On Thu 01-06-23 15:58:58, Christian Brauner wrote:
On Thu, Jun 01, 2023 at 12:58:24PM +0200, Jan Kara wrote:
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
fs/inode.c | 42 ++++++++++++++++++++++++++++++++++++++++++ fs/internal.h | 2 ++ fs/namei.c | 4 ++-- 3 files changed, 46 insertions(+), 2 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c index 577799b7855f..4000ab08bbc0 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1103,6 +1103,48 @@ void discard_new_inode(struct inode *inode) } EXPORT_SYMBOL(discard_new_inode); +/**
- lock_two_inodes - lock two inodes (may be regular files but also dirs)
- Lock any non-NULL argument. The caller must make sure that if he is passing
- in two directories, one is not ancestor of the other. Zero, one or two
- objects may be locked by this function.
- @inode1: first inode to lock
- @inode2: second inode to lock
- @subclass1: inode lock subclass for the first lock obtained
- @subclass2: inode lock subclass for the second lock obtained
- */
+void lock_two_inodes(struct inode *inode1, struct inode *inode2,
unsigned subclass1, unsigned subclass2)+{
- if (!inode1 || !inode2)
I think you forgot the opening bracket... I can just fix this up for you though.
Oh, yes. Apparently I forgot to rerun git-format-patch after fixing up this bit. I'm sorry for that. The patch series has survived full ext4 fstests run on my end.
Honza