linux-toradex.git/drivers/block/loop.c, branch v6.7-rc8 Linux kernel for Apalis and Colibri modules Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs 2023-08-28T18:04:18+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-08-28T18:04:18+00:00 511fb5bafed197ff76d9adf5448de67f1d0558ae 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->s_fs_info needs to be cleaned up by the fs_context->free() implementation before the superblock allocation function has been called successfully. After sget_fc() returned fs_context->s_fs_info has been transferred to sb->s_fs_info at which point sb->kill_sb() if fully responsible for cleanup. Adhering to these rules means that cleanup of sb->s_fs_info in fill_super() is to be avoided as it's brittle and inconsistent. Cleanup shouldn't be duplicated between sb->put_super() as sb->put_super() is only called if sb->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->kill_sb() instead of sb->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->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 ... 
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->s_fs_info needs
       to be cleaned up by the fs_context->free() implementation before
       the superblock allocation function has been called successfully.

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

       Cleanup shouldn't be duplicated between sb->put_super() as
       sb->put_super() is only called if sb->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->kill_sb() instead of sb->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->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
  ...
block: simplify the disk_force_media_change interface 2023-08-21T12:35:30+00:00 Christoph Hellwig hch@lst.de 2023-08-11T10:08:19+00:00 ab6860f62bfe329e11e5b5b7295b673c9c3a62d0 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 <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Message-Id: <20230811100828.1897174-9-hch@lst.de> Signed-off-by: Christian Brauner <brauner@kernel.org> 
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 <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Message-Id: <20230811100828.1897174-9-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
loop: do not enforce max_loop hard limit by (new) default 2023-07-21T19:20:57+00:00 Mauricio Faria de Oliveira mfo@canonical.com 2023-07-20T14:30:33+00:00 bb5faa99f0ce40756ab7bbbce4f16c01ca5ebd5a 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 >= 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 & patched): # ls -1 /dev/loop* /dev/loop-control # ./test-loop # - max_loop=8 (original & 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 <mfo@canonical.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20230720143033.841001-3-mfo@canonical.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
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 >= 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 & patched):

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

	# ./test-loop
	#

- max_loop=8 (original & 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 <mfo@canonical.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230720143033.841001-3-mfo@canonical.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
loop: deprecate autoloading callback loop_probe() 2023-07-21T19:20:48+00:00 Mauricio Faria de Oliveira mfo@canonical.com 2023-07-20T14:30:32+00:00 23881aec85f3219e8462e87c708815ee2cd82358 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 <mfo@canonical.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20230720143033.841001-2-mfo@canonical.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
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 <mfo@canonical.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230720143033.841001-2-mfo@canonical.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: replace fmode_t with a block-specific type for block open flags 2023-06-12T14:04:05+00:00 Christoph Hellwig hch@lst.de 2023-06-08T11:02:55+00:00 05bdb9965305bbfdae79b31d22df03d1e2cfcb22 The only overlap between the block open flags mapped into the fmode_t and other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and ->ioctl and stop abusing fmode_t. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd] Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE.  Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com>		[rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: remove the unused mode argument to ->release 2023-06-12T14:04:04+00:00 Christoph Hellwig hch@lst.de 2023-06-08T11:02:37+00:00 ae220766d87cd6799dbf918fea10613ae14c0654 The mode argument to the ->release block_device_operation is never used, so remove it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Christian Brauner <brauner@kernel.org> Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd] Link: https://lore.kernel.org/r/20230608110258.189493-10-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
The mode argument to the ->release block_device_operation is never used,
so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Jack Wang <jinpu.wang@ionos.com>			[rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: introduce holder ops 2023-06-05T16:53:04+00:00 Christoph Hellwig hch@lst.de 2023-06-01T09:44:52+00:00 0718afd47f70cf46877c39c25d06b786e1a3f36c Add a new blk_holder_ops structure, which is passed to blkdev_get_by_* and installed in the block_device for exclusive claims. It will be used to allow the block layer to call back into the user of the block device for thing like notification of a removed device or a device resize. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Add a new blk_holder_ops structure, which is passed to blkdev_get_by_* and
installed in the block_device for exclusive claims.  It will be used to
allow the block layer to call back into the user of the block device for
thing like notification of a removed device or a device resize.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
loop: LOOP_CONFIGURE: send uevents for partitions 2023-03-27T19:27:06+00:00 Alyssa Ross hi@alyssa.is 2023-03-20T12:54:30+00:00 bb430b69422640891b0b8db762885730579a4145 LOOP_CONFIGURE is, as far as I understand it, supposed to be a way to combine LOOP_SET_FD and LOOP_SET_STATUS64 into a single syscall. When using LOOP_SET_FD+LOOP_SET_STATUS64, a single uevent would be sent for each partition found on the loop device after the second ioctl(), but when using LOOP_CONFIGURE, no such uevent was being sent. In the old setup, uevents are disabled for LOOP_SET_FD, but not for LOOP_SET_STATUS64. This makes sense, as it prevents uevents being sent for a partially configured device during LOOP_SET_FD - they're only sent at the end of LOOP_SET_STATUS64. But for LOOP_CONFIGURE, uevents were disabled for the entire operation, so that final notification was never issued. To fix this, reduce the critical section to exclude the loop_reread_partitions() call, which causes the uevents to be issued, to after uevents are re-enabled, matching the behaviour of the LOOP_SET_FD+LOOP_SET_STATUS64 combination. I noticed this because Busybox's losetup program recently changed from using LOOP_SET_FD+LOOP_SET_STATUS64 to LOOP_CONFIGURE, and this broke my setup, for which I want a notification from the kernel any time a new partition becomes available. Signed-off-by: Alyssa Ross <hi@alyssa.is> [hch: reduced the critical section] Signed-off-by: Christoph Hellwig <hch@lst.de> Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl") Link: https://lore.kernel.org/r/20230320125430.55367-1-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
LOOP_CONFIGURE is, as far as I understand it, supposed to be a way to
combine LOOP_SET_FD and LOOP_SET_STATUS64 into a single syscall.  When
using LOOP_SET_FD+LOOP_SET_STATUS64, a single uevent would be sent for
each partition found on the loop device after the second ioctl(), but
when using LOOP_CONFIGURE, no such uevent was being sent.

