfqd->in_service_bic = NULL;
-+	}
-+
-+	bfq_clear_bfqq_wait_request(in_serv_bfqq);
-+	hrtimer_try_to_cancel(&bfqd->idle_slice_timer);
-+	bfqd->in_service_queue = NULL;
-+
-+	/*
-+	 * When this function is called, all in-service entities have
-+	 * been properly deactivated or requeued, so we can safely
-+	 * execute the final step: reset in_service_entity along the
-+	 * path from entity to the root.
-+	 */
-+	for_each_entity(entity)
-+		entity->sched_data->in_service_entity = NULL;
-+
-+	/*
-+	 * in_serv_entity is no longer in service, so, if it is in no
-+	 * service tree either, then release the service reference to
-+	 * the queue it represents (taken with bfq_get_entity).
-+	 */
-+	if (!in_serv_entity->on_st)
-+		bfq_put_queue(in_serv_bfqq);
-+}
-+
-+static void set_next_in_service_bfqq(struct bfq_data *bfqd)
-+{
-+	struct bfq_entity *entity = NULL;
-+	struct bfq_queue *bfqq;
-+	struct bfq_sched_data *sd = &bfqd->root_group->sched_data;
-+
-+	BUG_ON(!sd);
-+
-+	/* Traverse the path from the root to the in-service leaf entity */
-+	for (; sd ; sd = entity->my_sched_data) {
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		if (entity) {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+			"set_next_in_service_bfqq: lookup in this group");
-+		} else
-+			bfq_log_bfqg(bfqd, bfqd->root_group,
-+			"set_next_in_service_bfqq: lookup in root group");
-+#endif
-+
-+		entity = sd->next_in_service;
-+
-+		if (!entity) {
-+			bfqd->next_in_service_queue = NULL;
-+			return;
-+		}
-+
-+		/* Log some information */
-+		bfqq = bfq_entity_to_bfqq(entity);
-+		if (bfqq)
-+			bfq_log_bfqq(bfqd, bfqq,
-+			"set_next_in_service_bfqq: this queue, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+		else {
-+			struct bfq_group *bfqg =
-+				container_of(entity, struct bfq_group, entity);
-+
-+			bfq_log_bfqg(bfqd, bfqg,
-+			"set_next_in_service_bfqq: this entity, finish %llu",
-+				(((entity->finish>>10)*1000)>>10)>>2);
-+		}
-+#endif
-+
-+	}
-+	BUG_ON(!bfq_entity_to_bfqq(entity));
-+
-+	bfqd->next_in_service_queue = bfq_entity_to_bfqq(entity);
-+}
-+
-+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+				bool ins_into_idle_tree, bool expiration)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_deactivate_entity(entity, ins_into_idle_tree, expiration);
-+	set_next_in_service_bfqq(bfqd);
-+}
-+
-+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+	struct bfq_service_tree *st = bfq_entity_service_tree(entity);
-+
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+	BUG_ON(entity->tree != &st->active && entity->tree != &st->idle &&
-+	       entity->on_st);
-+
-+	bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq),
-+				    false);
-+	bfq_clear_bfqq_non_blocking_wait_rq(bfqq);
-+	set_next_in_service_bfqq(bfqd);
-+}
-+
-+static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *entity = &bfqq->entity;
-+
-+	bfq_activate_requeue_entity(entity, false,
-+				    bfqq == bfqd->in_service_queue);
-+	set_next_in_service_bfqq(bfqd);
-+}
-+
-+static void bfqg_stats_update_dequeue(struct bfq_group *bfqg);
-+
-+/*
-+ * Called when the bfqq no longer has requests pending, remove it from
-+ * the service tree. As a special case, it can be invoked during an
-+ * expiration.
-+ */
-+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
-+			      bool expiration)
-+{
-+	BUG_ON(!bfq_bfqq_busy(bfqq));
-+	BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
-+
-+	bfq_log_bfqq(bfqd, bfqq, "del from busy");
-+
-+	bfq_clear_bfqq_busy(bfqq);
-+
-+	BUG_ON(bfqd->busy_queues == 0);
-+	bfqd->busy_queues--;
-+
-+	if (!bfqq->dispatched)
-+		bfq_weights_tree_remove(bfqd, &bfqq->entity,
-+					&bfqd->queue_weights_tree);
-+
-+	if (bfqq->wr_coeff > 1)
-+		bfqd->wr_busy_queues--;
-+
-+	bfqg_stats_update_dequeue(bfqq_group(bfqq));
-+
-+	BUG_ON(bfqq->entity.budget < 0);
-+
-+	bfq_deactivate_bfqq(bfqd, bfqq, true, expiration);
-+}
-+
-+/*
-+ * Called when an inactive queue receives a new request.
