5241 				     struct walk_control *wc,  in reada_walk_down()  argument
5256 	if (path->slots[wc->level] < wc->reada_slot) {  in reada_walk_down()
5257 		wc->reada_count = wc->reada_count * 2 / 3;  in reada_walk_down()
5258 		wc->reada_count = max(wc->reada_count, 2);  in reada_walk_down()
5260 		wc->reada_count = wc->reada_count * 3 / 2;  in reada_walk_down()
5261 		wc->reada_count = min_t(int, wc->reada_count,  in reada_walk_down()
5265 	eb = path->nodes[wc->level];  in reada_walk_down()
5268 	for (slot = path->slots[wc->level]; slot < nritems; slot++) {  in reada_walk_down()
5269 		if (nread >= wc->reada_count)  in reada_walk_down()
5276 		if (slot == path->slots[wc->level])  in reada_walk_down()
5279 		if (wc->stage == UPDATE_BACKREF &&  in reada_walk_down()
5285 					       wc->level - 1, 1, &refs,  in reada_walk_down()
5292 		if (wc->stage == DROP_REFERENCE) {  in reada_walk_down()
5296 			if (wc->level == 1 &&  in reada_walk_down()
5299 			if (!wc->update_ref ||  in reada_walk_down()
5304 						  &wc->update_progress);  in reada_walk_down()
5308 			if (wc->level == 1 &&  in reada_walk_down()
5316 	wc->reada_slot = slot;  in reada_walk_down()
5322  * when wc->stage == UPDATE_BACKREF, this function updates
5330 				   struct walk_control *wc, int lookup_info)  in walk_down_proc()  argument
5333 	int level = wc->level;  in walk_down_proc()
5338 	if (wc->stage == UPDATE_BACKREF &&  in walk_down_proc()
5347 	    ((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||  in walk_down_proc()
5348 	     (wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {  in walk_down_proc()
5352 					       &wc->refs[level],  in walk_down_proc()
5353 					       &wc->flags[level],  in walk_down_proc()
5358 		BUG_ON(wc->refs[level] == 0);  in walk_down_proc()
5361 	if (wc->stage == DROP_REFERENCE) {  in walk_down_proc()
5362 		if (wc->refs[level] > 1)  in walk_down_proc()
5365 		if (path->locks[level] && !wc->keep_locks) {  in walk_down_proc()
5372 	/* wc->stage == UPDATE_BACKREF */  in walk_down_proc()
5373 	if (!(wc->flags[level] & flag)) {  in walk_down_proc()
5381 		wc->flags[level] |= flag;  in walk_down_proc()
5425  * when wc->stage == DROP_REFERENCE, this function checks
5428  * rooted at the block, this function changes wc->stage to
5438 				 struct walk_control *wc, int *lookup_info)  in do_walk_down()  argument
5449 	int level = wc->level;  in do_walk_down()
5461 	if (wc->stage == UPDATE_BACKREF &&  in do_walk_down()
5487 				       &wc->refs[level - 1],  in do_walk_down()
5488 				       &wc->flags[level - 1],  in do_walk_down()
5493 	if (unlikely(wc->refs[level - 1] == 0)) {  in do_walk_down()
5500 	if (wc->stage == DROP_REFERENCE) {  in do_walk_down()
5501 		if (wc->refs[level - 1] > 1) {  in do_walk_down()
5504 			    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))  in do_walk_down()
5507 			if (!wc->update_ref ||  in do_walk_down()
5513 			ret = btrfs_comp_cpu_keys(&key, &wc->update_progress);  in do_walk_down()
5517 			wc->stage = UPDATE_BACKREF;  in do_walk_down()
5518 			wc->shared_level = level - 1;  in do_walk_down()
5522 		    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))  in do_walk_down()
5535 			reada_walk_down(trans, root, wc, path);  in do_walk_down()
5556 	wc->level = level;  in do_walk_down()
5557 	if (wc->level == 1)  in do_walk_down()
5558 		wc->reada_slot = 0;  in do_walk_down()
5561 	wc->refs[level - 1] = 0;  in do_walk_down()
5562 	wc->flags[level - 1] = 0;  in do_walk_down()
5563 	if (wc->stage == DROP_REFERENCE) {  in do_walk_down()
5564 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {  in do_walk_down()
5585 		if (wc->restarted) {  in do_walk_down()
5593 			wc->restarted = 0;  in do_walk_down()
5618 		wc->drop_level = level;  in do_walk_down()
5619 		find_next_key(path, level, &wc->drop_progress);  in do_walk_down()
5643  * when wc->stage == DROP_REFERENCE, this function drops
5646  * when wc->stage == UPDATE_BACKREF, this function changes
5647  * wc->stage back to DROP_REFERENCE if we changed wc->stage
5655 				 struct walk_control *wc)  in walk_up_proc()  argument
5659 	int level = wc->level;  in walk_up_proc()
5663 	if (wc->stage == UPDATE_BACKREF) {  in walk_up_proc()
5664 		BUG_ON(wc->shared_level < level);  in walk_up_proc()
5665 		if (level < wc->shared_level)  in walk_up_proc()
5668 		ret = find_next_key(path, level + 1, &wc->update_progress);  in walk_up_proc()
