<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/md/md.c, branch v6.13</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux</title>
<updated>2024-11-19T00:50:08+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-11-19T00:50:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=77a0cfafa9af9c0d5b43534eb90d530c189edca1'/>
<id>77a0cfafa9af9c0d5b43534eb90d530c189edca1</id>
<content type='text'>
Pull block updates from Jens Axboe:

 - NVMe updates via Keith:
      - Use uring_cmd helper (Pavel)
      - Host Memory Buffer allocation enhancements (Christoph)
      - Target persistent reservation support (Guixin)
      - Persistent reservation tracing (Guixen)
      - NVMe 2.1 specification support (Keith)
      - Rotational Meta Support (Matias, Wang, Keith)
      - Volatile cache detection enhancment (Guixen)

 - MD updates via Song:
      - Maintainers update
      - raid5 sync IO fix
      - Enhance handling of faulty and blocked devices
      - raid5-ppl atomic improvement
      - md-bitmap fix

 - Support for manually defining embedded partition tables

 - Zone append fixes and cleanups

 - Stop sending the queued requests in the plug list to the driver
   -&gt;queue_rqs() handle in reverse order.

 - Zoned write plug cleanups

 - Cleanups disk stats tracking and add support for disk stats for
   passthrough IO

 - Add preparatory support for file system atomic writes

 - Add lockdep support for queue freezing. Already found a bunch of
   issues, and some fixes for that are in here. More will be coming.

 - Fix race between queue stopping/quiescing and IO queueing

 - ublk recovery improvements

 - Fix ublk mmap for 64k pages

 - Various fixes and cleanups

* tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux: (118 commits)
  MAINTAINERS: Update git tree for mdraid subsystem
  block: make struct rq_list available for !CONFIG_BLOCK
  block/genhd: use seq_put_decimal_ull for diskstats decimal values
  block: don't reorder requests in blk_mq_add_to_batch
  block: don't reorder requests in blk_add_rq_to_plug
  block: add a rq_list type
  block: remove rq_list_move
  virtio_blk: reverse request order in virtio_queue_rqs
  nvme-pci: reverse request order in nvme_queue_rqs
  btrfs: validate queue limits
  block: export blk_validate_limits
  nvmet: add tracing of reservation commands
  nvme: parse reservation commands's action and rtype to string
  nvmet: report ns's vwc not present
  md/raid5: Increase r5conf.cache_name size
  block: remove the ioprio field from struct request
  block: remove the write_hint field from struct request
  nvme: check ns's volatile write cache not present
  nvme: add rotational support
  nvme: use command set independent id ns if available
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block updates from Jens Axboe:

 - NVMe updates via Keith:
      - Use uring_cmd helper (Pavel)
      - Host Memory Buffer allocation enhancements (Christoph)
      - Target persistent reservation support (Guixin)
      - Persistent reservation tracing (Guixen)
      - NVMe 2.1 specification support (Keith)
      - Rotational Meta Support (Matias, Wang, Keith)
      - Volatile cache detection enhancment (Guixen)

 - MD updates via Song:
      - Maintainers update
      - raid5 sync IO fix
      - Enhance handling of faulty and blocked devices
      - raid5-ppl atomic improvement
      - md-bitmap fix

 - Support for manually defining embedded partition tables

 - Zone append fixes and cleanups

 - Stop sending the queued requests in the plug list to the driver
   -&gt;queue_rqs() handle in reverse order.

 - Zoned write plug cleanups

 - Cleanups disk stats tracking and add support for disk stats for
   passthrough IO

 - Add preparatory support for file system atomic writes

 - Add lockdep support for queue freezing. Already found a bunch of
   issues, and some fixes for that are in here. More will be coming.

