xfs: don't double-lock when deleting a self-referential directory

xfs: don't double-lock when deleting a self-referential directory

LOLLM notices that the dirtree scrubber can detect a directory that
refers to itself.  In this case, it's not correct for the directory tree
repair code to try to iolock/ilock both sc->ip and dp, because they're
the same inode.  Fix this by detecting that corner case and handling it
appropriately.

Cc: stable@vger.kernel.org # v6.10
Fixes: 3f31406aef493b ("xfs: fix corruptions in the directory tree")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>