4892 				     struct walk_control *wc,  in reada_walk_down()  argument
4907 	if (path->slots[wc->level] < wc->reada_slot) {  in reada_walk_down()
4908 		wc->reada_count = wc->reada_count * 2 / 3;  in reada_walk_down()
4909 		wc->reada_count = max(wc->reada_count, 2);  in reada_walk_down()
4911 		wc->reada_count = wc->reada_count * 3 / 2;  in reada_walk_down()
4912 		wc->reada_count = min_t(int, wc->reada_count,  in reada_walk_down()
4916 	eb = path->nodes[wc->level];  in reada_walk_down()
4919 	for (slot = path->slots[wc->level]; slot < nritems; slot++) {  in reada_walk_down()
4920 		if (nread >= wc->reada_count)  in reada_walk_down()
4927 		if (slot == path->slots[wc->level])  in reada_walk_down()
4930 		if (wc->stage == UPDATE_BACKREF &&  in reada_walk_down()
4936 					       wc->level - 1, 1, &refs,  in reada_walk_down()
4943 		if (wc->stage == DROP_REFERENCE) {  in reada_walk_down()
4947 			if (wc->level == 1 &&  in reada_walk_down()
4950 			if (!wc->update_ref ||  in reada_walk_down()
4955 						  &wc->update_progress);  in reada_walk_down()
4959 			if (wc->level == 1 &&  in reada_walk_down()
4967 	wc->reada_slot = slot;  in reada_walk_down()
4973  * when wc->stage == UPDATE_BACKREF, this function updates
4981 				   struct walk_control *wc, int lookup_info)  in walk_down_proc()  argument
4984 	int level = wc->level;  in walk_down_proc()
4989 	if (wc->stage == UPDATE_BACKREF &&  in walk_down_proc()
4998 	    ((wc->stage == DROP_REFERENCE && wc->refs[level] != 1) ||  in walk_down_proc()
4999 	     (wc->stage == UPDATE_BACKREF && !(wc->flags[level] & flag)))) {  in walk_down_proc()
5003 					       &wc->refs[level],  in walk_down_proc()
5004 					       &wc->flags[level]);  in walk_down_proc()
5008 		BUG_ON(wc->refs[level] == 0);  in walk_down_proc()
5011 	if (wc->stage == DROP_REFERENCE) {  in walk_down_proc()
5012 		if (wc->refs[level] > 1)  in walk_down_proc()
5015 		if (path->locks[level] && !wc->keep_locks) {  in walk_down_proc()
5022 	/* wc->stage == UPDATE_BACKREF */  in walk_down_proc()
5023 	if (!(wc->flags[level] & flag)) {  in walk_down_proc()
5032 		wc->flags[level] |= flag;  in walk_down_proc()
5076  * when wc->stage == DROP_REFERENCE, this function checks
5079  * rooted at the block, this function changes wc->stage to
5089 				 struct walk_control *wc, int *lookup_info)  in do_walk_down()  argument
5099 	int level = wc->level;  in do_walk_down()
5111 	if (wc->stage == UPDATE_BACKREF &&  in do_walk_down()
5132 				       &wc->refs[level - 1],  in do_walk_down()
5133 				       &wc->flags[level - 1]);  in do_walk_down()
5137 	if (unlikely(wc->refs[level - 1] == 0)) {  in do_walk_down()
5144 	if (wc->stage == DROP_REFERENCE) {  in do_walk_down()
5145 		if (wc->refs[level - 1] > 1) {  in do_walk_down()
5148 			    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))  in do_walk_down()
5151 			if (!wc->update_ref ||  in do_walk_down()
5157 			ret = btrfs_comp_cpu_keys(&key, &wc->update_progress);  in do_walk_down()
5161 			wc->stage = UPDATE_BACKREF;  in do_walk_down()
5162 			wc->shared_level = level - 1;  in do_walk_down()
5166 		    (wc->flags[0] & BTRFS_BLOCK_FLAG_FULL_BACKREF))  in do_walk_down()
5179 			reada_walk_down(trans, root, wc, path);  in do_walk_down()
5201 	wc->level = level;  in do_walk_down()
5202 	if (wc->level == 1)  in do_walk_down()
5203 		wc->reada_slot = 0;  in do_walk_down()
5206 	wc->refs[level - 1] = 0;  in do_walk_down()
5207 	wc->flags[level - 1] = 0;  in do_walk_down()
5208 	if (wc->stage == DROP_REFERENCE) {  in do_walk_down()
5209 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {  in do_walk_down()
5230 		if (wc->restarted) {  in do_walk_down()
5238 			wc->restarted = 0;  in do_walk_down()
5263 		wc->drop_level = level;  in do_walk_down()
5264 		find_next_key(path, level, &wc->drop_progress);  in do_walk_down()
5287  * when wc->stage == DROP_REFERENCE, this function drops
5290  * when wc->stage == UPDATE_BACKREF, this function changes
5291  * wc->stage back to DROP_REFERENCE if we changed wc->stage
5299 				 struct walk_control *wc)  in walk_up_proc()  argument
5303 	int level = wc->level;  in walk_up_proc()
5307 	if (wc->stage == UPDATE_BACKREF) {  in walk_up_proc()
5308 		BUG_ON(wc->shared_level < level);  in walk_up_proc()
5309 		if (level < wc->shared_level)  in walk_up_proc()
5312 		ret = find_next_key(path, level + 1, &wc->update_progress);  in walk_up_proc()
