linux-toradex.git/drivers/block/loop.c, branch v6.17-rc1

Merge tag 'for-6.17/block-20250728' of git://git.kernel.dk/linux

2025-07-28T23:43:54+00:00

Pull block updates from Jens Axboe:

 - MD pull request via Yu:
      - call del_gendisk synchronously (Xiao)
      - cleanup unused variable (John)
      - cleanup workqueue flags (Ryo)
      - fix faulty rdev can't be removed during resync (Qixing)

 - NVMe pull request via Christoph:
      - try PCIe function level reset on init failure (Keith Busch)
      - log TLS handshake failures at error level (Maurizio Lombardi)
      - pci-epf: do not complete commands twice if nvmet_req_init()
        fails (Rick Wertenbroek)
      - misc cleanups (Alok Tiwari)

 - Removal of the pktcdvd driver

   This has been more than a decade coming at this point, and some
   recently revealed breakages that had it causing issues even for cases
   where it isn't required made me re-pull the trigger on this one. It's
   known broken and nobody has stepped up to maintain the code

 - Series for ublk supporting batch commands, enabling the use of
   multishot where appropriate

 - Speed up ublk exit handling

 - Fix for the two-stage elevator fixing which could leak data

 - Convert NVMe to use the new IOVA based API

 - Increase default max transfer size to something more reasonable

 - Series fixing write operations on zoned DM devices

 - Add tracepoints for zoned block device operations

 - Prep series working towards improving blk-mq queue management in the
   presence of isolated CPUs

 - Don't allow updating of the block size of a loop device that is
   currently under exclusively ownership/open

 - Set chunk sectors from stacked device stripe size and use it for the
   atomic write size limit

 - Switch to folios in bcache read_super()

 - Fix for CD-ROM MRW exit flush handling

 - Various tweaks, fixes, and cleanups

* tag 'for-6.17/block-20250728' of git://git.kernel.dk/linux: (94 commits)
  block: restore two stage elevator switch while running nr_hw_queue update
  cdrom: Call cdrom_mrw_exit from cdrom_release function
  sunvdc: Balance device refcount in vdc_port_mpgroup_check
  nvme-pci: try function level reset on init failure
  dm: split write BIOs on zone boundaries when zone append is not emulated
  block: use chunk_sectors when evaluating stacked atomic write limits
  dm-stripe: limit chunk_sectors to the stripe size
  md/raid10: set chunk_sectors limit
  md/raid0: set chunk_sectors limit
  block: sanitize chunk_sectors for atomic write limits
  ilog2: add max_pow_of_two_factor()
  nvmet: pci-epf: Do not complete commands twice if nvmet_req_init() fails
  nvme-tcp: log TLS handshake failures at error level
  docs: nvme: fix grammar in nvme-pci-endpoint-target.rst
  nvme: fix typo in status code constant for self-test in progress
  nvmet: remove redundant assignment of error code in nvmet_ns_enable()
  nvme: fix incorrect variable in io cqes error message
  nvme: fix multiple spelling and grammar issues in host drivers
  block: fix blk_zone_append_update_request_bio() kernel-doc
  md/raid10: fix set but not used variable in sync_request_write()
  ...

loop: use kiocb helpers to fix lockdep warning

2025-07-16T12:33:44+00:00

The lockdep tool can report a circular lock dependency warning in the loop
driver's AIO read/write path:

```
[ 6540.587728] kworker/u96:5/72779 is trying to acquire lock:
[ 6540.593856] ff110001b5968440 (sb_writers#9){.+.+}-{0:0}, at: loop_process_work+0x11a/0xf70 [loop]
[ 6540.603786]
[ 6540.603786] but task is already holding lock:
[ 6540.610291] ff110001b5968440 (sb_writers#9){.+.+}-{0:0}, at: loop_process_work+0x11a/0xf70 [loop]
[ 6540.620210]
[ 6540.620210] other info that might help us debug this:
[ 6540.627499]  Possible unsafe locking scenario:
[ 6540.627499]
[ 6540.634110]        CPU0
[ 6540.636841]        ----
[ 6540.639574]   lock(sb_writers#9);
[ 6540.643281]   lock(sb_writers#9);
[ 6540.646988]
[ 6540.646988]  *** DEADLOCK ***
```

This patch fixes the issue by using the AIO-specific helpers
`kiocb_start_write()` and `kiocb_end_write()`. These functions are
designed to be used with a `kiocb` and manage write sequencing
correctly for asynchronous I/O without introducing the problematic
lock dependency.

The `kiocb` is already part of the `loop_cmd` struct, so this change
also simplifies the completion function `lo_rw_aio_do_completion()` by
using the `iocb` from the `cmd` struct directly, instead of retrieving
the loop device from the request queue.

Fixes: 39d86db34e41 ("loop: add file_start_write() and file_end_write()")
Cc: Changhui Zhong 
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20250716114808.3159657-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe

loop: Avoid updating block size under exclusive owner

2025-07-12T02:39:45+00:00

Syzbot came up with a reproducer where a loop device block size is
changed underneath a mounted filesystem. This causes a mismatch between
the block device block size and the block size stored in the superblock
causing confusion in various places such as fs/buffer.c. The particular
issue triggered by syzbot was a warning in __getblk_slow() due to
requested buffer size not matching block device block size.

Fix the problem by getting exclusive hold of the loop device to change
its block size. This fails if somebody (such as filesystem) has already
an exclusive ownership of the block device and thus prevents modifying
the loop device under some exclusive owner which doesn't expect it.

