<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux/drivers/block/loop.c, branch v6.8</title>
<subtitle>Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
</subtitle>
<id>https://git.shady.money/linux/atom?h=v6.8</id>
<link rel='self' href='https://git.shady.money/linux/atom?h=v6.8'/>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/'/>
<updated>2024-01-19T02:22:40Z</updated>
<entry>
<title>Merge tag 'for-6.8/block-2024-01-18' of git://git.kernel.dk/linux</title>
<updated>2024-01-19T02:22:40Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-01-19T02:22:40Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=9d1694dc91ce7b80bc96d6d8eaf1a1eca668d847'/>
<id>urn:sha1:9d1694dc91ce7b80bc96d6d8eaf1a1eca668d847</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - NVMe pull request via Keith:
      - tcp, fc, and rdma target fixes (Maurizio, Daniel, Hannes,
        Christoph)
      - discard fixes and improvements (Christoph)
      - timeout debug improvements (Keith, Max)
      - various cleanups (Daniel, Max, Giuxen)
      - trace event string fixes (Arnd)
      - shadow doorbell setup on reset fix (William)
      - a write zeroes quirk for SK Hynix (Jim)

 - MD pull request via Song:
      - Sparse warning since v6.0 (Bart)
      - /proc/mdstat regression since v6.7 (Yu Kuai)

 - Use symbolic error value (Christian)

 - IO Priority documentation update (Christian)

 - Fix for accessing queue limits without having entered the queue
   (Christoph, me)

 - Fix for loop dio support (Christoph)

 - Move null_blk off deprecated ida interface (Christophe)

 - Ensure nbd initializes full msghdr (Eric)

 - Fix for a regression with the folio conversion, which is now easier
   to hit because of an unrelated change (Matthew)

 - Remove redundant check in virtio-blk (Li)

 - Fix for a potential hang in sbitmap (Ming)

 - Fix for partial zone appending (Damien)

 - Misc changes and fixes (Bart, me, Kemeng, Dmitry)

* tag 'for-6.8/block-2024-01-18' of git://git.kernel.dk/linux: (45 commits)
  Documentation: block: ioprio: Update schedulers
  loop: fix the the direct I/O support check when used on top of block devices
  blk-mq: Remove the hctx 'run' debugfs attribute
  nbd: always initialize struct msghdr completely
  block: Fix iterating over an empty bio with bio_for_each_folio_all
  block: bio-integrity: fix kcalloc() arguments order
  virtio_blk: remove duplicate check if queue is broken in virtblk_done
  sbitmap: remove stale comment in sbq_calc_wake_batch
  block: Correct a documentation comment in blk-cgroup.c
  null_blk: Remove usage of the deprecated ida_simple_xx() API
  block: ensure we hold a queue reference when using queue limits
  blk-mq: rename blk_mq_can_use_cached_rq
  block: print symbolic error name instead of error code
  blk-mq: fix IO hang from sbitmap wakeup race
  nvmet-rdma: avoid circular locking dependency on install_queue()
  nvmet-tcp: avoid circular locking dependency on install_queue()
  nvme-pci: set doorbell config before unquiescing
  block: fix partial zone append completion handling in req_bio_endio()
  block/iocost: silence warning on 'last_period' potentially being unused
  md/raid1: Use blk_opf_t for read and write operations
  ...
</content>
</entry>
<entry>
<title>loop: fix the the direct I/O support check when used on top of block devices</title>
<updated>2024-01-18T15:20:52Z</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2024-01-17T17:59:01Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=baa7d536077dcdfe2b70c476a8873d1745d3de0f'/>
<id>urn:sha1:baa7d536077dcdfe2b70c476a8873d1745d3de0f</id>
<content type='text'>
__loop_update_dio only checks the alignment requirement for block backed
file systems, but misses them for the case where the loop device is
created directly on top of another block device.  Due to this creating
a loop device with default option plus the direct I/O flag on a &gt; 512 byte
sector size file system will lead to incorrect I/O being submitted to the
lower block device and a lot of error from the lock layer.  This can
be seen with xfstests generic/563.

Fix the code in __loop_update_dio by factoring the alignment check into
a helper, and calling that also for the struct block_device of a block
device inode.

Also remove the TODO comment talking about dynamically switching between
buffered and direct I/O, which is a would be a recipe for horrible
performance and occasional data loss.

