brintos / linux-shallow public Read only

1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (C) 2009 Oracle.  All rights reserved.4 */5 6#include <linux/sched.h>7#include <linux/pagemap.h>8#include <linux/writeback.h>9#include <linux/blkdev.h>10#include <linux/rbtree.h>11#include <linux/slab.h>12#include <linux/error-injection.h>13#include "ctree.h"14#include "disk-io.h"15#include "transaction.h"16#include "volumes.h"17#include "locking.h"18#include "btrfs_inode.h"19#include "async-thread.h"20#include "free-space-cache.h"21#include "qgroup.h"22#include "print-tree.h"23#include "delalloc-space.h"24#include "block-group.h"25#include "backref.h"26#include "misc.h"27#include "subpage.h"28#include "zoned.h"29#include "inode-item.h"30#include "space-info.h"31#include "fs.h"32#include "accessors.h"33#include "extent-tree.h"34#include "root-tree.h"35#include "file-item.h"36#include "relocation.h"37#include "super.h"38#include "tree-checker.h"39#include "raid-stripe-tree.h"40 41/*42 * Relocation overview43 *44 * [What does relocation do]45 *46 * The objective of relocation is to relocate all extents of the target block47 * group to other block groups.48 * This is utilized by resize (shrink only), profile converting, compacting49 * space, or balance routine to spread chunks over devices.50 *51 * 		Before		|		After52 * ------------------------------------------------------------------53 *  BG A: 10 data extents	| BG A: deleted54 *  BG B:  2 data extents	| BG B: 10 data extents (2 old + 8 relocated)55 *  BG C:  1 extents		| BG C:  3 data extents (1 old + 2 relocated)56 *57 * [How does relocation work]58 *59 * 1.   Mark the target block group read-only60 *      New extents won't be allocated from the target block group.61 *62 * 2.1  Record each extent in the target block group63 *      To build a proper map of extents to be relocated.64 *65 * 2.2  Build data reloc tree and reloc trees66 *      Data reloc tree will contain an inode, recording all newly relocated67 *      data extents.68 *      There will be only one data reloc tree for one data block group.69 *70 *      Reloc tree will be a special snapshot of its source tree, containing71 *      relocated tree blocks.72 *      Each tree referring to a tree block in target block group will get its73 *      reloc tree built.74 *75 * 2.3  Swap source tree with its corresponding reloc tree76 *      Each involved tree only refers to new extents after swap.77 *78 * 3.   Cleanup reloc trees and data reloc tree.79 *      As old extents in the target block group are still referenced by reloc80 *      trees, we need to clean them up before really freeing the target block81 *      group.82 *83 * The main complexity is in steps 2.2 and 2.3.84 *85 * The entry point of relocation is relocate_block_group() function.86 */87 88#define RELOCATION_RESERVED_NODES	25689/*90 * map address of tree root to tree91 */92struct mapping_node {93	struct {94		struct rb_node rb_node;95		u64 bytenr;96	}; /* Use rb_simle_node for search/insert */97	void *data;98};99 100struct mapping_tree {101	struct rb_root rb_root;102	spinlock_t lock;103};104 105/*106 * present a tree block to process107 */108struct tree_block {109	struct {110		struct rb_node rb_node;111		u64 bytenr;112	}; /* Use rb_simple_node for search/insert */113	u64 owner;114	struct btrfs_key key;115	u8 level;116	bool key_ready;117};118 119#define MAX_EXTENTS 128120 121struct file_extent_cluster {122	u64 start;123	u64 end;124	u64 boundary[MAX_EXTENTS];125	unsigned int nr;126	u64 owning_root;127};128 129/* Stages of data relocation. */130enum reloc_stage {131	MOVE_DATA_EXTENTS,132	UPDATE_DATA_PTRS133};134 135struct reloc_control {136	/* block group to relocate */137	struct btrfs_block_group *block_group;138	/* extent tree */139	struct btrfs_root *extent_root;140	/* inode for moving data */141	struct inode *data_inode;142 143	struct btrfs_block_rsv *block_rsv;144 145	struct btrfs_backref_cache backref_cache;146 147	struct file_extent_cluster cluster;148	/* tree blocks have been processed */149	struct extent_io_tree processed_blocks;150	/* map start of tree root to corresponding reloc tree */151	struct mapping_tree reloc_root_tree;152	/* list of reloc trees */153	struct list_head reloc_roots;154	/* list of subvolume trees that get relocated */155	struct list_head dirty_subvol_roots;156	/* size of metadata reservation for merging reloc trees */157	u64 merging_rsv_size;158	/* size of relocated tree nodes */159	u64 nodes_relocated;160	/* reserved size for block group relocation*/161	u64 reserved_bytes;162 163	u64 search_start;164	u64 extents_found;165 166	enum reloc_stage stage;167	bool create_reloc_tree;168	bool merge_reloc_tree;169	bool found_file_extent;170};171 172static void mark_block_processed(struct reloc_control *rc,173				 struct btrfs_backref_node *node)174{175	u32 blocksize;176 177	if (node->level == 0 ||178	    in_range(node->bytenr, rc->block_group->start,179		     rc->block_group->length)) {180		blocksize = rc->extent_root->fs_info->nodesize;181		set_extent_bit(&rc->processed_blocks, node->bytenr,182			       node->bytenr + blocksize - 1, EXTENT_DIRTY, NULL);183	}184	node->processed = 1;185}186 187/*188 * walk up backref nodes until reach node presents tree root189 */190static struct btrfs_backref_node *walk_up_backref(191		struct btrfs_backref_node *node,192		struct btrfs_backref_edge *edges[], int *index)193{194	struct btrfs_backref_edge *edge;195	int idx = *index;196 197	while (!list_empty(&node->upper)) {198		edge = list_entry(node->upper.next,199				  struct btrfs_backref_edge, list[LOWER]);200		edges[idx++] = edge;201		node = edge->node[UPPER];202	}203	BUG_ON(node->detached);204	*index = idx;205	return node;206}207 208/*209 * walk down backref nodes to find start of next reference path210 */211static struct btrfs_backref_node *walk_down_backref(212		struct btrfs_backref_edge *edges[], int *index)213{214	struct btrfs_backref_edge *edge;215	struct btrfs_backref_node *lower;216	int idx = *index;217 218	while (idx > 0) {219		edge = edges[idx - 1];220		lower = edge->node[LOWER];221		if (list_is_last(&edge->list[LOWER], &lower->upper)) {222			idx--;223			continue;224		}225		edge = list_entry(edge->list[LOWER].next,226				  struct btrfs_backref_edge, list[LOWER]);227		edges[idx - 1] = edge;228		*index = idx;229		return edge->node[UPPER];230	}231	*index = 0;232	return NULL;233}234 235static bool reloc_root_is_dead(const struct btrfs_root *root)236{237	/*238	 * Pair with set_bit/clear_bit in clean_dirty_subvols and239	 * btrfs_update_reloc_root. We need to see the updated bit before240	 * trying to access reloc_root241	 */242	smp_rmb();243	if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state))244		return true;245	return false;246}247 248/*249 * Check if this subvolume tree has valid reloc tree.250 *251 * Reloc tree after swap is considered dead, thus not considered as valid.252 * This is enough for most callers, as they don't distinguish dead reloc root253 * from no reloc root.  But btrfs_should_ignore_reloc_root() below is a254 * special case.255 */256static bool have_reloc_root(const struct btrfs_root *root)257{258	if (reloc_root_is_dead(root))259		return false;260	if (!root->reloc_root)261		return false;262	return true;263}264 265bool btrfs_should_ignore_reloc_root(const struct btrfs_root *root)266{267	struct btrfs_root *reloc_root;268 269	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))270		return false;271 272	/* This root has been merged with its reloc tree, we can ignore it */273	if (reloc_root_is_dead(root))274		return true;275 276	reloc_root = root->reloc_root;277	if (!reloc_root)278		return false;279 280	if (btrfs_header_generation(reloc_root->commit_root) ==281	    root->fs_info->running_transaction->transid)282		return false;283	/*284	 * If there is reloc tree and it was created in previous transaction285	 * backref lookup can find the reloc tree, so backref node for the fs286	 * tree root is useless for relocation.287	 */288	return true;289}290 291/*292 * find reloc tree by address of tree root293 */294struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr)295{296	struct reloc_control *rc = fs_info->reloc_ctl;297	struct rb_node *rb_node;298	struct mapping_node *node;299	struct btrfs_root *root = NULL;300 301	ASSERT(rc);302	spin_lock(&rc->reloc_root_tree.lock);303	rb_node = rb_simple_search(&rc->reloc_root_tree.rb_root, bytenr);304	if (rb_node) {305		node = rb_entry(rb_node, struct mapping_node, rb_node);306		root = node->data;307	}308	spin_unlock(&rc->reloc_root_tree.lock);309	return btrfs_grab_root(root);310}311 312/*313 * For useless nodes, do two major clean ups:314 *315 * - Cleanup the children edges and nodes316 *   If child node is also orphan (no parent) during cleanup, then the child317 *   node will also be cleaned up.318 *319 * - Freeing up leaves (level 0), keeps nodes detached320 *   For nodes, the node is still cached as "detached"321 *322 * Return false if @node is not in the @useless_nodes list.323 * Return true if @node is in the @useless_nodes list.324 */325static bool handle_useless_nodes(struct reloc_control *rc,326				 struct btrfs_backref_node *node)327{328	struct btrfs_backref_cache *cache = &rc->backref_cache;329	struct list_head *useless_node = &cache->useless_node;330	bool ret = false;331 332	while (!list_empty(useless_node)) {333		struct btrfs_backref_node *cur;334 335		cur = list_first_entry(useless_node, struct btrfs_backref_node,336				 list);337		list_del_init(&cur->list);338 339		/* Only tree root nodes can be added to @useless_nodes */340		ASSERT(list_empty(&cur->upper));341 342		if (cur == node)343			ret = true;344 345		/* The node is the lowest node */346		if (cur->lowest) {347			list_del_init(&cur->lower);348			cur->lowest = 0;349		}350 351		/* Cleanup the lower edges */352		while (!list_empty(&cur->lower)) {353			struct btrfs_backref_edge *edge;354			struct btrfs_backref_node *lower;355 356			edge = list_entry(cur->lower.next,357					struct btrfs_backref_edge, list[UPPER]);358			list_del(&edge->list[UPPER]);359			list_del(&edge->list[LOWER]);360			lower = edge->node[LOWER];361			btrfs_backref_free_edge(cache, edge);362 363			/* Child node is also orphan, queue for cleanup */364			if (list_empty(&lower->upper))365				list_add(&lower->list, useless_node);366		}367		/* Mark this block processed for relocation */368		mark_block_processed(rc, cur);369 370		/*371		 * Backref nodes for tree leaves are deleted from the cache.372		 * Backref nodes for upper level tree blocks are left in the373		 * cache to avoid unnecessary backref lookup.374		 */375		if (cur->level > 0) {376			list_add(&cur->list, &cache->detached);377			cur->detached = 1;378		} else {379			rb_erase(&cur->rb_node, &cache->rb_root);380			btrfs_backref_free_node(cache, cur);381		}382	}383	return ret;384}385 386/*387 * Build backref tree for a given tree block. Root of the backref tree388 * corresponds the tree block, leaves of the backref tree correspond roots of389 * b-trees that reference the tree block.390 *391 * The basic idea of this function is check backrefs of a given block to find392 * upper level blocks that reference the block, and then check backrefs of393 * these upper level blocks recursively. The recursion stops when tree root is394 * reached or backrefs for the block is cached.395 *396 * NOTE: if we find that backrefs for a block are cached, we know backrefs for397 * all upper level blocks that directly/indirectly reference the block are also398 * cached.399 */400static noinline_for_stack struct btrfs_backref_node *build_backref_tree(401			struct btrfs_trans_handle *trans,402			struct reloc_control *rc, struct btrfs_key *node_key,403			int level, u64 bytenr)404{405	struct btrfs_backref_iter *iter;406	struct btrfs_backref_cache *cache = &rc->backref_cache;407	/* For searching parent of TREE_BLOCK_REF */408	struct btrfs_path *path;409	struct btrfs_backref_node *cur;410	struct btrfs_backref_node *node = NULL;411	struct btrfs_backref_edge *edge;412	int ret;413 414	iter = btrfs_backref_iter_alloc(rc->extent_root->fs_info);415	if (!iter)416		return ERR_PTR(-ENOMEM);417	path = btrfs_alloc_path();418	if (!path) {419		ret = -ENOMEM;420		goto out;421	}422 423	node = btrfs_backref_alloc_node(cache, bytenr, level);424	if (!node) {425		ret = -ENOMEM;426		goto out;427	}428 429	node->lowest = 1;430	cur = node;431 432	/* Breadth-first search to build backref cache */433	do {434		ret = btrfs_backref_add_tree_node(trans, cache, path, iter,435						  node_key, cur);436		if (ret < 0)437			goto out;438 439		edge = list_first_entry_or_null(&cache->pending_edge,440				struct btrfs_backref_edge, list[UPPER]);441		/*442		 * The pending list isn't empty, take the first block to443		 * process444		 */445		if (edge) {446			list_del_init(&edge->list[UPPER]);447			cur = edge->node[UPPER];448		}449	} while (edge);450 451	/* Finish the upper linkage of newly added edges/nodes */452	ret = btrfs_backref_finish_upper_links(cache, node);453	if (ret < 0)454		goto out;455 456	if (handle_useless_nodes(rc, node))457		node = NULL;458out:459	btrfs_free_path(iter->path);460	kfree(iter);461	btrfs_free_path(path);462	if (ret) {463		btrfs_backref_error_cleanup(cache, node);464		return ERR_PTR(ret);465	}466	ASSERT(!node || !node->detached);467	ASSERT(list_empty(&cache->useless_node) &&468	       list_empty(&cache->pending_edge));469	return node;470}471 472/*473 * helper to add backref node for the newly created snapshot.474 * the backref node is created by cloning backref node that475 * corresponds to root of source tree476 */477static int clone_backref_node(struct btrfs_trans_handle *trans,478			      struct reloc_control *rc,479			      const struct btrfs_root *src,480			      struct btrfs_root *dest)481{482	struct btrfs_root *reloc_root = src->reloc_root;483	struct btrfs_backref_cache *cache = &rc->backref_cache;484	struct btrfs_backref_node *node = NULL;485	struct btrfs_backref_node *new_node;486	struct btrfs_backref_edge *edge;487	struct btrfs_backref_edge *new_edge;488	struct rb_node *rb_node;489 490	rb_node = rb_simple_search(&cache->rb_root, src->commit_root->start);491	if (rb_node) {492		node = rb_entry(rb_node, struct btrfs_backref_node, rb_node);493		if (node->detached)494			node = NULL;495		else496			BUG_ON(node->new_bytenr != reloc_root->node->start);497	}498 499	if (!node) {500		rb_node = rb_simple_search(&cache->rb_root,501					   reloc_root->commit_root->start);502		if (rb_node) {503			node = rb_entry(rb_node, struct btrfs_backref_node,504					rb_node);505			BUG_ON(node->detached);506		}507	}508 509	if (!node)510		return 0;511 512	new_node = btrfs_backref_alloc_node(cache, dest->node->start,513					    node->level);514	if (!new_node)515		return -ENOMEM;516 517	new_node->lowest = node->lowest;518	new_node->checked = 1;519	new_node->root = btrfs_grab_root(dest);520	ASSERT(new_node->root);521 522	if (!node->lowest) {523		list_for_each_entry(edge, &node->lower, list[UPPER]) {524			new_edge = btrfs_backref_alloc_edge(cache);525			if (!new_edge)526				goto fail;527 528			btrfs_backref_link_edge(new_edge, edge->node[LOWER],529						new_node, LINK_UPPER);530		}531	} else {532		list_add_tail(&new_node->lower, &cache->leaves);533	}534 535	rb_node = rb_simple_insert(&cache->rb_root, new_node->bytenr,536				   &new_node->rb_node);537	if (rb_node)538		btrfs_backref_panic(trans->fs_info, new_node->bytenr, -EEXIST);539 540	if (!new_node->lowest) {541		list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {542			list_add_tail(&new_edge->list[LOWER],543				      &new_edge->node[LOWER]->upper);544		}545	}546	return 0;547fail:548	while (!list_empty(&new_node->lower)) {549		new_edge = list_entry(new_node->lower.next,550				      struct btrfs_backref_edge, list[UPPER]);551		list_del(&new_edge->list[UPPER]);552		btrfs_backref_free_edge(cache, new_edge);553	}554	btrfs_backref_free_node(cache, new_node);555	return -ENOMEM;556}557 558/*559 * helper to add 'address of tree root -> reloc tree' mapping560 */561static int __add_reloc_root(struct btrfs_root *root)562{563	struct btrfs_fs_info *fs_info = root->fs_info;564	struct rb_node *rb_node;565	struct mapping_node *node;566	struct reloc_control *rc = fs_info->reloc_ctl;567 568	node = kmalloc(sizeof(*node), GFP_NOFS);569	if (!node)570		return -ENOMEM;571 572	node->bytenr = root->commit_root->start;573	node->data = root;574 575	spin_lock(&rc->reloc_root_tree.lock);576	rb_node = rb_simple_insert(&rc->reloc_root_tree.rb_root,577				   node->bytenr, &node->rb_node);578	spin_unlock(&rc->reloc_root_tree.lock);579	if (rb_node) {580		btrfs_err(fs_info,581			    "Duplicate root found for start=%llu while inserting into relocation tree",582			    node->bytenr);583		return -EEXIST;584	}585 586	list_add_tail(&root->root_list, &rc->reloc_roots);587	return 0;588}589 590/*591 * helper to delete the 'address of tree root -> reloc tree'592 * mapping593 */594static void __del_reloc_root(struct btrfs_root *root)595{596	struct btrfs_fs_info *fs_info = root->fs_info;597	struct rb_node *rb_node;598	struct mapping_node *node = NULL;599	struct reloc_control *rc = fs_info->reloc_ctl;600	bool put_ref = false;601 602	if (rc && root->node) {603		spin_lock(&rc->reloc_root_tree.lock);604		rb_node = rb_simple_search(&rc->reloc_root_tree.rb_root,605					   root->commit_root->start);606		if (rb_node) {607			node = rb_entry(rb_node, struct mapping_node, rb_node);608			rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);609			RB_CLEAR_NODE(&node->rb_node);610		}611		spin_unlock(&rc->reloc_root_tree.lock);612		ASSERT(!node || (struct btrfs_root *)node->data == root);613	}614 615	/*616	 * We only put the reloc root here if it's on the list.  