Like pci and virtio, we add a rdma helper for affinity
spreading. This achieves optimal mq affinity assignments
according to the underlying rdma device affinity maps.
Reviewed-by: NJens Axboe <axboe@fb.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMax Gurtovoy <maxg@mellanox.com>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

The BFQ I/O scheduler features an optimal fair-queuing
(proportional-share) scheduling algorithm, enriched with several
mechanisms to boost throughput and reduce latency for interactive and
real-time applications. This makes BFQ a large and complex piece of
code. This commit addresses this issue by splitting BFQ into three
main, independent components, and by moving each component into a
separate source file:
1. Main algorithm: handles the interaction with the kernel, and
decides which requests to dispatch; it uses the following two further
components to achieve its goals.
2. Scheduling engine (Hierarchical B-WF2Q+ scheduling algorithm):
computes the schedule, using weights and budgets provided by the above
component.
3. cgroups support: handles group operations (creation, destruction,
move, ...).
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

We tag as v0 the version of BFQ containing only BFQ's engine plus
hierarchical support. BFQ's engine is introduced by this commit, while
hierarchical support is added by next commit. We use the v0 tag to
distinguish this minimal version of BFQ from the versions containing
also the features and the improvements added by next commits. BFQ-v0
coincides with the version of BFQ submitted a few years ago [1], apart
from the introduction of preemption, described below.

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 [2] for
      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.

  - 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]).

- Weights can be assigned to processes only indirectly, through I/O
  priorities, and according to the relation:
  weight = 10 * (IOPRIO_BE_NR - ioprio).
  The next patch provides, instead, a cgroups interface through which
  weights can be assigned explicitly.

- 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.

- If the strict_guarantees 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
  queue receives its allotted share of the bandwidth (see
  Documentation/block/bfq-iosched.txt for more details). Setting
  strict_guarantees may evidently affect throughput.

[1] https://lkml.org/lkml/2008/4/1/234
    https://lkml.org/lkml/2008/11/11/148

[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
Signed-off-by: NFabio Checconi <fchecconi@gmail.com>
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NArianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The Kyber I/O scheduler is an I/O scheduler for fast devices designed to
scale to multiple queues. Users configure only two knobs, the target
read and synchronous write latencies, and the scheduler tunes itself to
achieve that latency goal.

The implementation is based on "tokens", built on top of the scalable
bitmap library. Tokens serve as a mechanism for limiting requests. There
are two tiers of tokens: queueing tokens and dispatch tokens.

A queueing token is required to allocate a request. In fact, these
tokens are actually the blk-mq internal scheduler tags, but the
scheduler manages the allocation directly in order to implement its
policy.

Dispatch tokens are device-wide and split up into two scheduling
domains: reads vs. writes. Each hardware queue dispatches batches
round-robin between the scheduling domains as long as tokens are
available for that domain.

These tokens can be used as the mechanism to enable various policies.
The policy Kyber uses is inspired by active queue management techniques
for network routing, similar to blk-wbt. The scheduler monitors
latencies and scales the number of dispatch tokens accordingly. Queueing
tokens are used to prevent starvation of synchronous requests by
asynchronous requests.

Various extensions are possible, including better heuristics and ionice
support. The new scheduler isn't set as the default yet.
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Similar to the PCI version, just calling into virtio instead.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

This patch implements the necessary logic to bring an Opal
enabled drive out of a factory-enabled into a working
Opal state.

This patch set also enables logic to save a password to
be replayed during a resume from suspend.
Signed-off-by: NScott Bauer <scott.bauer@intel.com>
Signed-off-by: NRafael Antognolli <Rafael.Antognolli@intel.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

We only need this code to support scsi, ide, cciss and virtio.  And at
least for virtio it's a deprecated feature to start with.

