brintos / linux-shallow public Read only

1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright (C) 2007 Oracle.  All rights reserved.4 */5 6#include <linux/fs.h>7#include <linux/slab.h>8#include <linux/sched.h>9#include <linux/sched/mm.h>10#include <linux/writeback.h>11#include <linux/pagemap.h>12#include <linux/blkdev.h>13#include <linux/uuid.h>14#include <linux/timekeeping.h>15#include "misc.h"16#include "ctree.h"17#include "disk-io.h"18#include "transaction.h"19#include "locking.h"20#include "tree-log.h"21#include "volumes.h"22#include "dev-replace.h"23#include "qgroup.h"24#include "block-group.h"25#include "space-info.h"26#include "fs.h"27#include "accessors.h"28#include "extent-tree.h"29#include "root-tree.h"30#include "dir-item.h"31#include "uuid-tree.h"32#include "ioctl.h"33#include "relocation.h"34#include "scrub.h"35 36static struct kmem_cache *btrfs_trans_handle_cachep;37 38/*39 * Transaction states and transitions40 *41 * No running transaction (fs tree blocks are not modified)42 * |43 * | To next stage:44 * |  Call start_transaction() variants. Except btrfs_join_transaction_nostart().45 * V46 * Transaction N [[TRANS_STATE_RUNNING]]47 * |48 * | New trans handles can be attached to transaction N by calling all49 * | start_transaction() variants.50 * |51 * | To next stage:52 * |  Call btrfs_commit_transaction() on any trans handle attached to53 * |  transaction N54 * V55 * Transaction N [[TRANS_STATE_COMMIT_PREP]]56 * |57 * | If there are simultaneous calls to btrfs_commit_transaction() one will win58 * | the race and the rest will wait for the winner to commit the transaction.59 * |60 * | The winner will wait for previous running transaction to completely finish61 * | if there is one.62 * |63 * Transaction N [[TRANS_STATE_COMMIT_START]]64 * |65 * | Then one of the following happens:66 * | - Wait for all other trans handle holders to release.67 * |   The btrfs_commit_transaction() caller will do the commit work.68 * | - Wait for current transaction to be committed by others.69 * |   Other btrfs_commit_transaction() caller will do the commit work.70 * |71 * | At this stage, only btrfs_join_transaction*() variants can attach72 * | to this running transaction.73 * | All other variants will wait for current one to finish and attach to74 * | transaction N+1.75 * |76 * | To next stage:77 * |  Caller is chosen to commit transaction N, and all other trans handle78 * |  haven been released.79 * V80 * Transaction N [[TRANS_STATE_COMMIT_DOING]]81 * |82 * | The heavy lifting transaction work is started.83 * | From running delayed refs (modifying extent tree) to creating pending84 * | snapshots, running qgroups.85 * | In short, modify supporting trees to reflect modifications of subvolume86 * | trees.87 * |88 * | At this stage, all start_transaction() calls will wait for this89 * | transaction to finish and attach to transaction N+1.90 * |91 * | To next stage:92 * |  Until all supporting trees are updated.93 * V94 * Transaction N [[TRANS_STATE_UNBLOCKED]]95 * |						    Transaction N+196 * | All needed trees are modified, thus we only    [[TRANS_STATE_RUNNING]]97 * | need to write them back to disk and update	    |98 * | super blocks.				    |99 * |						    |100 * | At this stage, new transaction is allowed to   |101 * | start.					    |102 * | All new start_transaction() calls will be	    |103 * | attached to transid N+1.			    |104 * |						    |105 * | To next stage:				    |106 * |  Until all tree blocks are super blocks are    |107 * |  written to block devices			    |108 * V						    |109 * Transaction N [[TRANS_STATE_COMPLETED]]	    V110 *   All tree blocks and super blocks are written.  Transaction N+1111 *   This transaction is finished and all its	    [[TRANS_STATE_COMMIT_START]]112 *   data structures will be cleaned up.	    | Life goes on113 */114static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {115	[TRANS_STATE_RUNNING]		= 0U,116	[TRANS_STATE_COMMIT_PREP]	= 0U,117	[TRANS_STATE_COMMIT_START]	= (__TRANS_START | __TRANS_ATTACH),118	[TRANS_STATE_COMMIT_DOING]	= (__TRANS_START |119					   __TRANS_ATTACH |120					   __TRANS_JOIN |121					   __TRANS_JOIN_NOSTART),122	[TRANS_STATE_UNBLOCKED]		= (__TRANS_START |123					   __TRANS_ATTACH |124					   __TRANS_JOIN |125					   __TRANS_JOIN_NOLOCK |126					   __TRANS_JOIN_NOSTART),127	[TRANS_STATE_SUPER_COMMITTED]	= (__TRANS_START |128					   __TRANS_ATTACH |129					   __TRANS_JOIN |130					   __TRANS_JOIN_NOLOCK |131					   __TRANS_JOIN_NOSTART),132	[TRANS_STATE_COMPLETED]		= (__TRANS_START |133					   __TRANS_ATTACH |134					   __TRANS_JOIN |135					   __TRANS_JOIN_NOLOCK |136					   __TRANS_JOIN_NOSTART),137};138 139void btrfs_put_transaction(struct btrfs_transaction *transaction)140{141	WARN_ON(refcount_read(&transaction->use_count) == 0);142	if (refcount_dec_and_test(&transaction->use_count)) {143		BUG_ON(!list_empty(&transaction->list));144		WARN_ON(!RB_EMPTY_ROOT(145				&transaction->delayed_refs.href_root.rb_root));146		WARN_ON(!xa_empty(&transaction->delayed_refs.dirty_extents));147		if (transaction->delayed_refs.pending_csums)148			btrfs_err(transaction->fs_info,149				  "pending csums is %llu",150				  transaction->delayed_refs.pending_csums);151		/*152		 * If any block groups are found in ->deleted_bgs then it's153		 * because the transaction was aborted and a commit did not154		 * happen (things failed before writing the new superblock155		 * and calling btrfs_finish_extent_commit()), so we can not156		 * discard the physical locations of the block groups.157		 */158		while (!list_empty(&transaction->deleted_bgs)) {159			struct btrfs_block_group *cache;160 161			cache = list_first_entry(&transaction->deleted_bgs,162						 struct btrfs_block_group,163						 bg_list);164			list_del_init(&cache->bg_list);165			btrfs_unfreeze_block_group(cache);166			btrfs_put_block_group(cache);167		}168		WARN_ON(!list_empty(&transaction->dev_update_list));169		kfree(transaction);170	}171}172 173static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)174{175	struct btrfs_transaction *cur_trans = trans->transaction;176	struct btrfs_fs_info *fs_info = trans->fs_info;177	struct btrfs_root *root, *tmp;178 179	/*180	 * At this point no one can be using this transaction to modify any tree181	 * and no one can start another transaction to modify any tree either.182	 */183	ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING);184 185	down_write(&fs_info->commit_root_sem);186 187	if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))188		fs_info->last_reloc_trans = trans->transid;189 190	list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,191				 dirty_list) {192		list_del_init(&root->dirty_list);193		free_extent_buffer(root->commit_root);194		root->commit_root = btrfs_root_node(root);195		extent_io_tree_release(&root->dirty_log_pages);196		btrfs_qgroup_clean_swapped_blocks(root);197	}198 199	/* We can free old roots now. */200	spin_lock(&cur_trans->dropped_roots_lock);201	while (!list_empty(&cur_trans->dropped_roots)) {202		root = list_first_entry(&cur_trans->dropped_roots,203					struct btrfs_root, root_list);204		list_del_init(&root->root_list);205		spin_unlock(&cur_trans->dropped_roots_lock);206		btrfs_free_log(trans, root);207		btrfs_drop_and_free_fs_root(fs_info, root);208		spin_lock(&cur_trans->dropped_roots_lock);209	}210	spin_unlock(&cur_trans->dropped_roots_lock);211 212	up_write(&fs_info->commit_root_sem);213}214 215static inline void extwriter_counter_inc(struct btrfs_transaction *trans,216					 unsigned int type)217{218	if (type & TRANS_EXTWRITERS)219		atomic_inc(&trans->num_extwriters);220}221 222static inline void extwriter_counter_dec(struct btrfs_transaction *trans,223					 unsigned int type)224{225	if (type & TRANS_EXTWRITERS)226		atomic_dec(&trans->num_extwriters);227}228 229static inline void extwriter_counter_init(struct btrfs_transaction *trans,230					  unsigned int type)231{232	atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));233}234 235static inline int extwriter_counter_read(struct btrfs_transaction *trans)236{237	return atomic_read(&trans->num_extwriters);238}239 240/*241 * To be called after doing the chunk btree updates right after allocating a new242 * chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a243 * chunk after all chunk btree updates and after finishing the second phase of244 * chunk allocation (btrfs_create_pending_block_groups()) in case some block245 * group had its chunk item insertion delayed to the second phase.246 */247void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)248{249	struct btrfs_fs_info *fs_info = trans->fs_info;250 251	if (!trans->chunk_bytes_reserved)252		return;253 254	btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,255				trans->chunk_bytes_reserved, NULL);256	trans->chunk_bytes_reserved = 0;257}258 259/*260 * either allocate a new transaction or hop into the existing one261 */262static noinline int join_transaction(struct btrfs_fs_info *fs_info,263				     unsigned int type)264{265	struct btrfs_transaction *cur_trans;266 267	spin_lock(&fs_info->trans_lock);268loop:269	/* The file system has been taken offline. No new transactions. */270	if (BTRFS_FS_ERROR(fs_info)) {271		spin_unlock(&fs_info->trans_lock);272		return -EROFS;273	}274 275	cur_trans = fs_info->running_transaction;276	if (cur_trans) {277		if (TRANS_ABORTED(cur_trans)) {278			spin_unlock(&fs_info->trans_lock);279			return cur_trans->aborted;280		}281		if (btrfs_blocked_trans_types[cur_trans->state] & type) {282			spin_unlock(&fs_info->trans_lock);283			return -EBUSY;284		}285		refcount_inc(&cur_trans->use_count);286		atomic_inc(&cur_trans->num_writers);287		extwriter_counter_inc(cur_trans, type);288		spin_unlock(&fs_info->trans_lock);289		btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);290		btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);291		return 0;292	}293	spin_unlock(&fs_info->trans_lock);294 295	/*296	 * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the297	 * current transaction, and commit it. If there is no transaction, just298	 * return ENOENT.299	 */300	if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)301		return -ENOENT;302 303	/*304	 * JOIN_NOLOCK only happens during the transaction commit, so305	 * it is impossible that ->running_transaction is NULL306	 */307	BUG_ON(type == TRANS_JOIN_NOLOCK);308 309	cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);310	if (!cur_trans)311		return -ENOMEM;312 313	btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);314	btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);315 316	spin_lock(&fs_info->trans_lock);317	if (fs_info->running_transaction) {318		/*319		 * someone started a transaction after we unlocked.  