xfs: set buf types when converting extent formats

commit fe22d552 upstream.

Conversion from local to extent format does not set the buffer type
correctly on the new extent buffer when a symlink data is moved out
of line.

Fix the symlink code and leave a comment in the generic bmap code
reminding us that the format-specific data copy needs to set the
destination buffer type appropriately.
Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
[ luis: backported to 3.16: libxfs infrastructure not available in 3.16 kernel ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/xfs/xfs_bmap.c

@@ -976,7 +976,11 @@ xfs_bmap_local_to_extents(
 	*firstblock = args.fsbno;
 	bp = xfs_btree_get_bufl(args.mp, tp, args.fsbno, 0);
 
-	/* initialise the block and copy the data */
+	/*
+	 * Initialise the block and copy the data
+	 *
+	 * Note: init_fn must set the buffer log item type correctly!
+	 */
 	init_fn(tp, bp, ip, ifp);
 
 	/* account for the change in fork size and log everything */

fs/xfs/xfs_symlink_remote.c

@@ -180,6 +180,8 @@ xfs_symlink_local_to_remote(
 	struct xfs_mount	*mp = ip->i_mount;
 	char			*buf;
 
+	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
+
 	if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 		bp->b_ops = NULL;
 		memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);