fs: claw back a few FMODE_* bits

There's a bunch of flags that are purely based on what the file
operations support while also never being conditionally set or unset.
IOW, they're not subject to change for individual files. Imho, such
flags don't need to live in f_mode they might as well live in the fops
structs itself. And the fops struct already has that lonely
mmap_supported_flags member. We might as well turn that into a generic
fop_flags member and move a few flags from FMODE_* space into FOP_*
space. That gets us four FMODE_* bits back and the ability for new
static flags that are about file ops to not have to live in FMODE_*
space but in their own FOP_* space. It's not the most beautiful thing
ever but it gets the job done. Yes, there'll be an additional pointer
chase but hopefully that won't matter for these flags.

I suspect there's a few more we can move into there and that we can also
redirect a bunch of new flag suggestions that follow this pattern into
the fop_flags field instead of f_mode.

Link: https://lore.kernel.org/r/20240328-gewendet-spargel-aa60a030ef74@brauner
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: fix module reference leakage from bdev_open_by_dev error path

At the time bdev_may_open() is called, module reference is grabbed
already, hence module reference should be released if bdev_may_open()
failed.

This problem is found by code review.

Fixes: ed5cc702d311 ("block: Add config option to not allow writing to mounted devices")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240406090930.2252838-22-yukuai1@huaweicloud.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: propagate partition scanning errors to the BLKRRPART ioctl

Commit 4601b4b130de ("block: reopen the device in blkdev_reread_part")
lost the propagation of I/O errors from the low-level read of the
partition table to the user space caller of the BLKRRPART.

Apparently some user space relies on, so restore the propagation. This
isn't exactly pretty as other block device open calls explicitly do not
are about these errors, so add a new BLK_OPEN_STRICT_SCAN to opt into
the error propagation.

Fixes: 4601b4b130de ("block: reopen the device in blkdev_reread_part")
Reported-by: Saranya Muruganandam <saranyamohan@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240417144743.2277601-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs,block: yield devices early

Currently a device is only really released once the umount returns to
userspace due to how file closing works. That ultimately could cause
an old umount assumption to be violated that concurrent umount and mount
don't fail. So an exclusively held device with a temporary holder should
be yielded before the filesystem is gone. Add a helper that allows
callers to do that. This also allows us to remove the two holder ops
that Linus wasn't excited about.

Link: https://lore.kernel.org/r/20240326-vfs-bdev-end_holder-v1-1-20af85202918@kernel.org
Fixes: f3a608827d1f ("bdev: open block device as files") # mainline only
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: count BLK_OPEN_RESTRICT_WRITES openers

The original changes in v6.8 do allow for a block device to be reopened
with BLK_OPEN_RESTRICT_WRITES provided the same holder is used as per
bdev_may_open(). I think this has a bug.

The first opener @f1 of that block device will set bdev->bd_writers to
-1. The second opener @f2 using the same holder will pass the check in
bdev_may_open() that bdev->bd_writers must not be greater than zero.

The first opener @f1 now closes the block device and in bdev_release()
will end up calling bdev_yield_write_access() which calls
bdev_writes_blocked() and sets bdev->bd_writers to 0 again.

Now @f2 holds a file to that block device which was opened with
exclusive write access but bdev->bd_writers has been reset to 0.

So now @f3 comes along and succeeds in opening the block device with
BLK_OPEN_WRITE betraying @f2's request to have exclusive write access.

This isn't a practical issue yet because afaict there's no codepath
inside the kernel that reopenes the same block device with
BLK_OPEN_RESTRICT_WRITES but it will be if there is.

Fix this by counting the number of BLK_OPEN_RESTRICT_WRITES openers. So
we only allow writes again once all BLK_OPEN_RESTRICT_WRITES openers are
done.

Link: https://lore.kernel.org/r/20240323-abtauchen-klauen-c2953810082d@brauner
Fixes: ed5cc702d311 ("block: Add config option to not allow writing to mounted devices")
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: handle BLK_OPEN_RESTRICT_WRITES correctly

Last kernel release we introduce CONFIG_BLK_DEV_WRITE_MOUNTED. By
default this option is set. When it is set the long-standing behavior
of being able to write to mounted block devices is enabled.

But in order to guard against unintended corruption by writing to the
block device buffer cache CONFIG_BLK_DEV_WRITE_MOUNTED can be turned
off. In that case it isn't possible to write to mounted block devices
anymore.

