linux.git/block/bdev.c, branch v6.6.131

block: fix race between set_blocksize and read paths

2025-10-23T14:16:38+00:00

commit c0e473a0d226479e8e925d5ba93f751d8df628e9 upstream.

With the new large sector size support, it's now the case that
set_blocksize can change i_blksize and the folio order in a manner that
conflicts with a concurrent reader and causes a kernel crash.

Specifically, let's say that udev-worker calls libblkid to detect the
labels on a block device. The read call can create an order-0 folio to
read the first 4096 bytes from the disk. But then udev is preempted.

Next, someone tries to mount an 8k-sectorsize filesystem from the same
block device. The filesystem calls set_blksize, which sets i_blksize to
8192 and the minimum folio order to 1.

Now udev resumes, still holding the order-0 folio it allocated. It then
tries to schedule a read bio and do_mpage_readahead tries to create
bufferheads for the folio. Unfortunately, blocks_per_folio == 0 because
the page size is 4096 but the blocksize is 8192 so no bufferheads are
attached and the bh walk never sets bdev. We then submit the bio with a
NULL block device and crash.

Therefore, truncate the page cache after flushing but before updating
i_blksize. However, that's not enough -- we also need to lock out file
IO and page faults during the update. Take both the i_rwsem and the
invalidate_lock in exclusive mode for invalidations, and in shared mode
for read/write operations.

I don't know if this is the correct fix, but xfs/259 found it.

Signed-off-by: Darrick J. Wong
Reviewed-by: Christoph Hellwig
Reviewed-by: Luis Chamberlain
Tested-by: Shin'ichiro Kawasaki
Link: https://lore.kernel.org/r/174543795699.4139148.2086129139322431423.stgit@frogsfrogsfrogs
Signed-off-by: Jens Axboe
[ use bdev->bd_inode instead ]
Signed-off-by: Mahmoud Adam
Signed-off-by: Greg Kroah-Hartman

block: Provide bdev_open_* functions

2024-03-26T22:19:40+00:00

[ Upstream commit e719b4d156749f02eafed31a3c515f2aa9dcc72a ]

Create struct bdev_handle that contains all parameters that need to be
passed to blkdev_put() and provide bdev_open_* functions that return
this structure instead of plain bdev pointer. This will eventually allow
us to pass one more argument to blkdev_put() (renamed to bdev_release())
without too much hassle.

Acked-by: Christoph Hellwig 
Reviewed-by: Christian Brauner 
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20230927093442.25915-1-jack@suse.cz
Signed-off-by: Christian Brauner 
Stable-dep-of: 0f28be64d132 ("erofs: fix lockdep false positives on initializing erofs_pseudo_mnt")
Signed-off-by: Sasha Levin

block: update the stable_writes flag in bdev_add

2023-12-03T06:33:03+00:00

[ Upstream commit 1898efcdbed32bb1c67269c985a50bab0dbc9493 ]

Propagate the per-queue stable_write flags into each bdev inode in bdev_add.
This makes sure devices that require stable writes have it set for I/O
on the block device node as well.

Note that this doesn't cover the case of a flag changing on a live device
yet.  We should handle that as well, but I plan to cover it as part of a
more general rework of how changing runtime paramters on block devices
works.

Fixes: 1cb039f3dc16 ("bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag")
Reported-by: Ilya Dryomov 
Signed-off-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20231025141020.192413-3-hch@lst.de
Tested-by: Ilya Dryomov 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

Merge tag 'vfs-6.6-merge-2' of ssh://gitolite.kernel.org/pub/scm/fs/xfs/xfs-linux

2023-08-23T11:06:55+00:00

Pull filesystem freezing updates from Darrick Wong:

New code for 6.6:

 * Allow the kernel to initiate a freeze of a filesystem.  The kernel
   and userspace can both hold a freeze on a filesystem at the same
   time; the freeze is not lifted until /both/ holders lift it.  This
   will enable us to fix a longstanding bug in XFS online fsck.