-+ */
-+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
-+{
-+	BUG_ON(bfq_bfqq_busy(bfqq));
-+	BUG_ON(bfqq == bfqd->in_service_queue);
-+
-+	bfq_log_bfqq(bfqd, bfqq, "add to busy");
-+
-+	bfq_activate_bfqq(bfqd, bfqq);
-+
-+	bfq_mark_bfqq_busy(bfqq);
-+	bfqd->busy_queues++;
-+
-+	if (!bfqq->dispatched)
-+		if (bfqq->wr_coeff == 1)
-+			bfq_weights_tree_add(bfqd, &bfqq->entity,
-+					     &bfqd->queue_weights_tree);
-+
-+	if (bfqq->wr_coeff > 1)
-+		bfqd->wr_busy_queues++;
-+}
-diff --git a/block/bfq.h b/block/bfq.h
-new file mode 100644
-index 000000000000..67d56670e678
---- /dev/null
-+++ b/block/bfq.h
-@@ -0,0 +1,933 @@
-+/*
-+ * BFQ v8r10-rc1 for 4.11.0: data structures and common functions prototypes.
-+ *
-+ * Based on ideas and code from CFQ:
-+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
-+ *
-+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
-+ *		      Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
-+ *
-+ * Copyright (C) 2017 Paolo Valente <paolo.valente@linaro.org>
-+ */
-+
-+#ifndef _BFQ_H
-+#define _BFQ_H
-+
-+#include <linux/blktrace_api.h>
-+#include <linux/hrtimer.h>
-+#include <linux/blk-cgroup.h>
-+
-+#define BFQ_IOPRIO_CLASSES	3
-+#define BFQ_CL_IDLE_TIMEOUT	(HZ/5)
-+
-+#define BFQ_MIN_WEIGHT			1
-+#define BFQ_MAX_WEIGHT			1000
-+#define BFQ_WEIGHT_CONVERSION_COEFF	10
-+
-+#define BFQ_DEFAULT_QUEUE_IOPRIO	4
-+
-+#define BFQ_WEIGHT_LEGACY_DFL	100
-+#define BFQ_DEFAULT_GRP_IOPRIO	0
-+#define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE
-+
-+/*
-+ * Soft real-time applications are extremely more latency sensitive
-+ * than interactive ones. Over-raise the weight of the former to
-+ * privilege them against the latter.
-+ */
-+#define BFQ_SOFTRT_WEIGHT_FACTOR	100
-+
-+struct bfq_entity;
-+
-+/**
-+ * struct bfq_service_tree - per ioprio_class service tree.
-+ *
-+ * Each service tree represents a B-WF2Q+ scheduler on its own.  Each
-+ * ioprio_class has its own independent scheduler, and so its own
-+ * bfq_service_tree.  All the fields are protected by the queue lock
-+ * of the containing bfqd.
-+ */
-+struct bfq_service_tree {
-+	/* tree for active entities (i.e., those backlogged) */
-+	struct rb_root active;
-+	/* tree for idle entities (i.e., not backlogged, with V <= F_i)*/
-+	struct rb_root idle;
-+
-+	struct bfq_entity *first_idle;	/* idle entity with minimum F_i */
-+	struct bfq_entity *last_idle;	/* idle entity with maximum F_i */
-+
-+	u64 vtime; /* scheduler virtual time */
-+	/* scheduler weight sum; active and idle entities contribute to it */
-+	unsigned long wsum;
-+};
-+
-+/**
-+ * struct bfq_sched_data - multi-class scheduler.
-+ *
-+ * bfq_sched_data is the basic scheduler queue.  It supports three
-+ * ioprio_classes, and can be used either as a toplevel queue or as an
-+ * intermediate queue on a hierarchical setup.  @next_in_service
-+ * points to the active entity of the sched_data service trees that
-+ * will be scheduled next. It is used to reduce the number of steps
-+ * needed for each hierarchical-schedule update.
-+ *
-+ * The supported ioprio_classes are the same as in CFQ, in descending
-+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
-+ * Requests from higher priority queues are served before all the
-+ * requests from lower priority queues; among requests of the same
-+ * queue requests are served according to B-WF2Q+.
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_sched_data {
-+	struct bfq_entity *in_service_entity;  /* entity in service */
-+	/* head-of-the-line entity in the scheduler (see comments above) */
-+	struct bfq_entity *next_in_service;
-+	/* array of service trees, one per ioprio_class */
-+	struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
-+	/* last time CLASS_IDLE was served */
-+	unsigned long bfq_class_idle_last_service;
-+
-+};
-+
-+/**
-+ * struct bfq_weight_counter - counter of the number of all active entities
-+ *                             with a given weight.
-+ */
-+struct bfq_weight_counter {
-+	unsigned int weight; /* weight of the entities this counter refers to */
-+	unsigned int num_active; /* nr of active entities with this weight */
-+	/*
-+	 * Weights tree member (see bfq_data's @queue_weights_tree and
-+	 * @group_weights_tree)
-+	 */
-+	struct rb_node weights_node;
-+};
-+
-+/**
-+ * struct bfq_entity - schedulable entity.
-+ *
-+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
-+ * cgroup hierarchy) or a bfq_group into the upper level scheduler.  Each
-+ * entity belongs to the sched_data of the parent group in the cgroup
-+ * hierarchy.  Non-leaf entities have also their own sched_data, stored
-+ * in @my_sched_data.