Reported-by: syzbot+01ef7a8da81a975e1ccd@syzkaller.appspotmail.com
Signed-off-by: Jan Kara 
Tested-by: syzbot+01ef7a8da81a975e1ccd@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20250711163202.19623-2-jack@suse.cz
Signed-off-by: Jens Axboe

loop: move lo_set_size() out of queue freeze

2025-06-11T12:41:45+00:00

It isn't necessary to freeze queue for updating disk size given submit_bio()
doesn't grab queue usage counter for checking eod.

Also many driver won't freeze queue for calling set_capacity_and_notify().

Move lo_set_size() out of queue freeze for fixing many lockdep warning
report.

Link: https://lore.kernel.org/linux-block/67ea99e0.050a0220.3c3d88.0042.GAE@google.com/
Reported-by: syzbot+9dd7dbb1a4b915dee638@syzkaller.appspotmail.com
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20250611084938.108829-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe

loop: add file_start_write() and file_end_write()

2025-05-27T16:14:26+00:00

file_start_write() and file_end_write() should be added around ->write_iter().

Recently we switch to ->write_iter() from vfs_iter_write(), and the
implied file_start_write() and file_end_write() are lost.

Also we never add them for dio code path, so add them back for covering
both.

Cc: Jeff Moyer 
Fixes: f2fed441c69b ("loop: stop using vfs_iter_{read,write} for buffered I/O")
Fixes: bc07c10a3603 ("block: loop: support DIO & AIO")
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20250527153405.837216-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe

loop: don't require ->write_iter for writable files in loop_configure

2025-05-20T15:16:23+00:00

Block devices can be opened read-write even if they can't be written to
for historic reasons.  Remove the check requiring file->f_op->write_iter
when the block devices was opened in loop_configure. The call to
loop_check_backing_file just below ensures the ->write_iter is present
for backing files opened for writing, which is the only check that is
actually needed.

Fixes: f5c84eff634b ("loop: Add sanity check for read/write_iter")
Reported-by: Christian Hesse 
Signed-off-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20250520135420.1177312-1-hch@lst.de
Signed-off-by: Jens Axboe

loop: Add sanity check for read/write_iter

2025-05-05T13:18:05+00:00

Some file systems do not support read_iter/write_iter, such as selinuxfs
in this issue.
So before calling them, first confirm that the interface is supported and
then call it.

It is releavant in that vfs_iter_read/write have the check, and removal
of their used caused szybot to be able to hit this issue.

Fixes: f2fed441c69b ("loop: stop using vfs_iter__{read,write} for buffered I/O")
Reported-by: syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6af973a3b8dfd2faefdc
Signed-off-by: Lizhi Xu 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20250428143626.3318717-1-lizhi.xu@windriver.com
Signed-off-by: Jens Axboe

loop: stop using vfs_iter_{read,write} for buffered I/O

2025-04-16T00:59:15+00:00

vfs_iter_{read,write} always perform direct I/O when the file has the
O_DIRECT flag set, which breaks disabling direct I/O using the
LOOP_SET_STATUS / LOOP_SET_STATUS64 ioctls.

This was recenly reported as a regression, but as far as I can tell
was only uncovered by better checking for block sizes and has been
around since the direct I/O support was added.

Fix this by using the existing aio code that calls the raw read/write
iter methods instead.  Note that despite the comments there is no need
for block drivers to ever call flush_dcache_page themselves, and the
call is a left-over from prehistoric times.

Fixes: ab1cb278bc70 ("block: loop: introduce ioctl command of LOOP_SET_DIRECT_IO")
Reported-by: Darrick J. Wong 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Ming Lei 
Tested-by: Darrick J. Wong 
Link: https://lore.kernel.org/r/20250409130940.3685677-1-hch@lst.de
Signed-off-by: Jens Axboe

loop: LOOP_SET_FD: send uevents for partitions

2025-04-15T19:15:21+00:00

Remove the suppression of the uevents before scanning for partitions.
The partitions inherit their suppression settings from their parent device,
which lead to the uevents being dropped.

This is similar to the same changes for LOOP_CONFIGURE done in
commit bb430b694226 ("loop: LOOP_CONFIGURE: send uevents for partitions").

Fixes: 498ef5c777d9 ("loop: suppress uevents while reconfiguring the device")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20250415-loop-uevent-changed-v3-1-60ff69ac6088@linutronix.de
Signed-off-by: Jens Axboe

loop: properly send KOBJ_CHANGED uevent for disk device

2025-04-15T14:58:42+00:00

The original commit message and the wording "uncork" in the code comment
indicate that it is expected that the suppressed event instances are
automatically sent after unsuppressing.
This is not the case, instead they are discarded.
In effect this means that no "changed" events are emitted on the device
itself by default.
While each discovered partition does trigger a changed event on the
device, devices without partitions don't have any event emitted.

This makes udev miss the device creation and prompted workarounds in
userspace. See the linked util-linux/losetup bug.

Explicitly emit the events and drop the confusingly worded comments.

Link: https://github.com/util-linux/util-linux/issues/2434
Fixes: 498ef5c777d9 ("loop: suppress uevents while reconfiguring the device")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh 
Link: https://lore.kernel.org/r/20250415-loop-uevent-changed-v2-1-0c4e6a923b2a@linutronix.de
Signed-off-by: Jens Axboe