Fixes: 2e5ab5f379f9 ("block: loop: prepare for supporing direct IO")
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Link: https://lore.kernel.org/r/20240117175901.871796-1-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
<entry>
<title>Merge tag 'for-6.8/block-2024-01-08' of git://git.kernel.dk/linux</title>
<updated>2024-01-11T21:58:04Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-01-11T21:58:04Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=01d550f0fcc06c7292f79a6f1453aac122d1d2c8'/>
<id>urn:sha1:01d550f0fcc06c7292f79a6f1453aac122d1d2c8</id>
<content type='text'>
Pull block updates from Jens Axboe:
 "Pretty quiet round this time around. This contains:

   - NVMe updates via Keith:
        - nvme fabrics spec updates (Guixin, Max)
        - nvme target udpates (Guixin, Evan)
        - nvme attribute refactoring (Daniel)
        - nvme-fc numa fix (Keith)

   - MD updates via Song:
        - Fix/Cleanup RCU usage from conf-&gt;disks[i].rdev (Yu Kuai)
        - Fix raid5 hang issue (Junxiao Bi)
        - Add Yu Kuai as Reviewer of the md subsystem
        - Remove deprecated flavors (Song Liu)
        - raid1 read error check support (Li Nan)
        - Better handle events off-by-1 case (Alex Lyakas)

   - Efficiency improvements for passthrough (Kundan)

   - Support for mapping integrity data directly (Keith)

   - Zoned write fix (Damien)

   - rnbd fixes (Kees, Santosh, Supriti)

   - Default to a sane discard size granularity (Christoph)

   - Make the default max transfer size naming less confusing
     (Christoph)

   - Remove support for deprecated host aware zoned model (Christoph)

   - Misc fixes (me, Li, Matthew, Min, Ming, Randy, liyouhong, Daniel,
     Bart, Christoph)"

* tag 'for-6.8/block-2024-01-08' of git://git.kernel.dk/linux: (78 commits)
  block: Treat sequential write preferred zone type as invalid
  block: remove disk_clear_zoned
  sd: remove the !ZBC &amp;&amp; blk_queue_is_zoned case in sd_read_block_characteristics
  drivers/block/xen-blkback/common.h: Fix spelling typo in comment
  blk-cgroup: fix rcu lockdep warning in blkg_lookup()
  blk-cgroup: don't use removal safe list iterators
  block: floor the discard granularity to the physical block size
  mtd_blkdevs: use the default discard granularity
  bcache: use the default discard granularity
  zram: use the default discard granularity
  null_blk: use the default discard granularity
  nbd: use the default discard granularity
  ubd: use the default discard granularity
  block: default the discard granularity to sector size
  bcache: discard_granularity should not be smaller than a sector
  block: remove two comments in bio_split_discard
  block: rename and document BLK_DEF_MAX_SECTORS
  loop: don't abuse BLK_DEF_MAX_SECTORS
  aoe: don't abuse BLK_DEF_MAX_SECTORS
  null_blk: don't cap max_hw_sectors to BLK_DEF_MAX_SECTORS
  ...
</content>
</entry>
<entry>
<title>loop: don't abuse BLK_DEF_MAX_SECTORS</title>
<updated>2023-12-27T17:46:01Z</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2023-12-27T09:23:04Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=3d77976c3a8586ab1fb6845e2061588b7d04934f'/>
<id>urn:sha1:3d77976c3a8586ab1fb6845e2061588b7d04934f</id>
<content type='text'>
BLK_DEF_MAX_SECTORS despite the confusing name is the default cap for
the max_sectors limits.  Don't use it to initialize max_hw_setors, which
is a hardware / driver capacility.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20231227092305.279567-4-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
<entry>
<title>loop: don't update discard limits from loop_set_status</title>
<updated>2023-12-27T17:43:46Z</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2023-12-27T08:20:20Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=34c7db44b4edccda315edcf02b9669aa173e090b'/>
<id>urn:sha1:34c7db44b4edccda315edcf02b9669aa173e090b</id>
<content type='text'>
loop_set_status doesn't change anything relevant to the discard and
write_zeroes setting, so don't bother calling loop_config_discard.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20231227082020.249427-1-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
<entry>
<title>fs: move file_start_write() into vfs_iter_write()</title>
<updated>2023-11-24T09:09:51Z</updated>
<author>
<name>Amir Goldstein</name>
<email>amir73il@gmail.com</email>
</author>
<published>2023-11-22T12:27:09Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=269aed7014b3db9acdbc5a5e163d8a6c62e0e770'/>
<id>urn:sha1:269aed7014b3db9acdbc5a5e163d8a6c62e0e770</id>
<content type='text'>
All the callers of vfs_iter_write() call file_start_write() just before
calling vfs_iter_write() except for target_core_file's fd_do_rw().