-+ *
-+ * Each entity stores independently its priority values; this would
-+ * allow different weights on different devices, but this
-+ * functionality is not exported to userspace by now.  Priorities and
-+ * weights are updated lazily, first storing the new values into the
-+ * new_* fields, then setting the @prio_changed flag.  As soon as
-+ * there is a transition in the entity state that allows the priority
-+ * update to take place the effective and the requested priority
-+ * values are synchronized.
-+ *
-+ * Unless cgroups are used, the weight value is calculated from the
-+ * ioprio to export the same interface as CFQ.  When dealing with
-+ * ``well-behaved'' queues (i.e., queues that do not spend too much
-+ * time to consume their budget and have true sequential behavior, and
-+ * when there are no external factors breaking anticipation) the
-+ * relative weights at each level of the cgroups hierarchy should be
-+ * guaranteed.  All the fields are protected by the queue lock of the
-+ * containing bfqd.
-+ */
-+struct bfq_entity {
-+	struct rb_node rb_node; /* service_tree member */
-+	/* pointer to the weight counter associated with this entity */
-+	struct bfq_weight_counter *weight_counter;
-+
-+	/*
-+	 * Flag, true if the entity is on a tree (either the active or
-+	 * the idle one of its service_tree) or is in service.
-+	 */
-+	bool on_st;
-+
-+	u64 finish; /* B-WF2Q+ finish timestamp (aka F_i) */
-+	u64 start;  /* B-WF2Q+ start timestamp (aka S_i) */
-+
-+	/* tree the entity is enqueued into; %NULL if not on a tree */
-+	struct rb_root *tree;
-+
-+	/*
-+	 * minimum start time of the (active) subtree rooted at this
-+	 * entity; used for O(log N) lookups into active trees
-+	 */
-+	u64 min_start;
-+
-+	/* amount of service received during the last service slot */
-+	int service;
-+
-+	/* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */
-+	int budget;
-+
-+	unsigned int weight;	 /* weight of the queue */
-+	unsigned int new_weight; /* next weight if a change is in progress */
-+
-+	/* original weight, used to implement weight boosting */
-+	unsigned int orig_weight;
-+
-+	/* parent entity, for hierarchical scheduling */
-+	struct bfq_entity *parent;
-+
-+	/*
-+	 * For non-leaf nodes in the hierarchy, the associated
-+	 * scheduler queue, %NULL on leaf nodes.
-+	 */
-+	struct bfq_sched_data *my_sched_data;
-+	/* the scheduler queue this entity belongs to */
-+	struct bfq_sched_data *sched_data;
-+
-+	/* flag, set to request a weight, ioprio or ioprio_class change  */
-+	int prio_changed;
-+};
-+
-+struct bfq_group;
-+
-+/**
-+ * struct bfq_queue - leaf schedulable entity.
-+ *
-+ * A bfq_queue is a leaf request queue; it can be associated with an
-+ * io_context or more, if it  is  async or shared  between  cooperating
-+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
-+ * does not disappear while a bfqq still references it (mostly to avoid
-+ * races between request issuing and task migration followed by cgroup
-+ * destruction).
-+ * All the fields are protected by the queue lock of the containing bfqd.
-+ */
-+struct bfq_queue {
-+	/* reference counter */
-+	int ref;
-+	/* parent bfq_data */
-+	struct bfq_data *bfqd;
-+
-+	/* current ioprio and ioprio class */
-+	unsigned short ioprio, ioprio_class;
-+	/* next ioprio and ioprio class if a change is in progress */
-+	unsigned short new_ioprio, new_ioprio_class;
-+
-+	/*
-+	 * Shared bfq_queue if queue is cooperating with one or more
-+	 * other queues.
-+	 */
-+	struct bfq_queue *new_bfqq;
-+	/* request-position tree member (see bfq_group's @rq_pos_tree) */
-+	struct rb_node pos_node;
-+	/* request-position tree root (see bfq_group's @rq_pos_tree) */
-+	struct rb_root *pos_root;
-+
-+	/* sorted list of pending requests */
-+	struct rb_root sort_list;
-+	/* if fifo isn't expired, next request to serve */
-+	struct request *next_rq;
-+	/* number of sync and async requests queued */
-+	int queued[2];
-+	/* number of sync and async requests currently allocated */
-+	int allocated[2];
-+	/* number of pending metadata requests */
-+	int meta_pending;
-+	/* fifo list of requests in sort_list */
-+	struct list_head fifo;
-+
-+	/* entity representing this queue in the scheduler */
-+	struct bfq_entity entity;
-+
-+	/* maximum budget allowed from the feedback mechanism */
-+	int max_budget;
-+	/* budget expiration (in jiffies) */
-+	unsigned long budget_timeout;
-+
-+	/* number of requests on the dispatch list or inside driver */
-+	int dispatched;
-+
-+	unsigned int flags; /* status flags.*/
-+
-+	/* node for active/idle bfqq list inside parent bfqd */
-+	struct list_head bfqq_list;
-+
-+	/* bit vector: a 1 for each seeky requests in history */
-+	u32 seek_history;
-+
-+	/* node for the device's burst list */
-+	struct hlist_node burst_list_node;
-+
-+	/* position of the last request enqueued */
-+	sector_t last_request_pos;
-+
-+	/* Number of consecutive pairs of request completion and
-+	 * arrival, such that the queue becomes idle after the
-+	 * completion, but the next request arrives within an idle
-+	 * time slice; used only if the queue's IO_bound flag has been
-+	 * cleared.
