177 	/* List of lower level edges, which link this node to its children */
178 	struct list_head lower;  member
211 #define LOWER	0  macro
215  * Represent an edge connecting upper and lower backref nodes.
219 	 * list[LOWER] is linked to btrfs_backref_node::upper of lower level
220 	 * node, and list[UPPER] is linked to btrfs_backref_node::lower of
281 					   struct btrfs_backref_node *lower,  in btrfs_backref_link_edge()  argument
285 	ASSERT(upper && lower && upper->level == lower->level + 1);  in btrfs_backref_link_edge()
286 	edge->node[LOWER] = lower;  in btrfs_backref_link_edge()
289 		list_add_tail(&edge->list[LOWER], &lower->upper);  in btrfs_backref_link_edge()
291 		list_add_tail(&edge->list[UPPER], &upper->lower);  in btrfs_backref_link_edge()
299 		ASSERT(list_empty(&node->lower));  in btrfs_backref_free_node()
349 	list_del_init(&node->lower);  in btrfs_backref_drop_node()