static inline void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
					   struct btrfs_backref_node *lower,
					   struct btrfs_backref_node *upper,
					   int link_which)
void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
			     struct btrfs_backref_node *lower,
			     struct btrfs_backref_node *upper,
			     int link_which)