Make sure320		 * to redo the checks above321		 */322		btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);323		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);324		kfree(cur_trans);325		goto loop;326	} else if (BTRFS_FS_ERROR(fs_info)) {327		spin_unlock(&fs_info->trans_lock);328		btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);329		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);330		kfree(cur_trans);331		return -EROFS;332	}333 334	cur_trans->fs_info = fs_info;335	atomic_set(&cur_trans->pending_ordered, 0);336	init_waitqueue_head(&cur_trans->pending_wait);337	atomic_set(&cur_trans->num_writers, 1);338	extwriter_counter_init(cur_trans, type);339	init_waitqueue_head(&cur_trans->writer_wait);340	init_waitqueue_head(&cur_trans->commit_wait);341	cur_trans->state = TRANS_STATE_RUNNING;342	/*343	 * One for this trans handle, one so it will live on until we344	 * commit the transaction.345	 */346	refcount_set(&cur_trans->use_count, 2);347	cur_trans->flags = 0;348	cur_trans->start_time = ktime_get_seconds();349 350	memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));351 352	cur_trans->delayed_refs.href_root = RB_ROOT_CACHED;353	xa_init(&cur_trans->delayed_refs.dirty_extents);354	atomic_set(&cur_trans->delayed_refs.num_entries, 0);355 356	/*357	 * although the tree mod log is per file system and not per transaction,358	 * the log must never go across transaction boundaries.359	 */360	smp_mb();361	if (!list_empty(&fs_info->tree_mod_seq_list))362		WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");363	if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))364		WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");365	atomic64_set(&fs_info->tree_mod_seq, 0);366 367	spin_lock_init(&cur_trans->delayed_refs.lock);368 369	INIT_LIST_HEAD(&cur_trans->pending_snapshots);370	INIT_LIST_HEAD(&cur_trans->dev_update_list);371	INIT_LIST_HEAD(&cur_trans->switch_commits);372	INIT_LIST_HEAD(&cur_trans->dirty_bgs);373	INIT_LIST_HEAD(&cur_trans->io_bgs);374	INIT_LIST_HEAD(&cur_trans->dropped_roots);375	mutex_init(&cur_trans->cache_write_mutex);376	spin_lock_init(&cur_trans->dirty_bgs_lock);377	INIT_LIST_HEAD(&cur_trans->deleted_bgs);378	spin_lock_init(&cur_trans->dropped_roots_lock);379	list_add_tail(&cur_trans->list, &fs_info->trans_list);380	extent_io_tree_init(fs_info, &cur_trans->dirty_pages,381			IO_TREE_TRANS_DIRTY_PAGES);382	extent_io_tree_init(fs_info, &cur_trans->pinned_extents,383			IO_TREE_FS_PINNED_EXTENTS);384	btrfs_set_fs_generation(fs_info, fs_info->generation + 1);385	cur_trans->transid = fs_info->generation;386	fs_info->running_transaction = cur_trans;387	cur_trans->aborted = 0;388	spin_unlock(&fs_info->trans_lock);389 390	return 0;391}392 393/*394 * This does all the record keeping required to make sure that a shareable root395 * is properly recorded in a given transaction.  This is required to make sure396 * the old root from before we joined the transaction is deleted when the397 * transaction commits.398 */399static int record_root_in_trans(struct btrfs_trans_handle *trans,400			       struct btrfs_root *root,401			       int force)402{403	struct btrfs_fs_info *fs_info = root->fs_info;404	int ret = 0;405 406	if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&407	    btrfs_get_root_last_trans(root) < trans->transid) || force) {408		WARN_ON(!force && root->commit_root != root->node);409 410		/*411		 * see below for IN_TRANS_SETUP usage rules412		 * we have the reloc mutex held now, so there413		 * is only one writer in this function414		 */415		set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);416 417		/* make sure readers find IN_TRANS_SETUP before418		 * they find our root->last_trans update419		 */420		smp_wmb();421 422		spin_lock(&fs_info->fs_roots_radix_lock);423		if (btrfs_get_root_last_trans(root) == trans->transid && !force) {424			spin_unlock(&fs_info->fs_roots_radix_lock);425			return 0;426		}427		radix_tree_tag_set(&fs_info->fs_roots_radix,428				   (unsigned long)btrfs_root_id(root),429				   BTRFS_ROOT_TRANS_TAG);430		spin_unlock(&fs_info->fs_roots_radix_lock);431		btrfs_set_root_last_trans(root, trans->transid);432 433		/* this is pretty tricky.  We don't want to434		 * take the relocation lock in btrfs_record_root_in_trans435		 * unless we're really doing the first setup for this root in436		 * this transaction.437		 *438		 * Normally we'd use root->last_trans as a flag to decide439		 * if we want to take the expensive mutex.440		 *441		 * But, we have to set root->last_trans before we442		 * init the relocation root, otherwise, we trip over warnings443		 * in ctree.c.  The solution used here is to flag ourselves444		 * with root IN_TRANS_SETUP.  When this is 1, we're still445		 * fixing up the reloc trees and everyone must wait.446		 *447		 * When this is zero, they can trust root->last_trans and fly448		 * through btrfs_record_root_in_trans without having to take the449		 * lock.  smp_wmb() makes sure that all the writes above are450		 * done before we pop in the zero below451		 */452		ret = btrfs_init_reloc_root(trans, root);453		smp_mb__before_atomic();454		clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);455	}456	return ret;457}458 459 460void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,461			    struct btrfs_root *root)462{463	struct btrfs_fs_info *fs_info = root->fs_info;464	struct btrfs_transaction *cur_trans = trans->transaction;465 466	/* Add ourselves to the transaction dropped list */467	spin_lock(&cur_trans->dropped_roots_lock);468	list_add_tail(&root->root_list, &cur_trans->dropped_roots);469	spin_unlock(&cur_trans->dropped_roots_lock);470 471	/* Make sure we don't try to update the root at commit time */472	spin_lock(&fs_info->fs_roots_radix_lock);473	radix_tree_tag_clear(&fs_info->fs_roots_radix,474			     (unsigned long)btrfs_root_id(root),475			     BTRFS_ROOT_TRANS_TAG);476	spin_unlock(&fs_info->fs_roots_radix_lock);477}478 479int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,480			       struct btrfs_root *root)481{482	struct btrfs_fs_info *fs_info = root->fs_info;483	int ret;484 485	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))486		return 0;487 488	/*489	 * see record_root_in_trans for comments about IN_TRANS_SETUP usage490	 * and barriers491	 */492	smp_rmb();493	if (btrfs_get_root_last_trans(root) == trans->transid &&494	    !