xfs: don't iunlock unlocked inodes

Don't iunlock an unlocked inode, which can happen if the parent pointer
scrubber bails out with sc->ip unlocked while trying to grab the parent
directory inode.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>

fs/xfs/scrub/scrub.c

@@ -159,7 +159,8 @@ xfs_scrub_teardown(
 		sc->tp = NULL;
 	}
 	if (sc->ip) {
-		xfs_iunlock(sc->ip, sc->ilock_flags);
+		if (sc->ilock_flags)
+			xfs_iunlock(sc->ip, sc->ilock_flags);
 		if (sc->ip != ip_in &&
 		    !xfs_internal_inum(sc->mp, sc->ip->i_ino))
 			iput(VFS_I(sc->ip));