This should shrink the kernel size for embedded device that only use,
say eMMC a bit.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

This fixes a couple of problems:

1. In the !CONFIG_DEBUG_FS case, the stub definitions were bogus.
2. In the !CONFIG_BLOCK case, blk-mq-debugfs.c shouldn't be compiled at
   all.

Fix the stub definitions and add a CONFIG_BLK_DEBUG_FS Kconfig option.

Fixes: 07e4fead ("blk-mq: create debugfs directory tree")
Signed-off-by: NOmar Sandoval <osandov@fb.com>

Augment Kconfig description.
Signed-off-by: NJens Axboe <axboe@fb.com>

In preparation for putting blk-mq debugging information in debugfs,
create a directory tree mirroring the one in sysfs:

    # tree -d /sys/kernel/debug/block
    /sys/kernel/debug/block
    |-- nvme0n1
    |   `-- mq
    |       |-- 0
    |       |   `-- cpu0
    |       |-- 1
    |       |   `-- cpu1
    |       |-- 2
    |       |   `-- cpu2
    |       `-- 3
    |           `-- cpu3
    `-- vda
        `-- mq
            `-- 0
                |-- cpu0
                |-- cpu1
                |-- cpu2
                `-- cpu3

Also add the scaffolding for the actual files that will go in here,
either under the hardware queue or software queue directories.
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This is basically identical to deadline-iosched, except it registers
as a MQ capable scheduler. This is still a single queue design.
Signed-off-by: NJens Axboe <axboe@fb.com>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>

This adds a set of hooks that intercepts the blk-mq path of
allocating/inserting/issuing/completing requests, allowing
us to develop a scheduler within that framework.

We reuse the existing elevator scheduler API on the registration
side, but augment that with the scheduler flagging support for
the blk-mq interfce, and with a separate set of ops hooks for MQ
devices.

We split driver and scheduler tags, so we can run the scheduling
independently of device queue depth.
Signed-off-by: NJens Axboe <axboe@fb.com>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>

We can hook this up to the block layer, to help throttle buffered
writes.

wbt registers a few trace points that can be used to track what is
happening in the system:

wbt_lat: 259:0: latency 2446318
wbt_stat: 259:0: rmean=2446318, rmin=2446318, rmax=2446318, rsamples=1,
               wmean=518866, wmin=15522, wmax=5330353, wsamples=57
wbt_step: 259:0: step down: step=1, window=72727272, background=8, normal=16, max=32

This shows a sync issue event (wbt_lat) that exceeded it's time. wbt_stat
dumps the current read/write stats for that window, and wbt_step shows a
step down event where we now scale back writes. Each trace includes the
device, 259:0 in this case.
Signed-off-by: NJens Axboe <axboe@fb.com>

For legacy block, we simply track them in the request queue. For
blk-mq, we track them on a per-sw queue basis, which we can then
sum up through the hardware queues and finally to a per device
state.

The stats are tracked in, roughly, 0.1s interval windows.

Add sysfs files to display the stats.

The feature is off by default, to avoid any extra overhead. In-kernel
users of it can turn it on by setting QUEUE_FLAG_STATS in the queue
flags. We currently don't turn it on if someone just reads any of
the stats files, that is something we could add as well.
Signed-off-by: NJens Axboe <axboe@fb.com>

Implement zoned block device zone information reporting and reset.
Zone information are reported as struct blk_zone. This implementation
does not differentiate between host-aware and host-managed device
models and is valid for both. Two functions are provided:
blkdev_report_zones for discovering the zone configuration of a
zoned block device, and blkdev_reset_zones for resetting the write
pointer of sequential zones. The helper function blk_queue_zone_size
and bdev_zone_size are also provided for, as the name suggest,
obtaining the zone size (in 512B sectors) of the zones of the device.
Signed-off-by: NHannes Reinecke <hare@suse.de>

