<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/md/dm-table.c, branch v5.19</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>dm: fix bio_set allocation</title>
<updated>2022-06-08T18:04:14+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-06-08T06:34:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=29dec90a0f1d961b93f34f910e9319d8cb23edbd'/>
<id>29dec90a0f1d961b93f34f910e9319d8cb23edbd</id>
<content type='text'>
The use of bioset_init_from_src mean that the pre-allocated pools weren't
used for anything except parameter passing, and the integrity pool
creation got completely lost for the actual live mapped_device.  Fix that
by assigning the actual preallocated dm_md_mempools to the mapped_device
and using that for I/O instead of creating new mempools.

Fixes: 2a2a4c510b76 ("dm: use bioset_init_from_src() to copy bio_set")
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The use of bioset_init_from_src mean that the pre-allocated pools weren't
used for anything except parameter passing, and the integrity pool
creation got completely lost for the actual live mapped_device.  Fix that
by assigning the actual preallocated dm_md_mempools to the mapped_device
and using that for I/O instead of creating new mempools.

Fixes: 2a2a4c510b76 ("dm: use bioset_init_from_src() to copy bio_set")
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>dm table: fix dm_table_supports_poll to return false if no data devices</title>
<updated>2022-05-31T18:44:17+00:00</updated>
<author>
<name>Mike Snitzer</name>
<email>snitzer@kernel.org</email>
</author>
<published>2022-05-31T16:16:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9571f829f30a89b888ec4c3a72f5a04573f0e058'/>
<id>9571f829f30a89b888ec4c3a72f5a04573f0e058</id>
<content type='text'>
It was reported that the "generic/250" test in xfstests (which uses
the dm-error target) demonstrates a regression where the kernel
crashes in bioset_exit().

Since commit cfc97abcbe0b ("dm: conditionally enable
BIOSET_PERCPU_CACHE for dm_io bioset") the bioset_init() for the dm_io
bioset will setup the bioset's per-cpu alloc cache if all devices have
QUEUE_FLAG_POLL set.

But there was an bug where a target that doesn't have any data devices
(and that doesn't even set the .iterate_devices dm target callback)
will incorrectly return true from dm_table_supports_poll().

Fix this by updating dm_table_supports_poll() to follow dm-table.c's
well-worn pattern for testing that _all_ targets in a DM table do in
fact have underlying devices that set QUEUE_FLAG_POLL.

NOTE: An additional block fix is still needed so that
bio_alloc_cache_destroy() clears the bioset's -&gt;cache member.
Otherwise, a DM device's table reload that transitions the DM device's
bioset from using a per-cpu alloc cache to _not_ using one will result
in bioset_exit() crashing in bio_alloc_cache_destroy() because dm's
dm_io bioset ("io_bs") was left with a stale -&gt;cache member.

Fixes: cfc97abcbe0b ("dm: conditionally enable BIOSET_PERCPU_CACHE for dm_io bioset")
Reported-by: Matthew Wilcox &lt;willy@infradead.org&gt;
Reported-by: Dave Chinner &lt;david@fromorbit.com&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
It was reported that the "generic/250" test in xfstests (which uses
the dm-error target) demonstrates a regression where the kernel
crashes in bioset_exit().

Since commit cfc97abcbe0b ("dm: conditionally enable
BIOSET_PERCPU_CACHE for dm_io bioset") the bioset_init() for the dm_io
bioset will setup the bioset's per-cpu alloc cache if all devices have
QUEUE_FLAG_POLL set.

But there was an bug where a target that doesn't have any data devices
(and that doesn't even set the .iterate_devices dm target callback)
will incorrectly return true from dm_table_supports_poll().

Fix this by updating dm_table_supports_poll() to follow dm-table.c's
well-worn pattern for testing that _all_ targets in a DM table do in
fact have underlying devices that set QUEUE_FLAG_POLL.

NOTE: An additional block fix is still needed so that
bio_alloc_cache_destroy() clears the bioset's -&gt;cache member.
Otherwise, a DM device's table reload that transitions the DM device's
bioset from using a per-cpu alloc cache to _not_ using one will result
in bioset_exit() crashing in bio_alloc_cache_destroy() because dm's
dm_io bioset ("io_bs") was left with a stale -&gt;cache member.