-+	 */
-+	unsigned int requests_within_timer;
-+
-+	/* pid of the process owning the queue, used for logging purposes */
-+	pid_t pid;
-+
-+	/*
-+	 * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL
-+	 * if the queue is shared.
-+	 */
-+	struct bfq_io_cq *bic;
-+
-+	/* current maximum weight-raising time for this queue */
-+	unsigned long wr_cur_max_time;
-+	/*
-+	 * Minimum time instant such that, only if a new request is
-+	 * enqueued after this time instant in an idle @bfq_queue with
-+	 * no outstanding requests, then the task associated with the
-+	 * queue it is deemed as soft real-time (see the comments on
-+	 * the function bfq_bfqq_softrt_next_start())
-+	 */
-+	unsigned long soft_rt_next_start;
-+	/*
-+	 * Start time of the current weight-raising period if
-+	 * the @bfq-queue is being weight-raised, otherwise
-+	 * finish time of the last weight-raising period.
-+	 */
-+	unsigned long last_wr_start_finish;
-+	/* factor by which the weight of this queue is multiplied */
-+	unsigned int wr_coeff;
-+	/*
-+	 * Time of the last transition of the @bfq_queue from idle to
-+	 * backlogged.
-+	 */
-+	unsigned long last_idle_bklogged;
-+	/*
-+	 * Cumulative service received from the @bfq_queue since the
-+	 * last transition from idle to backlogged.
-+	 */
-+	unsigned long service_from_backlogged;
-+	/*
-+	 * Value of wr start time when switching to soft rt
-+	 */
-+	unsigned long wr_start_at_switch_to_srt;
-+
-+	unsigned long split_time; /* time of last split */
-+};
-+
-+/**
-+ * struct bfq_ttime - per process thinktime stats.
-+ */
-+struct bfq_ttime {
-+	u64 last_end_request; /* completion time of last request */
-+
-+	u64 ttime_total; /* total process thinktime */
-+	unsigned long ttime_samples; /* number of thinktime samples */
-+	u64 ttime_mean; /* average process thinktime */
-+
-+};
-+
-+/**
-+ * struct bfq_io_cq - per (request_queue, io_context) structure.
-+ */
-+struct bfq_io_cq {
-+	/* associated io_cq structure */
-+	struct io_cq icq; /* must be the first member */
-+	/* array of two process queues, the sync and the async */
-+	struct bfq_queue *bfqq[2];
-+	/* associated @bfq_ttime struct */
-+	struct bfq_ttime ttime;
-+	/* per (request_queue, blkcg) ioprio */
-+	int ioprio;
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	uint64_t blkcg_serial_nr; /* the current blkcg serial */
-+#endif
-+
-+	/*
-+	 * Snapshot of the idle window before merging; taken to
-+	 * remember this value while the queue is merged, so as to be
-+	 * able to restore it in case of split.
-+	 */
-+	bool saved_idle_window;
-+	/*
-+	 * Same purpose as the previous two fields for the I/O bound
-+	 * classification of a queue.
-+	 */
-+	bool saved_IO_bound;
-+
-+	/*
-+	 * Same purpose as the previous fields for the value of the
-+	 * field keeping the queue's belonging to a large burst
-+	 */
-+	bool saved_in_large_burst;
-+	/*
-+	 * True if the queue belonged to a burst list before its merge
-+	 * with another cooperating queue.
-+	 */
-+	bool was_in_burst_list;
-+
-+	/*
-+	 * Similar to previous fields: save wr information.
-+	 */
-+	unsigned long saved_wr_coeff;
-+	unsigned long saved_last_wr_start_finish;
-+	unsigned long saved_wr_start_at_switch_to_srt;
-+	unsigned int saved_wr_cur_max_time;
-+};
-+
-+enum bfq_device_speed {
-+	BFQ_BFQD_FAST,
-+	BFQ_BFQD_SLOW,
-+};
-+
-+/**
-+ * struct bfq_data - per-device data structure.
-+ *
-+ * All the fields are protected by the @queue lock.
-+ */
-+struct bfq_data {
-+	/* request queue for the device */
-+	struct request_queue *queue;
-+
-+	/* root bfq_group for the device */
-+	struct bfq_group *root_group;
-+
-+	/*
-+	 * rbtree of weight counters of @bfq_queues, sorted by
-+	 * weight. Used to keep track of whether all @bfq_queues have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active and not
-+	 * weight-raised @bfq_queue (see the comments to the functions
-+	 * bfq_weights_tree_[add|remove] for further details).