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))495		return 0;496 497	mutex_lock(&fs_info->reloc_mutex);498	ret = record_root_in_trans(trans, root, 0);499	mutex_unlock(&fs_info->reloc_mutex);500 501	return ret;502}503 504static inline int is_transaction_blocked(struct btrfs_transaction *trans)505{506	return (trans->state >= TRANS_STATE_COMMIT_START &&507		trans->state < TRANS_STATE_UNBLOCKED &&508		!TRANS_ABORTED(trans));509}510 511/* wait for commit against the current transaction to become unblocked512 * when this is done, it is safe to start a new transaction, but the current513 * transaction might not be fully on disk.514 */515static void wait_current_trans(struct btrfs_fs_info *fs_info)516{517	struct btrfs_transaction *cur_trans;518 519	spin_lock(&fs_info->trans_lock);520	cur_trans = fs_info->running_transaction;521	if (cur_trans && is_transaction_blocked(cur_trans)) {522		refcount_inc(&cur_trans->use_count);523		spin_unlock(&fs_info->trans_lock);524 525		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);526		wait_event(fs_info->transaction_wait,527			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||528			   TRANS_ABORTED(cur_trans));529		btrfs_put_transaction(cur_trans);530	} else {531		spin_unlock(&fs_info->trans_lock);532	}533}534 535static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)536{537	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))538		return 0;539 540	if (type == TRANS_START)541		return 1;542 543	return 0;544}545 546static inline bool need_reserve_reloc_root(struct btrfs_root *root)547{548	struct btrfs_fs_info *fs_info = root->fs_info;549 550	if (!fs_info->reloc_ctl ||551	    !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||552	    btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||553	    root->reloc_root)554		return false;555 556	return true;557}558 559static int btrfs_reserve_trans_metadata(struct btrfs_fs_info *fs_info,560					enum btrfs_reserve_flush_enum flush,561					u64 num_bytes,562					u64 *delayed_refs_bytes)563{564	struct btrfs_space_info *si = fs_info->trans_block_rsv.space_info;565	u64 bytes = num_bytes + *delayed_refs_bytes;566	int ret;567 568	/*569	 * We want to reserve all the bytes we may need all at once, so we only570	 * do 1 enospc flushing cycle per transaction start.571	 */572	ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);573 574	/*575	 * If we are an emergency flush, which can steal from the global block576	 * reserve, then attempt to not reserve space for the delayed refs, as577	 * we will consume space for them from the global block reserve.578	 */579	if (ret && flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {580		bytes -= *delayed_refs_bytes;581		*delayed_refs_bytes = 0;582		ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);583	}584 585	return ret;586}587 588static struct btrfs_trans_handle *589start_transaction(struct btrfs_root *root, unsigned int num_items,590		  unsigned int type, enum btrfs_reserve_flush_enum flush,591		  bool enforce_qgroups)592{593	struct btrfs_fs_info *fs_info = root->fs_info;594	struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;595	struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;596	struct btrfs_trans_handle *h;597	struct btrfs_transaction *cur_trans;598	u64 num_bytes = 0;599	u64 qgroup_reserved = 0;600	u64 delayed_refs_bytes = 0;601	bool reloc_reserved = false;602	bool do_chunk_alloc = false;603	int ret;604 605	if (BTRFS_FS_ERROR(fs_info))606		return ERR_PTR(-EROFS);607 608	if (current->journal_info) {609		WARN_ON(type & TRANS_EXTWRITERS);610		h = current->journal_info;611		refcount_inc(&h->use_count);612		WARN_ON(refcount_read(&h->use_count) > 2);613		h->orig_rsv = h->block_rsv;614		h->block_rsv = NULL;615		goto got_it;616	}617 618	/*619	 * Do the reservation before we join the transaction so we can do all620	 * the appropriate flushing if need be.621	 */622	if (num_items && root != fs_info->chunk_root) {623		qgroup_reserved = num_items * fs_info->nodesize;624		/*625		 * Use prealloc for now, as there might be a currently running626		 * transaction that could free this reserved space prematurely627		 * by committing.628		 */629		ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserved,630							 enforce_qgroups, false);631		if (ret)632			return ERR_PTR(ret);633 634		num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);635		/*636		 * If we plan to insert/update/delete "num_items" from a btree,637		 * we will also generate delayed refs for extent buffers in the638		 * respective btree paths, so reserve space for the delayed refs639		 * that will be generated by the caller as it modifies btrees.640		 * Try to reserve them to avoid excessive use of the global641		 * block reserve.642		 */643		delayed_refs_bytes = btrfs_calc_delayed_ref_bytes(fs_info, num_items);644 645		/*646		 * Do the reservation for the relocation root creation647		 */648		if (need_reserve_reloc_root(root)) {649			num_bytes += fs_info->nodesize;650			reloc_reserved = true;651		}652 653		ret = btrfs_reserve_trans_metadata(fs_info, flush, num_bytes,654						   &delayed_refs_bytes);655		if (ret)656			goto reserve_fail;657 658		btrfs_block_rsv_add_bytes(trans_rsv, num_bytes, true);659 660		if (trans_rsv->space_info->force_alloc)661			do_chunk_alloc = true;662	} else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&663		   !btrfs_block_rsv_full(delayed_refs_rsv)) {664		/*665		 * Some people call with btrfs_start_transaction(root, 0)666		 * because they can be throttled, but have some other mechanism667		 * for reserving space.  