 - Fix race between queue stopping/quiescing and IO queueing

 - ublk recovery improvements

 - Fix ublk mmap for 64k pages

 - Various fixes and cleanups

* tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux: (118 commits)
  MAINTAINERS: Update git tree for mdraid subsystem
  block: make struct rq_list available for !CONFIG_BLOCK
  block/genhd: use seq_put_decimal_ull for diskstats decimal values
  block: don't reorder requests in blk_mq_add_to_batch
  block: don't reorder requests in blk_add_rq_to_plug
  block: add a rq_list type
  block: remove rq_list_move
  virtio_blk: reverse request order in virtio_queue_rqs
  nvme-pci: reverse request order in nvme_queue_rqs
  btrfs: validate queue limits
  block: export blk_validate_limits
  nvmet: add tracing of reservation commands
  nvme: parse reservation commands's action and rtype to string
  nvmet: report ns's vwc not present
  md/raid5: Increase r5conf.cache_name size
  block: remove the ioprio field from struct request
  block: remove the write_hint field from struct request
  nvme: check ns's volatile write cache not present
  nvme: add rotational support
  nvme: use command set independent id ns if available
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>md: don't record new badblocks for faulty rdev</title>
<updated>2024-11-06T00:08:38+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2024-10-31T03:31:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=29967332ced51a15a22f11381eeebbc500ba1858'/>
<id>29967332ced51a15a22f11381eeebbc500ba1858</id>
<content type='text'>
Faulty will be checked before issuing IO to the rdev, however, rdev can
be faulty at any time, hence it's possible that rdev_set_badblocks()
will be called for faulty rdev. In this case, mddev-&gt;sb_flags will be
set and some other path can be blocked by updating super block.

Since faulty rdev will not be accesed anymore, there is no need to
record new babblocks for faulty rdev and forcing updating super block.

Noted this is not a bugfix, just prevent updating superblock in some
corner cases, and will help to slice a bug related to external
metadata[1], testing also shows that devices are removed faster in the
case IO error.

[1] https://lore.kernel.org/all/f34452df-810b-48b2-a9b4-7f925699a9e7@linux.intel.com/

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Tested-by: Mariusz Tkaczyk &lt;mariusz.tkaczyk@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20241031033114.3845582-4-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Faulty will be checked before issuing IO to the rdev, however, rdev can
be faulty at any time, hence it's possible that rdev_set_badblocks()
will be called for faulty rdev. In this case, mddev-&gt;sb_flags will be
set and some other path can be blocked by updating super block.

Since faulty rdev will not be accesed anymore, there is no need to
record new babblocks for faulty rdev and forcing updating super block.

Noted this is not a bugfix, just prevent updating superblock in some
corner cases, and will help to slice a bug related to external
metadata[1], testing also shows that devices are removed faster in the
case IO error.

[1] https://lore.kernel.org/all/f34452df-810b-48b2-a9b4-7f925699a9e7@linux.intel.com/

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Tested-by: Mariusz Tkaczyk &lt;mariusz.tkaczyk@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20241031033114.3845582-4-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md: don't wait faulty rdev in md_wait_for_blocked_rdev()</title>
<updated>2024-11-06T00:08:38+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2024-10-31T03:31:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=50e8274855e7ab5499ff8296e09802874a3f03b1'/>
<id>50e8274855e7ab5499ff8296e09802874a3f03b1</id>
<content type='text'>
md_wait_for_blocked_rdev() is called for write IO while rdev is
blocked, howerver, rdev can be faulty after choosing this rdev to write,
and faulty rdev should never be accessed anymore, hence there is no point
to wait for faulty rdev to be unblocked.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Tested-by: Mariusz Tkaczyk &lt;mariusz.tkaczyk@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20241031033114.3845582-3-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
md_wait_for_blocked_rdev() is called for write IO while rdev is
blocked, howerver, rdev can be faulty after choosing this rdev to write,
and faulty rdev should never be accessed anymore, hence there is no point
to wait for faulty rdev to be unblocked.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Tested-by: Mariusz Tkaczyk &lt;mariusz.tkaczyk@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20241031033114.3845582-3-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md: ensure child flush IO does not affect origin bio-&gt;bi_status</title>
<updated>2024-10-17T18:35:36+00:00</updated>
<author>
<name>Li Nan</name>
<email>linan122@huawei.com</email>
</author>
<published>2024-09-19T06:30:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=62ce0782bbacd32ec10292b9bdd127330e9b6968'/>
<id>62ce0782bbacd32ec10292b9bdd127330e9b6968</id>
<content type='text'>
When a flush is issued to an RAID array, a child flush IO is created and
issued for each member disk in the RAID array. Since commit b75197e86e6d
("md: Remove flush handling"), each child flush IO has been chained with
the original bio. As a result, the failure of any child IO could modify
the bi_status of the original bio, potentially impacting the upper-layer
filesystem.

Fix the issue by preventing child flush IO from altering the original
bio-&gt;bi_status as before. However, this design introduces a known
issue: in the event of a power failure, if a flush IO on a member
disk fails, the upper layers may not be informed. This issue is not easy
to fix and will not be addressed for the time being in this issue.

Fixes: b75197e86e6d ("md: Remove flush handling")
Signed-off-by: Li Nan &lt;linan122@huawei.com&gt;
Reviewed-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240919063048.2887579-1-linan666@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When a flush is issued to an RAID array, a child flush IO is created and
issued for each member disk in the RAID array. Since commit b75197e86e6d
("md: Remove flush handling"), each child flush IO has been chained with
the original bio. As a result, the failure of any child IO could modify
the bi_status of the original bio, potentially impacting the upper-layer
filesystem.