-+	 */
-+	struct rb_root queue_weights_tree;
-+	/*
-+	 * rbtree of non-queue @bfq_entity weight counters, sorted by
-+	 * weight. Used to keep track of whether all @bfq_groups have
-+	 * the same weight. The tree contains one counter for each
-+	 * distinct weight associated to some active @bfq_group (see
-+	 * the comments to the functions bfq_weights_tree_[add|remove]
-+	 * for further details).
-+	 */
-+	struct rb_root group_weights_tree;
-+
-+	/*
-+	 * Number of bfq_queues containing requests (including the
-+	 * queue in service, even if it is idling).
-+	 */
-+	int busy_queues;
-+	/* number of weight-raised busy @bfq_queues */
-+	int wr_busy_queues;
-+	/* number of queued requests */
-+	int queued;
-+	/* number of requests dispatched and waiting for completion */
-+	int rq_in_driver;
-+
-+	/*
-+	 * Maximum number of requests in driver in the last
-+	 * @hw_tag_samples completed requests.
-+	 */
-+	int max_rq_in_driver;
-+	/* number of samples used to calculate hw_tag */
-+	int hw_tag_samples;
-+	/* flag set to one if the driver is showing a queueing behavior */
-+	int hw_tag;
-+
-+	/* number of budgets assigned */
-+	int budgets_assigned;
-+
-+	/*
-+	 * Timer set when idling (waiting) for the next request from
-+	 * the queue in service.
-+	 */
-+	struct hrtimer idle_slice_timer;
-+	/* delayed work to restart dispatching on the request queue */
-+	struct work_struct unplug_work;
-+
-+	/* bfq_queue in service */
-+	struct bfq_queue *in_service_queue;
-+	/* candidate bfq_queue to become the next in-service queue */
-+	struct bfq_queue *next_in_service_queue;
-+	/* bfq_io_cq (bic) associated with the @in_service_queue */
-+	struct bfq_io_cq *in_service_bic;
-+
-+	/* on-disk position of the last served request */
-+	sector_t last_position;
-+
-+	/* time of last request completion (ns) */
-+	u64 last_completion;
-+
-+	/* time of first rq dispatch in current observation interval (ns) */
-+	u64 first_dispatch;
-+	/* time of last rq dispatch in current observation interval (ns) */
-+	u64 last_dispatch;
-+
-+	/* beginning of the last budget */
-+	ktime_t last_budget_start;
-+	/* beginning of the last idle slice */
-+	ktime_t last_idling_start;
-+
-+	/* number of samples in current observation interval */
-+	int peak_rate_samples;
-+	/* num of samples of seq dispatches in current observation interval */
-+	u32 sequential_samples;
-+	/* total num of sectors transferred in current observation interval */
-+	u64 tot_sectors_dispatched;
-+	/* max rq size seen during current observation interval (sectors) */
-+	u32 last_rq_max_size;
-+	/* time elapsed from first dispatch in current observ. interval (us) */
-+	u64 delta_from_first;
-+	/* current estimate of device peak rate */
-+	u32 peak_rate;
-+
-+	/* maximum budget allotted to a bfq_queue before rescheduling */
-+	int bfq_max_budget;
-+
-+	/* list of all the bfq_queues active on the device */
-+	struct list_head active_list;
-+	/* list of all the bfq_queues idle on the device */
-+	struct list_head idle_list;
-+
-+	/*
-+	 * Timeout for async/sync requests; when it fires, requests
-+	 * are served in fifo order.
-+	 */
-+	u64 bfq_fifo_expire[2];
-+	/* weight of backward seeks wrt forward ones */
-+	unsigned int bfq_back_penalty;
-+	/* maximum allowed backward seek */
-+	unsigned int bfq_back_max;
-+	/* maximum idling time */
-+	u32 bfq_slice_idle;
-+
-+	/* user-configured max budget value (0 for auto-tuning) */
-+	int bfq_user_max_budget;
-+	/*
-+	 * Timeout for bfq_queues to consume their budget; used to
-+	 * prevent seeky queues from imposing long latencies to
-+	 * sequential or quasi-sequential ones (this also implies that
-+	 * seeky queues cannot receive guarantees in the service
-+	 * domain; after a timeout they are charged for the time they
-+	 * have been in service, to preserve fairness among them, but
-+	 * without service-domain guarantees).
-+	 */
-+	unsigned int bfq_timeout;
-+
-+	/*
-+	 * Number of consecutive requests that must be issued within
-+	 * the idle time slice to set again idling to a queue which
-+	 * was marked as non-I/O-bound (see the definition of the
-+	 * IO_bound flag for further details).
-+	 */
-+	unsigned int bfq_requests_within_timer;
-+
-+	/*
-+	 * Force device idling whenever needed to provide accurate
-+	 * service guarantees, without caring about throughput
-+	 * issues. CAVEAT: this may even increase latencies, in case
-+	 * of useless idling for processes that did stop doing I/O.
