super: wait until we passed kill super

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Recent rework moved block device closing out of sb->put_super() and into
sb->kill_sb() to avoid deadlocks as s_umount is held in put_super() and
blkdev_put() can end up taking s_umount again.

That means we need to move the removal of the superblock from @fs_supers
out of generic_shutdown_super() and into deactivate_locked_super() to
ensure that concurrent mounters don't fail to open block devices that
are still in use because blkdev_put() in sb->kill_sb() hasn't been
called yet.

We can now do this as we can make iterators through @fs_super and
@super_blocks wait without holding s_umount. Concurrent mounts will wait
until a dying superblock is fully dead so until sb->kill_sb() has been
called and SB_DEAD been set. Concurrent iterators can already discard
any SB_DYING superblock.

Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230818-vfs-super-fixes-v3-v3-4-9f0b1876e46b@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

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This commit is contained in:

Christian Brauner 2023-08-18 16:00:51 +02:00

parent 5e87491415

commit 2c18a63b76

2 changed files with 65 additions and 7 deletions

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71

fs/super.c

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1

include/linux/fs.h

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