[Damien: * Removed the zone cache
         * Implement report zones operation based on earlier proposal
           by Shaun Tancheff <shaun.tancheff@seagate.com>]
Signed-off-by: NDamien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NShaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: NShaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Replace the block-mq notifier list management with the multi instance
facility in the cpu hotplug state machine.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-block@vger.kernel.org
Cc: rt@linutronix.de
Cc: Christoph Hellwing <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

and building block/blk-mq-pci.o should depend on CONFIG_BLOCK

Fixes: 973c4e37 ("blk-mq: provide a default queue mapping for PCI device")
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Take the core badblocks implementation from md, and make it generally
available. This follows the same style as kernel implementations of
linked lists, rb-trees etc, where you can have a structure that can be
embedded anywhere, and accessor functions to manipulate the data.

The only changes in this copy of the code are ones to generalize
function/variable names from md-specific ones. Also add init and free
functions.
Signed-off-by: NVishal Verma <vishal.l.verma@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

The new name is irq_poll as iopoll is already taken.  Better suggestions
welcome.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>

The T10 Protection Information format is also used by some devices that
do not go through the SCSI layer (virtual block devices, NVMe). Relocate
the relevant functions to a block layer library that can be used without
involving SCSI.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Continue moving some of the block files that are scattered around.
bounce.c contains only code for bouncing the contents of a bio.
It's block proper code, not mm code.
Suggested-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Like commit f9c78b2b, move this block related file outside
of fs/ and into the core block directory, block/.
Signed-off-by: NJens Axboe <axboe@fb.com>

They really belong in block/, especially now since it's not in
drivers/block/ anymore. Additionally, the get_maintainer script
gets it wrong when in fs/.
Suggested-by: NChristoph Hellwig <hch@infradead.org>
Acked-by: NAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NJens Axboe <axboe@fb.com>

Linux currently has two models for block devices:

- The classic request_fn based approach, where drivers use struct
  request units for IO. The block layer provides various helper
  functionalities to let drivers share code, things like tag
  management, timeout handling, queueing, etc.

- The "stacked" approach, where a driver squeezes in between the
  block layer and IO submitter. Since this bypasses the IO stack,
  driver generally have to manage everything themselves.

With drivers being written for new high IOPS devices, the classic
request_fn based driver doesn't work well enough. The design dates
back to when both SMP and high IOPS was rare. It has problems with
scaling to bigger machines, and runs into scaling issues even on
smaller machines when you have IOPS in the hundreds of thousands
per device.

The stacked approach is then most often selected as the model
for the driver. But this means that everybody has to re-invent
everything, and along with that we get all the problems again
that the shared approach solved.

This commit introduces blk-mq, block multi queue support. The
design is centered around per-cpu queues for queueing IO, which
then funnel down into x number of hardware submission queues.
We might have a 1:1 mapping between the two, or it might be
an N:M mapping. That all depends on what the hardware supports.

blk-mq provides various helper functions, which include:

- Scalable support for request tagging. Most devices need to
  be able to uniquely identify a request both in the driver and
  to the hardware. The tagging uses per-cpu caches for freed
  tags, to enable cache hot reuse.

- Timeout handling without tracking request on a per-device
  basis. Basically the driver should be able to get a notification,
  if a request happens to fail.

- Optional support for non 1:1 mappings between issue and
  submission queues. blk-mq can redirect IO completions to the
  desired location.

- Support for per-request payloads. Drivers almost always need
  to associate a request structure with some driver private
  command structure. Drivers can tell blk-mq this at init time,
  and then any request handed to the driver will have the
  required size of memory associated with it.

- Support for merging of IO, and plugging. The stacked model
  gets neither of these. Even for high IOPS devices, merging
  sequential IO reduces per-command overhead and thus
  increases bandwidth.

For now, this is provided as a potential 3rd queueing model, with
the hope being that, as it matures, it can replace both the classic
and stacked model. That would get us back to having just 1 real
model for block devices, leaving the stacked approach to dm/md
devices (as it was originally intended).