-+	 */
-+	bool strict_guarantees;
-+
-+	/*
-+	 * Last time at which a queue entered the current burst of
-+	 * queues being activated shortly after each other; for more
-+	 * details about this and the following parameters related to
-+	 * a burst of activations, see the comments on the function
-+	 * bfq_handle_burst.
-+	 */
-+	unsigned long last_ins_in_burst;
-+	/*
-+	 * Reference time interval used to decide whether a queue has
-+	 * been activated shortly after @last_ins_in_burst.
-+	 */
-+	unsigned long bfq_burst_interval;
-+	/* number of queues in the current burst of queue activations */
-+	int burst_size;
-+
-+	/* common parent entity for the queues in the burst */
-+	struct bfq_entity *burst_parent_entity;
-+	/* Maximum burst size above which the current queue-activation
-+	 * burst is deemed as 'large'.
-+	 */
-+	unsigned long bfq_large_burst_thresh;
-+	/* true if a large queue-activation burst is in progress */
-+	bool large_burst;
-+	/*
-+	 * Head of the burst list (as for the above fields, more
-+	 * details in the comments on the function bfq_handle_burst).
-+	 */
-+	struct hlist_head burst_list;
-+
-+	/* if set to true, low-latency heuristics are enabled */
-+	bool low_latency;
-+	/*
-+	 * Maximum factor by which the weight of a weight-raised queue
-+	 * is multiplied.
-+	 */
-+	unsigned int bfq_wr_coeff;
-+	/* maximum duration of a weight-raising period (jiffies) */
-+	unsigned int bfq_wr_max_time;
-+
-+	/* Maximum weight-raising duration for soft real-time processes */
-+	unsigned int bfq_wr_rt_max_time;
-+	/*
-+	 * Minimum idle period after which weight-raising may be
-+	 * reactivated for a queue (in jiffies).
-+	 */
-+	unsigned int bfq_wr_min_idle_time;
-+	/*
-+	 * Minimum period between request arrivals after which
-+	 * weight-raising may be reactivated for an already busy async
-+	 * queue (in jiffies).
-+	 */
-+	unsigned long bfq_wr_min_inter_arr_async;
-+
-+	/* Max service-rate for a soft real-time queue, in sectors/sec */
-+	unsigned int bfq_wr_max_softrt_rate;
-+	/*
-+	 * Cached value of the product R*T, used for computing the
-+	 * maximum duration of weight raising automatically.
-+	 */
-+	u64 RT_prod;
-+	/* device-speed class for the low-latency heuristic */
-+	enum bfq_device_speed device_speed;
-+
-+	/* fallback dummy bfqq for extreme OOM conditions */
-+	struct bfq_queue oom_bfqq;
-+};
-+
-+enum bfqq_state_flags {
-+	BFQ_BFQQ_FLAG_just_created = 0,	/* queue just allocated */
-+	BFQ_BFQQ_FLAG_busy,		/* has requests or is in service */
-+	BFQ_BFQQ_FLAG_wait_request,	/* waiting for a request */
-+	BFQ_BFQQ_FLAG_non_blocking_wait_rq, /*
-+					     * waiting for a request
-+					     * without idling the device
-+					     */
-+	BFQ_BFQQ_FLAG_must_alloc,	/* must be allowed rq alloc */
-+	BFQ_BFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-+	BFQ_BFQQ_FLAG_idle_window,	/* slice idling enabled */
-+	BFQ_BFQQ_FLAG_sync,		/* synchronous queue */
-+	BFQ_BFQQ_FLAG_IO_bound,		/*
-+					 * bfqq has timed-out at least once
-+					 * having consumed at most 2/10 of
-+					 * its budget
-+					 */
-+	BFQ_BFQQ_FLAG_in_large_burst,	/*
-+					 * bfqq activated in a large burst,
-+					 * see comments to bfq_handle_burst.
