2505 	INIT_LIST_HEAD(&node->upper);
2528  * upper edges and any uncached nodes in the path.
2536 	struct btrfs_backref_node *upper;  local
2543 	while (!list_empty(&node->upper)) {
2544 		edge = list_entry(node->upper.next, struct btrfs_backref_edge,
2546 		upper = edge->node[UPPER];
2548 		list_del(&edge->list[UPPER]);
2551 		if (RB_EMPTY_NODE(&upper->rb_node)) {
2552 			BUG_ON(!list_empty(&node->upper));
2554 			node = upper;
2562 		if (list_empty(&upper->lower)) {
2563 			list_add_tail(&upper->lower, &cache->leaves);
2564 			upper->lowest = 1;
2621 	struct btrfs_backref_node *upper;  local
2654 		upper = btrfs_backref_alloc_node(cache, ref_key->offset,
2656 		if (!upper) {
2662 		 *  Backrefs for the upper level block isn't cached, add the
2665 		list_add_tail(&edge->list[UPPER], &cache->pending_edge);
2668 		upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
2669 		ASSERT(upper->checked);
2670 		INIT_LIST_HEAD(&edge->list[UPPER]);
2672 	btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER);
2695 	struct btrfs_backref_node *upper;  local
2786 			upper = btrfs_backref_alloc_node(cache, eb->start,
2788 			if (!upper) {
2794 			upper->owner = btrfs_header_owner(eb);
2796 				upper->cowonly = 1;
2803 				upper->checked = 0;
2805 				upper->checked = 1;
2812 			if (!upper->checked && need_check) {
2814 				list_add_tail(&edge->list[UPPER],
2817 				if (upper->checked)
2819 				INIT_LIST_HEAD(&edge->list[UPPER]);
2822 			upper = rb_entry(rb_node, struct btrfs_backref_node,
2824 			ASSERT(upper->checked);
2825 			INIT_LIST_HEAD(&edge->list[UPPER]);
2826 			if (!upper->owner)
2827 				upper->owner = btrfs_header_owner(eb);
2829 		btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER);
2835 		lower = upper;
2836 		upper = NULL;
2846  * NOTE: Even if the function returned 0, @cur is not yet cached as its upper
2883 	if (!list_empty(&cur->upper)) {
2888 		ASSERT(list_is_singular(&cur->upper));
2889 		edge = list_entry(cur->upper.next, struct btrfs_backref_edge,
2891 		ASSERT(list_empty(&edge->list[UPPER]));
2892 		exist = edge->node[UPPER];
2894 		 * Add the upper level block to pending list if we need check
2898 			list_add_tail(&edge->list[UPPER], &cache->pending_edge);
3005 	list_for_each_entry(edge, &start->upper, list[LOWER])
3006 		list_add_tail(&edge->list[UPPER], &pending_edge);
3009 		struct btrfs_backref_node *upper;  local
3013 				struct btrfs_backref_edge, list[UPPER]);
3014 		list_del_init(&edge->list[UPPER]);
3015 		upper = edge->node[UPPER];
3019 		if (upper->detached) {
3024 			if (list_empty(&lower->upper))
3032 		 * So if we have upper->rb_node populated, this means a cache
3033 		 * hit. We only need to link the edge, as @upper and all its
3036 		if (!RB_EMPTY_NODE(&upper->rb_node)) {
3037 			if (upper->lowest) {
3038 				list_del_init(&upper->lower);
3039 				upper->lowest = 0;
3042 			list_add_tail(&edge->list[UPPER], &upper->lower);
3047 		if (!upper->checked) {
3053 		if (start->cowonly != upper->cowonly) {
3059 		if (!upper->cowonly) {
3060 			rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
3061 						   &upper->rb_node);
3064 						upper->bytenr, -EEXIST);
3069 		list_add_tail(&edge->list[UPPER], &upper->lower);
3073 		 * to finish the upper linkage
3075 		list_for_each_entry(edge, &upper->upper, list[LOWER])
3076 			list_add_tail(&edge->list[UPPER], &pending_edge);
3085 	struct btrfs_backref_node *upper;  local
3095 				struct btrfs_backref_edge, list[UPPER]);
3096 		list_del(&edge->list[UPPER]);
3099 		upper = edge->node[UPPER];
3103 		 * Lower is no longer linked to any upper backref nodes and
3106 		if (list_empty(&lower->upper) &&
3110 		if (!RB_EMPTY_NODE(&upper->rb_node))
3113 		/* Add this guy's upper edges to the list to process */
3114 		list_for_each_entry(edge, &upper->upper, list[LOWER])
3115 			list_add_tail(&edge->list[UPPER],
3117 		if (list_empty(&upper->upper))
3118 			list_add(&upper->list, &cache->useless_node);