A filesystem may open its block devices with BLK_OPEN_RESTRICT_WRITES
which disallows concurrent BLK_OPEN_WRITE access. When we still had the
bdev handle around we could recognize BLK_OPEN_RESTRICT_WRITES because
the mode was passed around. Since we managed to get rid of the bdev
handle we changed that logic to recognize BLK_OPEN_RESTRICT_WRITES based
on whether the file was opened writable and writes to that block device
are blocked. That logic doesn't work because we do allow
BLK_OPEN_RESTRICT_WRITES to be specified without BLK_OPEN_WRITE.

Fix the detection logic and use an FMODE_* bit. We could've also abused
O_EXCL as an indicator that BLK_OPEN_RESTRICT_WRITES has been requested.
For userspace open paths O_EXCL will never be retained but for internal
opens where we open files that are never installed into a file
descriptor table this is fine. But it would be a gamble that this
doesn't cause bugs. Note that BLK_OPEN_RESTRICT_WRITES is an internal
only flag that cannot directly be raised by userspace. It is implicitly
raised during mounting.

Passes xftests and blktests with CONFIG_BLK_DEV_WRITE_MOUNTED set and
unset.

Link: https://lore.kernel.org/r/ZfyyEwu9Uq5Pgb94@casper.infradead.org
Link: https://lore.kernel.org/r/20240323-zielbereich-mittragen-6fdf14876c3e@brauner
Fixes: 321de651fa56 ("block: don't rely on BLK_OPEN_RESTRICT_WRITES when yielding write access")
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs,block: get holder during claim

Now that we open block devices as files we need to deal with the
realities that closing is a deferred operation. An operation on the
block device such as e.g., freeze, thaw, or removal that runs
concurrently with umount, tries to acquire a stable reference on the
holder. The holder might already be gone though. Make that reliable by
grabbing a passive reference to the holder during bdev_open() and
releasing it during bdev_release().

Fixes: f3a608827d1f ("bdev: open block device as files") # mainline only
Reported-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/r/ZfEQQ9jZZVes0WCZ@infradead.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Reported-by: https://lore.kernel.org/r/CAHj4cs8tbDwKRwfS1=DmooP73ysM__xAb2PQc6XsAmWR+VuYmg@mail.gmail.com
Link: https://lore.kernel.org/r/20240315-freibad-annehmbar-ca68c375af91@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: remove bdev_handle completely

We just need to use the holder to indicate whether a block device open
was exclusive or not. We did use to do that before but had to give that
up once we switched to struct bdev_handle. Before struct bdev_handle we
only stashed stuff in file->private_data if this was an exclusive open
but after struct bdev_handle we always set file->private_data to a
struct bdev_handle and so we had to use bdev_handle->mode or
bdev_handle->holder. Now that we don't use struct bdev_handle anymore we
can revert back to the old behavior.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-32-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: don't rely on BLK_OPEN_RESTRICT_WRITES when yielding write access

Make it possible to detected a block device that was opened with
restricted write access based only on BLK_OPEN_WRITE and
bdev->bd_writers < 0 so we won't have to claim another FMODE_* flag.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-31-adbd023e19cc@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: remove bdev pointer from struct bdev_handle

We can always go directly via:

* I_BDEV(bdev_file->f_inode)
* I_BDEV(bdev_file->f_mapping->host)

So keeping struct bdev in struct bdev_handle is redundant.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-30-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: make struct bdev_handle private to the block layer

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-29-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: make bdev_{release, open_by_dev}() private to block layer

Move both of them to the private block header. There's no caller in the
tree anymore that uses them directly.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-28-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: remove bdev_open_by_path()

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-27-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: open block device as files

Add two new helpers to allow opening block devices as files.
This is not the final infrastructure. This still opens the block device
before opening a struct a file. Until we have removed all references to
struct bdev_handle we can't switch the order:

* Introduce blk_to_file_flags() to translate from block specific to
flags usable to pen a new file.
* Introduce bdev_file_open_by_{dev,path}().
* Introduce temporary sb_bdev_handle() helper to retrieve a struct
bdev_handle from a block device file and update places that directly
reference struct bdev_handle to rely on it.
* Don't count block device openes against the number of open files. A
bdev_file_open_by_{dev,path}() file is never installed into any
file descriptor table.