-+					 */
-+	BFQ_BFQQ_FLAG_softrt_update,	/*
-+					 * may need softrt-next-start
-+					 * update
-+					 */
-+	BFQ_BFQQ_FLAG_coop,		/* bfqq is shared */
-+	BFQ_BFQQ_FLAG_split_coop	/* shared bfqq will be split */
-+};
-+
-+#define BFQ_BFQQ_FNS(name)						\
-+static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq)		\
-+{									\
-+	(bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name);			\
-+}									\
-+static int bfq_bfqq_##name(const struct bfq_queue *bfqq)		\
-+{									\
-+	return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0;	\
-+}
-+
-+BFQ_BFQQ_FNS(just_created);
-+BFQ_BFQQ_FNS(busy);
-+BFQ_BFQQ_FNS(wait_request);
-+BFQ_BFQQ_FNS(non_blocking_wait_rq);
-+BFQ_BFQQ_FNS(must_alloc);
-+BFQ_BFQQ_FNS(fifo_expire);
-+BFQ_BFQQ_FNS(idle_window);
-+BFQ_BFQQ_FNS(sync);
-+BFQ_BFQQ_FNS(IO_bound);
-+BFQ_BFQQ_FNS(in_large_burst);
-+BFQ_BFQQ_FNS(coop);
-+BFQ_BFQQ_FNS(split_coop);
-+BFQ_BFQQ_FNS(softrt_update);
-+#undef BFQ_BFQQ_FNS
-+
-+/* Logging facilities. */
-+#ifdef CONFIG_BFQ_REDIRECT_TO_CONSOLE
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	pr_crit("bfq%d%c %s " fmt "\n", 			\
-+		(bfqq)->pid,						\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',			\
-+		__pbuf, ##args);					\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	pr_crit("%s " fmt "\n", __pbuf, ##args);	\
-+} while (0)
-+
-+#else /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)		\
-+	pr_crit("bfq%d%c " fmt "\n", (bfqq)->pid,		\
-+		bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+		##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	pr_crit("bfq " fmt "\n", ##args)
-+
-+#else /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static struct bfq_group *bfqq_group(struct bfq_queue *bfqq);
-+static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg);
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	assert_spin_locked((bfqd)->queue->queue_lock);			\
-+	blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, \
-+			  (bfqq)->pid,			  \
-+			  bfq_bfqq_sync((bfqq)) ? 'S' : 'A',	\
-+			  __pbuf, ##args);				\
-+} while (0)
-+
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)	do {			\
-+	char __pbuf[128];						\
-+									\
-+	blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf));		\
-+	blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args);	\
-+} while (0)
-+
-+#else /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...)	\
-+	blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid,	\
-+			bfq_bfqq_sync((bfqq)) ? 'S' : 'A',		\
-+				##args)
-+#define bfq_log_bfqg(bfqd, bfqg, fmt, args...)		do {} while (0)
-+
-+#endif /* CONFIG_BFQ_GROUP_IOSCHED */
-+
-+#define bfq_log(bfqd, fmt, args...) \
-+	blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
-+#endif /* CONFIG_BFQ_REDIRECT_TO_CONSOLE */
-+
-+/* Expiration reasons. */
-+enum bfqq_expiration {
-+	BFQ_BFQQ_TOO_IDLE = 0,		/*
-+					 * queue has been idling for
-+					 * too long
-+					 */
-+	BFQ_BFQQ_BUDGET_TIMEOUT,	/* budget took too long to be used */
-+	BFQ_BFQQ_BUDGET_EXHAUSTED,	/* budget consumed */
-+	BFQ_BFQQ_NO_MORE_REQUESTS,	/* the queue has no more requests */
-+	BFQ_BFQQ_PREEMPTED		/* preemption in progress */
-+};
-+
-+
-+struct bfqg_stats {
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	/* number of ios merged */
-+	struct blkg_rwstat		merged;
-+	/* total time spent on device in ns, may not be accurate w/ queueing */
-+	struct blkg_rwstat		service_time;
-+	/* total time spent waiting in scheduler queue in ns */
-+	struct blkg_rwstat		wait_time;
-+	/* number of IOs queued up */
-+	struct blkg_rwstat		queued;
-+	/* total disk time and nr sectors dispatched by this group */
-+	struct blkg_stat		time;
-+	/* sum of number of ios queued across all samples */
-+	struct blkg_stat		avg_queue_size_sum;
-+	/* count of samples taken for average */
-+	struct blkg_stat		avg_queue_size_samples;
-+	/* how many times this group has been removed from service tree */
-+	struct blkg_stat		dequeue;
-+	/* total time spent waiting for it to be assigned a timeslice. */
-+	struct blkg_stat		group_wait_time;
-+	/* time spent idling for this blkcg_gq */
-+	struct blkg_stat		idle_time;
-+	/* total time with empty current active q with other requests queued */
-+	struct blkg_stat		empty_time;
-+	/* fields after this shouldn't be cleared on stat reset */
-+	uint64_t			start_group_wait_time;
-+	uint64_t			start_idle_time;
-+	uint64_t			start_empty_time;
-+	uint16_t			flags;
-+#endif
-+};
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+/*
-+ * struct bfq_group_data - per-blkcg storage for the blkio subsystem.
-+ *
-+ * @ps: @blkcg_policy_storage that this structure inherits
-+ * @weight: weight of the bfq_group
-+ */
-+struct bfq_group_data {
-+	/* must be the first member */
-+	struct blkcg_policy_data pd;
-+
-+	unsigned int weight;
-+};
-+
-+/**
-+ * struct bfq_group - per (device, cgroup) data structure.
-+ * @entity: schedulable entity to insert into the parent group sched_data.
-+ * @sched_data: own sched_data, to contain child entities (they may be
-+ *              both bfq_queues and bfq_groups).
-+ * @bfqd: the bfq_data for the device this group acts upon.
-+ * @async_bfqq: array of async queues for all the tasks belonging to
-+ *              the group, one queue per ioprio value per ioprio_class,
-+ *              except for the idle class that has only one queue.
-+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
-+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
-+ *             to avoid too many special cases during group creation/
-+ *             migration.
-+ * @active_entities: number of active entities belonging to the group;
-+ *                   unused for the root group. Used to know whether there
-+ *                   are groups with more than one active @bfq_entity
-+ *                   (see the comments to the function
-+ *                   bfq_bfqq_may_idle()).