There's a lot617	 * of places where the pattern is to splice the rc->reloc_roots, process618	 * the reloc roots, and then add the reloc root back onto619	 * rc->reloc_roots.  If we call __del_reloc_root while it's off of the620	 * list we don't want the reference being dropped, because the guy621	 * messing with the list is in charge of the reference.622	 */623	spin_lock(&fs_info->trans_lock);624	if (!list_empty(&root->root_list)) {625		put_ref = true;626		list_del_init(&root->root_list);627	}628	spin_unlock(&fs_info->trans_lock);629	if (put_ref)630		btrfs_put_root(root);631	kfree(node);632}633 634/*635 * helper to update the 'address of tree root -> reloc tree'636 * mapping637 */638static int __update_reloc_root(struct btrfs_root *root)639{640	struct btrfs_fs_info *fs_info = root->fs_info;641	struct rb_node *rb_node;642	struct mapping_node *node = NULL;643	struct reloc_control *rc = fs_info->reloc_ctl;644 645	spin_lock(&rc->reloc_root_tree.lock);646	rb_node = rb_simple_search(&rc->reloc_root_tree.rb_root,647				   root->commit_root->start);648	if (rb_node) {649		node = rb_entry(rb_node, struct mapping_node, rb_node);650		rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);651	}652	spin_unlock(&rc->reloc_root_tree.lock);653 654	if (!node)655		return 0;656	BUG_ON((struct btrfs_root *)node->data != root);657 658	spin_lock(&rc->reloc_root_tree.lock);659	node->bytenr = root->node->start;660	rb_node = rb_simple_insert(&rc->reloc_root_tree.rb_root,661				   node->bytenr, &node->rb_node);662	spin_unlock(&rc->reloc_root_tree.lock);663	if (rb_node)664		btrfs_backref_panic(fs_info, node->bytenr, -EEXIST);665	return 0;666}667 668static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,669					struct btrfs_root *root, u64 objectid)670{671	struct btrfs_fs_info *fs_info = root->fs_info;672	struct btrfs_root *reloc_root;673	struct extent_buffer *eb;674	struct btrfs_root_item *root_item;675	struct btrfs_key root_key;676	int ret = 0;677	bool must_abort = false;678 679	root_item = kmalloc(sizeof(*root_item), GFP_NOFS);680	if (!root_item)681		return ERR_PTR(-ENOMEM);682 683	root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;684	root_key.type = BTRFS_ROOT_ITEM_KEY;685	root_key.offset = objectid;686 687	if (btrfs_root_id(root) == objectid) {688		u64 commit_root_gen;689 690		/* called by btrfs_init_reloc_root */691		ret = btrfs_copy_root(trans, root, root->commit_root, &eb,692				      BTRFS_TREE_RELOC_OBJECTID);693		if (ret)694			goto fail;695 696		/*697		 * Set the last_snapshot field to the generation of the commit698		 * root - like this ctree.c:btrfs_block_can_be_shared() behaves699		 * correctly (returns true) when the relocation root is created700		 * either inside the critical section of a transaction commit701		 * (through transaction.c:qgroup_account_snapshot()) and when702		 * it's created before the transaction commit is started.703		 */704		commit_root_gen = btrfs_header_generation(root->commit_root);705		btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);706	} else {707		/*708		 * called by btrfs_reloc_post_snapshot_hook.709		 * the source tree is a reloc tree, all tree blocks710		 * modified after it was created have RELOC flag711		 * set in their headers. so it's OK to not update712		 * the 'last_snapshot'.713		 */714		ret = btrfs_copy_root(trans, root, root->node, &eb,715				      BTRFS_TREE_RELOC_OBJECTID);716		if (ret)717			goto fail;718	}719 720	/*721	 * We have changed references at this point, we must abort the722	 * transaction if anything fails.723	 */724	must_abort = true;725 726	memcpy(root_item, &root->root_item, sizeof(*root_item));727	btrfs_set_root_bytenr(root_item, eb->start);728	btrfs_set_root_level(root_item, btrfs_header_level(eb));729	btrfs_set_root_generation(root_item, trans->transid);730 731	if (btrfs_root_id(root) == objectid) {732		btrfs_set_root_refs(root_item, 0);733		memset(&root_item->drop_progress, 0,734		       sizeof(struct btrfs_disk_key));735		btrfs_set_root_drop_level(root_item, 0);736	}737 738	btrfs_tree_unlock(eb);739	free_extent_buffer(eb);740 741	ret = btrfs_insert_root(trans, fs_info->tree_root,742				&root_key, root_item);743	if (ret)744		goto fail;745 746	kfree(root_item);747 748	reloc_root = btrfs_read_tree_root(fs_info->tree_root, &root_key);749	if (IS_ERR(reloc_root)) {750		ret = PTR_ERR(reloc_root);751		goto abort;752	}753	set_bit(BTRFS_ROOT_SHAREABLE, &reloc_root->state);754	btrfs_set_root_last_trans(reloc_root, trans->transid);755	return reloc_root;756fail:757	kfree(root_item);758abort:759	if (must_abort)760		btrfs_abort_transaction(trans, ret);761	return ERR_PTR(ret);762}763 764/*765 * create reloc tree for a given fs tree. reloc tree is just a766 * snapshot of the fs tree with special root objectid.767 *768 * The reloc_root comes out of here with two references, one for769 * root->reloc_root, and another for being on the rc->reloc_roots list.770 */771int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,772			  struct btrfs_root *root)773{774	struct btrfs_fs_info *fs_info = root->fs_info;775	struct btrfs_root *reloc_root;776	struct reloc_control *rc = fs_info->reloc_ctl;777	struct btrfs_block_rsv *rsv;778	int clear_rsv = 0;779	int ret;780 781	if (!rc)782		return 0;783 784	/*785	 * The subvolume has reloc tree but the swap is finished, no need to786	 * create/update the dead reloc tree787	 */788	if (reloc_root_is_dead(root))789		return 0;790 791	/*792	 * This is subtle but important.  We do not do793	 * record_root_in_transaction for reloc roots, instead we record their794	 * corresponding fs root, and then here we update the last trans for the795	 * reloc root.  This means that we have to do this for the entire life796	 * of the reloc root, regardless of which stage of the relocation we are797	 * in.798	 */799	if (root->reloc_root) {800		reloc_root = root->reloc_root;801		btrfs_set_root_last_trans(reloc_root, trans->transid);802		return 0;803	}804 805	/*806	 * We are merging reloc roots, we do not need new reloc trees.  Also807	 * reloc trees never need their own reloc tree.808	 */809	if (!rc->create_reloc_tree || btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)810		return 0;811 812	if (!trans->reloc_reserved) {813		rsv = trans->block_rsv;814		trans->block_rsv = rc->block_rsv;815		clear_rsv = 1;816	}817	reloc_root = create_reloc_root(trans, root, btrfs_root_id(root));818	if (clear_rsv)819		trans->block_rsv = rsv;820	if (IS_ERR(reloc_root))821		return PTR_ERR(reloc_root);822 823	ret = __add_reloc_root(reloc_root);824	ASSERT(ret != -EEXIST);825	if (ret) {826		/* Pairs with create_reloc_root */827		btrfs_put_root(reloc_root);828		return ret;829	}830	root->reloc_root = btrfs_grab_root(reloc_root);831	return 0;832}833 834/*835 * update root item of reloc tree836 */837int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,838			    struct btrfs_root *root)839{840	struct btrfs_fs_info *fs_info = root->fs_info;841	struct btrfs_root *reloc_root;842	struct btrfs_root_item *root_item;843	int ret;844 845	if (!have_reloc_root(root))846		return 0;847 848	reloc_root = root->reloc_root;849	root_item = &reloc_root->root_item;850 851	/*852	 * We are probably ok here, but __del_reloc_root() will drop its ref of853	 * the root.  We have the ref for root->reloc_root, but just in case854	 * hold it while we update the reloc root.855	 */856	btrfs_grab_root(reloc_root);857 858	/* root->reloc_root will stay until current relocation finished */859	if (fs_info->reloc_ctl && fs_info->reloc_ctl->merge_reloc_tree &&860	    btrfs_root_refs(root_item) == 0) {861		set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);862		/*863		 * Mark the tree as dead before we change reloc_root so864		 * have_reloc_root will not touch it from now on.865		 */866		smp_wmb();867		__del_reloc_root(reloc_root);868	}869 870	if (reloc_root->commit_root != reloc_root->node) {871		__update_reloc_root(reloc_root);872		btrfs_set_root_node(root_item, reloc_root->node);873		free_extent_buffer(reloc_root->commit_root);874		reloc_root->commit_root = btrfs_root_node(reloc_root);875	}876 877	ret = btrfs_update_root(trans, fs_info->tree_root,878				&reloc_root->root_key, root_item);879	btrfs_put_root(reloc_root);880	return ret;881}882 883/*884 * get new location of data885 */886static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,887			    u64 bytenr, u64 num_bytes)888{889	struct btrfs_root *root = BTRFS_I(reloc_inode)->root;890	struct btrfs_path *path;891	struct btrfs_file_extent_item *fi;892	struct extent_buffer *leaf;893	int ret;894 895	path = btrfs_alloc_path();896	if (!path)897		return -ENOMEM;898 899	bytenr -= BTRFS_I(reloc_inode)->reloc_block_group_start;900	ret = btrfs_lookup_file_extent(NULL, root, path,901			btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);902	if (ret < 0)903		goto out;904	if (ret > 0) {905		ret = -ENOENT;906		goto out;907	}908 909	leaf = path->nodes[0];910	fi = btrfs_item_ptr(leaf, path->slots[0],911			    struct btrfs_file_extent_item);912 913	BUG_ON(btrfs_file_extent_offset(leaf, fi) ||914	       btrfs_file_extent_compression(leaf, fi) ||915	       btrfs_file_extent_encryption(leaf, fi) ||916	       btrfs_file_extent_other_encoding(leaf, fi));917 918	if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {919		ret = -EINVAL;920		goto out;921	}922 923	*new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);924	ret = 0;925out:926	btrfs_free_path(path);927	return ret;928}929 930/*931 * update file extent items in the tree leaf to point to932 * the new locations.933 */934static noinline_for_stack935int replace_file_extents(struct btrfs_trans_handle *trans,936			 struct reloc_control *rc,937			 struct btrfs_root *root,938			 struct extent_buffer *leaf)939{940	struct btrfs_fs_info *fs_info = root->fs_info;941	struct btrfs_key key;942	struct btrfs_file_extent_item *fi;943	struct btrfs_inode *inode = NULL;944	u64 parent;945	u64 bytenr;946	u64 new_bytenr = 0;947	u64 num_bytes;948	u64 end;949	u32 nritems;950	u32 i;951	int ret = 0;952	int first = 1;953	int dirty = 0;954 955	if (rc->stage != UPDATE_DATA_PTRS)956		return 0;957 958	/* reloc trees always use full backref */959	if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)960		parent = leaf->start;961	else962		parent = 0;963 964	nritems = btrfs_header_nritems(leaf);965	for (i = 0; i < nritems; i++) {966		struct btrfs_ref ref = { 0 };967 968		cond_resched();969		btrfs_item_key_to_cpu(leaf, &key, i);970		if (key.type != BTRFS_EXTENT_DATA_KEY)971			continue;972		fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);973		if (btrfs_file_extent_type(leaf, fi) ==974		    BTRFS_FILE_EXTENT_INLINE)975			continue;976		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);977		num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);978		if (bytenr == 0)979			continue;980		if (!in_range(bytenr, rc->block_group->start,981			      rc->block_group->length))982			continue;983 984		/*985		 * if we are modifying block in fs tree, wait for read_folio986		 * to complete and drop the extent cache987		 */988		if (btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID) {989			if (first) {990				inode = btrfs_find_first_inode(root, key.objectid);991				first = 0;992			} else if (inode && btrfs_ino(inode) < key.objectid) {993				btrfs_add_delayed_iput(inode);994				inode = btrfs_find_first_inode(root, key.objectid);995			}996			if (inode && btrfs_ino(inode) == key.objectid) {997				struct extent_state *cached_state = NULL;998 999				end = key.offset +1000				      btrfs_file_extent_num_bytes(leaf, fi);1001				WARN_ON(!IS_ALIGNED(key.offset,1002						    fs_info->sectorsize));1003				WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));1004				end--;1005				/* Take mmap lock to serialize with reflinks. */1006				if (!down_read_trylock(&inode->i_mmap_lock))1007					continue;1008				ret = try_lock_extent(&inode->io_tree, key.offset,1009						      end, &cached_state);1010				if (!ret) {1011					up_read(&inode->i_mmap_lock);1012					continue;1013				}1014 1015				btrfs_drop_extent_map_range(inode, key.offset, end, true);1016				unlock_extent(&inode->io_tree, key.offset, end,1017					      &cached_state);1018				up_read(&inode->i_mmap_lock);1019			}1020		}1021 1022		ret = get_new_location(rc->data_inode, &new_bytenr,1023				       bytenr, num_bytes);1024		if (ret) {1025			/*1026			 * Don't have to abort since we've not changed anything1027			 * in the file extent yet.1028			 */1029			break;1030		}1031 1032		btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);1033		dirty = 1;1034 1035		key.offset -= btrfs_file_extent_offset(leaf, fi);1036		ref.action = BTRFS_ADD_DELAYED_REF;1037		ref.bytenr = new_bytenr;1038		ref.num_bytes = num_bytes;1039		ref.parent = parent;1040		ref.owning_root = btrfs_root_id(root);1041		ref.ref_root = btrfs_header_owner(leaf);1042		btrfs_init_data_ref(&ref, key.objectid, key.offset,1043				    btrfs_root_id(root), false);1044		ret = btrfs_inc_extent_ref(trans, &ref);1045		if (ret) {1046			btrfs_abort_transaction(trans, ret);1047			break;1048		}1049 1050		ref.action = BTRFS_DROP_DELAYED_REF;1051		ref.bytenr = bytenr;1052		ref.num_bytes = num_bytes;1053		ref.parent = parent;1054		ref.owning_root = btrfs_root_id(root);1055		ref.ref_root = btrfs_header_owner(leaf);1056		btrfs_init_data_ref(&ref, key.objectid, key.offset,1057				    btrfs_root_id(root), false);1058		ret = btrfs_free_extent(trans, &ref);1059		if (ret) {1060			btrfs_abort_transaction(trans, ret);1061			break;1062		}1063	}1064	if (dirty)1065		btrfs_mark_buffer_dirty(trans, leaf);1066	if (inode)1067		btrfs_add_delayed_iput(inode);1068	return ret;1069}1070 1071static noinline_for_stack int memcmp_node_keys(const struct extent_buffer *eb,1072					       int slot, const struct btrfs_path *path,1073					       int level)1074{1075	struct btrfs_disk_key key1;1076	struct btrfs_disk_key key2;1077	btrfs_node_key(eb, &key1, slot);1078	btrfs_node_key(path->nodes[level], &key2, path->slots[level]);1079	return memcmp(&key1, &key2, sizeof(key1));1080}1081 1082/*1083 * try to replace tree blocks in fs tree with the new blocks1084 * in reloc tree. tree blocks haven't been modified since the1085 * reloc tree was create can be replaced.1086 *1087 * if a block was replaced, level of the block + 1 is returned.1088 * if no block got replaced, 0 is returned. if there are other1089 * errors, a negative error number is returned.1090 */1091static noinline_for_stack1092int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc,1093		 struct btrfs_root *dest, struct btrfs_root *src,1094		 struct btrfs_path *path, struct btrfs_key *next_key,1095		 int lowest_level, int max_level)1096{1097	struct btrfs_fs_info *fs_info = dest->fs_info;1098	struct extent_buffer *eb;1099	struct extent_buffer *parent;1100	struct btrfs_ref ref = { 0 };1101	struct btrfs_key key;1102	u64 old_bytenr;1103	u64 new_bytenr;1104	u64 old_ptr_gen;1105	u64 new_ptr_gen;1106	u64 last_snapshot;1107	u32 blocksize;1108	int cow = 0;1109	int level;1110	int ret;1111	int slot;1112 1113	ASSERT(btrfs_root_id(src) == BTRFS_TREE_RELOC_OBJECTID);1114	ASSERT(btrfs_root_id(dest) != BTRFS_TREE_RELOC_OBJECTID);1115 1116	last_snapshot = btrfs_root_last_snapshot(&src->root_item);1117again:1118	