Signed-off-by: Darrick J. Wong 
Message-Id: <20230822182604.GB11286@frogsfrogsfrogs>
Signed-off-by: Christian Brauner

block: call into the file system for ioctl BLKFLSBUF

2023-08-21T12:35:32+00:00

BLKFLSBUF is a historic ioctl that is called on a file handle to a
block device and syncs either the file system mounted on that block
device if there is one, or otherwise the just the data on the block
device.

Replace the get_super based syncing with a holder operation to remove
the last usage of get_super, and to also support syncing the file system
if the block device is not the main block device stored in s_dev.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Josef Bacik 
Message-Id: <20230811100828.1897174-16-hch@lst.de>
Signed-off-by: Christian Brauner

block: call into the file system for bdev_mark_dead

2023-08-21T12:35:32+00:00

Combine the newly merged bdev_mark_dead helper with the existing
mark_dead holder operation so that all operations that invalidate
a device that is dead or being removed now go through the holder
ops.  This allows file systems to explicitly shutdown either ASAP
(for a surprise removal) or after writing back data (for an orderly
removal), and do so not only for the main device.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Josef Bacik 
Message-Id: <20230811100828.1897174-15-hch@lst.de>
Signed-off-by: Christian Brauner

block: consolidate __invalidate_device and fsync_bdev

2023-08-21T12:35:31+00:00

We currently have two interfaces that take a block_devices and the find
a mounted file systems to flush or invaldidate data on it.  Both are a
bit problematic because they only work for the "main" block devices
that is used as s_dev for the super_block, and because they don't call
into the file system at all.

Merge the two into a new bdev_mark_dead helper that does both the
syncing and invalidation and which is properly documented.  This is
in preparation of merging the functionality into the ->mark_dead
holder operation so that it will work on additional block devices
used by a file systems and give us a single entry point for invalidation
of dead devices or media.

Note that a single standalone fsync_bdev call for an obscure ioctl
remains for now, but that one will also be deal with in a bit.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Josef Bacik 
Message-Id: <20230811100828.1897174-14-hch@lst.de>
Signed-off-by: Christian Brauner

fs: distinguish between user initiated freeze and kernel initiated freeze

2023-07-17T16:00:09+00:00

Userspace can freeze a filesystem using the FIFREEZE ioctl or by
suspending the block device; this state persists until userspace thaws
the filesystem with the FITHAW ioctl or resuming the block device.
Since commit 18e9e5104fcd ("Introduce freeze_super and thaw_super for
the fsfreeze ioctl") we only allow the first freeze command to succeed.

The kernel may decide that it is necessary to freeze a filesystem for
its own internal purposes, such as suspends in progress, filesystem fsck
activities, or quiescing a device prior to removal.  Userspace thaw
commands must never break a kernel freeze, and kernel thaw commands
shouldn't undo userspace's freeze command.

Introduce a couple of freeze holder flags and wire it into the
sb_writers state.  One kernel and one userspace freeze are allowed to
coexist at the same time; the filesystem will not thaw until both are
lifted.

I wonder if the f2fs/gfs2 code should be using a kernel freeze here, but
for now we'll use FREEZE_HOLDER_USERSPACE to preserve existing
behaviors.

Cc: mcgrof@kernel.org
Cc: jack@suse.cz
Cc: hch@infradead.org
Cc: ruansy.fnst@fujitsu.com
Signed-off-by: Darrick J. Wong 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Dave Chinner 
Reviewed-by: Jan Kara

block: Improve kernel-doc headers

2023-06-21T19:18:15+00:00

Fix the documentation of the devt_from_partuuid() return value.

Fix the following two recently introduced kernel-doc warnings:

block/bdev.c:570: warning: Function parameter or member 'hops' not described in 'bd_finish_claiming'
block/early-lookup.c:46: warning: Function parameter or member 'devt' not described in 'devt_from_partuuid'

Cc: Christoph Hellwig 
Fixes: 0718afd47f70 ("block: introduce holder ops")
Fixes: cf056a431215 ("init: improve the name_to_dev_t interface")
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20230621165054.743815-1-bvanassche@acm.org
Signed-off-by: Jens Axboe

block: document the holder argument to blkdev_get_by_path

2023-06-20T13:16:38+00:00

Reported-by: Stephen Rothwell 
Signed-off-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20230620043536.707249-1-hch@lst.de
Signed-off-by: Jens Axboe