ocfs2: Use ocfs2_rec_clusters in ocfs2_adjust_adjacent_records.

In ocfs2_adjust_adjacent_records, we will adjust adjacent records
according to the extent_list in the lower level. But actually
the lower level tree will either be a leaf or a branch. If we only
use ocfs2_is_empty_extent we will meet with some problem if the lower
tree is a branch (tree_depth > 1). So use !ocfs2_rec_clusters instead.
And actually only the leaf record can have holes. So add a BUG_ON
for non-leaf branch.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/alloc.c

@@ -1914,7 +1914,8 @@ static void ocfs2_adjust_adjacent_records(struct ocfs2_extent_rec *left_rec,
 	 * immediately to their right.
 	 */
 	left_clusters = le32_to_cpu(right_child_el->l_recs[0].e_cpos);
-	if (ocfs2_is_empty_extent(&right_child_el->l_recs[0])) {
+	if (!ocfs2_rec_clusters(right_child_el, &right_child_el->l_recs[0])) {
+		BUG_ON(right_child_el->l_tree_depth);
 		BUG_ON(le16_to_cpu(right_child_el->l_next_free_rec) <= 1);
 		left_clusters = le32_to_cpu(right_child_el->l_recs[1].e_cpos);
 	}