slot = path->slots[lowest_level];1119	btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);1120 1121	eb = btrfs_lock_root_node(dest);1122	level = btrfs_header_level(eb);1123 1124	if (level < lowest_level) {1125		btrfs_tree_unlock(eb);1126		free_extent_buffer(eb);1127		return 0;1128	}1129 1130	if (cow) {1131		ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb,1132				      BTRFS_NESTING_COW);1133		if (ret) {1134			btrfs_tree_unlock(eb);1135			free_extent_buffer(eb);1136			return ret;1137		}1138	}1139 1140	if (next_key) {1141		next_key->objectid = (u64)-1;1142		next_key->type = (u8)-1;1143		next_key->offset = (u64)-1;1144	}1145 1146	parent = eb;1147	while (1) {1148		level = btrfs_header_level(parent);1149		ASSERT(level >= lowest_level);1150 1151		ret = btrfs_bin_search(parent, 0, &key, &slot);1152		if (ret < 0)1153			break;1154		if (ret && slot > 0)1155			slot--;1156 1157		if (next_key && slot + 1 < btrfs_header_nritems(parent))1158			btrfs_node_key_to_cpu(parent, next_key, slot + 1);1159 1160		old_bytenr = btrfs_node_blockptr(parent, slot);1161		blocksize = fs_info->nodesize;1162		old_ptr_gen = btrfs_node_ptr_generation(parent, slot);1163 1164		if (level <= max_level) {1165			eb = path->nodes[level];1166			new_bytenr = btrfs_node_blockptr(eb,1167							path->slots[level]);1168			new_ptr_gen = btrfs_node_ptr_generation(eb,1169							path->slots[level]);1170		} else {1171			new_bytenr = 0;1172			new_ptr_gen = 0;1173		}1174 1175		if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {1176			ret = level;1177			break;1178		}1179 1180		if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||1181		    memcmp_node_keys(parent, slot, path, level)) {1182			if (level <= lowest_level) {1183				ret = 0;1184				break;1185			}1186 1187			eb = btrfs_read_node_slot(parent, slot);1188			if (IS_ERR(eb)) {1189				ret = PTR_ERR(eb);1190				break;1191			}1192			btrfs_tree_lock(eb);1193			if (cow) {1194				ret = btrfs_cow_block(trans, dest, eb, parent,1195						      slot, &eb,1196						      BTRFS_NESTING_COW);1197				if (ret) {1198					btrfs_tree_unlock(eb);1199					free_extent_buffer(eb);1200					break;1201				}1202			}1203 1204			btrfs_tree_unlock(parent);1205			free_extent_buffer(parent);1206 1207			parent = eb;1208			continue;1209		}1210 1211		if (!cow) {1212			btrfs_tree_unlock(parent);1213			free_extent_buffer(parent);1214			cow = 1;1215			goto again;1216		}1217 1218		btrfs_node_key_to_cpu(path->nodes[level], &key,1219				      path->slots[level]);1220		btrfs_release_path(path);1221 1222		path->lowest_level = level;1223		set_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &src->state);1224		ret = btrfs_search_slot(trans, src, &key, path, 0, 1);1225		clear_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &src->state);1226		path->lowest_level = 0;1227		if (ret) {1228			if (ret > 0)1229				ret = -ENOENT;1230			break;1231		}1232 1233		/*1234		 * Info qgroup to trace both subtrees.1235		 *1236		 * We must trace both trees.1237		 * 1) Tree reloc subtree1238		 *    If not traced, we will leak data numbers1239		 * 2) Fs subtree1240		 *    If not traced, we will double count old data1241		 *1242		 * We don't scan the subtree right now, but only record1243		 * the swapped tree blocks.1244		 * The real subtree rescan is delayed until we have new1245		 * CoW on the subtree root node before transaction commit.1246		 */1247		ret = btrfs_qgroup_add_swapped_blocks(trans, dest,1248				rc->block_group, parent, slot,1249				path->nodes[level], path->slots[level],1250				last_snapshot);1251		if (ret < 0)1252			break;1253		/*1254		 * swap blocks in fs tree and reloc tree.1255		 */1256		btrfs_set_node_blockptr(parent, slot, new_bytenr);1257		btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);1258		btrfs_mark_buffer_dirty(trans, parent);1259 1260		btrfs_set_node_blockptr(path->nodes[level],1261					path->slots[level], old_bytenr);1262		btrfs_set_node_ptr_generation(path->nodes[level],1263					      path->slots[level], old_ptr_gen);1264		btrfs_mark_buffer_dirty(trans, path->nodes[level]);1265 1266		ref.action = BTRFS_ADD_DELAYED_REF;1267		ref.bytenr = old_bytenr;1268		ref.num_bytes = blocksize;1269		ref.parent = path->nodes[level]->start;1270		ref.owning_root = btrfs_root_id(src);1271		ref.ref_root = btrfs_root_id(src);1272		btrfs_init_tree_ref(&ref, level - 1, 0, true);1273		ret = btrfs_inc_extent_ref(trans, &ref);1274		if (ret) {1275			btrfs_abort_transaction(trans, ret);1276			break;1277		}1278 1279		ref.action = BTRFS_ADD_DELAYED_REF;1280		ref.bytenr = new_bytenr;1281		ref.num_bytes = blocksize;1282		ref.parent = 0;1283		ref.owning_root = btrfs_root_id(dest);1284		ref.ref_root = btrfs_root_id(dest);1285		btrfs_init_tree_ref(&ref, level - 1, 0, true);1286		ret = btrfs_inc_extent_ref(trans, &ref);1287		if (ret) {1288			btrfs_abort_transaction(trans, ret);1289			break;1290		}1291 1292		/* We don't know the real owning_root, use 0. */1293		ref.action = BTRFS_DROP_DELAYED_REF;1294		ref.bytenr = new_bytenr;1295		ref.num_bytes = blocksize;1296		ref.parent = path->nodes[level]->start;1297		ref.owning_root = 0;1298		ref.ref_root = btrfs_root_id(src);1299		btrfs_init_tree_ref(&ref, level - 1, 0, true);1300		ret = btrfs_free_extent(trans, &ref);1301		if (ret) {1302			btrfs_abort_transaction(trans, ret);1303			break;1304		}1305 1306		/* We don't know the real owning_root, use 0. */1307		ref.action = BTRFS_DROP_DELAYED_REF;1308		ref.bytenr = old_bytenr;1309		ref.num_bytes = blocksize;1310		ref.parent = 0;1311		ref.owning_root = 0;1312		ref.ref_root = btrfs_root_id(dest);1313		btrfs_init_tree_ref(&ref, level - 1, 0, true);1314		ret = btrfs_free_extent(trans, &ref);1315		if (ret) {1316			btrfs_abort_transaction(trans, ret);1317			break;1318		}1319 1320		btrfs_unlock_up_safe(path, 0);1321 1322		ret = level;1323		break;1324	}1325	btrfs_tree_unlock(parent);1326	free_extent_buffer(parent);1327	return ret;1328}1329 1330/*1331 * helper to find next relocated block in reloc tree1332 */1333static noinline_for_stack1334int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,1335		       int *level)1336{1337	struct extent_buffer *eb;1338	int i;1339	u64 last_snapshot;1340	u32 nritems;1341 1342	last_snapshot = btrfs_root_last_snapshot(&root->root_item);1343 1344	for (i = 0; i < *level; i++) {1345		free_extent_buffer(path->nodes[i]);1346		path->nodes[i] = NULL;1347	}1348 1349	for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {1350		eb = path->nodes[i];1351		nritems = btrfs_header_nritems(eb);1352		while (path->slots[i] + 1 < nritems) {1353			path->slots[i]++;1354			if (btrfs_node_ptr_generation(eb, path->slots[i]) <=1355			    last_snapshot)1356				continue;1357 1358			*level = i;1359			return 0;1360		}1361		free_extent_buffer(path->nodes[i]);1362		path->nodes[i] = NULL;1363	}1364	return 1;1365}1366 1367/*1368 * walk down reloc tree to find relocated block of lowest level1369 */1370static noinline_for_stack1371int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,1372			 int *level)1373{1374	struct extent_buffer *eb = NULL;1375	int i;1376	u64 ptr_gen = 0;1377	u64 last_snapshot;1378	u32 nritems;1379 1380	last_snapshot = btrfs_root_last_snapshot(&root->root_item);1381 1382	for (i = *level; i > 0; i--) {1383		eb = path->nodes[i];1384		nritems = btrfs_header_nritems(eb);1385		while (path->slots[i] < nritems) {1386			ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);1387			if (ptr_gen > last_snapshot)1388				break;1389			path->slots[i]++;1390		}1391		if (path->slots[i] >= nritems) {1392			if (i == *level)1393				break;1394			*level = i + 1;1395			return 0;1396		}1397		if (i == 1) {1398			*level = i;1399			return 0;1400		}1401 1402		eb = btrfs_read_node_slot(eb, path->slots[i]);1403		if (IS_ERR(eb))1404			return PTR_ERR(eb);1405		BUG_ON(btrfs_header_level(eb) != i - 1);1406		path->nodes[i - 1] = eb;1407		path->slots[i - 1] = 0;1408	}1409	return 1;1410}1411 1412/*1413 * invalidate extent cache for file extents whose key in range of1414 * [min_key, max_key)1415 */1416static int invalidate_extent_cache(struct btrfs_root *root,1417				   const struct btrfs_key *min_key,1418				   const struct btrfs_key *max_key)1419{1420	struct btrfs_fs_info *fs_info = root->fs_info;1421	struct btrfs_inode *inode = NULL;1422	u64 objectid;1423	u64 start, end;1424	u64 ino;1425 1426	objectid = min_key->objectid;1427	while (1) {1428		struct extent_state *cached_state = NULL;1429 1430		cond_resched();1431		if (inode)1432			iput(&inode->vfs_inode);1433 1434		if (objectid > max_key->objectid)1435			break;1436 1437		inode = btrfs_find_first_inode(root, objectid);1438		if (!inode)1439			break;1440		ino = btrfs_ino(inode);1441 1442		if (ino > max_key->objectid) {1443			iput(&inode->vfs_inode);1444			break;1445		}1446 1447		objectid = ino + 1;1448		if (!S_ISREG(inode->vfs_inode.i_mode))1449			continue;1450 1451		if (unlikely(min_key->objectid == ino)) {1452			if (min_key->type > BTRFS_EXTENT_DATA_KEY)1453				continue;1454			if (min_key->type < BTRFS_EXTENT_DATA_KEY)1455				start = 0;1456			else {1457				start = min_key->offset;1458				WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));1459			}1460		} else {1461			start = 0;1462		}1463 1464		if (unlikely(max_key->objectid == ino)) {1465			if (max_key->type < BTRFS_EXTENT_DATA_KEY)1466				continue;1467			if (max_key->type > BTRFS_EXTENT_DATA_KEY) {1468				end = (u64)-1;1469			} else {1470				if (max_key->offset == 0)1471					continue;1472				end = max_key->offset;1473				WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));1474				end--;1475			}1476		} else {1477			end = (u64)-1;1478		}1479 1480		/* the lock_extent waits for read_folio to complete */1481		lock_extent(&inode->io_tree, start, end, &cached_state);1482		btrfs_drop_extent_map_range(inode, start, end, true);1483		unlock_extent(&inode->io_tree, start, end, &cached_state);1484	}1485	return 0;1486}1487 1488static int find_next_key(struct btrfs_path *path, int level,1489			 struct btrfs_key *key)1490 1491{1492	while (level < BTRFS_MAX_LEVEL) {1493		if (!path->nodes[level])1494			break;1495		if (path->slots[level] + 1 <1496		    btrfs_header_nritems(path->nodes[level])) {1497			btrfs_node_key_to_cpu(path->nodes[level], key,1498					      path->slots[level] + 1);1499			return 0;1500		}1501		level++;1502	}1503	return 1;1504}1505 1506/*1507 * Insert current subvolume into reloc_control::dirty_subvol_roots1508 */1509static int insert_dirty_subvol(struct btrfs_trans_handle *trans,1510			       struct reloc_control *rc,1511			       struct btrfs_root *root)1512{1513	struct btrfs_root *reloc_root = root->reloc_root;1514	struct btrfs_root_item *reloc_root_item;1515	int ret;1516 1517	/* @root must be a subvolume tree root with a valid reloc tree */1518	ASSERT(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID);1519	ASSERT(reloc_root);1520 1521	reloc_root_item = &reloc_root->root_item;1522	memset(&reloc_root_item->drop_progress, 0,1523		sizeof(reloc_root_item->drop_progress));1524	btrfs_set_root_drop_level(reloc_root_item, 0);1525	btrfs_set_root_refs(reloc_root_item, 0);1526	ret = btrfs_update_reloc_root(trans, root);1527	if (ret)1528		return ret;1529 1530	if (list_empty(&root->reloc_dirty_list)) {1531		btrfs_grab_root(root);1532		list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);1533	}1534 1535	return 0;1536}1537 1538static int clean_dirty_subvols(struct reloc_control *rc)1539{1540	struct btrfs_root *root;1541	struct btrfs_root *next;1542	int ret = 0;1543	int ret2;1544 1545	list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,1546				 reloc_dirty_list) {1547		if (btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID) {1548			/* Merged subvolume, cleanup its reloc root */1549			struct btrfs_root *reloc_root = root->reloc_root;1550 1551			list_del_init(&root->reloc_dirty_list);1552			root->reloc_root = NULL;1553			/*1554			 * Need barrier to ensure clear_bit() only happens after1555			 * root->reloc_root = NULL. Pairs with have_reloc_root.1556			 */1557			smp_wmb();1558			clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);1559			if (reloc_root) {1560				/*1561				 * btrfs_drop_snapshot drops our ref we hold for1562				 * ->reloc_root.  If it fails however we must1563				 * drop the ref ourselves.1564				 */1565				ret2 = btrfs_drop_snapshot(reloc_root, 0, 1);1566				if (ret2 < 0) {1567					btrfs_put_root(reloc_root);1568					if (!ret)1569						ret = ret2;1570				}1571			}1572			btrfs_put_root(root);1573		} else {1574			/* Orphan reloc tree, just clean it up */1575			ret2 = btrfs_drop_snapshot(root, 0, 1);1576			if (ret2 < 0) {1577				btrfs_put_root(root);1578				if (!ret)1579					ret = ret2;1580			}1581		}1582	}1583	return ret;1584}1585 1586/*1587 * merge the relocated tree blocks in reloc tree with corresponding1588 * fs tree.1589 */1590static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,1591					       struct btrfs_root *root)1592{1593	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;1594	struct btrfs_key key;1595	struct btrfs_key next_key;1596	struct btrfs_trans_handle *trans = NULL;1597	struct btrfs_root *reloc_root;1598	struct btrfs_root_item *root_item;1599	struct btrfs_path *path;1600	struct extent_buffer *leaf;1601	int reserve_level;1602	int level;1603	int max_level;1604	int replaced = 0;1605	int ret = 0;1606	u32 min_reserved;1607 1608	path = btrfs_alloc_path();1609	if (!path)1610		return -ENOMEM;1611	path->reada = READA_FORWARD;1612 1613	reloc_root = root->reloc_root;1614	root_item = &reloc_root->root_item;1615 1616	if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {1617		level = btrfs_root_level(root_item);1618		atomic_inc(&reloc_root->node->refs);1619		path->nodes[level] = reloc_root->node;1620		path->slots[level] = 0;1621	} else {1622		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);1623 1624		level = btrfs_root_drop_level(root_item);1625		BUG_ON(level == 0);1626		path->lowest_level = level;1627		ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);1628		path->lowest_level = 0;1629		if (ret < 0) {1630			btrfs_free_path(path);1631			return ret;1632		}1633 1634		btrfs_node_key_to_cpu(path->nodes[level], &next_key,1635				      path->slots[level]);1636		WARN_ON(memcmp(&key, &next_key, sizeof(key)));1637 1638		btrfs_unlock_up_safe(path, 0);1639	}1640 1641	/*1642	 * In merge_reloc_root(), we modify the upper level pointer to swap the1643	 * tree blocks between reloc tree and subvolume tree.  Thus for tree1644	 * block COW, we COW at most from level 1 to root level for each tree.1645	 *1646	 * Thus the needed metadata size is at most root_level * nodesize,1647	 * and * 2 since we have two trees to COW.1648	 */1649	reserve_level = max_t(int, 1, btrfs_root_level(root_item));1650	min_reserved = fs_info->nodesize * reserve_level * 2;1651	memset(&next_key, 0, sizeof(next_key));1652 1653	while (1) {1654		ret = btrfs_block_rsv_refill(fs_info, rc->block_rsv,1655					     min_reserved,1656					     BTRFS_RESERVE_FLUSH_LIMIT);1657		if (ret)1658			goto out;1659		trans = btrfs_start_transaction(root, 0);1660		if (IS_ERR(trans)) {1661			ret = PTR_ERR(trans);1662			trans = NULL;1663			goto out;1664		}1665 1666		/*1667		 * At this point we no longer have a reloc_control, so we can't1668		 * depend on btrfs_init_reloc_root to update our last_trans.1669		 *1670		 * But that's ok, we started the trans handle on our1671		 * corresponding fs_root, which means it's been added to the1672		 * dirty list.  