<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/block, branch v6.0-rc6</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'block-6.0-2022-09-16' of git://git.kernel.dk/linux-block</title>
<updated>2022-09-16T13:58:04+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-16T13:58:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=68e777e44c275e8dbc36f5a187c366e982d6a129'/>
<id>68e777e44c275e8dbc36f5a187c366e982d6a129</id>
<content type='text'>
Pull block fixes from Jens Axboe:
 "Two fixes for -rc6:

   - Fix a mixup of sectors and bytes in the secure erase ioctl
     (Mikulas)

   - Fix for a bad return value for a non-blocking bio/blk queue enter
     call (me)"

* tag 'block-6.0-2022-09-16' of git://git.kernel.dk/linux-block:
  blk-lib: fix blkdev_issue_secure_erase
  block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:
 "Two fixes for -rc6:

   - Fix a mixup of sectors and bytes in the secure erase ioctl
     (Mikulas)

   - Fix for a bad return value for a non-blocking bio/blk queue enter
     call (me)"

* tag 'block-6.0-2022-09-16' of git://git.kernel.dk/linux-block:
  blk-lib: fix blkdev_issue_secure_erase
  block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait
</pre>
</div>
</content>
</entry>
<entry>
<title>blk-lib: fix blkdev_issue_secure_erase</title>
<updated>2022-09-15T06:25:17+00:00</updated>
<author>
<name>Mikulas Patocka</name>
<email>mpatocka@redhat.com</email>
</author>
<published>2022-09-14T20:55:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c4fa368466cc1b60bb92f867741488930ddd6034'/>
<id>c4fa368466cc1b60bb92f867741488930ddd6034</id>
<content type='text'>
There's a bug in blkdev_issue_secure_erase. The statement
"unsigned int len = min_t(sector_t, nr_sects, max_sectors);"
sets the variable "len" to the length in sectors, but the statement
"bio-&gt;bi_iter.bi_size = len" treats it as if it were in bytes.
The statements "sector += len &lt;&lt; SECTOR_SHIFT" and "nr_sects -= len &lt;&lt;
SECTOR_SHIFT" are thinko.

This patch fixes it.

Signed-off-by: Mikulas Patocka &lt;mpatocka@redhat.com&gt;
Cc: stable@vger.kernel.org	# v5.19
Fixes: 44abff2c0b97 ("block: decouple REQ_OP_SECURE_ERASE from REQ_OP_DISCARD")
Link: https://lore.kernel.org/r/alpine.LRH.2.02.2209141549480.28100@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There's a bug in blkdev_issue_secure_erase. The statement
"unsigned int len = min_t(sector_t, nr_sects, max_sectors);"
sets the variable "len" to the length in sectors, but the statement
"bio-&gt;bi_iter.bi_size = len" treats it as if it were in bytes.
The statements "sector += len &lt;&lt; SECTOR_SHIFT" and "nr_sects -= len &lt;&lt;
SECTOR_SHIFT" are thinko.

This patch fixes it.

Signed-off-by: Mikulas Patocka &lt;mpatocka@redhat.com&gt;
Cc: stable@vger.kernel.org	# v5.19
Fixes: 44abff2c0b97 ("block: decouple REQ_OP_SECURE_ERASE from REQ_OP_DISCARD")
Link: https://lore.kernel.org/r/alpine.LRH.2.02.2209141549480.28100@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait</title>
<updated>2022-09-13T21:06:39+00:00</updated>
<author>
<name>Stefan Roesch</name>
<email>shr@fb.com</email>
</author>
<published>2022-09-12T16:53:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=56f99b8d06ef1ed1c9730948f9f05ac2b930a20b'/>
<id>56f99b8d06ef1ed1c9730948f9f05ac2b930a20b</id>
<content type='text'>
Today blk_queue_enter() and __bio_queue_enter() return -EBUSY for the
nowait code path. This is not correct: they should return -EAGAIN
instead.

This problem was detected by fio. The following command exposed the
above problem:

t/io_uring -p0 -d128 -b4096 -s32 -c32 -F1 -B0 -R0 -X1 -n24 -P1 -u1 -O0 /dev/ng0n1

By applying the patch, the retry case is handled correctly in the slow
path.

