xfs: enable the xfs_defer mechanism to process rmaps to update

Connect the xfs_defer mechanism with the pieces that we'll need to
handle deferred rmap updates.  We'll wire up the existing code to
our new deferred mechanism later.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_super.c

@@ -1876,6 +1876,7 @@ init_xfs_fs(void)
 			 XFS_BUILD_OPTIONS " enabled\n");
 
 	xfs_extent_free_init_defer_op();
+	xfs_rmap_update_init_defer_op();
 
 	xfs_dir_startup();