58 	struct list_head lower;  member
229 				  struct backref_node, lower);  in backref_cache_cleanup()
252 		INIT_LIST_HEAD(&node->lower);  in alloc_backref_node()
370 	struct backref_node *lower;  in walk_down_backref()  local
375 		lower = edge->node[LOWER];  in walk_down_backref()
376 		if (list_is_last(&edge->list[LOWER], &lower->upper)) {  in walk_down_backref()
414 	list_del(&node->lower);  in drop_backref_node()
452 		if (list_empty(&upper->lower)) {  in remove_backref_node()
453 			list_add_tail(&upper->lower, &cache->leaves);  in remove_backref_node()
674 	struct backref_node *lower;  local
909 		lower = cur;
914 				       lower->bytenr);
916 					list_add(&lower->list, &useless);
918 					lower->root = root;
939 				upper->level = lower->level + 1;
972 			list_add_tail(&edge->list[LOWER], &lower->upper);
973 			edge->node[LOWER] = lower;
978 			lower = upper;
1018 		list_add_tail(&node->lower, &cache->leaves);
1030 			lower = edge->node[LOWER];
1032 			if (list_empty(&lower->upper))
1033 				list_add(&lower->list, &useless);
1039 				list_del_init(&upper->lower);
1043 			list_add_tail(&edge->list[UPPER], &upper->lower);
1057 		list_add_tail(&edge->list[UPPER], &upper->lower);
1075 			list_del_init(&upper->lower);
1078 		while (!list_empty(&upper->lower)) {
1079 			edge = list_entry(upper->lower.next,
1083 			lower = edge->node[LOWER];
1086 			if (list_empty(&lower->upper))
1087 				list_add(&lower->list, &useless);
1103 			lower = list_entry(useless.next,
1105 			list_del_init(&lower->upper);
1184 		list_for_each_entry(edge, &node->lower, list[UPPER]) {
1192 				      &new_node->lower);
1195 		list_add_tail(&new_node->lower, &cache->leaves);
1204 		list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1211 	while (!list_empty(&new_node->lower)) {
1212 		new_edge = list_entry(new_node->lower.next,