Fix the issue by preventing child flush IO from altering the original
bio-&gt;bi_status as before. However, this design introduces a known
issue: in the event of a power failure, if a flush IO on a member
disk fails, the upper layers may not be informed. This issue is not easy
to fix and will not be addressed for the time being in this issue.

Fixes: b75197e86e6d ("md: Remove flush handling")
Signed-off-by: Li Nan &lt;linan122@huawei.com&gt;
Reviewed-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240919063048.2887579-1-linan666@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md: Add new_level sysfs interface</title>
<updated>2024-09-06T17:31:12+00:00</updated>
<author>
<name>Xiao Ni</name>
<email>xni@redhat.com</email>
</author>
<published>2024-09-04T23:54:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d981ed8419303ed12351eea8541ad6cb76455fe3'/>
<id>d981ed8419303ed12351eea8541ad6cb76455fe3</id>
<content type='text'>
Now reshape supports two ways: with backup file or without backup file.
For the situation without backup file, it needs to change data offset.
It doesn't need systemd service mdadm-grow-continue. So it can finish
the reshape job in one process environment. It can know the new level
from mdadm --grow command and can change to new level after reshape
finishes.

For the situation with backup file, it needs systemd service
mdadm-grow-continue to monitor reshape progress. So there are two process
envolved. One is mdadm --grow command whick kicks off reshape and wakes
up mdadm-grow-continue service. The second process is the service, which
doesn't know the new level from the first process.

In kernel space mddev-&gt;new_level is used to record the new level when
doing reshape. This patch adds a new interface to help mdadm update
new_level and sync it to metadata. Then mdadm-grow-continue can read the
right new_level.

Commit log revised by Song Liu. Please refer to the link for more details.

Signed-off-by: Xiao Ni &lt;xni@redhat.com&gt;
Link: https://lore.kernel.org/r/20240904235453.99120-1-xni@redhat.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now reshape supports two ways: with backup file or without backup file.
For the situation without backup file, it needs to change data offset.
It doesn't need systemd service mdadm-grow-continue. So it can finish
the reshape job in one process environment. It can know the new level
from mdadm --grow command and can change to new level after reshape
finishes.

For the situation with backup file, it needs systemd service
mdadm-grow-continue to monitor reshape progress. So there are two process
envolved. One is mdadm --grow command whick kicks off reshape and wakes
up mdadm-grow-continue service. The second process is the service, which
doesn't know the new level from the first process.

In kernel space mddev-&gt;new_level is used to record the new level when
doing reshape. This patch adds a new interface to help mdadm update
new_level and sync it to metadata. Then mdadm-grow-continue can read the
right new_level.

Commit log revised by Song Liu. Please refer to the link for more details.

Signed-off-by: Xiao Ni &lt;xni@redhat.com&gt;
Link: https://lore.kernel.org/r/20240904235453.99120-1-xni@redhat.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md: Report failed arrays as broken in mdstat</title>
<updated>2024-09-04T21:52:45+00:00</updated>
<author>
<name>Mateusz Kusiak</name>
<email>mateusz.kusiak@intel.com</email>
</author>
<published>2024-09-03T14:29:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2d2b3bc145b9d5b5c6f07d22291723ddb024ca76'/>
<id>2d2b3bc145b9d5b5c6f07d22291723ddb024ca76</id>
<content type='text'>
Depending on if array has personality, it is either reported as active or
inactive. This patch adds third status "broken" for arrays with
personality that became inoperative. The reason is end users tend to
assume that "active" indicates array is operational.

Add "broken" state for inoperative arrays with personality and refactor
the code.

Signed-off-by: Mateusz Kusiak &lt;mateusz.kusiak@intel.com&gt;
Link: https://lore.kernel.org/r/20240903142949.53628-1-mateusz.kusiak@intel.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Depending on if array has personality, it is either reported as active or
inactive. This patch adds third status "broken" for arrays with
personality that became inoperative. The reason is end users tend to
assume that "active" indicates array is operational.

Add "broken" state for inoperative arrays with personality and refactor
the code.

Signed-off-by: Mateusz Kusiak &lt;mateusz.kusiak@intel.com&gt;
Link: https://lore.kernel.org/r/20240903142949.53628-1-mateusz.kusiak@intel.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'md-6.12-bitmap' into md-6.12</title>
<updated>2024-08-28T21:55:57+00:00</updated>
<author>
<name>Song Liu</name>
<email>song@kernel.org</email>
</author>
<published>2024-08-28T21:55:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7f67fdae3372c323ad02601ab65502c9e488a521'/>
<id>7f67fdae3372c323ad02601ab65502c9e488a521</id>
<content type='text'>
From Yu Kuai (with minor changes by Song Liu):

The background is that currently bitmap is using a global spin_lock,
causing lock contention and huge IO performance degradation for all raid
levels.