We still want these guys to refill the668		 * delayed block_rsv so just add 1 items worth of reservation669		 * here.670		 */671		ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);672		if (ret)673			goto reserve_fail;674	}675again:676	h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);677	if (!h) {678		ret = -ENOMEM;679		goto alloc_fail;680	}681 682	/*683	 * If we are JOIN_NOLOCK we're already committing a transaction and684	 * waiting on this guy, so we don't need to do the sb_start_intwrite685	 * because we're already holding a ref.  We need this because we could686	 * have raced in and did an fsync() on a file which can kick a commit687	 * and then we deadlock with somebody doing a freeze.688	 *689	 * If we are ATTACH, it means we just want to catch the current690	 * transaction and commit it, so we needn't do sb_start_intwrite(). 691	 */692	if (type & __TRANS_FREEZABLE)693		sb_start_intwrite(fs_info->sb);694 695	if (may_wait_transaction(fs_info, type))696		wait_current_trans(fs_info);697 698	do {699		ret = join_transaction(fs_info, type);700		if (ret == -EBUSY) {701			wait_current_trans(fs_info);702			if (unlikely(type == TRANS_ATTACH ||703				     type == TRANS_JOIN_NOSTART))704				ret = -ENOENT;705		}706	} while (ret == -EBUSY);707 708	if (ret < 0)709		goto join_fail;710 711	cur_trans = fs_info->running_transaction;712 713	h->transid = cur_trans->transid;714	h->transaction = cur_trans;715	refcount_set(&h->use_count, 1);716	h->fs_info = root->fs_info;717 718	h->type = type;719	INIT_LIST_HEAD(&h->new_bgs);720	btrfs_init_metadata_block_rsv(fs_info, &h->delayed_rsv, BTRFS_BLOCK_RSV_DELOPS);721 722	smp_mb();723	if (cur_trans->state >= TRANS_STATE_COMMIT_START &&724	    may_wait_transaction(fs_info, type)) {725		current->journal_info = h;726		btrfs_commit_transaction(h);727		goto again;728	}729 730	if (num_bytes) {731		trace_btrfs_space_reservation(fs_info, "transaction",732					      h->transid, num_bytes, 1);733		h->block_rsv = trans_rsv;734		h->bytes_reserved = num_bytes;735		if (delayed_refs_bytes > 0) {736			trace_btrfs_space_reservation(fs_info,737						      "local_delayed_refs_rsv",738						      h->transid,739						      delayed_refs_bytes, 1);740			h->delayed_refs_bytes_reserved = delayed_refs_bytes;741			btrfs_block_rsv_add_bytes(&h->delayed_rsv, delayed_refs_bytes, true);742			delayed_refs_bytes = 0;743		}744		h->reloc_reserved = reloc_reserved;745	}746 747got_it:748	if (!current->journal_info)749		current->journal_info = h;750 751	/*752	 * If the space_info is marked ALLOC_FORCE then we'll get upgraded to753	 * ALLOC_FORCE the first run through, and then we won't allocate for754	 * anybody else who races in later.  We don't care about the return755	 * value here.756	 */757	if (do_chunk_alloc && num_bytes) {758		u64 flags = h->block_rsv->space_info->flags;759 760		btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),761				  CHUNK_ALLOC_NO_FORCE);762	}763 764	/*765	 * btrfs_record_root_in_trans() needs to alloc new extents, and may766	 * call btrfs_join_transaction() while we're also starting a767	 * transaction.768	 *769	 * Thus it need to be called after current->journal_info initialized,770	 * or we can deadlock.771	 */772	ret = btrfs_record_root_in_trans(h, root);773	if (ret) {774		/*775		 * The transaction handle is fully initialized and linked with776		 * other structures so it needs to be ended in case of errors,777		 * not just freed.778		 */779		btrfs_end_transaction(h);780		goto reserve_fail;781	}782	/*783	 * Now that we have found a transaction to be a part of, convert the784	 * qgroup reservation from prealloc to pertrans. A different transaction785	 * can't race in and free our pertrans out from under us.786	 */787	if (qgroup_reserved)788		btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved);789 790	return h;791 792join_fail:793	if (type & __TRANS_FREEZABLE)794		sb_end_intwrite(fs_info->sb);795	kmem_cache_free(btrfs_trans_handle_cachep, h);796alloc_fail:797	if (num_bytes)798		btrfs_block_rsv_release(fs_info, trans_rsv, num_bytes, NULL);799	if (delayed_refs_bytes)800		btrfs_space_info_free_bytes_may_use(fs_info, trans_rsv->space_info,801						    delayed_refs_bytes);802reserve_fail:803	btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved);804	return ERR_PTR(ret);805}806 807struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,808						   unsigned int num_items)809{810	return start_transaction(root, num_items, TRANS_START,811				 BTRFS_RESERVE_FLUSH_ALL, true);812}813 814struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(815					struct btrfs_root *root,816					unsigned int num_items)817{818	return start_transaction(root, num_items, TRANS_START,819				 BTRFS_RESERVE_FLUSH_ALL_STEAL, false);820}821 822struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)823{824	return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,825				 true);826}827 828struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)829{830	return start_transaction(root, 0, TRANS_JOIN_NOLOCK,831				 BTRFS_RESERVE_NO_FLUSH, true);832}833 834/*835 * Similar to regular join but it never starts a transaction when none is836 * running or when there's a running one at a state >= TRANS_STATE_UNBLOCKED.837 * This is similar to btrfs_attach_transaction() but it allows the join to838 * happen if the transaction commit already started but it's not yet in the839 * "doing" phase (the state is < TRANS_STATE_COMMIT_DOING).840 */841struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)842{843	return start_transaction(root, 0, TRANS_JOIN_NOSTART,844				 BTRFS_RESERVE_NO_FLUSH, true);845}846 847/*848 * Catch the running transaction.849 *850 * It is used when we want to commit the current the transaction, but851 * don't want to start a new one.852 *853 * Note: If this function return -ENOENT, it just means there is no854 * running transaction. But it is possible that the inactive transaction855 * is still in the memory, not fully on disk. If you hope there is no856 * inactive transaction in the fs when -ENOENT is returned, you should857 * invoke858 *     btrfs_attach_transaction_barrier()859 */860struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)861{862	return start_transaction(root, 0, TRANS_ATTACH,863				 BTRFS_RESERVE_NO_FLUSH, true);864}865 866/*867 * Catch the running transaction.868 *869 * It is similar to the above function, the difference is this one870 * will wait for all the inactive transactions until they fully871 * complete.872 */873struct btrfs_trans_handle *874btrfs_attach_transaction_barrier(struct btrfs_root *root)875{876	struct btrfs_trans_handle *trans;877 878	trans = start_transaction(root, 0, TRANS_ATTACH,879				  BTRFS_RESERVE_NO_FLUSH, true);880	if (trans == ERR_PTR(-ENOENT)) {881		int ret;882 883		ret = btrfs_wait_for_commit(root->fs_info, 0);884		if (ret)885			return ERR_PTR(ret);886	}887 888	return trans;889}890 891/* Wait for a transaction commit to reach at least the given state. */892static noinline void wait_for_commit(struct btrfs_transaction *commit,893				     const enum btrfs_trans_state min_state)894{895	struct btrfs_fs_info *fs_info = commit->fs_info;896	u64 transid = commit->transid;897	bool put = false;898 899	/*900	 * At the moment this function is called with min_state either being901	 * TRANS_STATE_COMPLETED or TRANS_STATE_SUPER_COMMITTED.902	 */903	if (min_state == TRANS_STATE_COMPLETED)904		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);905	else906		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);907 908	while (1) {909		wait_event(commit->commit_wait, commit->state >= min_state);910		if (put)911			btrfs_put_transaction(commit);912 913		if (min_state < TRANS_STATE_COMPLETED)914			break;915 916		/*917		 * A transaction isn't really completed until all of the918		 * previous transactions are completed, but with fsync we can919		 * end up with SUPER_COMMITTED transactions before a COMPLETED920		 * transaction. Wait for those.921		 */922 923		spin_lock(&fs_info->trans_lock);924		commit = list_first_entry_or_null(&fs_info->trans_list,925						  struct btrfs_transaction,926						  list);927		if (!commit || commit->transid > transid) {928			spin_unlock(&fs_info->trans_lock);929			break;930		}931		refcount_inc(&commit->use_count);932		put = true;933		spin_unlock(&fs_info->trans_lock);934	}935}936 937int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)938{939	struct btrfs_transaction *cur_trans = NULL, *t;940	int ret = 0;941 942	if (transid) {943		if (transid <= btrfs_get_last_trans_committed(fs_info))944			goto out;945 946		/* find specified transaction */947		spin_lock(&fs_info->trans_lock);948		list_for_each_entry(t, &fs_info->trans_list, list) {949			if (t->transid == transid) {950				cur_trans = t;951				refcount_inc(&cur_trans->use_count);952				ret = 0;953				break;954			}955			if (t->transid > transid) {956				ret = 0;957				break;958			}959		}960		spin_unlock(&fs_info->trans_lock);961 962		/*963		 * The specified transaction doesn't exist, or we964		 * raced with btrfs_commit_transaction965		 */966		if (!cur_trans) {967			if (transid > btrfs_get_last_trans_committed(fs_info))968				ret = -EINVAL;969			goto out;970		}971	} else {972		/* find newest transaction that is committing | committed */973		spin_lock(&fs_info->trans_lock);974		list_for_each_entry_reverse(t, &fs_info->trans_list,975					    list) {976			if (t->state >= TRANS_STATE_COMMIT_START) {977				if (t->state == TRANS_STATE_COMPLETED)978					break;979				cur_trans = t;980				refcount_inc(&cur_trans->use_count);981				break;982			}983		}984		spin_unlock(&fs_info->trans_lock);985		if (!cur_trans)986			goto out;  /* nothing committing|committed */987	}988 989	wait_for_commit(cur_trans, TRANS_STATE_COMPLETED);990	ret = cur_trans->aborted;991	btrfs_put_transaction(cur_trans);992out:993	return ret;994}995 996void btrfs_throttle(struct btrfs_fs_info *fs_info)997{998	wait_current_trans(fs_info);999}1000 1001bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans)1002{1003	struct btrfs_transaction *cur_trans = trans->transaction;1004 1005	if (cur_trans->state >= TRANS_STATE_COMMIT_START ||1006	    test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags))1007		return true;1008 1009	if (btrfs_check_space_for_delayed_refs(trans->fs_info))1010		return true;1011 1012	return !!btrfs_block_rsv_check(&trans->fs_info->global_block_rsv, 50);1013}1014 1015static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)1016 1017{1018	struct btrfs_fs_info *fs_info = trans->fs_info;1019 1020	if (!trans->block_rsv) {1021		ASSERT(!trans->bytes_reserved);1022		ASSERT(!trans->delayed_refs_bytes_reserved);1023		return;1024	}1025 1026	if (!trans->bytes_reserved) {1027		