179 	/* List of lower level edges, which link this node to its children */
180 	struct list_head lower;  member
213 #define LOWER	0  macro
217  * Represent an edge connecting upper and lower backref nodes.
221 	 * list[LOWER] is linked to btrfs_backref_node::upper of lower level
222 	 * node, and list[UPPER] is linked to btrfs_backref_node::lower of
283 					   struct btrfs_backref_node *lower,  in btrfs_backref_link_edge()  argument
287 	ASSERT(upper && lower && upper->level == lower->level + 1);  in btrfs_backref_link_edge()
288 	edge->node[LOWER] = lower;  in btrfs_backref_link_edge()
291 		list_add_tail(&edge->list[LOWER], &lower->upper);  in btrfs_backref_link_edge()
293 		list_add_tail(&edge->list[UPPER], &upper->lower);  in btrfs_backref_link_edge()
301 		ASSERT(list_empty(&node->lower));  in btrfs_backref_free_node()
351 	list_del_init(&node->lower);  in btrfs_backref_drop_node()