However, it's impossible to implement a new lock free bitmap with
current situation that md-bitmap exposes the internal implementation
with lots of exported apis. Hence bitmap_operations is invented, to
describe bitmap core implementation, and a new bitmap can be introduced
with a new bitmap_operations, we only need to switch to the new one
during initialization.

And with this we can build bitmap as kernel module, but that's not
our concern for now.

This version was tested with mdadm tests and lvm2 tests. This set does
not introduce new errors in these tests.

* md-6.12-bitmap: (42 commits)
  md/md-bitmap: make in memory structure internal
  md/md-bitmap: merge md_bitmap_enabled() into bitmap_operations
  md/md-bitmap: merge md_bitmap_wait_behind_writes() into bitmap_operations
  md/md-bitmap: merge md_bitmap_free() into bitmap_operations
  md/md-bitmap: merge md_bitmap_set_pages() into struct bitmap_operations
  md/md-bitmap: merge md_bitmap_copy_from_slot() into struct bitmap_operation.
  md/md-bitmap: merge get_bitmap_from_slot() into bitmap_operations
  md/md-bitmap: merge md_bitmap_resize() into bitmap_operations
  md/md-bitmap: pass in mddev directly for md_bitmap_resize()
  md/md-bitmap: merge md_bitmap_daemon_work() into bitmap_operations
  md/md-bitmap: merge bitmap_unplug() into bitmap_operations
  md/md-bitmap: merge md_bitmap_unplug_async() into md_bitmap_unplug()
  md/md-bitmap: merge md_bitmap_sync_with_cluster() into bitmap_operations
  md/md-bitmap: merge md_bitmap_cond_end_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_close_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_end_sync() into bitmap_operations
  md/md-bitmap: remove the parameter 'aborted' for md_bitmap_end_sync()
  md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_endwrite() into bitmap_operations
  md/md-bitmap: merge md_bitmap_startwrite() into bitmap_operations
  ...

Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
From Yu Kuai (with minor changes by Song Liu):

The background is that currently bitmap is using a global spin_lock,
causing lock contention and huge IO performance degradation for all raid
levels.

However, it's impossible to implement a new lock free bitmap with
current situation that md-bitmap exposes the internal implementation
with lots of exported apis. Hence bitmap_operations is invented, to
describe bitmap core implementation, and a new bitmap can be introduced
with a new bitmap_operations, we only need to switch to the new one
during initialization.

And with this we can build bitmap as kernel module, but that's not
our concern for now.

This version was tested with mdadm tests and lvm2 tests. This set does
not introduce new errors in these tests.

* md-6.12-bitmap: (42 commits)
  md/md-bitmap: make in memory structure internal
  md/md-bitmap: merge md_bitmap_enabled() into bitmap_operations
  md/md-bitmap: merge md_bitmap_wait_behind_writes() into bitmap_operations
  md/md-bitmap: merge md_bitmap_free() into bitmap_operations
  md/md-bitmap: merge md_bitmap_set_pages() into struct bitmap_operations
  md/md-bitmap: merge md_bitmap_copy_from_slot() into struct bitmap_operation.
  md/md-bitmap: merge get_bitmap_from_slot() into bitmap_operations
  md/md-bitmap: merge md_bitmap_resize() into bitmap_operations
  md/md-bitmap: pass in mddev directly for md_bitmap_resize()
  md/md-bitmap: merge md_bitmap_daemon_work() into bitmap_operations
  md/md-bitmap: merge bitmap_unplug() into bitmap_operations
  md/md-bitmap: merge md_bitmap_unplug_async() into md_bitmap_unplug()
  md/md-bitmap: merge md_bitmap_sync_with_cluster() into bitmap_operations
  md/md-bitmap: merge md_bitmap_cond_end_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_close_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_end_sync() into bitmap_operations
  md/md-bitmap: remove the parameter 'aborted' for md_bitmap_end_sync()
  md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_endwrite() into bitmap_operations
  md/md-bitmap: merge md_bitmap_startwrite() into bitmap_operations
  ...

Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md: Remove flush handling</title>
<updated>2024-08-28T00:19:55+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2024-08-27T11:06:16+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b75197e86e6d3de4e611869ef30a27cf414a5f77'/>
<id>b75197e86e6d3de4e611869ef30a27cf414a5f77</id>
<content type='text'>
For flush request, md has a special flush handling to merge concurrent
flush request into single one, however, the whole mechanism is based on
a disk level spin_lock 'mddev-&gt;lock'. And fsync can be called quite
often in some user cases, for consequence, spin lock from IO fast path can
cause performance degradation.

Fortunately, the block layer already has flush handling to merge
concurrent flush request, and it only acquires hctx level spin lock. (see
details in blk-flush.c)

This patch removes the flush handling in md, and converts to use general
block layer flush handling in underlying disks.

Flush test for 4 nvme raid10:
start 128 threads to do fsync 100000 times, on arm64, see how long it
takes.

Test script:
void* thread_func(void* arg) {
    int fd = *(int*)arg;
    for (int i = 0; i &lt; FSYNC_COUNT; i++) {
        fsync(fd);
    }
    return NULL;
}

int main() {
    int fd = open("/dev/md0", O_RDWR);
    if (fd &lt; 0) {
        perror("open");
        exit(1);
    }

    pthread_t threads[THREADS];
    struct timeval start, end;

    gettimeofday(&amp;start, NULL);

    for (int i = 0; i &lt; THREADS; i++) {
        pthread_create(&amp;threads[i], NULL, thread_func, &amp;fd);
    }

    for (int i = 0; i &lt; THREADS; i++) {
        pthread_join(threads[i], NULL);
    }

    gettimeofday(&amp;end, NULL);

    close(fd);

    long long elapsed = (end.tv_sec - start.tv_sec) * 1000000LL + (end.tv_usec - start.tv_usec);
    printf("Elapsed time: %lld microseconds\n", elapsed);

    return 0;
}

Test result: about 10 times faster:
Before this patch: 50943374 microseconds
After this patch:  5096347  microseconds

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240827110616.3860190-1-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
For flush request, md has a special flush handling to merge concurrent
flush request into single one, however, the whole mechanism is based on
a disk level spin_lock 'mddev-&gt;lock'. And fsync can be called quite
often in some user cases, for consequence, spin lock from IO fast path can
cause performance degradation.

Fortunately, the block layer already has flush handling to merge
concurrent flush request, and it only acquires hctx level spin lock. (see
details in blk-flush.c)

This patch removes the flush handling in md, and converts to use general
block layer flush handling in underlying disks.

Flush test for 4 nvme raid10:
start 128 threads to do fsync 100000 times, on arm64, see how long it
takes.

Test script:
void* thread_func(void* arg) {
    int fd = *(int*)arg;
    for (int i = 0; i &lt; FSYNC_COUNT; i++) {
        fsync(fd);
    }
    return NULL;
}

int main() {
    int fd = open("/dev/md0", O_RDWR);
    if (fd &lt; 0) {
        perror("open");
        exit(1);
    }

    pthread_t threads[THREADS];
    struct timeval start, end;

    gettimeofday(&amp;start, NULL);

    for (int i = 0; i &lt; THREADS; i++) {
        pthread_create(&amp;threads[i], NULL, thread_func, &amp;fd);
    }

    for (int i = 0; i &lt; THREADS; i++) {
        pthread_join(threads[i], NULL);
    }

    gettimeofday(&amp;end, NULL);

    close(fd);

    long long elapsed = (end.tv_sec - start.tv_sec) * 1000000LL + (end.tv_usec - start.tv_usec);
    printf("Elapsed time: %lld microseconds\n", elapsed);

    return 0;
}

Test result: about 10 times faster:
Before this patch: 50943374 microseconds
After this patch:  5096347  microseconds

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240827110616.3860190-1-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md/md-bitmap: merge md_bitmap_wait_behind_writes() into bitmap_operations</title>
<updated>2024-08-27T19:43:16+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2024-08-26T07:44:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=49f5f5e309e6127957babed7834f5a0e1022f936'/>
<id>49f5f5e309e6127957babed7834f5a0e1022f936</id>
<content type='text'>
So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240826074452.1490072-41-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240826074452.1490072-41-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>md/md-bitmap: merge md_bitmap_daemon_work() into bitmap_operations</title>
<updated>2024-08-27T19:43:14+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2024-08-26T07:44:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=18db2a9c60aefc61e796f6a384a952999d3b8885'/>
<id>18db2a9c60aefc61e796f6a384a952999d3b8885</id>
<content type='text'>
So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240826074452.1490072-34-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Link: https://lore.kernel.org/r/20240826074452.1490072-34-yukuai1@huaweicloud.com
Signed-off-by: Song Liu &lt;song@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