Fixes: cfc97abcbe0b ("dm: conditionally enable BIOSET_PERCPU_CACHE for dm_io bioset")
Reported-by: Matthew Wilcox &lt;willy@infradead.org&gt;
Reported-by: Dave Chinner &lt;david@fromorbit.com&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>dm: conditionally enable branching for less used features</title>
<updated>2022-05-05T21:31:34+00:00</updated>
<author>
<name>Mike Snitzer</name>
<email>snitzer@kernel.org</email>
</author>
<published>2022-03-26T18:14:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=442761fd2b297d65d1cb5786249e1e07a19e9122'/>
<id>442761fd2b297d65d1cb5786249e1e07a19e9122</id>
<content type='text'>
Use jump_labels to further reduce cost of unlikely branches for zoned
block devices, dm-stats and swap_bios throttling.

Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use jump_labels to further reduce cost of unlikely branches for zoned
block devices, dm-stats and swap_bios throttling.

Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>dm: conditionally enable BIOSET_PERCPU_CACHE for dm_io bioset</title>
<updated>2022-05-05T21:31:33+00:00</updated>
<author>
<name>Mike Snitzer</name>
<email>snitzer@kernel.org</email>
</author>
<published>2022-03-24T18:36:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cfc97abcbe0b1ffac441202fe330e697370ecbcc'/>
<id>cfc97abcbe0b1ffac441202fe330e697370ecbcc</id>
<content type='text'>
A bioset's per-cpu alloc cache may have broader utility in the future
but for now constrain it to being tightly coupled to QUEUE_FLAG_POLL.

Also change dm_io_complete() to use bio_clear_polled() so that it
properly clears all associated bio state on requeue.

This commit improves DM's hipri bio polling (REQ_POLLED) perf by
7 - 20% depending on the system.

Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
A bioset's per-cpu alloc cache may have broader utility in the future
but for now constrain it to being tightly coupled to QUEUE_FLAG_POLL.

Also change dm_io_complete() to use bio_clear_polled() so that it
properly clears all associated bio state on requeue.

This commit improves DM's hipri bio polling (REQ_POLLED) perf by
7 - 20% depending on the system.