Contributions in this patch from the following people:

Shaohua Li <shli@fusionio.com>
Alexander Gordeev <agordeev@redhat.com>
Christoph Hellwig <hch@infradead.org>
Mike Christie <michaelc@cs.wisc.edu>
Matias Bjorling <m@bjorling.me>
Jeff Moyer <jmoyer@redhat.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Recently commit bab55417 ("block: support embedded device command
line partition") introduced CONFIG_CMDLINE_PARSER.  However, that name
is too generic and sounds like it enables/disables generic kernel boot
arg processing, when it really is block specific.

Before this option becomes a part of a full/final release, add the BLK_
prefix to it so that it is clear in absence of any other context that it
is block specific.

In addition, fix up the following less critical items:
 - help text was not really at all helpful.
 - index file for Documentation was not updated
 - add the new arg to Documentation/kernel-parameters.txt
 - clarify wording in source comments
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Cai Zhiyong <caizhiyong@huawei.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Read block device partition table from command line.  The partition used
for fixed block device (eMMC) embedded device.  It is no MBR, save
storage space.  Bootloader can be easily accessed by absolute address of
data on the block device.  Users can easily change the partition.

This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference
"Documentation/block/cmdline-partition.txt"

[akpm@linux-foundation.org: fix printk text]
[yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()]
Signed-off-by: NCai Zhiyong <caizhiyong@huawei.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com>
Cc: Marius Groeger <mag@sysgo.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This moves the FC classes bsg code to the block layer and
makes it a lib so that other classes like iscsi and SAS can use it.

It is helpful because working with the request queue, bios,
creating scatterlists, etc are a pain that the LLD does not
have to worry about with normal IOs and should not have to
worry about for bsg requests.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

o Actual implementation of throttling policy in block layer. Currently it
  implements READ and WRITE bytes per second throttling logic. IOPS throttling
  comes in later patches.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Without ordering requirements, barrier and ordering are minomers.
Rename block/blk-barrier.c to block/blk-flush.c.  Rename of symbols
will follow.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NJens Axboe <jaxboe@fusionio.com>

Move blkdev_issue_discard from blk-barrier.c because it is
not barrier related.
Later the file will be populated by other helpers.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

o This is basic implementation of blkio controller cgroup interface. This is
  the common interface visible to user space and should be used by different
  IO control policies as we implement those.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

AS is mostly a subset of CFQ, so there's little point in still
providing this separate IO scheduler. Hopefully at some point we
can get down to one single IO scheduler again, at least this brings
us closer by having only one intelligent IO scheduler.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This borrows some code from NAPI and implements a polled completion
mode for block devices. The idea is the same as NAPI - instead of
doing the command completion when the irq occurs, schedule a dedicated
softirq in the hopes that we will complete more IO when the iopoll
handler is invoked. Devices have a budget of commands assigned, and will
stay in polled mode as long as they continue to consume their budget
from the iopoll softirq handler. If they do not, the device is set back
to interrupt completion mode.

This patch holds the core bits for blk-iopoll, device driver support
sold separately.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The initial patches to support this through sysfs export were broken
and have been if 0'ed out in any release. So lets just kill the code
and reclaim some space in struct request_queue, if anyone would later
like to fixup the sysfs bits, the git history can easily restore
the removed bits.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Impact: cleanup

Move blktrace.c to kernel/trace, also move its config entry.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Right now SCSI and others do their own command timeout handling.
Move those bits to the block layer.

Instead of having a timer per command, we try to be a bit more clever
and simply have one per-queue. This avoids the overhead of having to
tear down and setup a timer for each command, so it will result in a lot
less timer fiddling.
Signed-off-by: NMike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This patch exports the per-gendisk command filter to user space through
sysfs, so it can be changed by the system administrator.
All users of the old cmd filter have been converted to use the new one.

Original patch from Peter Jones.
Signed-off-by: NAdel Gadllah <adel.gadllah@gmail.com>
Signed-off-by: NPeter Jones <pjones@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>