At commit time we'll still call1673		 * btrfs_update_reloc_root() and update our root item1674		 * appropriately.1675		 */1676		btrfs_set_root_last_trans(reloc_root, trans->transid);1677		trans->block_rsv = rc->block_rsv;1678 1679		replaced = 0;1680		max_level = level;1681 1682		ret = walk_down_reloc_tree(reloc_root, path, &level);1683		if (ret < 0)1684			goto out;1685		if (ret > 0)1686			break;1687 1688		if (!find_next_key(path, level, &key) &&1689		    btrfs_comp_cpu_keys(&next_key, &key) >= 0) {1690			ret = 0;1691		} else {1692			ret = replace_path(trans, rc, root, reloc_root, path,1693					   &next_key, level, max_level);1694		}1695		if (ret < 0)1696			goto out;1697		if (ret > 0) {1698			level = ret;1699			btrfs_node_key_to_cpu(path->nodes[level], &key,1700					      path->slots[level]);1701			replaced = 1;1702		}1703 1704		ret = walk_up_reloc_tree(reloc_root, path, &level);1705		if (ret > 0)1706			break;1707 1708		BUG_ON(level == 0);1709		/*1710		 * save the merging progress in the drop_progress.1711		 * this is OK since root refs == 1 in this case.1712		 */1713		btrfs_node_key(path->nodes[level], &root_item->drop_progress,1714			       path->slots[level]);1715		btrfs_set_root_drop_level(root_item, level);1716 1717		btrfs_end_transaction_throttle(trans);1718		trans = NULL;1719 1720		btrfs_btree_balance_dirty(fs_info);1721 1722		if (replaced && rc->stage == UPDATE_DATA_PTRS)1723			invalidate_extent_cache(root, &key, &next_key);1724	}1725 1726	/*1727	 * handle the case only one block in the fs tree need to be1728	 * relocated and the block is tree root.1729	 */1730	leaf = btrfs_lock_root_node(root);1731	ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf,1732			      BTRFS_NESTING_COW);1733	btrfs_tree_unlock(leaf);1734	free_extent_buffer(leaf);1735out:1736	btrfs_free_path(path);1737 1738	if (ret == 0) {1739		ret = insert_dirty_subvol(trans, rc, root);1740		if (ret)1741			btrfs_abort_transaction(trans, ret);1742	}1743 1744	if (trans)1745		btrfs_end_transaction_throttle(trans);1746 1747	btrfs_btree_balance_dirty(fs_info);1748 1749	if (replaced && rc->stage == UPDATE_DATA_PTRS)1750		invalidate_extent_cache(root, &key, &next_key);1751 1752	return ret;1753}1754 1755static noinline_for_stack1756int prepare_to_merge(struct reloc_control *rc, int err)1757{1758	struct btrfs_root *root = rc->extent_root;1759	struct btrfs_fs_info *fs_info = root->fs_info;1760	struct btrfs_root *reloc_root;1761	struct btrfs_trans_handle *trans;1762	LIST_HEAD(reloc_roots);1763	u64 num_bytes = 0;1764	int ret;1765 1766	mutex_lock(&fs_info->reloc_mutex);1767	rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;1768	rc->merging_rsv_size += rc->nodes_relocated * 2;1769	mutex_unlock(&fs_info->reloc_mutex);1770 1771again:1772	if (!err) {1773		num_bytes = rc->merging_rsv_size;1774		ret = btrfs_block_rsv_add(fs_info, rc->block_rsv, num_bytes,1775					  BTRFS_RESERVE_FLUSH_ALL);1776		if (ret)1777			err = ret;1778	}1779 1780	trans = btrfs_join_transaction(rc->extent_root);1781	if (IS_ERR(trans)) {1782		if (!err)1783			btrfs_block_rsv_release(fs_info, rc->block_rsv,1784						num_bytes, NULL);1785		return PTR_ERR(trans);1786	}1787 1788	if (!err) {1789		if (num_bytes != rc->merging_rsv_size) {1790			btrfs_end_transaction(trans);1791			btrfs_block_rsv_release(fs_info, rc->block_rsv,1792						num_bytes, NULL);1793			goto again;1794		}1795	}1796 1797	rc->merge_reloc_tree = true;1798 1799	while (!list_empty(&rc->reloc_roots)) {1800		reloc_root = list_entry(rc->reloc_roots.next,1801					struct btrfs_root, root_list);1802		list_del_init(&reloc_root->root_list);1803 1804		root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,1805				false);1806		if (IS_ERR(root)) {1807			/*1808			 * Even if we have an error we need this reloc root1809			 * back on our list so we can clean up properly.1810			 */1811			list_add(&reloc_root->root_list, &reloc_roots);1812			btrfs_abort_transaction(trans, (int)PTR_ERR(root));1813			if (!err)1814				err = PTR_ERR(root);1815			break;1816		}1817 1818		if (unlikely(root->reloc_root != reloc_root)) {1819			if (root->reloc_root) {1820				btrfs_err(fs_info,1821"reloc tree mismatch, root %lld has reloc root key (%lld %u %llu) gen %llu, expect reloc root key (%lld %u %llu) gen %llu",1822					  btrfs_root_id(root),1823					  btrfs_root_id(root->reloc_root),1824					  root->reloc_root->root_key.type,1825					  root->reloc_root->root_key.offset,1826					  btrfs_root_generation(1827						  &root->reloc_root->root_item),1828					  btrfs_root_id(reloc_root),1829					  reloc_root->root_key.type,1830					  reloc_root->root_key.offset,1831					  btrfs_root_generation(1832						  &reloc_root->root_item));1833			} else {1834				btrfs_err(fs_info,1835"reloc tree mismatch, root %lld has no reloc root, expect reloc root key (%lld %u %llu) gen %llu",1836					  btrfs_root_id(root),1837					  btrfs_root_id(reloc_root),1838					  reloc_root->root_key.type,1839					  reloc_root->root_key.offset,1840					  btrfs_root_generation(1841						  &reloc_root->root_item));1842			}1843			list_add(&reloc_root->root_list, &reloc_roots);1844			btrfs_put_root(root);1845			btrfs_abort_transaction(trans, -EUCLEAN);1846			if (!err)1847				err = -EUCLEAN;1848			break;1849		}1850 1851		/*1852		 * set reference count to 1, so btrfs_recover_relocation1853		 * knows it should resumes merging1854		 */1855		if (!err)1856			btrfs_set_root_refs(&reloc_root->root_item, 1);1857		ret = btrfs_update_reloc_root(trans, root);1858 1859		/*1860		 * Even if we have an error we need this reloc root back on our1861		 * list so we can clean up properly.1862		 */1863		list_add(&reloc_root->root_list, &reloc_roots);1864		btrfs_put_root(root);1865 1866		if (ret) {1867			btrfs_abort_transaction(trans, ret);1868			if (!err)1869				err = ret;1870			break;1871		}1872	}1873 1874	list_splice(&reloc_roots, &rc->reloc_roots);1875 1876	if (!err)1877		err = btrfs_commit_transaction(trans);1878	else1879		btrfs_end_transaction(trans);1880	return err;1881}1882 1883static noinline_for_stack1884void free_reloc_roots(struct list_head *list)1885{1886	struct btrfs_root *reloc_root, *tmp;1887 1888	list_for_each_entry_safe(reloc_root, tmp, list, root_list)1889		__del_reloc_root(reloc_root);1890}1891 1892static noinline_for_stack1893void merge_reloc_roots(struct reloc_control *rc)1894{1895	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;1896	struct btrfs_root *root;1897	struct btrfs_root *reloc_root;1898	LIST_HEAD(reloc_roots);1899	int found = 0;1900	int ret = 0;1901again:1902	root = rc->extent_root;1903 1904	/*1905	 * this serializes us with btrfs_record_root_in_transaction,1906	 * we have to make sure nobody is in the middle of1907	 * adding their roots to the list while we are1908	 * doing this splice1909	 */1910	mutex_lock(&fs_info->reloc_mutex);1911	list_splice_init(&rc->reloc_roots, &reloc_roots);1912	mutex_unlock(&fs_info->reloc_mutex);1913 1914	while (!list_empty(&reloc_roots)) {1915		found = 1;1916		reloc_root = list_entry(reloc_roots.next,1917					struct btrfs_root, root_list);1918 1919		root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,1920					 false);1921		if (btrfs_root_refs(&reloc_root->root_item) > 0) {1922			if (WARN_ON(IS_ERR(root))) {1923				/*1924				 * For recovery we read the fs roots on mount,1925				 * and if we didn't find the root then we marked1926				 * the reloc root as a garbage root.  For normal1927				 * relocation obviously the root should exist in1928				 * memory.  However there's no reason we can't1929				 * handle the error properly here just in case.1930				 */1931				ret = PTR_ERR(root);1932				goto out;1933			}1934			if (WARN_ON(root->reloc_root != reloc_root)) {1935				/*1936				 * This can happen if on-disk metadata has some1937				 * corruption, e.g. bad reloc tree key offset.1938				 */1939				ret = -EINVAL;1940				goto out;1941			}1942			ret = merge_reloc_root(rc, root);1943			btrfs_put_root(root);1944			if (ret) {1945				if (list_empty(&reloc_root->root_list))1946					list_add_tail(&reloc_root->root_list,1947						      &reloc_roots);1948				goto out;1949			}1950		} else {1951			if (!IS_ERR(root)) {1952				if (root->reloc_root == reloc_root) {1953					root->reloc_root = NULL;1954					btrfs_put_root(reloc_root);1955				}1956				clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE,1957					  &root->state);1958				btrfs_put_root(root);1959			}1960 1961			list_del_init(&reloc_root->root_list);1962			/* Don't forget to queue this reloc root for cleanup */1963			list_add_tail(&reloc_root->reloc_dirty_list,1964				      &rc->dirty_subvol_roots);1965		}1966	}1967 1968	if (found) {1969		found = 0;1970		goto again;1971	}1972out:1973	if (ret) {1974		btrfs_handle_fs_error(fs_info, ret, NULL);1975		free_reloc_roots(&reloc_roots);1976 1977		/* new reloc root may be added */1978		mutex_lock(&fs_info->reloc_mutex);1979		list_splice_init(&rc->reloc_roots, &reloc_roots);1980		mutex_unlock(&fs_info->reloc_mutex);1981		free_reloc_roots(&reloc_roots);1982	}1983 1984	/*1985	 * We used to have1986	 *1987	 * BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));1988	 *1989	 * here, but it's wrong.  If we fail to start the transaction in1990	 * prepare_to_merge() we will have only 0 ref reloc roots, none of which1991	 * have actually been removed from the reloc_root_tree rb tree.  This is1992	 * fine because we're bailing here, and we hold a reference on the root1993	 * for the list that holds it, so these roots will be cleaned up when we1994	 * do the reloc_dirty_list afterwards.  Meanwhile the root->reloc_root1995	 * will be cleaned up on unmount.1996	 *1997	 * The remaining nodes will be cleaned up by free_reloc_control.1998	 */1999}2000 2001static void free_block_list(struct rb_root *blocks)2002{2003	struct tree_block *block;2004	struct rb_node *rb_node;2005	while ((rb_node = rb_first(blocks))) {2006		block = rb_entry(rb_node, struct tree_block, rb_node);2007		rb_erase(rb_node, blocks);2008		kfree(block);2009	}2010}2011 2012static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,2013				      struct btrfs_root *reloc_root)2014{2015	struct btrfs_fs_info *fs_info = reloc_root->fs_info;2016	struct btrfs_root *root;2017	int ret;2018 2019	if (btrfs_get_root_last_trans(reloc_root) == trans->transid)2020		return 0;2021 2022	root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset, false);2023 2024	/*2025	 * This should succeed, since we can't have a reloc root without having2026	 * already looked up the actual root and created the reloc root for this2027	 * root.2028	 *2029	 * However if there's some sort of corruption where we have a ref to a2030	 * reloc root without a corresponding root this could return ENOENT.2031	 */2032	if (IS_ERR(root)) {2033		ASSERT(0);2034		return PTR_ERR(root);2035	}2036	if (root->reloc_root != reloc_root) {2037		ASSERT(0);2038		btrfs_err(fs_info,2039			  "root %llu has two reloc roots associated with it",2040			  reloc_root->root_key.offset);2041		btrfs_put_root(root);2042		return -EUCLEAN;2043	}2044	ret = btrfs_record_root_in_trans(trans, root);2045	btrfs_put_root(root);2046 2047	return ret;2048}2049 2050static noinline_for_stack2051struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,2052				     struct reloc_control *rc,2053				     struct btrfs_backref_node *node,2054				     struct btrfs_backref_edge *edges[])2055{2056	struct btrfs_backref_node *next;2057	struct btrfs_root *root;2058	int index = 0;2059	int ret;2060 2061	next = node;2062	while (1) {2063		cond_resched();2064		next = walk_up_backref(next, edges, &index);2065		root = next->root;2066 2067		/*2068		 * If there is no root, then our references for this block are2069		 * incomplete, as we should be able to walk all the way up to a2070		 * block that is owned by a root.2071		 *2072		 * This path is only for SHAREABLE roots, so if we come upon a2073		 * non-SHAREABLE root then we have backrefs that resolve2074		 * improperly.2075		 *2076		 * Both of these cases indicate file system corruption, or a bug2077		 * in the backref walking code.2078		 */2079		if (!root) {2080			ASSERT(0);2081			btrfs_err(trans->fs_info,2082		"bytenr %llu doesn't have a backref path ending in a root",2083				  node->bytenr);2084			return ERR_PTR(-EUCLEAN);2085		}2086		if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {2087			ASSERT(0);2088			btrfs_err(trans->fs_info,2089	"bytenr %llu has multiple refs with one ending in a non-shareable root",2090				  node->bytenr);2091			return ERR_PTR(-EUCLEAN);2092		}2093 2094		if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {2095			ret = record_reloc_root_in_trans(trans, root);2096			if (ret)2097				return ERR_PTR(ret);2098			break;2099		}2100 2101		ret = btrfs_record_root_in_trans(trans, root);2102		if (ret)2103			return ERR_PTR(ret);2104		root = root->reloc_root;2105 2106		/*2107		 * We could have raced with another thread which failed, so2108		 * root->reloc_root may not be set, return ENOENT in this case.2109		 */2110		if (!root)2111			return ERR_PTR(-ENOENT);2112 2113		if (next->new_bytenr != root->node->start) {2114			/*2115			 * We just created the reloc root, so we shouldn't have2116			 * ->new_bytenr set and this shouldn't be in the changed2117			 *  list.  If it is then we have multiple roots pointing2118			 *  at the same bytenr which indicates corruption, or2119			 *  we've made a mistake in the backref walking code.2120			 */2121			ASSERT(next->new_bytenr == 0);2122			ASSERT(list_empty(&next->list));2123			if (next->new_bytenr || !list_empty(&next->list)) {2124				btrfs_err(trans->fs_info,2125	"bytenr %llu possibly has multiple roots pointing at the same bytenr %llu",2126					  node->bytenr, next->bytenr);2127				return ERR_PTR(-EUCLEAN);2128			}2129 2130			next->new_bytenr = root->node->start;2131			btrfs_put_root(next->root);2132			next->root = btrfs_grab_root(root);2133			ASSERT(next->root);2134			list_add_tail(&next->list,2135				      &rc->backref_cache.changed);2136			mark_block_processed(rc, next);2137			break;2138		}2139 2140		WARN_ON(1);2141		root = NULL;2142		next = walk_down_backref(edges, &index);2143		if (!next || next->level <= node->level)2144			break;2145	}2146	if (!root) {2147		/*2148		 * This can happen if there's fs corruption or if there's a bug2149		 * in the backref lookup code.2150		 */2151		ASSERT(0);2152		return ERR_PTR(-ENOENT);2153	}2154 2155	next = node;2156	/* setup backref node path for btrfs_reloc_cow_block */2157	while (1) {2158		rc->backref_cache.path[next->level] = next;2159		if (--index < 0)2160			break;2161		next = edges[index]->node[UPPER];2162	}2163	return root;2164}2165 2166/*2167 * Select a tree root for relocation.2168 *2169 * Return NULL if the block is not shareable. We should use do_relocation() in2170 * this case.2171 *2172 * Return a tree root pointer if the block is shareable.2173 * Return -ENOENT if the block is root of reloc tree.2174 */2175static noinline_for_stack2176struct btrfs_root *select_one_root(struct btrfs_backref_node *node)2177{2178	struct btrfs_backref_node *next;2179	struct btrfs_root *root;2180	struct btrfs_root *fs_root = NULL;2181	struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];2182	int index = 0;2183 2184	next = node;2185	while (1) {2186		cond_resched();2187		next = walk_up_backref(next, edges, &index);2188		root = next->root;2189 2190		/*2191		 * This can occur if we have incomplete extent refs leading all2192		 * the way up a particular path, in this case return -EUCLEAN.2193		 */2194		if (!root)2195			return ERR_PTR(-EUCLEAN);2196 2197		/* No other choice for non-shareable tree */2198		if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))2199			return root;2200 2201		if (btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID)2202			fs_root = root;2203 2204		if (next != node)2205			return NULL;2206 2207		next = walk_down_backref(edges, &index);2208		if (!next || next->level <= node->level)2209			break;2210	}2211 2212	if (!fs_root)2213		return ERR_PTR(-ENOENT);2214	return fs_root;2215}2216 2217static noinline_for_stack u64 calcu_metadata_size(struct reloc_control *rc,2218						  struct btrfs_backref_node *node)2219{2220	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;2221	struct btrfs_backref_node *next = node;2222	struct btrfs_backref_edge *edge;2223	struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];2224	u64 num_bytes = 0;2225	int index = 0;2226 2227	BUG_ON(node->processed);2228 2229	while (next) {2230		cond_resched();2231		while (1) {2232			if (next->processed)2233				break;2234 2235			num_bytes += fs_info->nodesize;2236 2237			if (list_empty(&next->upper))2238				break;2239 2240			edge = list_entry(next->upper.next,2241					struct btrfs_backref_edge, list[LOWER]);2242			edges[index++] = edge;2243			next = edge->node[UPPER];2244		}2245		next = walk_down_backref(edges, &index);2246	}2247	return num_bytes;2248}2249 2250static int reserve_metadata_space(struct btrfs_trans_handle *trans,2251				  struct reloc_control *rc,2252				  struct btrfs_backref_node *node)2253{2254	struct btrfs_root *root = rc->extent_root;2255	struct btrfs_fs_info *fs_info = root->fs_info;2256	u64 num_bytes;2257	int ret;2258	u64 tmp;2259 2260	num_bytes = calcu_metadata_size(rc, node) * 2;2261 2262	trans->block_rsv = rc->block_rsv;2263	rc->reserved_bytes += num_bytes;2264 2265	/*2266	 * We are under a transaction here so we can only do limited flushing.2267	 * If we get an enospc just kick back -EAGAIN so we know to drop