Signed-off-by: Mike Snitzer &lt;snitzer@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: decouple REQ_OP_SECURE_ERASE from REQ_OP_DISCARD</title>
<updated>2022-04-18T01:49:59+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-04-15T04:52:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=44abff2c0b970ae3d310b97617525dc01f248d7c'/>
<id>44abff2c0b970ae3d310b97617525dc01f248d7c</id>
<content type='text'>
Secure erase is a very different operation from discard in that it is
a data integrity operation vs hint.  Fully split the limits and helper
infrastructure to make the separation more clear.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt; [drbd]
Acked-by: Ryusuke Konishi &lt;konishi.ryusuke@gmail.com&gt; [nifs2]
Acked-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt; [f2fs]
Acked-by: Coly Li &lt;colyli@suse.de&gt; [bcache]
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Acked-by: Chao Yu &lt;chao@kernel.org&gt;
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-27-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Secure erase is a very different operation from discard in that it is
a data integrity operation vs hint.  Fully split the limits and helper
infrastructure to make the separation more clear.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt; [drbd]
Acked-by: Ryusuke Konishi &lt;konishi.ryusuke@gmail.com&gt; [nifs2]
Acked-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt; [f2fs]
Acked-by: Coly Li &lt;colyli@suse.de&gt; [bcache]
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Acked-by: Chao Yu &lt;chao@kernel.org&gt;
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-27-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: remove QUEUE_FLAG_DISCARD</title>
<updated>2022-04-18T01:49:59+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-04-15T04:52:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=70200574cc229f6ba038259e8142af2aa09e6976'/>
<id>70200574cc229f6ba038259e8142af2aa09e6976</id>
<content type='text'>
Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt; [drbd]
Acked-by: Jan Höppner &lt;hoeppner@linux.ibm.com&gt; [s390]
Acked-by: Coly Li &lt;colyli@suse.de&gt; [bcache]
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt; [drbd]
Acked-by: Jan Höppner &lt;hoeppner@linux.ibm.com&gt; [s390]
Acked-by: Coly Li &lt;colyli@suse.de&gt; [bcache]
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: add a bdev_stable_writes helper</title>
<updated>2022-04-18T01:49:59+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-04-15T04:52:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=36d254893aa6a6e204075c3cce94bb572ac32c04'/>
<id>36d254893aa6a6e204075c3cce94bb572ac32c04</id>
<content type='text'>
Add a helper to check the stable writes flag based on the block_device
instead of having to poke into the block layer internal request_queue.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-15-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add a helper to check the stable writes flag based on the block_device
instead of having to poke into the block layer internal request_queue.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-15-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: add a bdev_nonrot helper</title>
<updated>2022-04-18T01:49:59+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-04-15T04:52:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=10f0d2a517796b8f6dc04fb0cc3e49003ae6b0bc'/>
<id>10f0d2a517796b8f6dc04fb0cc3e49003ae6b0bc</id>
<content type='text'>
Add a helper to check the nonrot flag based on the block_device instead
of having to poke into the block layer internal request_queue.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-12-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add a helper to check the nonrot flag based on the block_device instead
of having to poke into the block layer internal request_queue.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
Acked-by: David Sterba &lt;dsterba@suse.com&gt; [btrfs]
Reviewed-by: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Link: https://lore.kernel.org/r/20220415045258.199825-12-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi</title>
<updated>2022-03-25T02:37:53+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-03-25T02:37:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6f2689a7662809ff39f2b24e452d11569c21ea2f'/>
<id>6f2689a7662809ff39f2b24e452d11569c21ea2f</id>
<content type='text'>
Pull SCSI updates from James Bottomley:
 "This series consists of the usual driver updates (qla2xxx, pm8001,
  libsas, smartpqi, scsi_debug, lpfc, iscsi, mpi3mr) plus minor updates
  and bug fixes.

  The high blast radius core update is the removal of write same, which
  affects block and several non-SCSI devices. The other big change,
  which is more local, is the removal of the SCSI pointer"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (281 commits)
  scsi: scsi_ioctl: Drop needless assignment in sg_io()
  scsi: bsg: Drop needless assignment in scsi_bsg_sg_io_fn()
  scsi: lpfc: Copyright updates for 14.2.0.0 patches
  scsi: lpfc: Update lpfc version to 14.2.0.0
  scsi: lpfc: SLI path split: Refactor BSG paths
  scsi: lpfc: SLI path split: Refactor Abort paths
  scsi: lpfc: SLI path split: Refactor SCSI paths
  scsi: lpfc: SLI path split: Refactor CT paths
  scsi: lpfc: SLI path split: Refactor misc ELS paths
  scsi: lpfc: SLI path split: Refactor VMID paths
  scsi: lpfc: SLI path split: Refactor FDISC paths
  scsi: lpfc: SLI path split: Refactor LS_RJT paths
  scsi: lpfc: SLI path split: Refactor LS_ACC paths
  scsi: lpfc: SLI path split: Refactor the RSCN/SCR/RDF/EDC/FARPR paths
  scsi: lpfc: SLI path split: Refactor PLOGI/PRLI/ADISC/LOGO paths
  scsi: lpfc: SLI path split: Refactor base ELS paths and the FLOGI path
  scsi: lpfc: SLI path split: Introduce lpfc_prep_wqe
  scsi: lpfc: SLI path split: Refactor fast and slow paths to native SLI4
  scsi: lpfc: SLI path split: Refactor lpfc_iocbq
  scsi: lpfc: Use kcalloc()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull SCSI updates from James Bottomley:
 "This series consists of the usual driver updates (qla2xxx, pm8001,
  libsas, smartpqi, scsi_debug, lpfc, iscsi, mpi3mr) plus minor updates
  and bug fixes.