-+ * @rq_pos_tree: rbtree sorted by next_request position, used when
-+ *               determining if two or more queues have interleaving
-+ *               requests (see bfq_find_close_cooperator()).
-+ *
-+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
-+ * there is a set of bfq_groups, each one collecting the lower-level
-+ * entities belonging to the group that are acting on the same device.
-+ *
-+ * Locking works as follows:
-+ *    o @bfqd is protected by the queue lock, RCU is used to access it
-+ *      from the readers.
-+ *    o All the other fields are protected by the @bfqd queue lock.
-+ */
-+struct bfq_group {
-+	/* must be the first member */
-+	struct blkg_policy_data pd;
-+
-+	struct bfq_entity entity;
-+	struct bfq_sched_data sched_data;
-+
-+	void *bfqd;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct bfq_entity *my_entity;
-+
-+	int active_entities;
-+
-+	struct rb_root rq_pos_tree;
-+
-+	struct bfqg_stats stats;
-+};
-+
-+#else
-+struct bfq_group {
-+	struct bfq_sched_data sched_data;
-+
-+	struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
-+	struct bfq_queue *async_idle_bfqq;
-+
-+	struct rb_root rq_pos_tree;
-+};
-+#endif
-+
-+static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity);
-+
-+static unsigned int bfq_class_idx(struct bfq_entity *entity)
-+{
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+
-+	return bfqq ? bfqq->ioprio_class - 1 :
-+		BFQ_DEFAULT_GRP_CLASS - 1;
-+}
-+
-+static struct bfq_service_tree *
-+bfq_entity_service_tree(struct bfq_entity *entity)
-+{
-+	struct bfq_sched_data *sched_data = entity->sched_data;
-+	struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
-+	unsigned int idx = bfq_class_idx(entity);
-+
-+	BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
-+	BUG_ON(sched_data == NULL);
-+
-+	if (bfqq)
-+		bfq_log_bfqq(bfqq->bfqd, bfqq,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+	else {
-+		struct bfq_group *bfqg =
-+			container_of(entity, struct bfq_group, entity);
-+
-+		bfq_log_bfqg((struct bfq_data *)bfqg->bfqd, bfqg,
-+			     "entity_service_tree %p %d",
-+			     sched_data->service_tree + idx, idx);
-+	}
-+#endif
-+	return sched_data->service_tree + idx;
-+}
-+
-+static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync)
-+{
-+	return bic->bfqq[is_sync];
-+}
-+
-+static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq,
-+			 bool is_sync)
-+{
-+	bic->bfqq[is_sync] = bfqq;
-+}
-+
-+static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
-+{
-+	return bic->icq.q->elevator->elevator_data;
-+}
-+
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	struct bfq_entity *group_entity = bfqq->entity.parent;
-+
-+	if (!group_entity)
-+		group_entity = &bfqq->bfqd->root_group->entity;
-+
-+	return container_of(group_entity, struct bfq_group, entity);
-+}
-+
-+#else
-+
-+static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq)
-+{
-+	return bfqq->bfqd->root_group;
-+}
-+
-+#endif
-+
-+static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio);
-+static void bfq_put_queue(struct bfq_queue *bfqq);
-+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
-+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
-+				       struct bio *bio, bool is_sync,
-+				       struct bfq_io_cq *bic);
-+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
-+				    struct bfq_group *bfqg);
-+#ifdef CONFIG_BFQ_GROUP_IOSCHED
-+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
-+#endif
-+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
-+
-+#endif /* _BFQ_H */
-diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
-index 01a696b0a4d3..29d537ddc261 100644
---- a/include/linux/blkdev.h
-+++ b/include/linux/blkdev.h
-@@ -48,7 +48,7 @@ struct rq_wb;
-  * Maximum number of blkcg policies allowed to be registered concurrently.
-  * Defined here to simplify include dependency.
-  */
--#define BLKCG_MAX_POLS		2
-+#define BLKCG_MAX_POLS		3
- 
- typedef void (rq_end_io_fn)(struct request *, int);
- 
diff --git a/modules/user/aszlig/system/kernel.nix b/modules/user/aszlig/system/kernel.nix
index afbbb759..4d0a4120 100644
--- a/modules/user/aszlig/system/kernel.nix
+++ b/modules/user/aszlig/system/kernel.nix
@@ -8,12 +8,12 @@
   config = lib.mkIf config.vuizvui.user.aszlig.system.kernel.enable {
     boot = {
       kernelPatches = lib.singleton {
-        name = "bfq-v8r7";
-        patch = ./bfq.patch;
+        name = "bfq";
+        patch = pkgs.runCommand "empty.patch" {} "touch \"$out\"";
         extraConfig = ''
+          SCSI_MQ_DEFAULT y
           IOSCHED_BFQ y
-          DEFAULT_BFQ y
-          DEFAULT_CFQ n
+          BFQ_GROUP_IOSCHED y
           DEFAULT_IOSCHED bfq
         '';
       };