xfs: advance the findparent inode scan cursor while holding ILOCK

LOLLM pointed out a race condition in xrep_findparent_scan -- the
directory live update hook holds the directory ILOCK when it calls the
xchk_iscan_want_live_update predicate to figure out if it needs to
remember the live update, but xrep_findparent_scan drops the directory
ILOCK before advancing the cursor.  Therefore, it's possible for a live
update to check the scan cursor after the scan drops the ILOCK but
before the scan updates its cursor.  If this happens, we'll fail to
record the live update.  Fix this by moving the cursor update logic
inside xrep_findparent_walk_directory.

Note that for non-directories it's ok to advance the cursor without
holding any ILOCK because the findparent scan only cares about directory
parents, not the children.

Cc: stable@vger.kernel.org # v6.10
Fixes: a07b45576264e7 ("xfs: scan the filesystem to repair a directory dotdot entry")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

0 files changed, 0 insertions, 0 deletions