One idea that came to mind was to use kernel_tmpfile_open() which
would require us to pass a path and it would then call do_dentry_open()
going through the regular fops->open::blkdev_open() path. But then we're
back to the problem of routing block specific flags such as
BLK_OPEN_RESTRICT_WRITES through the open path and would have to waste
FMODE_* flags every time we add a new one. With this we can avoid using
a flag bit and we have more leeway in how we open block devices from
bdev_open_by_{dev,path}().

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-1-adbd023e19cc@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: remove SLAB_MEM_SPREAD flag usage

The SLAB_MEM_SPREAD flag is already a no-op as of 6.8-rc1, remove
its usage so we can delete it from slab. No functional change.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lore.kernel.org/r/20240224134646.829105-1-chengming.zhou@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Fix a memory leak in bdev_open_by_dev()

If we early exit here, 'handle' needs to be freed, or some memory leaks.

Fixes: ed5cc702d311 ("block: Add config option to not allow writing to mounted devices")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/8eaec334781e695810aaa383b55de00ca4ab1352.1703439383.git.christophe.jaillet@wanadoo.fr
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: Add config option to not allow writing to mounted devices

Writing to mounted devices is dangerous and can lead to filesystem
corruption as well as crashes. Furthermore syzbot comes with more and
more involved examples how to corrupt block device under a mounted
filesystem leading to kernel crashes and reports we can do nothing
about. Add tracking of writers to each block device and a kernel cmdline
argument which controls whether other writeable opens to block devices
open with BLK_OPEN_RESTRICT_WRITES flag are allowed. We will make
filesystems use this flag for used devices.

Note that this effectively only prevents modification of the particular
block device's page cache by other writers. The actual device content
can still be modified by other means - e.g. by issuing direct scsi
commands, by doing writes through devices lower in the storage stack
(e.g. in case loop devices, DM, or MD are involved) etc. But blocking
direct modifications of the block device page cache is enough to give
filesystems a chance to perform data validation when loading data from
the underlying storage and thus prevent kernel crashes.

Syzbot can use this cmdline argument option to avoid uninteresting
crashes. Also users whose userspace setup does not need writing to
mounted block devices can set this option for hardening.

Link: https://lore.kernel.org/all/60788e5d-5c7c-1142-e554-c21d709acfd9@linaro.org
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231101174325.10596-3-jack@suse.cz
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: Remove blkdev_get_by_*() functions

blkdev_get_by_*() and blkdev_put() functions are now unused. Remove
them.

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231101174325.10596-2-jack@suse.cz
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: implement freeze and thaw holder operations

The old method of implementing block device freeze and thaw operations
required us to rely on get_active_super() to walk the list of all
superblocks on the system to find any superblock that might use the
block device. This is wasteful and not very pleasant overall.

Now that we can finally go straight from block device to owning
superblock things become way simpler.

Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-5-599c19f4faac@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: surface the error from sync_blockdev()

When freeze_super() is called, sync_filesystem() will be called which
calls sync_blockdev() and already surfaces any errors. Do the same for
block devices that aren't owned by a superblock and also for filesystems
that don't call sync_blockdev() internally but implicitly rely on
bdev_freeze() to do it.

Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-3-599c19f4faac@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

bdev: rename freeze and thaw helpers

We have bdev_mark_dead() etc and we're going to move block device
freezing to holder ops in the next patch. Make the naming consistent:

* freeze_bdev() -> bdev_freeze()
* thaw_bdev() -> bdev_thaw()

Also document the return code.

Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-2-599c19f4faac@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: update the stable_writes flag in bdev_add

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 <idryomov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231025141020.192413-3-hch@lst.de
Tested-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

treewide: mark stuff as __ro_after_init

__read_mostly predates __ro_after_init. Many variables which are marked
__read_mostly should have been __ro_after_init from day 1.

Also, mark some stuff as "const" and "__init" while I'm at it.

