linux.git/drivers/block/loop.c, branch v6.18.21

loop: remove redundant __GFP_NOWARN flag

2025-10-08T12:27:53+00:00

GFP_NOWAIT already includes __GFP_NOWARN, so let's remove the
redundant __GFP_NOWARN.

Signed-off-by: Pedro Demarchi Gomes 
Reviewed-by: Yu Kuai 
Signed-off-by: Jens Axboe

loop: fix backing file reference leak on validation error

2025-10-02T21:25:47+00:00

loop_change_fd() and loop_configure() call loop_check_backing_file()
to validate the new backing file. If validation fails, the reference
acquired by fget() was not dropped, leaking a file reference.

Fix this by calling fput(file) before returning the error.

Cc: stable@vger.kernel.org
Cc: Markus Elfring 
CC: Yang Erkun 
Cc: Ming Lei 
Cc: Yu Kuai 
Fixes: f5c84eff634b ("loop: Add sanity check for read/write_iter")
Signed-off-by: Li Chen 
Reviewed-by: Ming Lei 
Reviewed-by: Yang Erkun 
Signed-off-by: Jens Axboe

loop: fix zero sized loop for block special file

2025-08-25T13:46:57+00:00

By default, /dev/sda is block special file from devtmpfs, getattr will
return file size as zero, causing loop failed for raw block device.

We can add bdev_statx() to return device size, however this may
introduce changes that are not acknowledged by user. Fix this problem by
reverting changes for block special file, file mapping host is set to
bdev inode while opening, and use i_size_read() directly to get device
size.

Fixes: 47b71abd5846 ("loop: use vfs_getattr_nosec for accurate file size")
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-lkp/202508200409.b2459c02-lkp@intel.com
Signed-off-by: Yu Kuai 
Reviewed-by: Ming Lei 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20250825093205.3684121-1-yukuai1@huaweicloud.com
[axboe: fix spelling error]
Signed-off-by: Jens Axboe

loop: use vfs_getattr_nosec for accurate file size

2025-08-18T19:10:35+00:00

Use vfs_getattr_nosec() in lo_calculate_size() for getting the file
size, rather than just read the cached inode size via i_size_read().
This provides better results than cached inode data, particularly for
network filesystems where metadata may be stale.

Signed-off-by: Rajeev Mishra 
Reviewed-by: Yu Kuai 
Link: https://lore.kernel.org/r/20250818184821.115033-3-rajeevm@hpe.com
[axboe: massage commit message]
Signed-off-by: Jens Axboe

loop: Consolidate size calculation logic into lo_calculate_size()

2025-08-18T19:10:25+00:00

Renamed get_size to lo_calculate_size and merged the logic from get_size
and get_loop_size into a single function. Update all callers to use
lo_calculate_size. This is done in preparation for improving the size
detection logic.

Signed-off-by: Rajeev Mishra 
Reviewed-by: Yu Kuai 
Link: https://lore.kernel.org/r/20250818184821.115033-2-rajeevm@hpe.com
[axboe: massage commit message]
Signed-off-by: Jens Axboe

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