Signed-off-by: Stefan Roesch &lt;shr@fb.com&gt;
Fixes: bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set")
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Today blk_queue_enter() and __bio_queue_enter() return -EBUSY for the
nowait code path. This is not correct: they should return -EAGAIN
instead.

This problem was detected by fio. The following command exposed the
above problem:

t/io_uring -p0 -d128 -b4096 -s32 -c32 -F1 -B0 -R0 -X1 -n24 -P1 -u1 -O0 /dev/ng0n1

By applying the patch, the retry case is handled correctly in the slow
path.

Signed-off-by: Stefan Roesch &lt;shr@fb.com&gt;
Fixes: bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set")
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.0-2022-09-09' of git://git.kernel.dk/linux-block</title>
<updated>2022-09-09T19:03:08+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-09T19:03:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9ebc0ecb21b53e1a592f4ac9af927f7ff605f306'/>
<id>9ebc0ecb21b53e1a592f4ac9af927f7ff605f306</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - NVMe pull via Christoph:
      - fix a use after free in nvmet (Bart Van Assche)
      - fix a use after free when detecting digest errors
        (Sagi Grimberg)
      - fix regression that causes sporadic TCP requests to time out
        (Sagi Grimberg)
      - fix two off by ones errors in the nvmet ZNS support
        (Dennis Maisenbacher)
      - requeue aen after firmware activation (Keith Busch)

 - Fix missing request flags in debugfs code (me)

 - Partition scan fix (Ming)

* tag 'block-6.0-2022-09-09' of git://git.kernel.dk/linux-block:
  block: add missing request flags to debugfs code
  nvme: requeue aen after firmware activation
  nvmet: fix mar and mor off-by-one errors
  nvme-tcp: fix regression that causes sporadic requests to time out
  nvme-tcp: fix UAF when detecting digest errors
  nvmet: fix a use-after-free
  block: don't add partitions if GD_SUPPRESS_PART_SCAN is set
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - NVMe pull via Christoph:
      - fix a use after free in nvmet (Bart Van Assche)
      - fix a use after free when detecting digest errors
        (Sagi Grimberg)
      - fix regression that causes sporadic TCP requests to time out
        (Sagi Grimberg)
      - fix two off by ones errors in the nvmet ZNS support
        (Dennis Maisenbacher)
      - requeue aen after firmware activation (Keith Busch)

 - Fix missing request flags in debugfs code (me)

 - Partition scan fix (Ming)

* tag 'block-6.0-2022-09-09' of git://git.kernel.dk/linux-block:
  block: add missing request flags to debugfs code
  nvme: requeue aen after firmware activation
  nvmet: fix mar and mor off-by-one errors
  nvme-tcp: fix regression that causes sporadic requests to time out
  nvme-tcp: fix UAF when detecting digest errors
  nvmet: fix a use-after-free
  block: don't add partitions if GD_SUPPRESS_PART_SCAN is set
</pre>
</div>
</content>
</entry>
<entry>
<title>block: add missing request flags to debugfs code</title>
<updated>2022-09-09T11:57:52+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2022-09-08T23:26:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=745ed37277c5a7202180aa276c87db1362c90fe5'/>
<id>745ed37277c5a7202180aa276c87db1362c90fe5</id>
<content type='text'>
We're missing TIMED_OUT and RESV. Particularly the former is handy
for debugging, let's get them added.

Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We're missing TIMED_OUT and RESV. Particularly the former is handy
for debugging, let's get them added.

Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: don't add partitions if GD_SUPPRESS_PART_SCAN is set</title>
<updated>2022-09-03T17:29:03+00:00</updated>
<author>
<name>Ming Lei</name>
<email>ming.lei@redhat.com</email>
</author>
<published>2022-08-23T10:38:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=748008e1da926a814cc0a054c81ca614408b1b0c'/>
<id>748008e1da926a814cc0a054c81ca614408b1b0c</id>
<content type='text'>
Commit b9684a71fca7 ("block, loop: support partitions without scanning")
adds GD_SUPPRESS_PART_SCAN for replacing part function of
GENHD_FL_NO_PART. But looks blk_add_partitions() is missed, since
loop doesn't want to add partitions if GENHD_FL_NO_PART was set.
And it causes regression on libblockdev (as called from udisks) which
operates with the LO_FLAGS_PARTSCAN.

