To boost throughput on devices with internal queueing and in scenarios
where device idling is not strictly needed, bfq immediately starts
serving a new bfq_queue if the in-service bfq_queue remains without
pending I/O, even if new I/O may arrive soon for the latter queue. Then,
if such I/O actually arrives soon, bfq preempts the new in-service
bfq_queue so as to give the previous queue a chance to go on being
served (in case the previous queue should actually be the one to be
served, according to its timestamps).

However, the in-service bfq_queue, say Q, may also be without further
budget when it remains also pending I/O. Since bfq changes budgets
dynamically to fit the needs of bfq_queues, this happens more often than
one may expect. If this happens, then there is no point in trying to go
on serving Q when new I/O arrives for it soon: Q would be expired
immediately after being selected for service. This would only cause
useless overhead. This commit avoids such a useless selection.
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The speed at which a bfq_queue receives I/O is one of the parameters by
which bfq decides whether the queue is soft real-time (i.e., whether the
queue contains the I/O of a soft real-time application). In particular,
when a bfq_queue remains without outstanding I/O requests, bfq computes
the minimum time instant, named soft_rt_next_start, at which the next
request of the queue may arrive for the queue to be deemed as soft real
time.

Unfortunately this filtering may cause problems with a queue in
interactive weight raising. In fact, such a queue may be conveying the
I/O needed to load a soft real-time application. The latter will
actually exhibit a soft real-time I/O pattern after it finally starts
doing its job. But, if soft_rt_next_start is updated for an interactive
bfq_queue, and the queue has received a lot of service before remaining
with no outstanding request (likely to happen on a fast device), then
soft_rt_next_start is assigned such a high value that, for a very long
time, the queue is prevented from being possibly considered as soft real
time.

This commit removes the updating of soft_rt_next_start for bfq_queues in
interactive weight raising.
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We can't touch a bio after ->make_request_fn(), for all we know it could
already have been completed by the time this function returns.

This reverts commit 698cef17.

Reported-by: syzbot+4df6ca820108fd248943@syzkaller.appspotmail.com
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch avoids that sparse reports the following warnings:

  CHECK   block/blk-wbt.c
block/blk-wbt.c:600:6: warning: symbol 'wbt_issue' was not declared. Should it be static?
block/blk-wbt.c:620:6: warning: symbol 'wbt_requeue' was not declared. Should it be static?
  CC      block/blk-wbt.o
block/blk-wbt.c:600:6: warning: no previous prototype for wbt_issue [-Wmissing-prototypes]
 void wbt_issue(struct rq_qos *rqos, struct request *rq)
      ^~~~~~~~~
block/blk-wbt.c:620:6: warning: no previous prototype for wbt_requeue [-Wmissing-prototypes]
 void wbt_requeue(struct rq_qos *rqos, struct request *rq)
      ^~~~~~~~~~~
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Swap REQ_NOWAIT and REQ_NOUNMAP and add REQ_HIPRI.
Acked-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Except for blk_queue_split(), bio_split() is used for splitting bio too,
then the remained bio is often resubmit to queue via generic_make_request().
So the same queue enter recursion exits in this case too. Unfortunatley
commit cd4a4ae4 doesn't help this case.

This patch covers the above case by setting BIO_QUEUE_ENTERED before calling
q->make_request_fn.

In theory the per-bio flag is used to simulate one stack variable, it is
just fine to clear it after q->make_request_fn is returned. Especially
the same bio can't be submitted from another context.

Fixes: cd4a4ae4 ("block: don't use blocking queue entered for recursive bio submits")
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: NeilBrown <neilb@suse.com>
Reviewed-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Remove the imprecise and sloppy:

  "This files is licensed under the GPL."

license notice in the top level comment.

1) The file already contains a SPDX license identifier which clearly
   states that the license of the file is GPL V2 only

2) The notice resolves to GPL v1 or later for scanners which is just
   contrary to the intent of SPDX identifiers to provide clear and non
   ambiguous license information. Aside of that the value add of this
   notice is below zero,

Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Matias Bjorling <mb@lightnvm.io>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Fixes: 6a5ac984 ("block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n")
Reviewed-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We need to pass bio->bi_opf after bio intergrity preparing, otherwise
the flag of REQ_INTEGRITY may not be set on the allocated request, then
breaks block integrity.