In the old setup, uevents are disabled for LOOP_SET_FD, but not for
LOOP_SET_STATUS64.  This makes sense, as it prevents uevents being
sent for a partially configured device during LOOP_SET_FD - they're
only sent at the end of LOOP_SET_STATUS64.  But for LOOP_CONFIGURE,
uevents were disabled for the entire operation, so that final
notification was never issued.  To fix this, reduce the critical
section to exclude the loop_reread_partitions() call, which causes
the uevents to be issued, to after uevents are re-enabled, matching
the behaviour of the LOOP_SET_FD+LOOP_SET_STATUS64 combination.

I noticed this because Busybox's losetup program recently changed from
using LOOP_SET_FD+LOOP_SET_STATUS64 to LOOP_CONFIGURE, and this broke
my setup, for which I want a notification from the kernel any time a
new partition becomes available.

Signed-off-by: Alyssa Ross <hi@alyssa.is>
[hch: reduced the critical section]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl")
Link: https://lore.kernel.org/r/20230320125430.55367-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
loop: Fix use-after-free issues 2023-03-15T01:20:48+00:00 Bart Van Assche bvanassche@acm.org 2023-03-14T18:21:54+00:00 9b0cb770f5d7b1ff40bea7ca385438ee94570eec do_req_filebacked() calls blk_mq_complete_request() synchronously or asynchronously when using asynchronous I/O unless memory allocation fails. Hence, modify loop_handle_cmd() such that it does not dereference 'cmd' nor 'rq' after do_req_filebacked() finished unless we are sure that the request has not yet been completed. This patch fixes the following kernel crash: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000054 Call trace: css_put.42938+0x1c/0x1ac loop_process_work+0xc8c/0xfd4 loop_rootcg_workfn+0x24/0x34 process_one_work+0x244/0x558 worker_thread+0x400/0x8fc kthread+0x16c/0x1e0 ret_from_fork+0x10/0x20 Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Dan Schatzberg <schatzberg.dan@gmail.com> Fixes: c74d40e8b5e2 ("loop: charge i/o to mem and blk cg") Fixes: bc07c10a3603 ("block: loop: support DIO & AIO") Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230314182155.80625-1-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk> 
do_req_filebacked() calls blk_mq_complete_request() synchronously or
asynchronously when using asynchronous I/O unless memory allocation fails.
Hence, modify loop_handle_cmd() such that it does not dereference 'cmd' nor
'rq' after do_req_filebacked() finished unless we are sure that the request
has not yet been completed. This patch fixes the following kernel crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000054
Call trace:
 css_put.42938+0x1c/0x1ac
 loop_process_work+0xc8c/0xfd4
 loop_rootcg_workfn+0x24/0x34
 process_one_work+0x244/0x558
 worker_thread+0x400/0x8fc
 kthread+0x16c/0x1e0
 ret_from_fork+0x10/0x20

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
Fixes: c74d40e8b5e2 ("loop: charge i/o to mem and blk cg")
Fixes: bc07c10a3603 ("block: loop: support DIO & AIO")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230314182155.80625-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
loop: loop_set_status_from_info() check before assignment 2023-02-23T03:43:09+00:00 Zhong Jinghua zhongjinghua@huawei.com 2023-02-21T09:50:27+00:00 9f6ad5d533d1c71e51bdd06a5712c4fbc8768dfa In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should be checked before reassignment, because if an overflow error occurs, the original correct value will be changed to the wrong value, and it will not be changed back. More, the original patch did not solve the problem, the value was set and ioctl returned an error, but the subsequent io used the value in the loop driver, which still caused an alarm: loop_handle_cmd do_req_filebacked loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; lo_rw_aio cmd->iocb.ki_pos = pos Fixes: c490a0b5a4f3 ("loop: Check for overflow while configuring loop") Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20230221095027.3656193-1-zhongjinghua@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
In loop_set_status_from_info(), lo->lo_offset and lo->lo_sizelimit should
be checked before reassignment, because if an overflow error occurs, the
original correct value will be changed to the wrong value, and it will not
be changed back.

More, the original patch did not solve the problem, the value was set and
ioctl returned an error, but the subsequent io used the value in the loop
driver, which still caused an alarm:

loop_handle_cmd
 do_req_filebacked
  loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
  lo_rw_aio
   cmd->iocb.ki_pos = pos

Fixes: c490a0b5a4f3 ("loop: Check for overflow while configuring loop")
Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20230221095027.3656193-1-zhongjinghua@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>