the2268	 * transaction and try to refill when we can flush all the things.2269	 */2270	ret = btrfs_block_rsv_refill(fs_info, rc->block_rsv, num_bytes,2271				     BTRFS_RESERVE_FLUSH_LIMIT);2272	if (ret) {2273		tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;2274		while (tmp <= rc->reserved_bytes)2275			tmp <<= 1;2276		/*2277		 * only one thread can access block_rsv at this point,2278		 * so we don't need hold lock to protect block_rsv.2279		 * we expand more reservation size here to allow enough2280		 * space for relocation and we will return earlier in2281		 * enospc case.2282		 */2283		rc->block_rsv->size = tmp + fs_info->nodesize *2284				      RELOCATION_RESERVED_NODES;2285		return -EAGAIN;2286	}2287 2288	return 0;2289}2290 2291/*2292 * relocate a block tree, and then update pointers in upper level2293 * blocks that reference the block to point to the new location.2294 *2295 * if called by link_to_upper, the block has already been relocated.2296 * in that case this function just updates pointers.2297 */2298static int do_relocation(struct btrfs_trans_handle *trans,2299			 struct reloc_control *rc,2300			 struct btrfs_backref_node *node,2301			 struct btrfs_key *key,2302			 struct btrfs_path *path, int lowest)2303{2304	struct btrfs_backref_node *upper;2305	struct btrfs_backref_edge *edge;2306	struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];2307	struct btrfs_root *root;2308	struct extent_buffer *eb;2309	u32 blocksize;2310	u64 bytenr;2311	int slot;2312	int ret = 0;2313 2314	/*2315	 * If we are lowest then this is the first time we're processing this2316	 * block, and thus shouldn't have an eb associated with it yet.2317	 */2318	ASSERT(!lowest || !node->eb);2319 2320	path->lowest_level = node->level + 1;2321	rc->backref_cache.path[node->level] = node;2322	list_for_each_entry(edge, &node->upper, list[LOWER]) {2323		cond_resched();2324 2325		upper = edge->node[UPPER];2326		root = select_reloc_root(trans, rc, upper, edges);2327		if (IS_ERR(root)) {2328			ret = PTR_ERR(root);2329			goto next;2330		}2331 2332		if (upper->eb && !upper->locked) {2333			if (!lowest) {2334				ret = btrfs_bin_search(upper->eb, 0, key, &slot);2335				if (ret < 0)2336					goto next;2337				BUG_ON(ret);2338				bytenr = btrfs_node_blockptr(upper->eb, slot);2339				if (node->eb->start == bytenr)2340					goto next;2341			}2342			btrfs_backref_drop_node_buffer(upper);2343		}2344 2345		if (!upper->eb) {2346			ret = btrfs_search_slot(trans, root, key, path, 0, 1);2347			if (ret) {2348				if (ret > 0)2349					ret = -ENOENT;2350 2351				btrfs_release_path(path);2352				break;2353			}2354 2355			if (!upper->eb) {2356				upper->eb = path->nodes[upper->level];2357				path->nodes[upper->level] = NULL;2358			} else {2359				BUG_ON(upper->eb != path->nodes[upper->level]);2360			}2361 2362			upper->locked = 1;2363			path->locks[upper->level] = 0;2364 2365			slot = path->slots[upper->level];2366			btrfs_release_path(path);2367		} else {2368			ret = btrfs_bin_search(upper->eb, 0, key, &slot);2369			if (ret < 0)2370				goto next;2371			BUG_ON(ret);2372		}2373 2374		bytenr = btrfs_node_blockptr(upper->eb, slot);2375		if (lowest) {2376			if (bytenr != node->bytenr) {2377				btrfs_err(root->fs_info,2378		"lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",2379					  bytenr, node->bytenr, slot,2380					  upper->eb->start);2381				ret = -EIO;2382				goto next;2383			}2384		} else {2385			if (node->eb->start == bytenr)2386				goto next;2387		}2388 2389		blocksize = root->fs_info->nodesize;2390		eb = btrfs_read_node_slot(upper->eb, slot);2391		if (IS_ERR(eb)) {2392			ret = PTR_ERR(eb);2393			goto next;2394		}2395		btrfs_tree_lock(eb);2396 2397		if (!node->eb) {2398			ret = btrfs_cow_block(trans, root, eb, upper->eb,2399					      slot, &eb, BTRFS_NESTING_COW);2400			btrfs_tree_unlock(eb);2401			free_extent_buffer(eb);2402			if (ret < 0)2403				goto next;2404			/*2405			 * We've just COWed this block, it should have updated2406			 * the correct backref node entry.2407			 */2408			ASSERT(node->eb == eb);2409		} else {2410			struct btrfs_ref ref = {2411				.action = BTRFS_ADD_DELAYED_REF,2412				.bytenr = node->eb->start,2413				.num_bytes = blocksize,2414				.parent = upper->eb->start,2415				.owning_root = btrfs_header_owner(upper->eb),2416				.ref_root = btrfs_header_owner(upper->eb),2417			};2418 2419			btrfs_set_node_blockptr(upper->eb, slot,2420						node->eb->start);2421			btrfs_set_node_ptr_generation(upper->eb, slot,2422						      trans->transid);2423			btrfs_mark_buffer_dirty(trans, upper->eb);2424 2425			btrfs_init_tree_ref(&ref, node->level,2426					    btrfs_root_id(root), false);2427			ret = btrfs_inc_extent_ref(trans, &ref);2428			if (!ret)2429				ret = btrfs_drop_subtree(trans, root, eb,2430							 upper->eb);2431			if (ret)2432				btrfs_abort_transaction(trans, ret);2433		}2434next:2435		if (!upper->pending)2436			btrfs_backref_drop_node_buffer(upper);2437		else2438			btrfs_backref_unlock_node_buffer(upper);2439		if (ret)2440			break;2441	}2442 2443	if (!ret && node->pending) {2444		btrfs_backref_drop_node_buffer(node);2445		list_move_tail(&node->list, &rc->backref_cache.changed);2446		node->pending = 0;2447	}2448 2449	path->lowest_level = 0;2450 2451	/*2452	 * We should have allocated all of our space in the block rsv and thus2453	 * shouldn't ENOSPC.2454	 */2455	ASSERT(ret != -ENOSPC);2456	return ret;2457}2458 2459static int link_to_upper(struct btrfs_trans_handle *trans,2460			 struct reloc_control *rc,2461			 struct btrfs_backref_node *node,2462			 struct btrfs_path *path)2463{2464	struct btrfs_key key;2465 2466	btrfs_node_key_to_cpu(node->eb, &key, 0);2467	return do_relocation(trans, rc, node, &key, path, 0);2468}2469 2470static int finish_pending_nodes(struct btrfs_trans_handle *trans,2471				struct reloc_control *rc,2472				struct btrfs_path *path, int err)2473{2474	LIST_HEAD(list);2475	struct btrfs_backref_cache *cache = &rc->backref_cache;2476	struct btrfs_backref_node *node;2477	int level;2478	int ret;2479 2480	for (level = 0; level < BTRFS_MAX_LEVEL; level++) {2481		while (!list_empty(&cache->pending[level])) {2482			node = list_entry(cache->pending[level].next,2483					  struct btrfs_backref_node, list);2484			list_move_tail(&node->list, &list);2485			BUG_ON(!node->pending);2486 2487			if (!err) {2488				ret = link_to_upper(trans, rc, node, path);2489				if (ret < 0)2490					err = ret;2491			}2492		}2493		list_splice_init(&list, &cache->pending[level]);2494	}2495	return err;2496}2497 2498/*2499 * mark a block and all blocks directly/indirectly reference the block2500 * as processed.2501 */2502static void update_processed_blocks(struct reloc_control *rc,2503				    struct btrfs_backref_node *node)2504{2505	struct btrfs_backref_node *next = node;2506	struct btrfs_backref_edge *edge;2507	struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];2508	int index = 0;2509 2510	while (next) {2511		cond_resched();2512		while (1) {2513			if (next->processed)2514				break;2515 2516			mark_block_processed(rc, next);2517 2518			if (list_empty(&next->upper))2519				break;2520 2521			edge = list_entry(next->upper.next,2522					struct btrfs_backref_edge, list[LOWER]);2523			edges[index++] = edge;2524			next = edge->node[UPPER];2525		}2526		next = walk_down_backref(edges, &index);2527	}2528}2529 2530static int tree_block_processed(u64 bytenr, struct reloc_control *rc)2531{2532	u32 blocksize = rc->extent_root->fs_info->nodesize;2533 2534	if (test_range_bit(&rc->processed_blocks, bytenr,2535			   bytenr + blocksize - 1, EXTENT_DIRTY, NULL))2536		return 1;2537	return 0;2538}2539 2540static int get_tree_block_key(struct btrfs_fs_info *fs_info,2541			      struct tree_block *block)2542{2543	struct btrfs_tree_parent_check check = {2544		.level = block->level,2545		.owner_root = block->owner,2546		.transid = block->key.offset2547	};2548	struct extent_buffer *eb;2549 2550	eb = read_tree_block(fs_info, block->bytenr, &check);2551	if (IS_ERR(eb))2552		return PTR_ERR(eb);2553	if (!extent_buffer_uptodate(eb)) {2554		free_extent_buffer(eb);2555		return -EIO;2556	}2557	if (block->level == 0)2558		btrfs_item_key_to_cpu(eb, &block->key, 0);2559	else2560		btrfs_node_key_to_cpu(eb, &block->key, 0);2561	free_extent_buffer(eb);2562	block->key_ready = true;2563	return 0;2564}2565 2566/*2567 * helper function to relocate a tree block2568 */2569static int relocate_tree_block(struct btrfs_trans_handle *trans,2570				struct reloc_control *rc,2571				struct btrfs_backref_node *node,2572				struct btrfs_key *key,2573				struct btrfs_path *path)2574{2575	struct btrfs_root *root;2576	int ret = 0;2577 2578	if (!node)2579		return 0;2580 2581	/*2582	 * If we fail here we want to drop our backref_node because we are going2583	 * to start over and regenerate the tree for it.2584	 */2585	ret = reserve_metadata_space(trans, rc, node);2586	if (ret)2587		goto out;2588 2589	BUG_ON(node->processed);2590	root = select_one_root(node);2591	if (IS_ERR(root)) {2592		ret = PTR_ERR(root);2593 2594		/* See explanation in select_one_root for the -EUCLEAN case. */2595		ASSERT(ret == -ENOENT);2596		if (ret == -ENOENT) {2597			ret = 0;2598			update_processed_blocks(rc, node);2599		}2600		goto out;2601	}2602 2603	if (root) {2604		if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {2605			/*2606			 * This block was the root block of a root, and this is2607			 * the first time we're processing the block and thus it2608			 * should not have had the ->new_bytenr modified and2609			 * should have not been included on the changed list.2610			 *2611			 * However in the case of corruption we could have2612			 * multiple refs pointing to the same block improperly,2613			 * and thus we would trip over these checks.  ASSERT()2614			 * for the developer case, because it could indicate a2615			 * bug in the backref code, however error out for a2616			 * normal user in the case of corruption.2617			 */2618			ASSERT(node->new_bytenr == 0);2619			ASSERT(list_empty(&node->list));2620			if (node->new_bytenr || !list_empty(&node->list)) {2621				btrfs_err(root->fs_info,2622				  "bytenr %llu has improper references to it",2623					  node->bytenr);2624				ret = -EUCLEAN;2625				goto out;2626			}2627			ret = btrfs_record_root_in_trans(trans, root);2628			if (ret)2629				goto out;2630			/*2631			 * Another thread could have failed, need to check if we2632			 * have reloc_root actually set.2633			 */2634			if (!root->reloc_root) {2635				ret = -ENOENT;2636				goto out;2637			}2638			root = root->reloc_root;2639			node->new_bytenr = root->node->start;2640			btrfs_put_root(node->root);2641			node->root = btrfs_grab_root(root);2642			ASSERT(node->root);2643			list_add_tail(&node->list, &rc->backref_cache.changed);2644		} else {2645			path->lowest_level = node->level;2646			if (root == root->fs_info->chunk_root)2647				btrfs_reserve_chunk_metadata(trans, false);2648			ret = btrfs_search_slot(trans, root, key, path, 0, 1);2649			btrfs_release_path(path);2650			if (root == root->fs_info->chunk_root)2651				btrfs_trans_release_chunk_metadata(trans);2652			if (ret > 0)2653				ret = 0;2654		}2655		if (!ret)2656			update_processed_blocks(rc, node);2657	} else {2658		ret = do_relocation(trans, rc, node, key, path, 1);2659	}2660out:2661	if (ret || node->level == 0 || node->cowonly)2662		btrfs_backref_cleanup_node(&rc->backref_cache, node);2663	return ret;2664}2665 2666/*2667 * relocate a list of blocks2668 */2669static noinline_for_stack2670int relocate_tree_blocks(struct btrfs_trans_handle *trans,2671			 struct reloc_control *rc, struct rb_root *blocks)2672{2673	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;2674	struct btrfs_backref_node *node;2675	struct btrfs_path *path;2676	struct tree_block *block;2677	struct tree_block *next;2678	int ret = 0;2679 2680	path = btrfs_alloc_path();2681	if (!path) {2682		ret = -ENOMEM;2683		goto out_free_blocks;2684	}2685 2686	/* Kick in readahead for tree blocks with missing keys */2687	rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {2688		if (!block->key_ready)2689			btrfs_readahead_tree_block(fs_info, block->bytenr,2690						   block->owner, 0,2691						   block->level);2692	}2693 2694	/* Get first keys */2695	rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {2696		if (!block->key_ready) {2697			ret = get_tree_block_key(fs_info, block);2698			if (ret)2699				goto out_free_path;2700		}2701	}2702 2703	/* Do tree relocation */2704	rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {2705		node = build_backref_tree(trans, rc, &block->key,2706					  block->level, block->bytenr);2707		if (IS_ERR(node)) {2708			ret = PTR_ERR(node);2709			goto out;2710		}2711 2712		ret = relocate_tree_block(trans, rc, node, &block->key,2713					  path);2714		if (ret < 0)2715			break;2716	}2717out:2718	ret = finish_pending_nodes(trans, rc, path, ret);2719 2720out_free_path:2721	btrfs_free_path(path);2722out_free_blocks:2723	free_block_list(blocks);2724	return ret;2725}2726 2727static noinline_for_stack int prealloc_file_extent_cluster(struct reloc_control *rc)2728{2729	const struct file_extent_cluster *cluster = &rc->cluster;2730	struct btrfs_inode *inode = BTRFS_I(rc->data_inode);2731	u64 alloc_hint = 0;2732	u64 start;2733	u64 end;2734	u64 offset = inode->reloc_block_group_start;2735	u64 num_bytes;2736	int nr;2737	int ret = 0;2738	u64 i_size = i_size_read(&inode->vfs_inode);2739	u64 prealloc_start = cluster->start - offset;2740	u64 prealloc_end = cluster->end - offset;2741	u64 cur_offset = prealloc_start;2742 2743	/*2744	 * For subpage case, previous i_size may not be aligned to PAGE_SIZE.2745	 * This means the range [i_size, PAGE_END + 1) is filled with zeros by2746	 * btrfs_do_readpage() call of previously relocated file cluster.2747	 *2748	 * If the current cluster starts in the above range, btrfs_do_readpage()2749	 * will skip the read, and relocate_one_folio() will later writeback2750	 * the padding zeros as new data, causing data corruption.2751	 *2752	 * Here we have to manually invalidate the range (i_size, PAGE_END + 1).2753	 */2754	if (!PAGE_ALIGNED(i_size)) {2755		struct address_space *mapping = inode->vfs_inode.i_mapping;2756		struct btrfs_fs_info *fs_info = inode->root->fs_info;2757		const u32 sectorsize = fs_info->sectorsize;2758		struct folio *folio;2759 2760		ASSERT(sectorsize < PAGE_SIZE);2761		ASSERT(IS_ALIGNED(i_size, sectorsize));2762 2763		/*2764		 * Subpage can't handle page with DIRTY but without UPTODATE2765		 * bit as it can lead to the following deadlock:2766		 *2767		 * btrfs_read_folio()2768		 * | Page already *locked*2769		 * |- btrfs_lock_and_flush_ordered_range()2770		 *    |- btrfs_start_ordered_extent()2771		 *       |- extent_write_cache_pages()2772		 *          |- lock_page()2773		 *             We try to lock the page we already hold.2774		 *2775		 * Here we just writeback the whole data reloc inode, so that2776		 * we will be ensured to have no dirty range in the page, and2777		 * are safe to clear the uptodate bits.2778		 *2779		 * This shouldn't cause too much overhead, as we need to write2780		 * the data back anyway.2781		 */2782		ret = filemap_write_and_wait(mapping);2783		if (ret < 0)2784			return ret;2785 2786		clear_extent_bits(&inode->io_tree, i_size,2787				  round_up(i_size, PAGE_SIZE) - 1,2788				  EXTENT_UPTODATE);2789		folio = filemap_lock_folio(mapping, i_size >> PAGE_SHIFT);2790		/*2791		 * If page is freed we don't need to do anything then, as we2792		 * will re-read the whole page anyway.2793		 */2794		if (!IS_ERR(folio)) {2795			btrfs_subpage_clear_uptodate(fs_info, folio, i_size,2796					round_up(i_size, PAGE_SIZE) - i_size);2797			folio_unlock(folio);2798			folio_put(folio);2799		}2800	}2801 2802	BUG_ON(cluster->start != cluster->boundary[0]);2803	ret = btrfs_alloc_data_chunk_ondemand(inode,2804					      prealloc_end + 1 - prealloc_start);2805	if (ret)2806		return ret;2807 2808	btrfs_inode_lock(inode, 0);2809	for (nr = 0; nr < cluster->nr; nr++) {2810		struct extent_state *cached_state = NULL;2811 2812		start = cluster->boundary[nr] - offset;2813		if (nr + 1 < cluster->nr)2814			end = cluster->boundary[nr + 1] - 1 - offset;2815		else2816			end = cluster->end - offset;2817 2818		lock_extent(&inode->io_tree, start, end, &cached_state);2819		num_bytes = end + 1 - start;2820		ret = btrfs_prealloc_file_range(&inode->vfs_inode, 0, start,2821						num_bytes, num_bytes,2822						end + 1, &alloc_hint);2823		