Fixes the issue by not adding partitions if GD_SUPPRESS_PART_SCAN is
set.

Fixes: b9684a71fca7 ("block, loop: support partitions without scanning")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20220823103819.395776-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit b9684a71fca7 ("block, loop: support partitions without scanning")
adds GD_SUPPRESS_PART_SCAN for replacing part function of
GENHD_FL_NO_PART. But looks blk_add_partitions() is missed, since
loop doesn't want to add partitions if GENHD_FL_NO_PART was set.
And it causes regression on libblockdev (as called from udisks) which
operates with the LO_FLAGS_PARTSCAN.

Fixes the issue by not adding partitions if GD_SUPPRESS_PART_SCAN is
set.

Fixes: b9684a71fca7 ("block, loop: support partitions without scanning")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20220823103819.395776-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.0-2022-08-26' of git://git.kernel.dk/linux-block</title>
<updated>2022-08-26T18:05:54+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-08-26T18:05:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3e5c673f0d75bc22b3c26eade87e4db4f374cd34'/>
<id>3e5c673f0d75bc22b3c26eade87e4db4f374cd34</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - MD pull request via Song:
      - Fix for clustered raid (Guoqing Jiang)
      - req_op fix (Bart Van Assche)
      - Fix race condition in raid recreate (David Sloan)

 - loop configuration overflow fix (Siddh)

 - Fix missing commit_rqs call for certain conditions (Yu)

* tag 'block-6.0-2022-08-26' of git://git.kernel.dk/linux-block:
  md: call __md_stop_writes in md_stop
  Revert "md-raid: destroy the bitmap after destroying the thread"
  md: Flush workqueue md_rdev_misc_wq in md_alloc()
  md/raid10: Fix the data type of an r10_sync_page_io() argument
  loop: Check for overflow while configuring loop
  blk-mq: fix io hung due to missing commit_rqs
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - MD pull request via Song:
      - Fix for clustered raid (Guoqing Jiang)
      - req_op fix (Bart Van Assche)
      - Fix race condition in raid recreate (David Sloan)

 - loop configuration overflow fix (Siddh)

 - Fix missing commit_rqs call for certain conditions (Yu)

* tag 'block-6.0-2022-08-26' of git://git.kernel.dk/linux-block:
  md: call __md_stop_writes in md_stop
  Revert "md-raid: destroy the bitmap after destroying the thread"
  md: Flush workqueue md_rdev_misc_wq in md_alloc()
  md/raid10: Fix the data type of an r10_sync_page_io() argument
  loop: Check for overflow while configuring loop
  blk-mq: fix io hung due to missing commit_rqs
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.0-2022-08-19' of git://git.kernel.dk/linux-block</title>
<updated>2022-08-20T17:17:05+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-08-20T17:17:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b9bce6e5533a08e0223d629541b4f39ffea48333'/>
<id>b9bce6e5533a08e0223d629541b4f39ffea48333</id>
<content type='text'>
Pull block fixes from Jens Axboe:
 "A few fixes that should go into this release:

   - Small series of patches for ublk (ZiyangZhang)

   - Remove dead function (Yu)

   - Fix for running a block queue in case of resource starvation
     (Yufen)"

* tag 'block-6.0-2022-08-19' of git://git.kernel.dk/linux-block:
  blk-mq: run queue no matter whether the request is the last request
  blk-mq: remove unused function blk_mq_queue_stopped()
  ublk_drv: do not add a re-issued request aborted previously to ioucmd's task_work
  ublk_drv: update comment for __ublk_fail_req()
  ublk_drv: check ubq_daemon_is_dying() in __ublk_rq_task_work()
  ublk_drv: update iod-&gt;addr for UBLK_IO_NEED_GET_DATA
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:
 "A few fixes that should go into this release:

   - Small series of patches for ublk (ZiyangZhang)