5314 			wc->update_ref = 0;  in walk_up_proc()
5316 		wc->stage = DROP_REFERENCE;  in walk_up_proc()
5317 		wc->shared_level = -1;  in walk_up_proc()
5332 						       &wc->refs[level],  in walk_up_proc()
5333 						       &wc->flags[level]);  in walk_up_proc()
5339 			BUG_ON(wc->refs[level] == 0);  in walk_up_proc()
5340 			if (wc->refs[level] == 1) {  in walk_up_proc()
5348 	/* wc->stage == DROP_REFERENCE */  in walk_up_proc()
5349 	BUG_ON(wc->refs[level] > 1 && !path->locks[level]);  in walk_up_proc()
5351 	if (wc->refs[level] == 1) {  in walk_up_proc()
5353 			if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5377 		if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5382 		if (wc->flags[level + 1] & BTRFS_BLOCK_FLAG_FULL_BACKREF)  in walk_up_proc()
5389 	btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1);  in walk_up_proc()
5391 	wc->refs[level] = 0;  in walk_up_proc()
5392 	wc->flags[level] = 0;  in walk_up_proc()
5404 				   struct walk_control *wc)  in walk_down_tree()  argument
5406 	int level = wc->level;  in walk_down_tree()
5411 		ret = walk_down_proc(trans, root, path, wc, lookup_info);  in walk_down_tree()
5422 		ret = do_walk_down(trans, root, path, wc, &lookup_info);  in walk_down_tree()
5428 		level = wc->level;  in walk_down_tree()
5436 				 struct walk_control *wc, int max_level)  in walk_up_tree()  argument
5438 	int level = wc->level;  in walk_up_tree()
5443 		wc->level = level;  in walk_up_tree()
5449 			ret = walk_up_proc(trans, root, path, wc);  in walk_up_tree()
5488 	struct walk_control *wc;  in btrfs_drop_snapshot()  local
5503 	wc = kzalloc(sizeof(*wc), GFP_NOFS);  in btrfs_drop_snapshot()
5504 	if (!wc) {  in btrfs_drop_snapshot()
5541 		memset(&wc->update_progress, 0,  in btrfs_drop_snapshot()
5542 		       sizeof(wc->update_progress));  in btrfs_drop_snapshot()
5545 		memcpy(&wc->update_progress, &key,  in btrfs_drop_snapshot()
5546 		       sizeof(wc->update_progress));  in btrfs_drop_snapshot()
5572 						level, 1, &wc->refs[level],  in btrfs_drop_snapshot()
5573 						&wc->flags[level]);  in btrfs_drop_snapshot()
5578 			BUG_ON(wc->refs[level] == 0);  in btrfs_drop_snapshot()
5585 			WARN_ON(wc->refs[level] != 1);  in btrfs_drop_snapshot()
5590 	wc->restarted = test_bit(BTRFS_ROOT_DEAD_TREE, &root->state);  in btrfs_drop_snapshot()
5591 	wc->level = level;  in btrfs_drop_snapshot()
5592 	wc->shared_level = -1;  in btrfs_drop_snapshot()
5593 	wc->stage = DROP_REFERENCE;  in btrfs_drop_snapshot()
5594 	wc->update_ref = update_ref;  in btrfs_drop_snapshot()
5595 	wc->keep_locks = 0;  in btrfs_drop_snapshot()
5596 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);  in btrfs_drop_snapshot()
5600 		ret = walk_down_tree(trans, root, path, wc);  in btrfs_drop_snapshot()
5606 		ret = walk_up_tree(trans, root, path, wc, BTRFS_MAX_LEVEL);  in btrfs_drop_snapshot()
5613 			BUG_ON(wc->stage != DROP_REFERENCE);  in btrfs_drop_snapshot()
5617 		if (wc->stage == DROP_REFERENCE) {  in btrfs_drop_snapshot()
5618 			wc->drop_level = wc->level;  in btrfs_drop_snapshot()
5619 			btrfs_node_key_to_cpu(path->nodes[wc->drop_level],  in btrfs_drop_snapshot()
5620 					      &wc->drop_progress,  in btrfs_drop_snapshot()
5621 					      path->slots[wc->drop_level]);  in btrfs_drop_snapshot()
5624 				      &wc->drop_progress);  in btrfs_drop_snapshot()
5625 		btrfs_set_root_drop_level(root_item, wc->drop_level);  in btrfs_drop_snapshot()
5627 		BUG_ON(wc->level == 0);  in btrfs_drop_snapshot()
5707 	kfree(wc);  in btrfs_drop_snapshot()
5735 	struct walk_control *wc;  in btrfs_drop_subtree()  local
5747 	wc = kzalloc(sizeof(*wc), GFP_NOFS);  in btrfs_drop_subtree()
5748 	if (!wc) {  in btrfs_drop_subtree()
5765 	wc->refs[parent_level] = 1;  in btrfs_drop_subtree()
5766 	wc->flags[parent_level] = BTRFS_BLOCK_FLAG_FULL_BACKREF;  in btrfs_drop_subtree()
5767 	wc->level = level;  in btrfs_drop_subtree()
5768 	wc->shared_level = -1;  in btrfs_drop_subtree()
5769 	wc->stage = DROP_REFERENCE;  in btrfs_drop_subtree()
5770 	wc->update_ref = 0;  in btrfs_drop_subtree()
5771 	wc->keep_locks = 1;  in btrfs_drop_subtree()
5772 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(fs_info);  in btrfs_drop_subtree()
5775 		wret = walk_down_tree(trans, root, path, wc);  in btrfs_drop_subtree()
5781 		wret = walk_up_tree(trans, root, path, wc, parent_level);  in btrfs_drop_subtree()
5788 	kfree(wc);  in btrfs_drop_subtree()