cur_offset = end + 1;2824		unlock_extent(&inode->io_tree, start, end, &cached_state);2825		if (ret)2826			break;2827	}2828	btrfs_inode_unlock(inode, 0);2829 2830	if (cur_offset < prealloc_end)2831		btrfs_free_reserved_data_space_noquota(inode->root->fs_info,2832					       prealloc_end + 1 - cur_offset);2833	return ret;2834}2835 2836static noinline_for_stack int setup_relocation_extent_mapping(struct reloc_control *rc)2837{2838	struct btrfs_inode *inode = BTRFS_I(rc->data_inode);2839	struct extent_map *em;2840	struct extent_state *cached_state = NULL;2841	u64 offset = inode->reloc_block_group_start;2842	u64 start = rc->cluster.start - offset;2843	u64 end = rc->cluster.end - offset;2844	int ret = 0;2845 2846	em = alloc_extent_map();2847	if (!em)2848		return -ENOMEM;2849 2850	em->start = start;2851	em->len = end + 1 - start;2852	em->disk_bytenr = rc->cluster.start;2853	em->disk_num_bytes = em->len;2854	em->ram_bytes = em->len;2855	em->flags |= EXTENT_FLAG_PINNED;2856 2857	lock_extent(&inode->io_tree, start, end, &cached_state);2858	ret = btrfs_replace_extent_map_range(inode, em, false);2859	unlock_extent(&inode->io_tree, start, end, &cached_state);2860	free_extent_map(em);2861 2862	return ret;2863}2864 2865/*2866 * Allow error injection to test balance/relocation cancellation2867 */2868noinline int btrfs_should_cancel_balance(const struct btrfs_fs_info *fs_info)2869{2870	return atomic_read(&fs_info->balance_cancel_req) ||2871		atomic_read(&fs_info->reloc_cancel_req) ||2872		fatal_signal_pending(current);2873}2874ALLOW_ERROR_INJECTION(btrfs_should_cancel_balance, TRUE);2875 2876static u64 get_cluster_boundary_end(const struct file_extent_cluster *cluster,2877				    int cluster_nr)2878{2879	/* Last extent, use cluster end directly */2880	if (cluster_nr >= cluster->nr - 1)2881		return cluster->end;2882 2883	/* Use next boundary start*/2884	return cluster->boundary[cluster_nr + 1] - 1;2885}2886 2887static int relocate_one_folio(struct reloc_control *rc,2888			      struct file_ra_state *ra,2889			      int *cluster_nr, unsigned long index)2890{2891	const struct file_extent_cluster *cluster = &rc->cluster;2892	struct inode *inode = rc->data_inode;2893	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);2894	u64 offset = BTRFS_I(inode)->reloc_block_group_start;2895	const unsigned long last_index = (cluster->end - offset) >> PAGE_SHIFT;2896	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);2897	struct folio *folio;2898	u64 folio_start;2899	u64 folio_end;2900	u64 cur;2901	int ret;2902	const bool use_rst = btrfs_need_stripe_tree_update(fs_info, rc->block_group->flags);2903 2904	ASSERT(index <= last_index);2905	folio = filemap_lock_folio(inode->i_mapping, index);2906	if (IS_ERR(folio)) {2907 2908		/*2909		 * On relocation we're doing readahead on the relocation inode,2910		 * but if the filesystem is backed by a RAID stripe tree we can2911		 * get ENOENT (e.g. due to preallocated extents not being2912		 * mapped in the RST) from the lookup.2913		 *2914		 * But readahead doesn't handle the error and submits invalid2915		 * reads to the device, causing a assertion failures.2916		 */2917		if (!use_rst)2918			page_cache_sync_readahead(inode->i_mapping, ra, NULL,2919						  index, last_index + 1 - index);2920		folio = __filemap_get_folio(inode->i_mapping, index,2921					    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,2922					    mask);2923		if (IS_ERR(folio))2924			return PTR_ERR(folio);2925	}2926 2927	WARN_ON(folio_order(folio));2928 2929	if (folio_test_readahead(folio) && !use_rst)2930		page_cache_async_readahead(inode->i_mapping, ra, NULL,2931					   folio, last_index + 1 - index);2932 2933	if (!folio_test_uptodate(folio)) {2934		btrfs_read_folio(NULL, folio);2935		folio_lock(folio);2936		if (!folio_test_uptodate(folio)) {2937			ret = -EIO;2938			goto release_folio;2939		}2940	}2941 2942	/*2943	 * We could have lost folio private when we dropped the lock to read the2944	 * folio above, make sure we set_page_extent_mapped here so we have any2945	 * of the subpage blocksize stuff we need in place.2946	 */2947	ret = set_folio_extent_mapped(folio);2948	if (ret < 0)2949		goto release_folio;2950 2951	folio_start = folio_pos(folio);2952	folio_end = folio_start + PAGE_SIZE - 1;2953 2954	/*2955	 * Start from the cluster, as for subpage case, the cluster can start2956	 * inside the folio.2957	 */2958	cur = max(folio_start, cluster->boundary[*cluster_nr] - offset);2959	while (cur <= folio_end) {2960		struct extent_state *cached_state = NULL;2961		u64 extent_start = cluster->boundary[*cluster_nr] - offset;2962		u64 extent_end = get_cluster_boundary_end(cluster,2963						*cluster_nr) - offset;2964		u64 clamped_start = max(folio_start, extent_start);2965		u64 clamped_end = min(folio_end, extent_end);2966		u32 clamped_len = clamped_end + 1 - clamped_start;2967 2968		/* Reserve metadata for this range */2969		ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),2970						      clamped_len, clamped_len,2971						      false);2972		if (ret)2973			goto release_folio;2974 2975		/* Mark the range delalloc and dirty for later writeback */2976		lock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end,2977			    &cached_state);2978		ret = btrfs_set_extent_delalloc(BTRFS_I(inode), clamped_start,2979						clamped_end, 0, &cached_state);2980		if (ret) {2981			clear_extent_bit(&BTRFS_I(inode)->io_tree,2982					 clamped_start, clamped_end,2983					 EXTENT_LOCKED | EXTENT_BOUNDARY,2984					 &cached_state);2985			btrfs_delalloc_release_metadata(BTRFS_I(inode),2986							clamped_len, true);2987			btrfs_delalloc_release_extents(BTRFS_I(inode),2988						       clamped_len);2989			goto release_folio;2990		}2991		btrfs_folio_set_dirty(fs_info, folio, clamped_start, clamped_len);2992 2993		/*2994		 * Set the boundary if it's inside the folio.2995		 * Data relocation requires the destination extents to have the2996		 * same size as the source.2997		 * EXTENT_BOUNDARY bit prevents current extent from being merged2998		 * with previous extent.2999		 */3000		if (in_range(cluster->boundary[*cluster_nr] - offset, folio_start, PAGE_SIZE)) {3001			u64 boundary_start = cluster->boundary[*cluster_nr] -3002						offset;3003			u64 boundary_end = boundary_start +3004					   fs_info->sectorsize - 1;3005 3006			set_extent_bit(&BTRFS_I(inode)->io_tree,3007				       boundary_start, boundary_end,3008				       EXTENT_BOUNDARY, NULL);3009		}3010		unlock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end,3011			      &cached_state);3012		btrfs_delalloc_release_extents(BTRFS_I(inode), clamped_len);3013		cur += clamped_len;3014 3015		/* Crossed extent end, go to next extent */3016		if (cur >= extent_end) {3017			(*cluster_nr)++;3018			/* Just finished the last extent of the cluster, exit. */3019			if (*cluster_nr >= cluster->nr)3020				break;3021		}3022	}3023	folio_unlock(folio);3024	folio_put(folio);3025 3026	balance_dirty_pages_ratelimited(inode->i_mapping);3027	btrfs_throttle(fs_info);3028	if (btrfs_should_cancel_balance(fs_info))3029		ret = -ECANCELED;3030	return ret;3031 3032release_folio:3033	folio_unlock(folio);3034	folio_put(folio);3035	return ret;3036}3037 3038static int relocate_file_extent_cluster(struct reloc_control *rc)3039{3040	struct inode *inode = rc->data_inode;3041	const struct file_extent_cluster *cluster = &rc->cluster;3042	u64 offset = BTRFS_I(inode)->reloc_block_group_start;3043	unsigned long index;3044	unsigned long last_index;3045	struct file_ra_state *ra;3046	int cluster_nr = 0;3047	int ret = 0;3048 3049	if (!cluster->nr)3050		return 0;3051 3052	ra = kzalloc(sizeof(*ra), GFP_NOFS);3053	if (!ra)3054		return -ENOMEM;3055 3056	ret = prealloc_file_extent_cluster(rc);3057	if (ret)3058		goto out;3059 3060	file_ra_state_init(ra, inode->i_mapping);3061 3062	ret = setup_relocation_extent_mapping(rc);3063	if (ret)3064		goto out;3065 3066	last_index = (cluster->end - offset) >> PAGE_SHIFT;3067	for (index = (cluster->start - offset) >> PAGE_SHIFT;3068	     index <= last_index && !ret; index++)3069		ret = relocate_one_folio(rc, ra, &cluster_nr, index);3070	if (ret == 0)3071		WARN_ON(cluster_nr != cluster->nr);3072out:3073	kfree(ra);3074	return ret;3075}3076 3077static noinline_for_stack int relocate_data_extent(struct reloc_control *rc,3078					   const struct btrfs_key *extent_key)3079{3080	struct inode *inode = rc->data_inode;3081	struct file_extent_cluster *cluster = &rc->cluster;3082	int ret;3083	struct btrfs_root *root = BTRFS_I(inode)->root;3084 3085	if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {3086		ret = relocate_file_extent_cluster(rc);3087		if (ret)3088			return ret;3089		cluster->nr = 0;3090	}3091 3092	/*3093	 * Under simple quotas, we set root->relocation_src_root when we find3094	 * the extent. If adjacent extents have different owners, we can't merge3095	 * them while relocating. Handle this by storing the owning root that3096	 * started a cluster and if we see an extent from a different root break3097	 * cluster formation (just like the above case of non-adjacent extents).3098	 *3099	 * Without simple quotas, relocation_src_root is always 0, so we should3100	 * never see a mismatch, and it should have no effect on relocation3101	 * clusters.3102	 */3103	if (cluster->nr > 0 && cluster->owning_root != root->relocation_src_root) {3104		u64 tmp = root->relocation_src_root;3105 3106		/*3107		 * root->relocation_src_root is the state that actually affects3108		 * the preallocation we do here, so set it to the root owning3109		 * the cluster we need to relocate.3110		 */3111		root->relocation_src_root = cluster->owning_root;3112		ret = relocate_file_extent_cluster(rc);3113		if (ret)3114			return ret;3115		cluster->nr = 0;3116		/* And reset it back for the current extent's owning root. */3117		root->relocation_src_root = tmp;3118	}3119 3120	if (!cluster->nr) {3121		cluster->start = extent_key->objectid;3122		cluster->owning_root = root->relocation_src_root;3123	}3124	else3125		BUG_ON(cluster->nr >= MAX_EXTENTS);3126	cluster->end = extent_key->objectid + extent_key->offset - 1;3127	cluster->boundary[cluster->nr] = extent_key->objectid;3128	cluster->nr++;3129 3130	if (cluster->nr >= MAX_EXTENTS) {3131		ret = relocate_file_extent_cluster(rc);3132		if (ret)3133			return ret;3134		cluster->nr = 0;3135	}3136	return 0;3137}3138 3139/*3140 * helper to add a tree block to the list.3141 * the major work is getting the generation and level of the block3142 */3143static int add_tree_block(struct reloc_control *rc,3144			  const struct btrfs_key *extent_key,3145			  struct btrfs_path *path,3146			  struct rb_root *blocks)3147{3148	struct extent_buffer *eb;3149	struct btrfs_extent_item *ei;3150	struct btrfs_tree_block_info *bi;3151	struct tree_block *block;3152	struct rb_node *rb_node;3153	u32 item_size;3154	int level = -1;3155	u64 generation;3156	u64 owner = 0;3157 3158	eb =  path->nodes[0];3159	item_size = btrfs_item_size(eb, path->slots[0]);3160 3161	if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||3162	    item_size >= sizeof(*ei) + sizeof(*bi)) {3163		unsigned long ptr = 0, end;3164 3165		ei = btrfs_item_ptr(eb, path->slots[0],3166				struct btrfs_extent_item);3167		end = (unsigned long)ei + item_size;3168		if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {3169			bi = (struct btrfs_tree_block_info *)(ei + 1);3170			level = btrfs_tree_block_level(eb, bi);3171			ptr = (unsigned long)(bi + 1);3172		} else {3173			level = (int)extent_key->offset;3174			ptr = (unsigned long)(ei + 1);3175		}3176		generation = btrfs_extent_generation(eb, ei);3177 3178		/*3179		 * We're reading random blocks without knowing their owner ahead3180		 * of time.  This is ok most of the time, as all reloc roots and3181		 * fs roots have the same lock type.  However normal trees do3182		 * not, and the only way to know ahead of time is to read the3183		 * inline ref offset.  We know it's an fs root if3184		 *3185		 * 1. There's more than one ref.3186		 * 2. There's a SHARED_DATA_REF_KEY set.3187		 * 3. FULL_BACKREF is set on the flags.3188		 *3189		 * Otherwise it's safe to assume that the ref offset == the3190		 * owner of this block, so we can use that when calling3191		 * read_tree_block.3192		 */3193		if (btrfs_extent_refs(eb, ei) == 1 &&3194		    !(btrfs_extent_flags(eb, ei) &3195		      BTRFS_BLOCK_FLAG_FULL_BACKREF) &&3196		    ptr < end) {3197			struct btrfs_extent_inline_ref *iref;3198			int type;3199 3200			iref = (struct btrfs_extent_inline_ref *)ptr;3201			type = btrfs_get_extent_inline_ref_type(eb, iref,3202							BTRFS_REF_TYPE_BLOCK);3203			if (type == BTRFS_REF_TYPE_INVALID)3204				return -EINVAL;3205			if (type == BTRFS_TREE_BLOCK_REF_KEY)3206				owner = btrfs_extent_inline_ref_offset(eb, iref);3207		}3208	} else {3209		btrfs_print_leaf(eb);3210		btrfs_err(rc->block_group->fs_info,3211			  "unrecognized tree backref at tree block %llu slot %u",3212			  eb->start, path->slots[0]);3213		btrfs_release_path(path);3214		return -EUCLEAN;3215	}3216 3217	btrfs_release_path(path);3218 3219	BUG_ON(level == -1);3220 3221	block = kmalloc(sizeof(*block), GFP_NOFS);3222	if (!block)3223		return -ENOMEM;3224 3225	block->bytenr = extent_key->objectid;3226	block->key.objectid = rc->extent_root->fs_info->nodesize;3227	block->key.offset = generation;3228	block->level = level;3229	block->key_ready = false;3230	block->owner = owner;3231 3232	rb_node = rb_simple_insert(blocks, block->bytenr, &block->rb_node);3233	if (rb_node)3234		btrfs_backref_panic(rc->extent_root->fs_info, block->bytenr,3235				    -EEXIST);3236 3237	return 0;3238}3239 3240/*3241 * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY3242 */3243static int __add_tree_block(struct reloc_control *rc,3244			    u64 bytenr, u32 blocksize,3245			    struct rb_root *blocks)3246{3247	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;3248	struct btrfs_path *path;3249	struct btrfs_key key;3250	int ret;3251	bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);3252 3253	if (tree_block_processed(bytenr, rc))3254		return 0;3255 3256	if (rb_simple_search(blocks, bytenr))3257		return 0;3258 3259	path = btrfs_alloc_path();3260	if (!path)3261		return -ENOMEM;3262again:3263	key.objectid = bytenr;3264	if (skinny) {3265		key.type = BTRFS_METADATA_ITEM_KEY;3266		key.offset = (u64)-1;3267	} else {3268		key.type = BTRFS_EXTENT_ITEM_KEY;3269		key.offset = blocksize;3270	}3271 3272	path->search_commit_root = 1;3273	path->skip_locking = 1;3274	ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);3275	if (ret < 0)3276		goto out;3277 3278	if (ret > 0 && skinny) {3279		if (path->slots[0]) {3280			path->slots[0]--;3281			btrfs_item_key_to_cpu(path->nodes[0], &key,3282					      path->slots[0]);3283			if (key.objectid == bytenr &&3284			    (key.type == BTRFS_METADATA_ITEM_KEY ||3285			     (key.type == BTRFS_EXTENT_ITEM_KEY &&3286			      key.offset == blocksize)))3287				ret = 0;3288		}3289 3290		if (ret) {3291			skinny = false;3292			btrfs_release_path(path);3293			goto again;3294		}3295	}3296	if (ret) {3297		ASSERT(ret == 1);3298		btrfs_print_leaf(path->nodes[0]);3299		btrfs_err(fs_info,3300	     "tree block extent item (%llu) is not found in extent tree",3301		     bytenr);3302		WARN_ON(1);3303		ret = -EINVAL;3304		goto out;3305	}3306 3307	ret = add_tree_block(rc, &key, path, blocks);3308out:3309	btrfs_free_path(path);3310	return ret;3311}3312 3313static int delete_block_group_cache(struct btrfs_fs_info *fs_info,3314				    struct btrfs_block_group *block_group,3315				    struct inode *inode,3316				    u64 ino)3317{3318	struct btrfs_root *root = fs_info->tree_root;3319	struct btrfs_trans_handle *trans;3320	int ret = 0;3321 3322	if (inode)3323		goto truncate;3324 3325	inode = btrfs_iget(ino, root);3326	if (IS_ERR(inode))3327		return -ENOENT;3328 3329truncate:3330	ret = btrfs_check_trunc_cache_free_space(fs_info,3331						 &fs_info->global_block_rsv);3332	if (ret)3333		goto out;3334 3335	trans = btrfs_join_transaction(root);3336	if (IS_ERR(trans)) {3337		ret = PTR_ERR(trans);3338		goto out;3339	}3340 3341	ret = btrfs_truncate_free_space_cache(trans, block_group, inode);3342 3343	btrfs_end_transaction(trans);3344	btrfs_btree_balance_dirty(fs_info);3345out:3346	iput(inode);3347	return ret;3348}3349 3350/*3351 * Locate the free space cache EXTENT_DATA in root tree leaf and delete the3352 * cache inode, to avoid free space cache data extent blocking data relocation.3353 */3354static int