xfs: set buf types when converting extent formats

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.

cc: <stable@vger.kernel.org> # 3.10 to current
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>

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index b5eb474..4e20fe7 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -973,7 +973,11 @@
 	*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 */