   - Remove dead function (Yu)

   - Fix for running a block queue in case of resource starvation
     (Yufen)"

* tag 'block-6.0-2022-08-19' of git://git.kernel.dk/linux-block:
  blk-mq: run queue no matter whether the request is the last request
  blk-mq: remove unused function blk_mq_queue_stopped()
  ublk_drv: do not add a re-issued request aborted previously to ioucmd's task_work
  ublk_drv: update comment for __ublk_fail_req()
  ublk_drv: check ubq_daemon_is_dying() in __ublk_rq_task_work()
  ublk_drv: update iod-&gt;addr for UBLK_IO_NEED_GET_DATA
</pre>
</div>
</content>
</entry>
<entry>
<title>blk-mq: fix io hung due to missing commit_rqs</title>
<updated>2022-08-19T20:45:58+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2022-07-26T12:22:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=65fac0d54f374625b43a9d6ad1f2c212bd41f518'/>
<id>65fac0d54f374625b43a9d6ad1f2c212bd41f518</id>
<content type='text'>
Currently, in virtio_scsi, if 'bd-&gt;last' is not set to true while
dispatching request, such io will stay in driver's queue, and driver
will wait for block layer to dispatch more rqs. However, if block
layer failed to dispatch more rq, it should trigger commit_rqs to
inform driver.

There is a problem in blk_mq_try_issue_list_directly() that commit_rqs
won't be called:

// assume that queue_depth is set to 1, list contains two rq
blk_mq_try_issue_list_directly
 blk_mq_request_issue_directly
 // dispatch first rq
 // last is false
  __blk_mq_try_issue_directly
   blk_mq_get_dispatch_budget
   // succeed to get first budget
   __blk_mq_issue_directly
    scsi_queue_rq
     cmd-&gt;flags |= SCMD_LAST
      virtscsi_queuecommand
       kick = (sc-&gt;flags &amp; SCMD_LAST) != 0
       // kick is false, first rq won't issue to disk
 queued++

 blk_mq_request_issue_directly
 // dispatch second rq
  __blk_mq_try_issue_directly
   blk_mq_get_dispatch_budget
   // failed to get second budget
 ret == BLK_STS_RESOURCE
  blk_mq_request_bypass_insert
 // errors is still 0

 if (!list_empty(list) || errors &amp;&amp; ...)
  // won't pass, commit_rqs won't be called

In this situation, first rq relied on second rq to dispatch, while
second rq relied on first rq to complete, thus they will both hung.

Fix the problem by also treat 'BLK_STS_*RESOURCE' as 'errors' since
it means that request is not queued successfully.

Same problem exists in blk_mq_dispatch_rq_list(), 'BLK_STS_*RESOURCE'
can't be treated as 'errors' here, fix the problem by calling
commit_rqs if queue_rq return 'BLK_STS_*RESOURCE'.

Fixes: d666ba98f849 ("blk-mq: add mq_ops-&gt;commit_rqs()")
Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Link: https://lore.kernel.org/r/20220726122224.1790882-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, in virtio_scsi, if 'bd-&gt;last' is not set to true while
dispatching request, such io will stay in driver's queue, and driver
will wait for block layer to dispatch more rqs. However, if block
layer failed to dispatch more rq, it should trigger commit_rqs to
inform driver.

There is a problem in blk_mq_try_issue_list_directly() that commit_rqs
won't be called:

// assume that queue_depth is set to 1, list contains two rq
blk_mq_try_issue_list_directly
 blk_mq_request_issue_directly
 // dispatch first rq
 // last is false
  __blk_mq_try_issue_directly
   blk_mq_get_dispatch_budget
   // succeed to get first budget
   __blk_mq_issue_directly
    scsi_queue_rq
     cmd-&gt;flags |= SCMD_LAST
      virtscsi_queuecommand
       kick = (sc-&gt;flags &amp; SCMD_LAST) != 0
       // kick is false, first rq won't issue to disk
 queued++

 blk_mq_request_issue_directly
 // dispatch second rq
  __blk_mq_try_issue_directly
   blk_mq_get_dispatch_budget
   // failed to get second budget
 ret == BLK_STS_RESOURCE
  blk_mq_request_bypass_insert
 // errors is still 0

 if (!list_empty(list) || errors &amp;&amp; ...)
  // won't pass, commit_rqs won't be called

In this situation, first rq relied on second rq to dispatch, while
second rq relied on first rq to complete, thus they will both hung.