Fixes: f9afca4d ("blk-mq: pass in request/bio flags to queue mapping")
Cc: Hannes Reinecke <hare@suse.com>
Cc: Keith Busch <keith.busch@intel.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Comments on function __bfq_deactivate_entity contains two imprecise or
wrong statements:
1) The function performs the deactivation of the entity.
2) The function must be invoked only if the entity is on a service tree.

This commits replaces both statements with the correct ones:
1) The functions updates sched_data and service trees for the entity,
so as to represent entity as inactive (which is only part of the steps
needed for the deactivation of the entity).
2) The function must be invoked on every entity being deactivated.
Signed-off-by: NPaolo Valente <paolo.valente@linaro.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Commit 5f0ed774 ("block: sum requests in the plug structure") removed
the request_count parameter from block_attempt_plug_merge(), but did not
remove the associated kerneldoc comment, introducing this warning to the
docs build:

  ./block/blk-core.c:685: warning: Excess function parameter 'request_count' description in 'blk_attempt_plug_merge'

Remove the obsolete description and make things a little quieter.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

There was some confusion about what these functions did.  Make it clear
that this is a hint for upper layers to pass to the block layer, and
that it does not guarantee that I/O will not be submitted between a
start and finish plug.
Reported-by: N"Darrick J. Wong" <darrick.wong@oracle.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Besides the OSD command set that never got traction, the only SCSI
command using bidirectional buffers is XDWRITEREAD in the 10 and 32 byte
variants, which is extremely esoteric and has been removed from the spec
again as of SBC4r15.  It probably doesn't make sense to keep the support
code around just for that, so start deprecating the support.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

An earlier commit 7fcf2b03 ("blkcg: change blkg reference counting
to use percpu_ref") moved around the release call from blkg_put() to be
a part of the percpu_ref cleanup. Remove the additional unused code
which should have been removed earlier.
Signed-off-by: NDennis Zhou <dennis@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The implementation of blkg_tryget_closest() wasn't super obvious and
became a point of suspicion when debugging [1]. So let's clean it up so
it's obviously not the problem.

Also add missing RCU read locking to bio_clone_blkg_association(), which
got exposed by adding the RCU read lock held check in
blkg_tryget_closest().

[1] https://lore.kernel.org/linux-block/a7e97e4b-0dd8-3a54-23b7-a0f27b17fde8@kernel.dk/Signed-off-by: NDennis Zhou <dennis@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The Kconfig lexer supports special characters such as '.' and '/' in
the parameter context. In my understanding, the reason is just to
support bare file paths in the source statement.

I do not see a good reason to complicate Kconfig for the room of
ambiguity.

The majority of code already surrounds file paths with double quotes,
and it makes sense since file paths are constant string literals.

Make it treewide consistent now.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NWolfram Sang <wsa@the-dreams.de>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NIngo Molnar <mingo@kernel.org>

sbq_wake_ptr() checks sbq->ws_active to know if it needs to loop
the wait indexes or not. This requires the use of the sbitmap
waitqueue wrappers, but kyber doesn't use those for its domain
token waitqueue handling.

Convert kyber to use the helpers. This fixes a hang with waiting
for domain tokens.

Fixes: 5d2ee712 ("sbitmap: optimize wakeup check")
Tested-by: NMing Lei <ming.lei@redhat.com>
Reported-by: NMing Lei <ming.lei@redhat.com>
Reviewed-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blkg_lookup_create() may be called from pool_map() in which
irq state is saved, so we have to do that in blkg_lookup_create().

Otherwise, the following lockdep warning can be triggered:

[  104.258537] ================================
[  104.259129] WARNING: inconsistent lock state
[  104.259725] 4.20.0-rc6+ #545 Not tainted
[  104.260268] --------------------------------
[  104.260865] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[  104.261727] swapper/49/0 [HC0[0]:SC1[1]:HE0:SE0] takes:
[  104.262444] 00000000db365b5d (&(&pool->lock)->rlock#3){+.?.}, at: thin_endio+0xcf/0x2a3 [dm_thin_pool]
[  104.263747] {SOFTIRQ-ON-W} state was registered at:
[  104.264417]   _raw_spin_unlock_irq+0x29/0x4c
[  104.265014]   blkg_lookup_create+0xdc/0xe6
[  104.265609]   bio_associate_blkg_from_css+0xd3/0x13f
[  104.266312]   bio_associate_blkg+0x15a/0x1bb
[  104.266913]   pool_map+0xe8/0x103 [dm_thin_pool]
[  104.267572]   __map_bio+0x98/0x29c [dm_mod]
[  104.268162]   __split_and_process_non_flush+0x29e/0x306 [dm_mod]
[  104.269003]   __split_and_process_bio+0x16a/0x25b [dm_mod]
[  104.269971]   __dm_make_request.isra.14+0xdc/0x124 [dm_mod]
[  104.270973]   generic_make_request+0x3f5/0x68b
[  104.271676]   process_prepared_mapping+0x166/0x1ef [dm_thin_pool]
[  104.272531]   schedule_zero+0x239/0x273 [dm_thin_pool]
[  104.273245]   process_cell+0x60c/0x6f1 [dm_thin_pool]
[  104.273967]   do_worker+0x60c/0xca8 [dm_thin_pool]
[  104.274635]   process_one_work+0x4eb/0x834
[  104.275203]   worker_thread+0x318/0x484
[  104.275740]   kthread+0x1d1/0x1e1
[  104.276203]   ret_from_fork+0x3a/0x50
[  104.276714] irq event stamp: 170003
[  104.277201] hardirqs last  enabled at (170002): [<ffffffff81bcc33e>] _raw_spin_unlock_irqrestore+0x44/0x6b
[  104.278535] hardirqs last disabled at (170003): [<ffffffff81bcc1ad>] _raw_spin_lock_irqsave+0x20/0x55
[  104.280273] softirqs last  enabled at (169978): [<ffffffff810d13d4>] irq_enter+0x4c/0x73
[  104.281617] softirqs last disabled at (169979): [<ffffffff810d1479>] irq_exit+0x7e/0x11d
[  104.282744]
[  104.282744] other info that might help us debug this:
[  104.283640]  Possible unsafe locking scenario:
[  104.283640]
[  104.284452]        CPU0
[  104.284803]        ----
[  104.285150]   lock(&(&pool->lock)->rlock#3);
[  104.285762]   <Interrupt>
[  104.286130]     lock(&(&pool->lock)->rlock#3);
[  104.286750]
[  104.286750]  *** DEADLOCK ***
[  104.286750]
[  104.287564] no locks held by swapper/49/0.
[  104.288129]
[  104.288129] stack backtrace:
[  104.288738] CPU: 49 PID: 0 Comm: swapper/49 Not tainted 4.20.0-rc6+ #545
[  104.289700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014
[  104.290858] Call Trace:
[  104.291204]  <IRQ>
[  104.291502]  dump_stack+0x9a/0xe6
[  104.291968]  mark_lock+0x56c/0x7a6
[  104.292442]  ? check_usage_backwards+0x209/0x209
[  104.293086]  __lock_acquire+0x400/0x15bf
[  104.293662]  ? check_chain_key+0x150/0x1aa
[  104.294236]  lock_acquire+0x1a6/0x1e3
[  104.294768]  ? thin_endio+0xcf/0x2a3 [dm_thin_pool]
[  104.295444]  ? _raw_spin_unlock_irqrestore+0x44/0x6b
[  104.296143]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
[  104.297031]  _raw_spin_lock_irqsave+0x46/0x55
[  104.297659]  ? thin_endio+0xcf/0x2a3 [dm_thin_pool]
[  104.298335]  thin_endio+0xcf/0x2a3 [dm_thin_pool]
[  104.298997]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
[  104.299886]  ? check_flags+0x20a/0x20a
[  104.300408]  ? lock_acquire+0x1a6/0x1e3
[  104.300954]  ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool]
[  104.301865]  clone_endio+0x1bb/0x22d [dm_mod]
[  104.302491]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
[  104.303200]  ? bio_disassociate_blkg+0xc6/0x15f
[  104.303836]  ? bio_endio+0x2b2/0x2da
[  104.304349]  clone_endio+0x1f3/0x22d [dm_mod]
[  104.304978]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
[  104.305709]  ? bio_disassociate_blkg+0xc6/0x15f
[  104.306333]  ? bio_endio+0x2b2/0x2da
[  104.306853]  clone_endio+0x1f3/0x22d [dm_mod]
[  104.307476]  ? disable_write_zeroes+0x20/0x20 [dm_mod]
[  104.308185]  ? bio_disassociate_blkg+0xc6/0x15f
[  104.308817]  ? bio_endio+0x2b2/0x2da
[  104.309319]  blk_update_request+0x2de/0x4cc
[  104.309927]  blk_mq_end_request+0x2a/0x183
[  104.310498]  blk_done_softirq+0x16a/0x1a6
[  104.311051]  ? blk_softirq_cpu_dead+0xe2/0xe2
[  104.311653]  ? __lock_is_held+0x2a/0x87
[  104.312186]  __do_softirq+0x250/0x4e8
[  104.312705]  irq_exit+0x7e/0x11d
[  104.313157]  call_function_single_interrupt+0xf/0x20
[  104.313860]  </IRQ>
[  104.314163] RIP: 0010:native_safe_halt+0x2/0x3
[  104.314792] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 cc 3f 7a ff 48 8b 03 a8 08 74 0b 65 81 25 9d 31 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 <c3> f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 a2 0d 5c ff e8
[  104.317339] RSP: 0018:ffff888106c9fdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04
[  104.318390] RAX: 1ffff11020d92100 RBX: 0000000000000000 RCX: ffffffff81159ac7
[  104.319366] RDX: 1ffffffff05d5e69 RSI: 0000000000000007 RDI: ffff888106c90d1c
[  104.320339] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001
[  104.321313] R10: ffffed1025d57ba0 R11: ffffed1025d57b9f R12: 1ffff11020d93fbf
[  104.322328] R13: 0000000000000031 R14: ffff888106c90040 R15: 0000000000000000
[  104.323307]  ? lockdep_hardirqs_on+0x26b/0x278
[  104.323927]  default_idle+0xd9/0x1a8
[  104.324427]  do_idle+0x162/0x2b2
[  104.324891]  ? arch_cpu_idle_exit+0x28/0x28
[  104.325467]  ? mark_held_locks+0x28/0x7f
[  104.326031]  ? _raw_spin_unlock_irqrestore+0x44/0x6b
[  104.326719]  cpu_startup_entry+0x1d/0x1f
[  104.327261]  start_secondary+0x2cb/0x308
[  104.327806]  ? set_cpu_sibling_map+0x8a3/0x8a3
[  104.328421]  secondary_startup_64+0xa4/0xb0