  The high blast radius core update is the removal of write same, which
  affects block and several non-SCSI devices. The other big change,
  which is more local, is the removal of the SCSI pointer"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (281 commits)
  scsi: scsi_ioctl: Drop needless assignment in sg_io()
  scsi: bsg: Drop needless assignment in scsi_bsg_sg_io_fn()
  scsi: lpfc: Copyright updates for 14.2.0.0 patches
  scsi: lpfc: Update lpfc version to 14.2.0.0
  scsi: lpfc: SLI path split: Refactor BSG paths
  scsi: lpfc: SLI path split: Refactor Abort paths
  scsi: lpfc: SLI path split: Refactor SCSI paths
  scsi: lpfc: SLI path split: Refactor CT paths
  scsi: lpfc: SLI path split: Refactor misc ELS paths
  scsi: lpfc: SLI path split: Refactor VMID paths
  scsi: lpfc: SLI path split: Refactor FDISC paths
  scsi: lpfc: SLI path split: Refactor LS_RJT paths
  scsi: lpfc: SLI path split: Refactor LS_ACC paths
  scsi: lpfc: SLI path split: Refactor the RSCN/SCR/RDF/EDC/FARPR paths
  scsi: lpfc: SLI path split: Refactor PLOGI/PRLI/ADISC/LOGO paths
  scsi: lpfc: SLI path split: Refactor base ELS paths and the FLOGI path
  scsi: lpfc: SLI path split: Introduce lpfc_prep_wqe
  scsi: lpfc: SLI path split: Refactor fast and slow paths to native SLI4
  scsi: lpfc: SLI path split: Refactor lpfc_iocbq
  scsi: lpfc: Use kcalloc()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>dm: support bio polling</title>
<updated>2022-03-09T17:21:56+00:00</updated>
<author>
<name>Ming Lei</name>
<email>ming.lei@redhat.com</email>
</author>
<published>2022-03-05T02:08:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b99fdcdc36369d2a3a26bf44736d420eb629d8b7'/>
<id>b99fdcdc36369d2a3a26bf44736d420eb629d8b7</id>
<content type='text'>
Support bio polling (REQ_POLLED) in the following approach:

1) only support io polling on normal READ/WRITE, and other abnormal IOs
still fallback to IRQ mode, so the target io (and DM's clone bio) is
exactly inside the dm io.

2) hold one refcnt on io-&gt;io_count after submitting this dm bio with
REQ_POLLED

3) support dm native bio splitting, any dm io instance associated with
current bio will be added into one list which head is bio-&gt;bi_private
which will be recovered before ending this bio

4) implement .poll_bio() callback, call bio_poll() on the single target
bio inside the dm io which is retrieved via bio-&gt;bi_bio_drv_data; call
dm_io_dec_pending() after the target io is done in .poll_bio()

5) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
which is based on Jeffle's previous patch.

These changes are good for a 30-35% IOPS improvement for polled IO.

For detailed test results please see (Jens, thanks for testing!):
https://listman.redhat.com/archives/dm-devel/2022-March/049868.html
or https://marc.info/?l=linux-block&amp;m=164684246214700&amp;w=2

Tested-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@redhat.com&gt;
</content>
<content type='xhtml'>
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Support bio polling (REQ_POLLED) in the following approach:

1) only support io polling on normal READ/WRITE, and other abnormal IOs
still fallback to IRQ mode, so the target io (and DM's clone bio) is
exactly inside the dm io.

2) hold one refcnt on io-&gt;io_count after submitting this dm bio with
REQ_POLLED

3) support dm native bio splitting, any dm io instance associated with
current bio will be added into one list which head is bio-&gt;bi_private
which will be recovered before ending this bio

4) implement .poll_bio() callback, call bio_poll() on the single target
bio inside the dm io which is retrieved via bio-&gt;bi_bio_drv_data; call
dm_io_dec_pending() after the target io is done in .poll_bio()

5) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
which is based on Jeffle's previous patch.

These changes are good for a 30-35% IOPS improvement for polled IO.

For detailed test results please see (Jens, thanks for testing!):
https://listman.redhat.com/archives/dm-devel/2022-March/049868.html
or https://marc.info/?l=linux-block&amp;m=164684246214700&amp;w=2

Tested-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Mike Snitzer &lt;snitzer@redhat.com&gt;
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