ASSERT(!trans->delayed_refs_bytes_reserved);1028		return;1029	}1030 1031	ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);1032	trace_btrfs_space_reservation(fs_info, "transaction",1033				      trans->transid, trans->bytes_reserved, 0);1034	btrfs_block_rsv_release(fs_info, trans->block_rsv,1035				trans->bytes_reserved, NULL);1036	trans->bytes_reserved = 0;1037 1038	if (!trans->delayed_refs_bytes_reserved)1039		return;1040 1041	trace_btrfs_space_reservation(fs_info, "local_delayed_refs_rsv",1042				      trans->transid,1043				      trans->delayed_refs_bytes_reserved, 0);1044	btrfs_block_rsv_release(fs_info, &trans->delayed_rsv,1045				trans->delayed_refs_bytes_reserved, NULL);1046	trans->delayed_refs_bytes_reserved = 0;1047}1048 1049static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,1050				   int throttle)1051{1052	struct btrfs_fs_info *info = trans->fs_info;1053	struct btrfs_transaction *cur_trans = trans->transaction;1054	int ret = 0;1055 1056	if (refcount_read(&trans->use_count) > 1) {1057		refcount_dec(&trans->use_count);1058		trans->block_rsv = trans->orig_rsv;1059		return 0;1060	}1061 1062	btrfs_trans_release_metadata(trans);1063	trans->block_rsv = NULL;1064 1065	btrfs_create_pending_block_groups(trans);1066 1067	btrfs_trans_release_chunk_metadata(trans);1068 1069	if (trans->type & __TRANS_FREEZABLE)1070		sb_end_intwrite(info->sb);1071 1072	WARN_ON(cur_trans != info->running_transaction);1073	WARN_ON(atomic_read(&cur_trans->num_writers) < 1);1074	atomic_dec(&cur_trans->num_writers);1075	extwriter_counter_dec(cur_trans, trans->type);1076 1077	cond_wake_up(&cur_trans->writer_wait);1078 1079	btrfs_lockdep_release(info, btrfs_trans_num_extwriters);1080	btrfs_lockdep_release(info, btrfs_trans_num_writers);1081 1082	btrfs_put_transaction(cur_trans);1083 1084	if (current->journal_info == trans)1085		current->journal_info = NULL;1086 1087	if (throttle)1088		btrfs_run_delayed_iputs(info);1089 1090	if (TRANS_ABORTED(trans) || BTRFS_FS_ERROR(info)) {1091		wake_up_process(info->transaction_kthread);1092		if (TRANS_ABORTED(trans))1093			ret = trans->aborted;1094		else1095			ret = -EROFS;1096	}1097 1098	kmem_cache_free(btrfs_trans_handle_cachep, trans);1099	return ret;1100}1101 1102int btrfs_end_transaction(struct btrfs_trans_handle *trans)1103{1104	return __btrfs_end_transaction(trans, 0);1105}1106 1107int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)1108{1109	return __btrfs_end_transaction(trans, 1);1110}1111 1112/*1113 * when btree blocks are allocated, they have some corresponding bits set for1114 * them in one of two extent_io trees.  This is used to make sure all of1115 * those extents are sent to disk but does not wait on them1116 */1117int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,1118			       struct extent_io_tree *dirty_pages, int mark)1119{1120	int ret = 0;1121	struct address_space *mapping = fs_info->btree_inode->i_mapping;1122	struct extent_state *cached_state = NULL;1123	u64 start = 0;1124	u64 end;1125 1126	while (find_first_extent_bit(dirty_pages, start, &start, &end,1127				     mark, &cached_state)) {1128		bool wait_writeback = false;1129 1130		ret = convert_extent_bit(dirty_pages, start, end,1131					 EXTENT_NEED_WAIT,1132					 mark, &cached_state);1133		/*1134		 * convert_extent_bit can return -ENOMEM, which is most of the1135		 * time a temporary error. So when it happens, ignore the error1136		 * and wait for writeback of this range to finish - because we1137		 * failed to set the bit EXTENT_NEED_WAIT for the range, a call1138		 * to __btrfs_wait_marked_extents() would not know that1139		 * writeback for this range started and therefore wouldn't1140		 * wait for it to finish - we don't want to commit a1141		 * superblock that points to btree nodes/leafs for which1142		 * writeback hasn't finished yet (and without errors).1143		 * We cleanup any entries left in the io tree when committing1144		 * the transaction (through extent_io_tree_release()).1145		 */1146		if (ret == -ENOMEM) {1147			ret = 0;1148			wait_writeback = true;1149		}1150		if (!ret)1151			ret = filemap_fdatawrite_range(mapping, start, end);1152		if (!ret && wait_writeback)1153			ret = filemap_fdatawait_range(mapping, start, end);1154		free_extent_state(cached_state);1155		if (ret)1156			break;1157		cached_state = NULL;1158		cond_resched();1159		start = end + 1;1160	}1161	return ret;1162}1163 1164/*1165 * when btree blocks are allocated, they have some corresponding bits set for1166 * them in one of two extent_io trees.  This is used to make sure all of1167 * those extents are on disk for transaction or log commit.  We wait1168 * on all the pages and clear them from the dirty pages state tree1169 */1170static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,1171				       struct extent_io_tree *dirty_pages)1172{1173	struct address_space *mapping = fs_info->btree_inode->i_mapping;1174	struct extent_state *cached_state = NULL;1175	u64 start = 0;1176	u64 end;1177	int ret = 0;1178 1179	while (find_first_extent_bit(dirty_pages, start, &start, &end,1180				     EXTENT_NEED_WAIT, &cached_state)) {1181		/*1182		 * Ignore -ENOMEM errors returned by clear_extent_bit().1183		 * When committing the transaction, we'll remove any entries1184		 * left in the io tree. For a log commit, we don't remove them1185		 * after committing the log because the tree can be accessed1186		 * concurrently - we do it only at transaction commit time when1187		 * it's safe to do it (through extent_io_tree_release()).1188		 */1189		ret = clear_extent_bit(dirty_pages, start, end,1190				       