5670 			wc->update_ref = 0;  in walk_up_proc()
5672 		wc->stage = DROP_REFERENCE;  in walk_up_proc()
5673 		wc->shared_level = -1;  in walk_up_proc()
5688 						       &wc->refs[level],  in walk_up_proc()
5689 						       &wc->flags[level],  in walk_up_proc()
5696 			BUG_ON(wc->refs[level] == 0);  in walk_up_proc()
5697 			if (wc->refs[level] == 1) {  in walk_up_proc()
5705 	/* wc->stage == DROP_REFERENCE */  in walk_up_proc()
5706 	BUG_ON(wc->refs[level] > 1 && !path->locks[level]);  in walk_up_proc()
5708 	if (wc->refs[level] == 1) {  in walk_up_proc()
5710 			if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5733 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5738 		if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5746 			      wc->refs[level] == 1);  in walk_up_proc()
5748 	wc->refs[level] = 0;  in walk_up_proc()
5749 	wc->flags[level] = 0;  in walk_up_proc()
5761 				   struct walk_control *wc)  in walk_down_tree()  argument
5763 	int level = wc->level;  in walk_down_tree()
5768 		ret = walk_down_proc(trans, root, path, wc, lookup_info);  in walk_down_tree()
5779 		ret = do_walk_down(trans, root, path, wc, &lookup_info);  in walk_down_tree()
5785 		level = wc->level;  in walk_down_tree()
5793 				 struct walk_control *wc, int max_level)  in walk_up_tree()  argument
5795 	int level = wc->level;  in walk_up_tree()
5800 		wc->level = level;  in walk_up_tree()
5806 			ret = walk_up_proc(trans, root, path, wc);  in walk_up_tree()
5847 	struct walk_control *wc;  in btrfs_drop_snapshot()  local
5863 	wc = kzalloc(sizeof(*wc), GFP_NOFS);  in btrfs_drop_snapshot()
5864 	if (!wc) {  in btrfs_drop_snapshot()
5903 		memset(&wc->update_progress, 0,  in btrfs_drop_snapshot()
5904 		       sizeof(wc->update_progress));  in btrfs_drop_snapshot()
5907 		memcpy(&wc->update_progress, &key,  in btrfs_drop_snapshot()
5908 		       sizeof(wc->update_progress));  in btrfs_drop_snapshot()
5934 						level, 1, &wc->refs[level],  in btrfs_drop_snapshot()
5935 						&wc->flags[level], NULL);  in btrfs_drop_snapshot()
5940 			BUG_ON(wc->refs[level] == 0);  in btrfs_drop_snapshot()
5947 			WARN_ON(wc->refs[level] != 1);  in btrfs_drop_snapshot()
5952 	wc->restarted = test_bit(BTRFS_ROOT_DEAD_TREE, &root->state);  in btrfs_drop_snapshot()
5953 	wc->level = level;  in btrfs_drop_snapshot()
5954 	wc->shared_level = -1;  in btrfs_drop_snapshot()
5955 	wc->stage = DROP_REFERENCE;  in btrfs_drop_snapshot()
5956 	wc->update_ref = update_ref;  in btrfs_drop_snapshot()
5957 	wc->keep_locks = 0;  in btrfs_drop_snapshot()
5958 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);  in btrfs_drop_snapshot()
5962 		ret = walk_down_tree(trans, root, path, wc);  in btrfs_drop_snapshot()
5969 		ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);  in btrfs_drop_snapshot()
5977 			BUG_ON(wc->stage != DROP_REFERENCE);  in btrfs_drop_snapshot()
5981 		if (wc->stage == DROP_REFERENCE) {  in btrfs_drop_snapshot()
5982 			wc->drop_level = wc->level;  in btrfs_drop_snapshot()
5983 			btrfs_node_key_to_cpu(path->nodes[wc->drop_level],  in btrfs_drop_snapshot()
5984 					      &wc->drop_progress,  in btrfs_drop_snapshot()
5985 					      path->slots[wc->drop_level]);  in btrfs_drop_snapshot()
5988 				      &wc->drop_progress);  in btrfs_drop_snapshot()
5989 		btrfs_set_root_drop_level(root_item, wc->drop_level);  in btrfs_drop_snapshot()
5991 		BUG_ON(wc->level == 0);  in btrfs_drop_snapshot()
6077 	kfree(wc);  in btrfs_drop_snapshot()
6112 	struct walk_control *wc;  in btrfs_drop_subtree()  local
6124 	wc = kzalloc(sizeof(*wc), GFP_NOFS);  in btrfs_drop_subtree()
6125 	if (!wc) {  in btrfs_drop_subtree()
6142 	wc->refs[parent_level] = 1;  in btrfs_drop_subtree()
6143 	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;  in btrfs_drop_subtree()
6144 	wc->level = level;  in btrfs_drop_subtree()
6145 	wc->shared_level = -1;  in btrfs_drop_subtree()
6146 	wc->stage = DROP_REFERENCE;  in btrfs_drop_subtree()
6147 	wc->update_ref = 0;  in btrfs_drop_subtree()
6148 	wc->keep_locks = 1;  in btrfs_drop_subtree()
6149 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);  in btrfs_drop_subtree()
6152 		wret = walk_down_tree(trans, root, path, wc);  in btrfs_drop_subtree()
6158 		wret = walk_up_tree(trans, root, path, wc, parent_level);  in btrfs_drop_subtree()
6165 	kfree(wc);  in btrfs_drop_subtree()