xfs: use xfs_ilock_attr_map_shared in xfs_attr_list_int

We might not have read in the extent list at this point, so make sure we
take the ilock exclusively if we have to do so.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_attr_list.c

@@ -507,17 +507,17 @@ xfs_attr_list_int(
 {
 	int error;
 	xfs_inode_t *dp = context->dp;
+	uint		lock_mode;
 
 	XFS_STATS_INC(xs_attr_list);
 
 	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
 		return EIO;
 
-	xfs_ilock(dp, XFS_ILOCK_SHARED);
-
 	/*
 	 * Decide on what work routines to call based on the inode size.
 	 */
+	lock_mode = xfs_ilock_attr_map_shared(dp);
 	if (!xfs_inode_hasattr(dp)) {
 		error = 0;
 	} else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL) {
@@ -527,9 +527,7 @@ xfs_attr_list_int(
 	} else {
 		error = xfs_attr_node_list(context);
 	}
-
-	xfs_iunlock(dp, XFS_ILOCK_SHARED);
-
+	xfs_iunlock(dp, lock_mode);
 	return error;
 }