delete_v1_space_cache(struct extent_buffer *leaf,3355				 struct btrfs_block_group *block_group,3356				 u64 data_bytenr)3357{3358	u64 space_cache_ino;3359	struct btrfs_file_extent_item *ei;3360	struct btrfs_key key;3361	bool found = false;3362	int i;3363	int ret;3364 3365	if (btrfs_header_owner(leaf) != BTRFS_ROOT_TREE_OBJECTID)3366		return 0;3367 3368	for (i = 0; i < btrfs_header_nritems(leaf); i++) {3369		u8 type;3370 3371		btrfs_item_key_to_cpu(leaf, &key, i);3372		if (key.type != BTRFS_EXTENT_DATA_KEY)3373			continue;3374		ei = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);3375		type = btrfs_file_extent_type(leaf, ei);3376 3377		if ((type == BTRFS_FILE_EXTENT_REG ||3378		     type == BTRFS_FILE_EXTENT_PREALLOC) &&3379		    btrfs_file_extent_disk_bytenr(leaf, ei) == data_bytenr) {3380			found = true;3381			space_cache_ino = key.objectid;3382			break;3383		}3384	}3385	if (!found)3386		return -ENOENT;3387	ret = delete_block_group_cache(leaf->fs_info, block_group, NULL,3388					space_cache_ino);3389	return ret;3390}3391 3392/*3393 * helper to find all tree blocks that reference a given data extent3394 */3395static noinline_for_stack int add_data_references(struct reloc_control *rc,3396						  const struct btrfs_key *extent_key,3397						  struct btrfs_path *path,3398						  struct rb_root *blocks)3399{3400	struct btrfs_backref_walk_ctx ctx = { 0 };3401	struct ulist_iterator leaf_uiter;3402	struct ulist_node *ref_node = NULL;3403	const u32 blocksize = rc->extent_root->fs_info->nodesize;3404	int ret = 0;3405 3406	btrfs_release_path(path);3407 3408	ctx.bytenr = extent_key->objectid;3409	ctx.skip_inode_ref_list = true;3410	ctx.fs_info = rc->extent_root->fs_info;3411 3412	ret = btrfs_find_all_leafs(&ctx);3413	if (ret < 0)3414		return ret;3415 3416	ULIST_ITER_INIT(&leaf_uiter);3417	while ((ref_node = ulist_next(ctx.refs, &leaf_uiter))) {3418		struct btrfs_tree_parent_check check = { 0 };3419		struct extent_buffer *eb;3420 3421		eb = read_tree_block(ctx.fs_info, ref_node->val, &check);3422		if (IS_ERR(eb)) {3423			ret = PTR_ERR(eb);3424			break;3425		}3426		ret = delete_v1_space_cache(eb, rc->block_group,3427					    extent_key->objectid);3428		free_extent_buffer(eb);3429		if (ret < 0)3430			break;3431		ret = __add_tree_block(rc, ref_node->val, blocksize, blocks);3432		if (ret < 0)3433			break;3434	}3435	if (ret < 0)3436		free_block_list(blocks);3437	ulist_free(ctx.refs);3438	return ret;3439}3440 3441/*3442 * helper to find next unprocessed extent3443 */3444static noinline_for_stack3445int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,3446		     struct btrfs_key *extent_key)3447{3448	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;3449	struct btrfs_key key;3450	struct extent_buffer *leaf;3451	u64 start, end, last;3452	int ret;3453 3454	last = rc->block_group->start + rc->block_group->length;3455	while (1) {3456		bool block_found;3457 3458		cond_resched();3459		if (rc->search_start >= last) {3460			ret = 1;3461			break;3462		}3463 3464		key.objectid = rc->search_start;3465		key.type = BTRFS_EXTENT_ITEM_KEY;3466		key.offset = 0;3467 3468		path->search_commit_root = 1;3469		path->skip_locking = 1;3470		ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,3471					0, 0);3472		if (ret < 0)3473			break;3474next:3475		leaf = path->nodes[0];3476		if (path->slots[0] >= btrfs_header_nritems(leaf)) {3477			ret = btrfs_next_leaf(rc->extent_root, path);3478			if (ret != 0)3479				break;3480			leaf = path->nodes[0];3481		}3482 3483		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);3484		if (key.objectid >= last) {3485			ret = 1;3486			break;3487		}3488 3489		if (key.type != BTRFS_EXTENT_ITEM_KEY &&3490		    key.type != BTRFS_METADATA_ITEM_KEY) {3491			path->slots[0]++;3492			goto next;3493		}3494 3495		if (key.type == BTRFS_EXTENT_ITEM_KEY &&3496		    key.objectid + key.offset <= rc->search_start) {3497			path->slots[0]++;3498			goto next;3499		}3500 3501		if (key.type == BTRFS_METADATA_ITEM_KEY &&3502		    key.objectid + fs_info->nodesize <=3503		    rc->search_start) {3504			path->slots[0]++;3505			goto next;3506		}3507 3508		block_found = find_first_extent_bit(&rc->processed_blocks,3509						    key.objectid, &start, &end,3510						    EXTENT_DIRTY, NULL);3511 3512		if (block_found && start <= key.objectid) {3513			btrfs_release_path(path);3514			rc->search_start = end + 1;3515		} else {3516			if (key.type == BTRFS_EXTENT_ITEM_KEY)3517				rc->search_start = key.objectid + key.offset;3518			else3519				rc->search_start = key.objectid +3520					fs_info->nodesize;3521			memcpy(extent_key, &key, sizeof(key));3522			return 0;3523		}3524	}3525	btrfs_release_path(path);3526	return ret;3527}3528 3529static void set_reloc_control(struct reloc_control *rc)3530{3531	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;3532 3533	mutex_lock(&fs_info->reloc_mutex);3534	fs_info->reloc_ctl = rc;3535	mutex_unlock(&fs_info->reloc_mutex);3536}3537 3538static void unset_reloc_control(struct reloc_control *rc)3539{3540	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;3541 3542	mutex_lock(&fs_info->reloc_mutex);3543	fs_info->reloc_ctl = NULL;3544	mutex_unlock(&fs_info->reloc_mutex);3545}3546 3547static noinline_for_stack3548int prepare_to_relocate(struct reloc_control *rc)3549{3550	struct btrfs_trans_handle *trans;3551	int ret;3552 3553	rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,3554					      BTRFS_BLOCK_RSV_TEMP);3555	if (!rc->block_rsv)3556		return -ENOMEM;3557 3558	memset(&rc->cluster, 0, sizeof(rc->cluster));3559	rc->search_start = rc->block_group->start;3560	rc->extents_found = 0;3561	rc->nodes_relocated = 0;3562	rc->merging_rsv_size = 0;3563	rc->reserved_bytes = 0;3564	rc->block_rsv->size = rc->extent_root->fs_info->nodesize *3565			      RELOCATION_RESERVED_NODES;3566	ret = btrfs_block_rsv_refill(rc->extent_root->fs_info,3567				     rc->block_rsv, rc->block_rsv->size,3568				     BTRFS_RESERVE_FLUSH_ALL);3569	if (ret)3570		return ret;3571 3572	rc->create_reloc_tree = true;3573	set_reloc_control(rc);3574 3575	trans = btrfs_join_transaction(rc->extent_root);3576	if (IS_ERR(trans)) {3577		unset_reloc_control(rc);3578		/*3579		 * extent tree is not a ref_cow tree and has no reloc_root to3580		 * cleanup.  And callers are responsible to free the above3581		 * block rsv.3582		 */3583		return PTR_ERR(trans);3584	}3585 3586	ret = btrfs_commit_transaction(trans);3587	if (ret)3588		unset_reloc_control(rc);3589 3590	return ret;3591}3592 3593static noinline_for_stack int relocate_block_group(struct reloc_control *rc)3594{3595	struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;3596	struct rb_root blocks = RB_ROOT;3597	struct btrfs_key key;3598	struct btrfs_trans_handle *trans = NULL;3599	struct btrfs_path *path;3600	struct btrfs_extent_item *ei;3601	u64 flags;3602	int ret;3603	int err = 0;3604	int progress = 0;3605 3606	path = btrfs_alloc_path();3607	if (!path)3608		return -ENOMEM;3609	path->reada = READA_FORWARD;3610 3611	ret = prepare_to_relocate(rc);3612	if (ret) {3613		err = ret;3614		goto out_free;3615	}3616 3617	while (1) {3618		rc->reserved_bytes = 0;3619		ret = btrfs_block_rsv_refill(fs_info, rc->block_rsv,3620					     rc->block_rsv->size,3621					     BTRFS_RESERVE_FLUSH_ALL);3622		if (ret) {3623			err = ret;3624			break;3625		}3626		progress++;3627		trans = btrfs_start_transaction(rc->extent_root, 0);3628		if (IS_ERR(trans)) {3629			err = PTR_ERR(trans);3630			trans = NULL;3631			break;3632		}3633restart:3634		if (rc->backref_cache.last_trans != trans->transid)3635			btrfs_backref_release_cache(&rc->backref_cache);3636		rc->backref_cache.last_trans = trans->transid;3637 3638		ret = find_next_extent(rc, path, &key);3639		if (ret < 0)3640			err = ret;3641		if (ret != 0)3642			break;3643 3644		rc->extents_found++;3645 3646		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],3647				    struct btrfs_extent_item);3648		flags = btrfs_extent_flags(path->nodes[0], ei);3649 3650		/*3651		 * If we are relocating a simple quota owned extent item, we3652		 * need to note the owner on the reloc data root so that when3653		 * we allocate the replacement item, we can attribute it to the3654		 * correct eventual owner (rather than the reloc data root).3655		 */3656		if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE) {3657			struct btrfs_root *root = BTRFS_I(rc->data_inode)->root;3658			u64 owning_root_id = btrfs_get_extent_owner_root(fs_info,3659								 path->nodes[0],3660								 path->slots[0]);3661 3662			root->relocation_src_root = owning_root_id;3663		}3664 3665		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {3666			ret = add_tree_block(rc, &key, path, &blocks);3667		} else if (rc->stage == UPDATE_DATA_PTRS &&3668			   (flags & BTRFS_EXTENT_FLAG_DATA)) {3669			ret = add_data_references(rc, &key, path, &blocks);3670		} else {3671			btrfs_release_path(path);3672			ret = 0;3673		}3674		if (ret < 0) {3675			err = ret;3676			break;3677		}3678 3679		if (!RB_EMPTY_ROOT(&blocks)) {3680			ret = relocate_tree_blocks(trans, rc, &blocks);3681			if (ret < 0) {3682				if (ret != -EAGAIN) {3683					err = ret;3684					break;3685				}3686				rc->extents_found--;3687				rc->search_start = key.objectid;3688			}3689		}3690 3691		btrfs_end_transaction_throttle(trans);3692		btrfs_btree_balance_dirty(fs_info);3693		trans = NULL;3694 3695		if (rc->stage == MOVE_DATA_EXTENTS &&3696		    (flags & BTRFS_EXTENT_FLAG_DATA)) {3697			rc->found_file_extent = true;3698			ret = relocate_data_extent(rc, &key);3699			if (ret < 0) {3700				err = ret;3701				break;3702			}3703		}3704		if (btrfs_should_cancel_balance(fs_info)) {3705			err = -ECANCELED;3706			break;3707		}3708	}3709	if (trans && progress && err == -ENOSPC) {3710		ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);3711		if (ret == 1) {3712			err = 0;3713			progress = 0;3714			goto restart;3715		}3716	}3717 3718	btrfs_release_path(path);3719	clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);3720 3721	if (trans) {3722		btrfs_end_transaction_throttle(trans);3723		btrfs_btree_balance_dirty(fs_info);3724	}3725 3726	if (!err) {3727		ret = relocate_file_extent_cluster(rc);3728		if (ret < 0)3729			err = ret;3730	}3731 3732	rc->create_reloc_tree = false;3733	set_reloc_control(rc);3734 3735	btrfs_backref_release_cache(&rc->backref_cache);3736	btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1, NULL);3737 3738	/*3739	 * Even in the case when the relocation is cancelled, we should all go3740	 * through prepare_to_merge() and merge_reloc_roots().3741	 *3742	 * For error (including cancelled balance), prepare_to_merge() will3743	 * mark all reloc trees orphan, then queue them for cleanup in3744	 * merge_reloc_roots()3745	 */3746	err = prepare_to_merge(rc, err);3747 3748	merge_reloc_roots(rc);3749 3750	rc->merge_reloc_tree = false;3751	unset_reloc_control(rc);3752	btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1, NULL);3753 3754	/* get rid of pinned extents */3755	trans = btrfs_join_transaction(rc->extent_root);3756	if (IS_ERR(trans)) {3757		err = PTR_ERR(trans);3758		goto out_free;3759	}3760	ret = btrfs_commit_transaction(trans);3761	if (ret && !err)3762		err = ret;3763out_free:3764	ret = clean_dirty_subvols(rc);3765	if (ret < 0 && !err)3766		err = ret;3767	btrfs_free_block_rsv(fs_info, rc->block_rsv);3768	btrfs_free_path(path);3769	return err;3770}3771 3772static int __insert_orphan_inode(struct btrfs_trans_handle *trans,3773				 struct btrfs_root *root, u64 objectid)3774{3775	struct btrfs_path *path;3776	struct btrfs_inode_item *item;3777	struct extent_buffer *leaf;3778	int ret;3779 3780	path = btrfs_alloc_path();3781	if (!path)3782		return -ENOMEM;3783 3784	ret = btrfs_insert_empty_inode(trans, root, path, objectid);3785	if (ret)3786		goto out;3787 3788	leaf = path->nodes[0];3789	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);3790	memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));3791	btrfs_set_inode_generation(leaf, item, 1);3792	btrfs_set_inode_size(leaf, item, 0);3793	btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);3794	btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |3795					  BTRFS_INODE_PREALLOC);3796	btrfs_mark_buffer_dirty(trans, leaf);3797out:3798	btrfs_free_path(path);3799	return ret;3800}3801 3802static void delete_orphan_inode(struct btrfs_trans_handle *trans,3803				struct btrfs_root *root, u64 objectid)3804{3805	struct btrfs_path *path;3806	struct btrfs_key key;3807	int ret = 0;3808 3809	path = btrfs_alloc_path();3810	if (!path) {3811		ret = -ENOMEM;3812		goto out;3813	}3814 3815	key.objectid = objectid;3816	key.type = BTRFS_INODE_ITEM_KEY;3817	key.offset = 0;3818	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);3819	if (ret) {3820		if (ret > 0)3821			ret = -ENOENT;3822		goto out;3823	}3824	ret = btrfs_del_item(trans, root, path);3825out:3826	if (ret)3827		btrfs_abort_transaction(trans, ret);3828	btrfs_free_path(path);3829}3830 3831/*3832 * helper to create inode for data relocation.3833 * the inode is in data relocation tree and its link count is 03834 */3835static noinline_for_stack struct inode *create_reloc_inode(3836					struct btrfs_fs_info *fs_info,3837					const struct btrfs_block_group *group)3838{3839	struct inode *inode = NULL;3840	struct btrfs_trans_handle *trans;3841	struct btrfs_root *root;3842	u64 objectid;3843	int ret = 0;3844 3845	root = btrfs_grab_root(fs_info->data_reloc_root);3846	trans = btrfs_start_transaction(root, 6);3847	if (IS_ERR(trans)) {3848		btrfs_put_root(root);3849		return ERR_CAST(trans);3850	}3851 3852	ret = btrfs_get_free_objectid(root, &objectid);3853	if (ret)3854		goto out;3855 3856	ret = __insert_orphan_inode(trans, root, objectid);3857	if (ret)3858		goto out;3859 3860	inode = btrfs_iget(objectid, root);3861	if (IS_ERR(inode)) {3862		delete_orphan_inode(trans, root, objectid);3863		ret = PTR_ERR(inode);3864		inode = NULL;3865		goto out;3866	}3867	BTRFS_I(inode)->reloc_block_group_start = group->start;3868 3869	ret = btrfs_orphan_add(trans, BTRFS_I(inode));3870out:3871	btrfs_put_root(root);3872	btrfs_end_transaction(trans);3873	btrfs_btree_balance_dirty(fs_info);3874	if (ret) {3875		iput(inode);3876		inode = ERR_PTR(ret);3877	}3878	return inode;3879}3880 3881/*3882 * Mark start of chunk relocation that is cancellable. Check if the cancellation3883 * has been requested meanwhile and don't start in that case.3884 *3885 * Return:3886 *   0             success3887 *   -EINPROGRESS  operation is already in progress, that's probably a bug3888 *   -ECANCELED    cancellation request was set before the operation started3889 */3890static int reloc_chunk_start(struct btrfs_fs_info *fs_info)3891{3892	if (test_and_set_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) {3893		/* This should not happen */3894		btrfs_err(fs_info, "reloc already running, cannot start");3895		return -EINPROGRESS;3896	}3897 3898	if (atomic_read(&fs_info->reloc_cancel_req) > 0) {3899		btrfs_info(fs_info, "chunk relocation canceled on start");3900		/*3901		 * On cancel, clear all requests but let the caller mark3902		 * the end after cleanup operations.3903		 */3904		atomic_set(&fs_info->reloc_cancel_req, 0);3905		return -ECANCELED;3906	}3907	return 0;3908}3909 3910/*3911 * Mark end of chunk relocation that is cancellable and wake any waiters.3912 */3913static void reloc_chunk_end(struct btrfs_fs_info *fs_info)3914{3915	/* Requested after start, clear bit first so any waiters can continue */3916	if (atomic_read(&fs_info->reloc_cancel_req) > 0)3917		btrfs_info(fs_info, "chunk relocation canceled during operation");3918	clear_and_wake_up_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags);3919	atomic_set(&fs_info->reloc_cancel_req, 0);3920}3921 3922static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)3923{3924	struct reloc_control *rc;3925 3926	rc = kzalloc(sizeof(*rc), GFP_NOFS);3927	if (!rc)3928		return NULL;3929 3930	INIT_LIST_HEAD(&rc->reloc_roots);3931	INIT_LIST_HEAD(&rc->dirty_subvol_roots);3932	btrfs_backref_init_cache(fs_info, &rc->backref_cache, true);3933	rc->reloc_root_tree.rb_root = RB_ROOT;3934	spin_lock_init(&rc->reloc_root_tree.lock);3935	extent_io_tree_init(fs_info, &rc->processed_blocks, IO_TREE_RELOC_BLOCKS);3936	return rc;3937}3938 3939static void free_reloc_control(struct reloc_control *rc)3940{3941	struct mapping_node *node, *tmp;3942 3943	free_reloc_roots(&rc->reloc_roots);3944	rbtree_postorder_for_each_entry_safe(node, tmp,3945			&rc->reloc_root_tree.rb_root, rb_node)3946		kfree(node);3947 3948	kfree(rc);3949}3950 3951/*3952 * Print the block group being relocated3953 */3954static void describe_relocation(struct btrfs_block_group *block_group)3955{3956	char buf[128] = {'\0'};3957 3958	btrfs_describe_block_groups(block_group->flags, buf, sizeof(buf));3959 3960	btrfs_info(block_group->fs_info, "relocating block group %llu flags %s",3961		   block_group->start, buf);3962}3963 3964static const char *stage_to_string(enum reloc_stage stage)3965{3966	if (stage == MOVE_DATA_EXTENTS)3967		return "move data extents";3968	if (stage == UPDATE_DATA_PTRS)3969		return "update data pointers";3970	return "unknown";3971}3972 3973/*3974 * function to relocate all extents in a block group.3975 */3976int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)3977{3978	struct btrfs_block_group *bg;3979	struct btrfs_root *extent_root = btrfs_extent_root(fs_info, group_start);3980	struct reloc_control *rc;3981	struct inode *inode;3982	struct btrfs_path *path;3983	int ret;3984	int rw = 0;3985	int err = 0;3986 3987	/*3988	 * This only gets set if we had a half-deleted snapshot on mount.  