Fix the problem by also treat 'BLK_STS_*RESOURCE' as 'errors' since
it means that request is not queued successfully.

Same problem exists in blk_mq_dispatch_rq_list(), 'BLK_STS_*RESOURCE'
can't be treated as 'errors' here, fix the problem by calling
commit_rqs if queue_rq return 'BLK_STS_*RESOURCE'.

Fixes: d666ba98f849 ("blk-mq: add mq_ops-&gt;commit_rqs()")
Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Link: https://lore.kernel.org/r/20220726122224.1790882-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blk-mq: run queue no matter whether the request is the last request</title>
<updated>2022-08-18T13:39:01+00:00</updated>
<author>
<name>Yufen Yu</name>
<email>yuyufen@huawei.com</email>
</author>
<published>2022-08-03T02:33:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d3b38596875dbc709b4e721a5873f4663d8a9ea2'/>
<id>d3b38596875dbc709b4e721a5873f4663d8a9ea2</id>
<content type='text'>
We do test on a virtio scsi device (/dev/sda) and the default mq
scheduler is 'none'. We found a IO hung as following:

blk_finish_plug
  blk_mq_plug_issue_direct
      scsi_mq_get_budget
      //get budget_token fail and sdev-&gt;restarts=1

			     	 scsi_end_request
				   scsi_run_queue_async
                                   //sdev-&gt;restart=0 and run queue

     blk_mq_request_bypass_insert
        //add request to hctx-&gt;dispatch list

  //continue to dispath plug list
  blk_mq_dispatch_plug_list
      blk_mq_try_issue_list_directly
        //success issue all requests from plug list

After .get_budget fail, scsi_mq_get_budget will increase 'restarts'.
Normally, it will run hw queue when io complete and set 'restarts'
as 0. But if we run queue before adding request to the dispatch list
and blk_mq_dispatch_plug_list also success issue all requests, then
on one will run queue, and the request will be stall in the dispatch
list and cannot complete forever.

It is wrong to use last request of plug list to decide if run queue is
needed since all the remained requests in plug list may be from other
hctxs. To fix the bug, pass run_queue as true always to
blk_mq_request_bypass_insert().

Fix-suggested-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Yufen Yu &lt;yuyufen@huawei.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Fixes: dc5fc361d891 ("block: attempt direct issue of plug list")
Link: https://lore.kernel.org/r/20220803023355.3687360-1-yuyufen@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We do test on a virtio scsi device (/dev/sda) and the default mq
scheduler is 'none'. We found a IO hung as following:

blk_finish_plug
  blk_mq_plug_issue_direct
      scsi_mq_get_budget
      //get budget_token fail and sdev-&gt;restarts=1

			     	 scsi_end_request
				   scsi_run_queue_async
                                   //sdev-&gt;restart=0 and run queue

     blk_mq_request_bypass_insert
        //add request to hctx-&gt;dispatch list

  //continue to dispath plug list
  blk_mq_dispatch_plug_list
      blk_mq_try_issue_list_directly
        //success issue all requests from plug list

After .get_budget fail, scsi_mq_get_budget will increase 'restarts'.
Normally, it will run hw queue when io complete and set 'restarts'
as 0. But if we run queue before adding request to the dispatch list
and blk_mq_dispatch_plug_list also success issue all requests, then
on one will run queue, and the request will be stall in the dispatch
list and cannot complete forever.

It is wrong to use last request of plug list to decide if run queue is
needed since all the remained requests in plug list may be from other
hctxs. To fix the bug, pass run_queue as true always to
blk_mq_request_bypass_insert().

Fix-suggested-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Yufen Yu &lt;yuyufen@huawei.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Fixes: dc5fc361d891 ("block: attempt direct issue of plug list")
Link: https://lore.kernel.org/r/20220803023355.3687360-1-yuyufen@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
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