[akpm@linux-foundation.org: revert sysctl_nr_open_min, sysctl_nr_open_max changes due to arm warning]
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/4f6bb9c0-abba-4ee4-a7aa-89265e886817@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

block: move bdev_mark_dead out of disk_check_media_change

disk_check_media_change is mostly called from ->open where it makes
little sense to mark the file system on the device as dead, as we
are just opening it. So instead of calling bdev_mark_dead from
disk_check_media_change move it into the few callers that are not
in an open instance. This avoid calling into bdev_mark_dead and
thus taking s_umount with open_mutex held.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231017184823.1383356-4-hch@lst.de
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: Avoid grabbing sb->s_umount under bdev->bd_holder_lock

The implementation of bdev holder operations such as fs_bdev_mark_dead()
and fs_bdev_sync() grab sb->s_umount semaphore under
bdev->bd_holder_lock. This is problematic because it leads to
disk->open_mutex -> sb->s_umount lock ordering which is counterintuitive
(usually we grab higher level (e.g. filesystem) locks first and lower
level (e.g. block layer) locks later) and indeed makes lockdep complain
about possible locking cycles whenever we open a block device while
holding sb->s_umount semaphore. Implement a function
bdev_super_lock_shared() which safely transitions from holding
bdev->bd_holder_lock to holding sb->s_umount on alive superblock without
introducing the problematic lock dependency. We use this function
fs_bdev_sync() and fs_bdev_mark_dead().

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231018152924.3858-1-jack@suse.cz
Link: https://lore.kernel.org/r/20231017184823.1383356-1-hch@lst.de
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: Use bdev_open_by_dev() in blkdev_open()

Convert blkdev_open() to use bdev_open_by_dev(). To be able to propagate
handle from blkdev_open() to blkdev_release() we need to stop using
existence of file->private_data to determine exclusive block device
opens. Use bdev_handle->mode for this purpose since file->f_flags
isn't usable for this (O_EXCL is cleared from the flags during open).

Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-2-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: Provide bdev_open_* functions

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 <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-1-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: call into the file system for ioctl BLKFLSBUF

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 <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Message-Id: <20230811100828.1897174-16-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: call into the file system for bdev_mark_dead

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 <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Message-Id: <20230811100828.1897174-15-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block: consolidate __invalidate_device and fsync_bdev

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 <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Message-Id: <20230811100828.1897174-14-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs: distinguish between user initiated freeze and kernel initiated freeze

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 <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>

block: Improve kernel-doc headers

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 <hch@lst.de>
Fixes: 0718afd47f70 ("block: introduce holder ops")
Fixes: cf056a431215 ("init: improve the name_to_dev_t interface")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230621165054.743815-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: document the holder argument to blkdev_get_by_path

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230620043536.707249-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: replace fmode_t with a block-specific type for block open flags

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: use the holder as indication for exclusive opens

The current interface for exclusive opens is rather confusing as it
requires both the FMODE_EXCL flag and a holder. Remove the need to pass
FMODE_EXCL and just key off the exclusive open off a non-NULL holder.

For blkdev_put this requires adding the holder argument, which provides
better debug checking that only the holder actually releases the hold,
but at the same time allows removing the now superfluous mode argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: David Sterba <dsterba@suse.com> [btrfs]
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Link: https://lore.kernel.org/r/20230608110258.189493-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the unused mode argument to ->release

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: pass a gendisk to ->open

->open is only called on the whole device. Make that explicit by
passing a gendisk instead of the block_device.

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/20230608110258.189493-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: also call ->open for incremental partition opens

For whole devices ->open is called for each open, but for partitions it
is only called on the first open of a partition, e.g.:

open("/dev/vdb", ...)
open("/dev/vdb", ...)
- 2 call to ->open

open("/dev/vdb1", ...)
open("/dev/vdb", ...)
- 2 call to ->open

open("/dev/vdb", ...)
open("/dev/vdb", ...)
- just open call to ->open

This is problematic as various block drivers look at open flags and
might not do all the required setup if the earlier open was with an
odd flag like O_NDELAY or the magic 3 ioctl-only open mode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Phillip Potter <phil@philpotter.co.uk>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: introduce holder ops

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>

block: turn bdev_lock into a mutex

There is no reason for this lock to spin, and being able to sleep under
it will come in handy soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: refactor bd_may_claim

The long if/else chain obsfucates the actual logic. Tidy it up to be
more structured. Also drop the whole argument, as it can be trivially
derived from bdev using bdev_whole, and having the bdev_whole in the
function makes it easier to follow.

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/20230601094459.1350643-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: factor out a bd_end_claim helper from blkdev_put

Move all the logic to release an exclusive claim into a helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: sync part's ->bd_has_submit_bio with disk's

submit_bio() always uses bio->bi_bdev->bd_has_submit_bio to decide if
disk's ->submit_bio() is called, and bio->bi_bdev could point to one
partition device.