Fixes: b978962a ("blkcg: update blkg_lookup_create() to do locking")
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now that the the SCSI layer replaced the use of the cluster flag with
segment size limits and the DMA boundary we can remove the cluster flag
from the block layer.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

block consumers will need it for polling requests that
are sent with blk_execute_rq_nowait. Also, get rid of
blk_tag_to_qc_t and open-code it instead.
Reviewed-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The queue mapping of type poll only exists when set->map[HCTX_TYPE_POLL].nr_queues
is bigger than zero, so enhance the constraint by checking .nr_queues of type poll
before enabling IO poll.

Otherwise IO race & timeout can be observed when running block/007.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

There's a single user of this function, dm, and dm just wants
to check if IO is inflight, not that it's just allocated.

This fixes a hang with srp/002 in blktests with dm, where it tries
to suspend but waits for inflight IO to finish first. As it checks
for just allocated requests, this fails.
Tested-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

From 7e849dd9 ("nvme-pci: don't share queue maps"), the mapping
table won't be initialized actually if map->nr_queues is zero, so
we can't use blk_mq_map_queue_type() to retrieve hctx any more.

This way still may cause broken mapping, fix it by skipping zero-queues
maps in blk_mq_map_swqueue().

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The blk-iolatency controller measures the time from rq_qos_throttle() to
rq_qos_done_bio() and attributes this time to the first bio that needs
to create the request. This means if a bio is plug-mergeable or
bio-mergeable, it gets to bypass the blk-iolatency controller.

The recent series [1], to tag all bios w/ blkgs undermined how iolatency
was determining which bios it was charging and should process in
rq_qos_done_bio(). Because all bios are being tagged, this caused the
atomic_t for the struct rq_wait inflight count to underflow and result
in a stall.

This patch adds a new flag BIO_TRACKED to let controllers know that a
bio is going through the rq_qos path. blk-iolatency now checks if this
flag is set to see if it should process the bio in rq_qos_done_bio().

Overloading BLK_QUEUE_ENTERED works, but makes the flag rules confusing.
BIO_THROTTLED was another candidate, but the flag is set for all bios
that have gone through blk-throttle code. Overloading a flag comes with
the burden of making sure that when either implementation changes, a
change in setting rules for one doesn't cause a bug in the other. So
here, we unfortunately opt for adding a new flag.