We3989	 * cannot allow relocation to start while we're still trying to clean up3990	 * these pending deletions.3991	 */3992	ret = wait_on_bit(&fs_info->flags, BTRFS_FS_UNFINISHED_DROPS, TASK_INTERRUPTIBLE);3993	if (ret)3994		return ret;3995 3996	/* We may have been woken up by close_ctree, so bail if we're closing. */3997	if (btrfs_fs_closing(fs_info))3998		return -EINTR;3999 4000	bg = btrfs_lookup_block_group(fs_info, group_start);4001	if (!bg)4002		return -ENOENT;4003 4004	/*4005	 * Relocation of a data block group creates ordered extents.  Without4006	 * sb_start_write(), we can freeze the filesystem while unfinished4007	 * ordered extents are left. Such ordered extents can cause a deadlock4008	 * e.g. when syncfs() is waiting for their completion but they can't4009	 * finish because they block when joining a transaction, due to the4010	 * fact that the freeze locks are being held in write mode.4011	 */4012	if (bg->flags & BTRFS_BLOCK_GROUP_DATA)4013		ASSERT(sb_write_started(fs_info->sb));4014 4015	if (btrfs_pinned_by_swapfile(fs_info, bg)) {4016		btrfs_put_block_group(bg);4017		return -ETXTBSY;4018	}4019 4020	rc = alloc_reloc_control(fs_info);4021	if (!rc) {4022		btrfs_put_block_group(bg);4023		return -ENOMEM;4024	}4025 4026	ret = reloc_chunk_start(fs_info);4027	if (ret < 0) {4028		err = ret;4029		goto out_put_bg;4030	}4031 4032	rc->extent_root = extent_root;4033	rc->block_group = bg;4034 4035	ret = btrfs_inc_block_group_ro(rc->block_group, true);4036	if (ret) {4037		err = ret;4038		goto out;4039	}4040	rw = 1;4041 4042	path = btrfs_alloc_path();4043	if (!path) {4044		err = -ENOMEM;4045		goto out;4046	}4047 4048	inode = lookup_free_space_inode(rc->block_group, path);4049	btrfs_free_path(path);4050 4051	if (!IS_ERR(inode))4052		ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);4053	else4054		ret = PTR_ERR(inode);4055 4056	if (ret && ret != -ENOENT) {4057		err = ret;4058		goto out;4059	}4060 4061	rc->data_inode = create_reloc_inode(fs_info, rc->block_group);4062	if (IS_ERR(rc->data_inode)) {4063		err = PTR_ERR(rc->data_inode);4064		rc->data_inode = NULL;4065		goto out;4066	}4067 4068	describe_relocation(rc->block_group);4069 4070	btrfs_wait_block_group_reservations(rc->block_group);4071	btrfs_wait_nocow_writers(rc->block_group);4072	btrfs_wait_ordered_roots(fs_info, U64_MAX, rc->block_group);4073 4074	ret = btrfs_zone_finish(rc->block_group);4075	WARN_ON(ret && ret != -EAGAIN);4076 4077	while (1) {4078		enum reloc_stage finishes_stage;4079 4080		mutex_lock(&fs_info->cleaner_mutex);4081		ret = relocate_block_group(rc);4082		mutex_unlock(&fs_info->cleaner_mutex);4083		if (ret < 0)4084			err = ret;4085 4086		finishes_stage = rc->stage;4087		/*4088		 * We may have gotten ENOSPC after we already dirtied some4089		 * extents.  If writeout happens while we're relocating a4090		 * different block group we could end up hitting the4091		 * BUG_ON(rc->stage == UPDATE_DATA_PTRS) in4092		 * btrfs_reloc_cow_block.  Make sure we write everything out4093		 * properly so we don't trip over this problem, and then break4094		 * out of the loop if we hit an error.4095		 */4096		if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {4097			ret = btrfs_wait_ordered_range(BTRFS_I(rc->data_inode), 0,4098						       (u64)-1);4099			if (ret)4100				err = ret;4101			invalidate_mapping_pages(rc->data_inode->i_mapping,4102						 0, -1);4103			rc->stage = UPDATE_DATA_PTRS;4104		}4105 4106		if (err < 0)4107			goto out;4108 4109		if (rc->extents_found == 0)4110			break;4111 4112		btrfs_info(fs_info, "found %llu extents, stage: %s",4113			   rc->extents_found, stage_to_string(finishes_stage));4114	}4115 4116	WARN_ON(rc->block_group->pinned > 0);4117	WARN_ON(rc->block_group->reserved > 0);4118	WARN_ON(rc->block_group->used > 0);4119out:4120	if (err && rw)4121		btrfs_dec_block_group_ro(rc->block_group);4122	iput(rc->data_inode);4123out_put_bg:4124	btrfs_put_block_group(bg);4125	reloc_chunk_end(fs_info);4126	free_reloc_control(rc);4127	return err;4128}4129 4130static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)4131{4132	struct btrfs_fs_info *fs_info = root->fs_info;4133	struct btrfs_trans_handle *trans;4134	int ret, err;4135 4136	trans = btrfs_start_transaction(fs_info->tree_root, 0);4137	if (IS_ERR(trans))4138		return PTR_ERR(trans);4139 4140	memset(&root->root_item.drop_progress, 0,4141		sizeof(root->root_item.drop_progress));4142	btrfs_set_root_drop_level(&root->root_item, 0);4143	btrfs_set_root_refs(&root->root_item, 0);4144	ret = btrfs_update_root(trans, fs_info->tree_root,4145				&root->root_key, &root->root_item);4146 4147	err = btrfs_end_transaction(trans);4148	if (err)4149		return err;4150	return ret;4151}4152 4153/*4154 * recover relocation interrupted by system crash.4155 *4156 * this function resumes merging reloc trees with corresponding fs trees.4157 * this is important for keeping the sharing of tree blocks4158 */4159int btrfs_recover_relocation(struct btrfs_fs_info *fs_info)4160{4161	LIST_HEAD(reloc_roots);4162	struct btrfs_key key;4163	struct btrfs_root *fs_root;4164	struct btrfs_root *reloc_root;4165	struct btrfs_path *path;4166	struct extent_buffer *leaf;4167	struct reloc_control *rc = NULL;4168	struct btrfs_trans_handle *trans;4169	int ret2;4170	int ret = 0;4171 4172	path = btrfs_alloc_path();4173	if (!path)4174		return -ENOMEM;4175	path->reada = READA_BACK;4176 4177	key.objectid = BTRFS_TREE_RELOC_OBJECTID;4178	key.type = BTRFS_ROOT_ITEM_KEY;4179	key.offset = (u64)-1;4180 4181	while (1) {4182		ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,4183					path, 0, 0);4184		if (ret < 0)4185			goto out;4186		if (ret > 0) {4187			if (path->slots[0] == 0)4188				break;4189			path->slots[0]--;4190		}4191		ret = 0;4192		leaf = path->nodes[0];4193		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);4194		btrfs_release_path(path);4195 4196		if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||4197		    key.type != BTRFS_ROOT_ITEM_KEY)4198			break;4199 4200		reloc_root = btrfs_read_tree_root(fs_info->tree_root, &key);4201		if (IS_ERR(reloc_root)) {4202			ret = PTR_ERR(reloc_root);4203			goto out;4204		}4205 4206		set_bit(BTRFS_ROOT_SHAREABLE, &reloc_root->state);4207		list_add(&reloc_root->root_list, &reloc_roots);4208 4209		if (btrfs_root_refs(&reloc_root->root_item) > 0) {4210			fs_root = btrfs_get_fs_root(fs_info,4211					reloc_root->root_key.offset, false);4212			if (IS_ERR(fs_root)) {4213				ret = PTR_ERR(fs_root);4214				if (ret != -ENOENT)4215					goto out;4216				ret = mark_garbage_root(reloc_root);4217				if (ret < 0)4218					goto out;4219				ret = 0;4220			} else {4221				btrfs_put_root(fs_root);4222			}4223		}4224 4225		if (key.offset == 0)4226			break;4227 4228		key.offset--;4229	}4230	btrfs_release_path(path);4231 4232	if (list_empty(&reloc_roots))4233		goto out;4234 4235	rc = alloc_reloc_control(fs_info);4236	if (!rc) {4237		ret = -ENOMEM;4238		goto out;4239	}4240 4241	ret = reloc_chunk_start(fs_info);4242	if (ret < 0)4243		goto out_end;4244 4245	rc->extent_root = btrfs_extent_root(fs_info, 0);4246 4247	set_reloc_control(rc);4248 4249	trans = btrfs_join_transaction(rc->extent_root);4250	if (IS_ERR(trans)) {4251		ret = PTR_ERR(trans);4252		goto out_unset;4253	}4254 4255	rc->merge_reloc_tree = true;4256 4257	while (!list_empty(&reloc_roots)) {4258		reloc_root = list_entry(reloc_roots.next,4259					struct btrfs_root, root_list);4260		list_del(&reloc_root->root_list);4261 4262		if (btrfs_root_refs(&reloc_root->root_item) == 0) {4263			list_add_tail(&reloc_root->root_list,4264				      &rc->reloc_roots);4265			continue;4266		}4267 4268		fs_root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,4269					    false);4270		if (IS_ERR(fs_root)) {4271			ret = PTR_ERR(fs_root);4272			list_add_tail(&reloc_root->root_list, &reloc_roots);4273			btrfs_end_transaction(trans);4274			goto out_unset;4275		}4276 4277		ret = __add_reloc_root(reloc_root);4278		ASSERT(ret != -EEXIST);4279		if (ret) {4280			list_add_tail(&reloc_root->root_list, &reloc_roots);4281			btrfs_put_root(fs_root);4282			btrfs_end_transaction(trans);4283			goto out_unset;4284		}4285		fs_root->reloc_root = btrfs_grab_root(reloc_root);4286		btrfs_put_root(fs_root);4287	}4288 4289	ret = btrfs_commit_transaction(trans);4290	if (ret)4291		goto out_unset;4292 4293	merge_reloc_roots(rc);4294 4295	unset_reloc_control(rc);4296 4297	trans = btrfs_join_transaction(rc->extent_root);4298	if (IS_ERR(trans)) {4299		ret = PTR_ERR(trans);4300		goto out_clean;4301	}4302	ret = btrfs_commit_transaction(trans);4303out_clean:4304	ret2 = clean_dirty_subvols(rc);4305	if (ret2 < 0 && !ret)4306		ret = ret2;4307out_unset:4308	unset_reloc_control(rc);4309out_end:4310	reloc_chunk_end(fs_info);4311	free_reloc_control(rc);4312out:4313	free_reloc_roots(&reloc_roots);4314 4315	btrfs_free_path(path);4316 4317	if (ret == 0) {4318		/* cleanup orphan inode in data relocation tree */4319		fs_root = btrfs_grab_root(fs_info->data_reloc_root);4320		ASSERT(fs_root);4321		ret = btrfs_orphan_cleanup(fs_root);4322		btrfs_put_root(fs_root);4323	}4324	return ret;4325}4326 4327/*4328 * helper to add ordered checksum for data relocation.4329 *4330 * cloning checksum properly handles the nodatasum extents.4331 * it also saves CPU time to re-calculate the checksum.4332 */4333int btrfs_reloc_clone_csums(struct btrfs_ordered_extent *ordered)4334{4335	struct btrfs_inode *inode = ordered->inode;4336	struct btrfs_fs_info *fs_info = inode->root->fs_info;4337	u64 disk_bytenr = ordered->file_offset + inode->reloc_block_group_start;4338	struct btrfs_root *csum_root = btrfs_csum_root(fs_info, disk_bytenr);4339	LIST_HEAD(list);4340	int ret;4341 4342	ret = btrfs_lookup_csums_list(csum_root, disk_bytenr,4343				      disk_bytenr + ordered->num_bytes - 1,4344				      &list, false);4345	if (ret < 0) {4346		btrfs_mark_ordered_extent_error(ordered);4347		return ret;4348	}4349 4350	while (!list_empty(&list)) {4351		struct btrfs_ordered_sum *sums =4352			list_entry(list.next, struct btrfs_ordered_sum, list);4353 4354		list_del_init(&sums->list);4355 4356		/*4357		 * We need to offset the new_bytenr based on where the csum is.4358		 * We need to do this because we will read in entire prealloc4359		 * extents but we may have written to say the middle of the4360		 * prealloc extent, so we need to make sure the csum goes with4361		 * the right disk offset.4362		 *4363		 * We can do this because the data reloc inode refers strictly4364		 * to the on disk bytes, so we don't have to worry about4365		 * disk_len vs real len like with real inodes since it's all4366		 * disk length.4367		 */4368		sums->logical = ordered->disk_bytenr + sums->logical - disk_bytenr;4369		btrfs_add_ordered_sum(ordered, sums);4370	}4371 4372	return 0;4373}4374 4375int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,4376			  struct btrfs_root *root,4377			  const struct extent_buffer *buf,4378			  struct extent_buffer *cow)4379{4380	struct btrfs_fs_info *fs_info = root->fs_info;4381	struct reloc_control *rc;4382	struct btrfs_backref_node *node;4383	int first_cow = 0;4384	int level;4385	int ret = 0;4386 4387	rc = fs_info->reloc_ctl;4388	if (!rc)4389		return 0;4390 4391	BUG_ON(rc->stage == UPDATE_DATA_PTRS && btrfs_is_data_reloc_root(root));4392 4393	level = btrfs_header_level(buf);4394	if (btrfs_header_generation(buf) <=4395	    btrfs_root_last_snapshot(&root->root_item))4396		first_cow = 1;4397 4398	if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID && rc->create_reloc_tree) {4399		WARN_ON(!first_cow && level == 0);4400 4401		node = rc->backref_cache.path[level];4402		BUG_ON(node->bytenr != buf->start &&4403		       node->new_bytenr != buf->start);4404 4405		btrfs_backref_drop_node_buffer(node);4406		atomic_inc(&cow->refs);4407		node->eb = cow;4408		node->new_bytenr = cow->start;4409 4410		if (!node->pending) {4411			list_move_tail(&node->list,4412				       &rc->backref_cache.pending[level]);4413			node->pending = 1;4414		}4415 4416		if (first_cow)4417			mark_block_processed(rc, node);4418 4419		if (first_cow && level > 0)4420			rc->nodes_relocated += buf->len;4421	}4422 4423	if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)4424		ret = replace_file_extents(trans, rc, root, cow);4425	return ret;4426}4427 4428/*4429 * called before creating snapshot. it calculates metadata reservation4430 * required for relocating tree blocks in the snapshot4431 */4432void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,4433			      u64 *bytes_to_reserve)4434{4435	struct btrfs_root *root = pending->root;4436	struct reloc_control *rc = root->fs_info->reloc_ctl;4437 4438	if (!rc || !have_reloc_root(root))4439		return;4440 4441	if (!rc->merge_reloc_tree)4442		return;4443 4444	root = root->reloc_root;4445	BUG_ON(btrfs_root_refs(&root->root_item) == 0);4446	/*4447	 * relocation is in the stage of merging trees. the space4448	 * used by merging a reloc tree is twice the size of4449	 * relocated tree nodes in the worst case. half for cowing4450	 * the reloc tree, half for cowing the fs tree. the space4451	 * used by cowing the reloc tree will be freed after the4452	 * tree is dropped. if we create snapshot, cowing the fs4453	 * tree may use more space than it frees. so we need4454	 * reserve extra space.4455	 */4456	*bytes_to_reserve += rc->nodes_relocated;4457}4458 4459/*4460 * called after snapshot is created. migrate block reservation4461 * and create reloc root for the newly created snapshot4462 *4463 * This is similar to btrfs_init_reloc_root(), we come out of here with two4464 * references held on the reloc_root, one for root->reloc_root and one for4465 * rc->reloc_roots.4466 */4467int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,4468			       struct btrfs_pending_snapshot *pending)4469{4470	struct btrfs_root *root = pending->root;4471	struct btrfs_root *reloc_root;4472	struct btrfs_root *new_root;4473	struct reloc_control *rc = root->fs_info->reloc_ctl;4474	int ret;4475 4476	if (!rc || !have_reloc_root(root))4477		return 0;4478 4479	rc = root->fs_info->reloc_ctl;4480	rc->merging_rsv_size += rc->nodes_relocated;4481 4482	if (rc->merge_reloc_tree) {4483		ret = btrfs_block_rsv_migrate(&pending->block_rsv,4484					      rc->block_rsv,4485					      rc->nodes_relocated, true);4486		if (ret)4487			return ret;4488	}4489 4490	new_root = pending->snap;4491	reloc_root = create_reloc_root(trans, root->reloc_root, btrfs_root_id(new_root));4492	if (IS_ERR(reloc_root))4493		return PTR_ERR(reloc_root);4494 4495	ret = __add_reloc_root(reloc_root);4496	ASSERT(ret != -EEXIST);4497	if (ret) {4498		/* Pairs with create_reloc_root */4499		btrfs_put_root(reloc_root);4500		return ret;4501	}4502	new_root->reloc_root = btrfs_grab_root(reloc_root);4503 4504	if (rc->create_reloc_tree)4505		ret = clone_backref_node(trans, rc, root, reloc_root);4506	return ret;4507}4508 4509/*4510 * Get the current bytenr for the block group which is being relocated.4511 *4512 * Return U64_MAX if no running relocation.4513 */4514u64 btrfs_get_reloc_bg_bytenr(const struct btrfs_fs_info *fs_info)4515{4516	u64 logical = U64_MAX;4517 4518	lockdep_assert_held(&fs_info->reloc_mutex);4519 4520	if (fs_info->reloc_ctl && fs_info->reloc_ctl->block_group)4521		logical = fs_info->reloc_ctl->block_group->start;4522	return logical;4523}4524