So we have to sync part bdev's ->bd_has_submit_bio with disk's.

Reported-by: Changhui Zhong <czhong@redhat.com>
Link: https://lore.kernel.org/linux-block/ZEdItaPqif8fp85H@ovpn-8-24.pek2.redhat.com/T/#t
Fixes: 9f4107b07b17 ("block: store bdev->bd_disk->fops->submit_bio state in bdev")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230425034154.110099-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Cleanup set_capacity()/bdev_set_nr_sectors()

The code for setting a block device capacity (bd_nr_sectors field of
struct block_device) is duplicated in set_capacity() and
bdev_set_nr_sectors(). Clean this up by making bdev_set_nr_sectors()
a block layer internal function defined in block/bdev.c instead of
having this function statically defined in block/partitions/core.c.
With this change, set_capacity() implementation can be simplified to
only calling bdev_set_nr_sectors().

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230424131318.79935-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: store bdev->bd_disk->fops->submit_bio state in bdev

We have a long chain of memory dereferencing just to whether or not
this disk has a special submit_bio helper. As that's not necessarily
the common case, add a bd_has_submit_bio state in the bdev to avoid
traversing this memory dependency chain if we don't need to.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove ->rw_page

The ->rw_page method is a special purpose bypass of the usual bio handling
path that is limited to single-page reads and writes and synchronous which
causes a lot of extra code in the drivers, callers and the block layer.

The only remaining user is the MM swap code. Switch that swap code to
simply submit a single-vec on-stack bio an synchronously wait on it based
on a newly added QUEUE_FLAG_SYNCHRONOUS flag set by the drivers that
currently implement ->rw_page instead. While this touches one extra cache
line and executes extra code, it simplifies the block layer and drivers
and ensures that all feastures are properly supported by all drivers, e.g.
right now ->rw_page bypassed cgroup writeback entirely.

[akpm@linux-foundation.org: fix comment typo, per Dan]
Link: https://lkml.kernel.org/r/20230125133436.447864-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

block: bdev & blktrace: use consistent function doc. notation

Use only one hyphen in kernel-doc notation between the function name
and its short description.

The is the documented kerenl-doc format. It also fixes the HTML
presentation to be consistent with other functions.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Link: https://lore.kernel.org/r/20221201070331.25685-1-rdunlap@infradead.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

vfs: support STATX_DIOALIGN on block devices

Add support for STATX_DIOALIGN to block devices, so that direct I/O
alignment restrictions are exposed to userspace in a generic way.

Note that this breaks the tradition of stat operating only on the block
device node, not the block device itself. However, it was felt that
doing this is preferable, in order to make the interface useful and
avoid needing separate interfaces for regular files and block devices.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220827065851.135710-3-ebiggers@kernel.org

block: stop using bdevname in bdev_write_inode

Just use the %pg format specifier instead. Also reformat the
printk statement to be more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20220713055317.1888500-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: add sync_blockdev_range()

sync_blockdev_range() is to support syncing multiple sectors
with as few block device requests as possible, it is helpful
to make the block device to give full play to its performance.

Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Andy Wu <Andy.Wu@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

block: turn bdev->bd_openers into an atomic_t

All manipulation of bd_openers is under disk->open_mutex and will remain
so for the foreseeable future. But at least one place reads it without
the lock (blkdev_get) and there are more to be added. So make sure the
compiler does not do turn the increments and decrements into non-atomic
sequences by using an atomic_t.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220330052917.2566582-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs: allocate inode by using alloc_inode_sb()

The inode allocation is supposed to use alloc_inode_sb(), so convert
kmem_cache_alloc() of all filesystems to alloc_inode_sb().

Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Theodore Ts'o <tytso@mit.edu> [ext4]
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

block: remove redundant semicolon

Remove redundant semicolon from block/bdev.c

Signed-off-by: Nian Yanchuan <yanchuan@nfschina.com>
Link: https://lore.kernel.org/r/20220227170124.GA14658@localhost.localdomain
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: default BLOCK_LEGACY_AUTOLOAD to y

As Luis reported, losetup currently doesn't properly create the loop
device without this if the device node already exists because old
scripts created it manually. So default to y for now and remove the
aggressive removal schedule.