[1] https://lore.kernel.org/lkml/20181205171039.73066-1-dennis@kernel.org/

Fixes: 5cdf2e3f ("blkcg: associate blkg when associating a device")
Signed-off-by: NDennis Zhou <dennis@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

When a request is added to rq list of sw queue(ctx), the rq may be from
a different type of hctx, especially after multi queue mapping is
introduced.

So when dispach request from sw queue via blk_mq_flush_busy_ctxs() or
blk_mq_dequeue_from_ctx(), one request belonging to other queue type of
hctx can be dispatched to current hctx in case that read queue or poll
queue is enabled.

This patch fixes this issue by introducing per-queue-type list.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>

Changed by me to not use separately cacheline aligned lists, just
place them all in the same cacheline where we had just the one list
and lock before.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For a zoned block device using mq-deadline, if a write request for a
zone is received while another write was already dispatched for the same
zone, dd_dispatch_request() will return NULL and the newly inserted
write request is kept in the scheduler queue waiting for the ongoing
zone write to complete. With this behavior, when no other request has
been dispatched, rq_list in blk_mq_sched_dispatch_requests() is empty
and blk_mq_sched_mark_restart_hctx() not called. This in turn leads to
__blk_mq_free_request() call of blk_mq_sched_restart() to not run the
queue when the already dispatched write request completes. The newly
dispatched request stays stuck in the scheduler queue until eventually
another request is submitted.

This problem does not affect SCSI disk as the SCSI stack handles queue
restart on request completion. However, this problem is can be triggered
the nullblk driver with zoned mode enabled.

Fix this by always requesting a queue restart in dd_dispatch_request()
if no request was dispatched while WRITE requests are queued.

Fixes: 5700f691 ("mq-deadline: Introduce zone locking support")
Cc: <stable@vger.kernel.org>
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>

Add missing export of blk_mq_sched_restart()
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We should check if a given queue map actually has queues enabled before
dispatching to it.  This allows drivers to not initialize optional but
not used map types, which subsequently will allow fixing problems with
queue map rebuilds for that case.
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Now we only export hctx->type via sysfs, and there isn't such info
in hctx entry under debugfs. We often use debugfs only to diagnose
queue mapping issue, so add the support in debugfs.

Queue mapping becomes a bit more complicated after multiple queue
mapping is supported, we may write blktest to verify if queue mapping
is valid based on blk-mq-debugfs.

Given not necessary to export hctx->type twice, so remove the export
from sysfs.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Type of each element in queue mapping table is 'unsigned int,
intead of 'struct blk_mq_queue_map)', so fix it.

Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This information is helpful to either investigate issues, or understand
wbt's internal behaviour.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk-mq-debugfs has been proved as very helpful for debug some
tough issues, such as IO hang.

We have seen blk-wbt related IO hang several times, even inside
Red Hat BZ, there is such report not sovled yet, so this patch
adds support debugfs on rq_qos.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This prevents a HIPRI bio from being submitted through a stacking
driver that does not support polling and thus won't poll for I/O
completion.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Replace blk_mq_request_issue_directly with blk_mq_try_issue_directly
in blk_insert_cloned_request and kill it as nobody uses it any more.
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It is not necessary to issue request directly with bypass 'true'
in blk_mq_sched_insert_requests and handle the non-issued requests
itself. Just set bypass to 'false' and let blk_mq_try_issue_directly
handle them totally. Remove the blk_rq_can_direct_dispatch check,
because blk_mq_try_issue_directly can handle it well.If request is
direct-issued unsuccessfully, insert the reset.
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Merge blk_mq_try_issue_directly and __blk_mq_try_issue_directly
into one interface to unify the interfaces to issue requests
directly. The merged interface takes over the requests totally,
it could insert, end or do nothing based on the return value of
.queue_rq and 'bypass' parameter. Then caller needn't any other
handling any more and then code could be cleaned up.

And also the commit c616cbee ( blk-mq: punt failed direct issue
to dispatch list ) always inserts requests to hctx dispatch list
whenever get a BLK_STS_RESOURCE or BLK_STS_DEV_RESOURCE, this is
overkill and will harm the merging. We just need to do that for
the requests that has been through .queue_rq. This patch also
could fix this.
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>