Move file_start_write() from the callers into vfs_iter_write().
fd_do_rw() calls vfs_iter_write() with a non-regular file, so
file_start_write() is a no-op.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara &lt;jack@suse.cz&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Signed-off-by: Amir Goldstein &lt;amir73il@gmail.com&gt;
Link: https://lore.kernel.org/r/20231122122715.2561213-11-amir73il@gmail.com
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs</title>
<updated>2023-08-28T18:04:18Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-08-28T18:04:18Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=511fb5bafed197ff76d9adf5448de67f1d0558ae'/>
<id>urn:sha1:511fb5bafed197ff76d9adf5448de67f1d0558ae</id>
<content type='text'>
Pull superblock updates from Christian Brauner:
 "This contains the super rework that was ready for this cycle. The
  first part changes the order of how we open block devices and allocate
  superblocks, contains various cleanups, simplifications, and a new
  mechanism to wait on superblock state changes.

  This unblocks work to ultimately limit the number of writers to a
  block device. Jan has already scheduled follow-up work that will be
  ready for v6.7 and allows us to restrict the number of writers to a
  given block device. That series builds on this work right here.

  The second part contains filesystem freezing updates.

  Overview:

  The generic superblock changes are rougly organized as follows
  (ignoring additional minor cleanups):

   (1) Removal of the bd_super member from struct block_device.

       This was a very odd back pointer to struct super_block with
       unclear rules. For all relevant places we have other means to get
       the same information so just get rid of this.

   (2) Simplify rules for superblock cleanup.

       Roughly, everything that is allocated during fs_context
       initialization and that's stored in fs_context-&gt;s_fs_info needs
       to be cleaned up by the fs_context-&gt;free() implementation before
       the superblock allocation function has been called successfully.

       After sget_fc() returned fs_context-&gt;s_fs_info has been
       transferred to sb-&gt;s_fs_info at which point sb-&gt;kill_sb() if
       fully responsible for cleanup. Adhering to these rules means that
       cleanup of sb-&gt;s_fs_info in fill_super() is to be avoided as it's
       brittle and inconsistent.

       Cleanup shouldn't be duplicated between sb-&gt;put_super() as
       sb-&gt;put_super() is only called if sb-&gt;s_root has been set aka
       when the filesystem has been successfully born (SB_BORN). That
       complexity should be avoided.

       This also means that block devices are to be closed in
       sb-&gt;kill_sb() instead of sb-&gt;put_super(). More details in the
       lower section.

   (3) Make it possible to lookup or create a superblock before opening
       block devices

       There's a subtle dependency on (2) as some filesystems did rely
       on fill_super() to be called in order to correctly clean up
       sb-&gt;s_fs_info. All these filesystems have been fixed.

   (4) Switch most filesystem to follow the same logic as the generic
       mount code now does as outlined in (3).

   (5) Use the superblock as the holder of the block device. We can now
       easily go back from block device to owning superblock.

   (6) Export and extend the generic fs_holder_ops and use them as
       holder ops everywhere and remove the filesystem specific holder
       ops.

   (7) Call from the block layer up into the filesystem layer when the
       block device is removed, allowing to shut down the filesystem
       without risk of deadlocks.

   (8) Get rid of get_super().

       We can now easily go back from the block device to owning
       superblock and can call up from the block layer into the
       filesystem layer when the device is removed. So no need to wade
       through all registered superblock to find the owning superblock
       anymore"

Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/

* tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits)
  super: use higher-level helper for {freeze,thaw}
  super: wait until we passed kill super
  super: wait for nascent superblocks
  super: make locking naming consistent
  super: use locking helpers
  fs: simplify invalidate_inodes
  fs: remove get_super
  block: call into the file system for ioctl BLKFLSBUF
  block: call into the file system for bdev_mark_dead
  block: consolidate __invalidate_device and fsync_bdev
  block: drop the "busy inodes on changed media" log message
  dasd: also call __invalidate_device when setting the device offline
  amiflop: don't call fsync_bdev in FDFMTBEG
  floppy: call disk_force_media_change when changing the format
  block: simplify the disk_force_media_change interface
  nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl
  xfs use fs_holder_ops for the log and RT devices
  xfs: drop s_umount over opening the log and RT devices
  ext4: use fs_holder_ops for the log device
  ext4: drop s_umount over opening the log device
  ...
</content>
</entry>
<entry>
<title>block: simplify the disk_force_media_change interface</title>
<updated>2023-08-21T12:35:30Z</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2023-08-11T10:08:19Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=ab6860f62bfe329e11e5b5b7295b673c9c3a62d0'/>
<id>urn:sha1:ab6860f62bfe329e11e5b5b7295b673c9c3a62d0</id>
<content type='text'>
Hard code the events to DISK_EVENT_MEDIA_CHANGE as that is the only
useful use case, and drop the superfluous return value.

Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Message-Id: &lt;20230811100828.1897174-9-hch@lst.de&gt;
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>loop: do not enforce max_loop hard limit by (new) default</title>
<updated>2023-07-21T19:20:57Z</updated>
<author>
<name>Mauricio Faria de Oliveira</name>
<email>mfo@canonical.com</email>
</author>
<published>2023-07-20T14:30:33Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=bb5faa99f0ce40756ab7bbbce4f16c01ca5ebd5a'/>
<id>urn:sha1:bb5faa99f0ce40756ab7bbbce4f16c01ca5ebd5a</id>
<content type='text'>
Problem:

The max_loop parameter is used for 2 different purposes:

1) initial number of loop devices to pre-create on init
2) maximum number of loop devices to add on access/open()

Historically, its default value (zero) caused 1) to create non-zero
number of devices (CONFIG_BLK_DEV_LOOP_MIN_COUNT), and no hard limit on
2) to add devices with autoloading.

However, the default value changed in commit 85c50197716c ("loop: Fix
the max_loop commandline argument treatment when it is set to 0") to
CONFIG_BLK_DEV_LOOP_MIN_COUNT, for max_loop=0 not to pre-create devices.

That does improve 1), but unfortunately it breaks 2), as the default
behavior changed from no-limit to hard-limit.

Example:

For example, this userspace code broke for N &gt;= CONFIG, if the user
relied on the default value 0 for max_loop:

    mknod("/dev/loopN");
    open("/dev/loopN");  // now fails with ENXIO

Though affected users may "fix" it with (loop.)max_loop=0, this means to
require a kernel parameter change on stable kernel update (that commit
Fixes: an old commit in stable).

Solution:

The original semantics for the default value in 2) can be applied if the
parameter is not set (ie, default behavior).

This still keeps the intended function in 1) and 2) if set, and that
commit's intended improvement in 1) if max_loop=0.

Before 85c50197716c:
  - default:     1) CONFIG devices   2) no limit
  - max_loop=0:  1) CONFIG devices   2) no limit
  - max_loop=X:  1) X devices        2) X limit

After 85c50197716c:
  - default:     1) CONFIG devices   2) CONFIG limit (*)
  - max_loop=0:  1) 0 devices (*)    2) no limit
  - max_loop=X:  1) X devices        2) X limit

This commit:
  - default:     1) CONFIG devices   2) no limit (*)
  - max_loop=0:  1) 0 devices        2) no limit
  - max_loop=X:  1) X devices        2) X limit

Future:

The issue/regression from that commit only affects code under the
CONFIG_BLOCK_LEGACY_AUTOLOAD deprecation guard, thus the fix too is
contained under it.

Once that deprecated functionality/code is removed, the purpose 2) of
max_loop (hard limit) is no longer in use, so the module parameter
description can be changed then.

Tests:

Linux 6.4-rc7
CONFIG_BLK_DEV_LOOP_MIN_COUNT=8
CONFIG_BLOCK_LEGACY_AUTOLOAD=y

- default (original)

	# ls -1 /dev/loop*
	/dev/loop-control
	/dev/loop0
	...
	/dev/loop7

	# ./test-loop
	open: /dev/loop8: No such device or address

- default (patched)

	# ls -1 /dev/loop*
	/dev/loop-control
	/dev/loop0
	...
	/dev/loop7

	# ./test-loop
	#

- max_loop=0 (original &amp; patched):

	# ls -1 /dev/loop*
	/dev/loop-control

	# ./test-loop
	#

- max_loop=8 (original &amp; patched):

	# ls -1 /dev/loop*
	/dev/loop-control
	/dev/loop0
	...
	/dev/loop7

	# ./test-loop
	open: /dev/loop8: No such device or address

- max_loop=0 (patched; CONFIG_BLOCK_LEGACY_AUTOLOAD is not set)

	# ls -1 /dev/loop*
	/dev/loop-control

	# ./test-loop
	open: /dev/loop8: No such device or address

Fixes: 85c50197716c ("loop: Fix the max_loop commandline argument treatment when it is set to 0")
Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20230720143033.841001-3-mfo@canonical.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
<entry>
<title>loop: deprecate autoloading callback loop_probe()</title>
<updated>2023-07-21T19:20:48Z</updated>
<author>
<name>Mauricio Faria de Oliveira</name>
<email>mfo@canonical.com</email>
</author>
<published>2023-07-20T14:30:32Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=23881aec85f3219e8462e87c708815ee2cd82358'/>
<id>urn:sha1:23881aec85f3219e8462e87c708815ee2cd82358</id>
<content type='text'>
The 'probe' callback in __register_blkdev() is only used under the
CONFIG_BLOCK_LEGACY_AUTOLOAD deprecation guard.

The loop_probe() function is only used for that callback, so guard it
too, accordingly.

See commit fbdee71bb5d8 ("block: deprecate autoloading based on dev_t").

Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20230720143033.841001-2-mfo@canonical.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
</entry>
</feed>
