fs: Establish locking order for unrelated directories

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commit f23ce75718 upstream.

Currently the locking order of inode locks for directories that are not
in ancestor relationship is not defined because all operations that
needed to lock two directories like this were serialized by
sb->s_vfs_rename_mutex. However some filesystems need to lock two
subdirectories for RENAME_EXCHANGE operations and for this we need the
locking order established even for two tree-unrelated directories.
Provide a helper function lock_two_inodes() that establishes lock
ordering for any two inodes and use it in lock_two_directories().

CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230601105830.13168-4-jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Jan Kara 2023-06-01 12:58:24 +02:00 • committed by Greg Kroah-Hartman

parent f55aaecb4d

commit 4cbd5eb173

3 changed files with 46 additions and 2 deletions

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42

fs/inode.c

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2

fs/internal.h

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4

fs/namei.c

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