Reported-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220225181440.1351591-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: deprecate autoloading based on dev_t

Make the legacy dev_t based autoloading optional and add a deprecation
warning. This kind of autoloading has ceased to be useful about 20 years
ago.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220104071647.164918-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

mm: remove cleancache

Patch series "remove Xen tmem leftovers".

Since the removal of the Xen tmem driver in 2019, the cleancache hooks
are entirely unused, as are large parts of frontswap. This series
against linux-next (with the folio changes included) removes
cleancaches, and cuts down frontswap to the bits actually used by zswap.

This patch (of 13):

The cleancache subsystem is unused since the removal of Xen tmem driver
in commit 814bbf49dcd0 ("xen: remove tmem driver").

[akpm@linux-foundation.org: remove now-unreachable code]

Link: https://lkml.kernel.org/r/20211224062246.1258487-1-hch@lst.de
Link: https://lkml.kernel.org/r/20211224062246.1258487-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

bdev: Improve lookup_bdev documentation

Add a Context section and rewrite the rest to be clearer.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Link: https://lore.kernel.org/r/20211213171113.3097631-1-willy@infradead.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: Remove redundant initialization of variable ret

The variable ret is being initialized with a value that is never
read, it is being updated later on. The assignment is redundant and
can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20211126230652.1175636-1-colin.i.king@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove the GENHD_FL_HIDDEN check in blkdev_get_no_open

Hidden gendisks never hash the block device inode, so this can't happen.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE to disk->event_flags

GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE is all about the event reporting
mechanism, so move it to the event_flags field.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211122130625.1136848-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: avoid to touch unloaded module instance when opening bdev

disk->fops->owner is grabbed in blkdev_get_no_open() after the disk
kobject refcount is increased. This way can't make sure that
disk->fops->owner is still alive since del_gendisk() still can move
on if the kobject refcount of disk is grabbed by open() and
disk->fops->open() isn't called yet.

Fixes the issue by moving try_module_get() into blkdev_get_by_dev()
with ->open_mutex() held, then we can drain the in-progress open()
in del_gendisk(). Meantime new open() won't succeed because disk
becomes not alive.

This way is reasonable because blkdev_get_no_open() needn't to touch
disk->fops or defined callbacks.

Cc: Christoph Hellwig <hch@lst.de>
Cc: czhong@redhat.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211111020343.316126-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: simplify the block device syncing code

Get rid of the indirections and just provide a sync_bdevs
helper for the generic sync code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211019062530.2174626-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: remove __sync_blockdev

Instead offer a new sync_blockdev_nowait helper for the !wait case.
This new helper is exported as it will grow modular callers in a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211019062530.2174626-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs: bdev: fix conflicting comment from lookup_bdev

We switched to directly use dev_t to get block device, lookup changed the
meaning of use, now we fix this conflicting comment.

Fixes: 4e7b5671c6a8 ("block: remove i_bdev")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211021071344.1600362-1-liu.yun@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: use bdev_get_queue() in bdev.c

Convert bdev->bd_disk->queue to bdev_get_queue(), it's uses a cached
queue pointer and so is faster.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a352936ce5d9ac719645b1e29b173d931ebcdc02.1634219547.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: cache request queue in bdev

There are tons of places where we need to get a request_queue only
having bdev, which turns into bdev->bd_disk->queue. There are probably a
hundred of such places considering inline helpers, and enough of them
are in hot paths.

Cache queue pointer in struct block_device and make use of it in
bdev_get_queue().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a3bfaecdd28956f03629d0ca5c63ebc096e1c809.1634219547.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move integrity handling out of <linux/blkdev.h>

Split the integrity/metadata handling definitions out into a new header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210920123328.1399408-17-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: genhd: fix double kfree() in __alloc_disk_node()

syzbot is reporting use-after-free read at bdev_free_inode() [1], for
kfree() from __alloc_disk_node() is called before bdev_free_inode()
(which is called after RCU grace period) reads bdev->bd_disk and calls
kfree(bdev->bd_disk).

Fix use-after-free read followed by double kfree() problem
by making sure that bdev->bd_disk is NULL when calling iput().

Link: https://syzkaller.appspot.com/bug?extid=8281086e8a6fbfbd952a [1]
Reported-by: syzbot <syzbot+8281086e8a6fbfbd952a@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/e6dd13c5-8db0-4392-6e78-a42ee5d2a1c4@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block: move fs/block_dev.c to block/bdev.c

Move it together with the rest of the block layer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210907141303.1371844-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>