178 	/* List of lower level edges, which link this node to its children */
179 	struct list_head lower;  member
212 #define LOWER	0  macro
216  * Represent an edge connecting upper and lower backref nodes.
220 	 * list[LOWER] is linked to btrfs_backref_node::upper of lower level
221 	 * node, and list[UPPER] is linked to btrfs_backref_node::lower of
282 					   struct btrfs_backref_node *lower,  in btrfs_backref_link_edge()  argument
286 	ASSERT(upper && lower && upper->level == lower->level + 1);  in btrfs_backref_link_edge()
287 	edge->node[LOWER] = lower;  in btrfs_backref_link_edge()
290 		list_add_tail(&edge->list[LOWER], &lower->upper);  in btrfs_backref_link_edge()
292 		list_add_tail(&edge->list[UPPER], &upper->lower);  in btrfs_backref_link_edge()
347 	list_del(&node->lower);  in btrfs_backref_drop_node()