EXTENT_NEED_WAIT, &cached_state);1191		if (ret == -ENOMEM)1192			ret = 0;1193		if (!ret)1194			ret = filemap_fdatawait_range(mapping, start, end);1195		free_extent_state(cached_state);1196		if (ret)1197			break;1198		cached_state = NULL;1199		cond_resched();1200		start = end + 1;1201	}1202	return ret;1203}1204 1205static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,1206		       struct extent_io_tree *dirty_pages)1207{1208	bool errors = false;1209	int err;1210 1211	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);1212	if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))1213		errors = true;1214 1215	if (errors && !err)1216		err = -EIO;1217	return err;1218}1219 1220int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)1221{1222	struct btrfs_fs_info *fs_info = log_root->fs_info;1223	struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;1224	bool errors = false;1225	int err;1226 1227	ASSERT(btrfs_root_id(log_root) == BTRFS_TREE_LOG_OBJECTID);1228 1229	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);1230	if ((mark & EXTENT_DIRTY) &&1231	    test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))1232		errors = true;1233 1234	if ((mark & EXTENT_NEW) &&1235	    test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))1236		errors = true;1237 1238	if (errors && !err)1239		err = -EIO;1240	return err;1241}1242 1243/*1244 * When btree blocks are allocated the corresponding extents are marked dirty.1245 * This function ensures such extents are persisted on disk for transaction or1246 * log commit.1247 *1248 * @trans: transaction whose dirty pages we'd like to write1249 */1250static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)1251{1252	int ret;1253	int ret2;1254	struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;1255	struct btrfs_fs_info *fs_info = trans->fs_info;1256	struct blk_plug plug;1257 1258	blk_start_plug(&plug);1259	ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);1260	blk_finish_plug(&plug);1261	ret2 = btrfs_wait_extents(fs_info, dirty_pages);1262 1263	extent_io_tree_release(&trans->transaction->dirty_pages);1264 1265	if (ret)1266		return ret;1267	else if (ret2)1268		return ret2;1269	else1270		return 0;1271}1272 1273/*1274 * this is used to update the root pointer in the tree of tree roots.1275 *1276 * But, in the case of the extent allocation tree, updating the root1277 * pointer may allocate blocks which may change the root of the extent1278 * allocation tree.1279 *1280 * So, this loops and repeats and makes sure the cowonly root didn't1281 * change while the root pointer was being updated in the metadata.1282 */1283static int update_cowonly_root(struct btrfs_trans_handle *trans,1284			       struct btrfs_root *root)1285{1286	int ret;1287	u64 old_root_bytenr;1288	u64 old_root_used;1289	struct btrfs_fs_info *fs_info = root->fs_info;1290	struct btrfs_root *tree_root = fs_info->tree_root;1291 1292	old_root_used = btrfs_root_used(&root->root_item);1293 1294	while (1) {1295		old_root_bytenr = btrfs_root_bytenr(&root->root_item);1296		if (old_root_bytenr == root->node->start &&1297		    old_root_used == btrfs_root_used(&root->root_item))1298			break;1299 1300		btrfs_set_root_node(&root->root_item, root->node);1301		ret = btrfs_update_root(trans, tree_root,1302					&root->root_key,1303					&root->root_item);1304		if (ret)1305			return ret;1306 1307		old_root_used = btrfs_root_used(&root->root_item);1308	}1309 1310	return 0;1311}1312 1313/*1314 * update all the cowonly tree roots on disk1315 *1316 * The error handling in this function may not be obvious. Any of the1317 * failures will cause the file system to go offline. We still need1318 * to clean up the delayed refs.1319 */1320static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)1321{1322	struct btrfs_fs_info *fs_info = trans->fs_info;1323	struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;1324	struct list_head *io_bgs = &trans->transaction->io_bgs;1325	struct list_head *next;1326	struct extent_buffer *eb;1327	int ret;1328 1329	/*1330	 * At this point no one can be using this transaction to modify any tree1331	 * and no one can start another transaction to modify any tree either.1332	 */1333	ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);1334 1335	eb = btrfs_lock_root_node(fs_info->tree_root);1336	ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,1337			      0, &eb, BTRFS_NESTING_COW);1338	btrfs_tree_unlock(eb);1339	free_extent_buffer(eb);1340 1341	if (ret)1342		return ret;1343 1344	ret = btrfs_run_dev_stats(trans);1345	if (ret)1346		return ret;1347	ret = btrfs_run_dev_replace(trans);1348	if (ret)1349		return ret;1350	ret = btrfs_run_qgroups(trans);1351	if (ret)1352		return ret;1353 1354	ret = btrfs_setup_space_cache(trans);1355	if (ret)1356		return ret;1357 1358again:1359	while (!list_empty(&fs_info->dirty_cowonly_roots)) {1360		struct btrfs_root *root;1361		next = fs_info->dirty_cowonly_roots.next;1362		list_del_init(next);1363		root = list_entry(next, struct btrfs_root, dirty_list);1364		clear_bit(BTRFS_ROOT_DIRTY, &root->state);1365 1366		list_add_tail(&root->dirty_list,1367			      &trans->transaction->switch_commits);1368		ret = update_cowonly_root(trans, root);1369		if (ret)1370			return ret;1371	}1372 1373	/* Now flush any delayed refs generated by updating all of the roots */1374	ret = btrfs_run_delayed_refs(trans, U64_MAX);1375	if (ret)1376		return ret;1377 1378	while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {1379		ret = btrfs_write_dirty_block_groups(trans);1380		if (ret)1381			return ret;1382 1383		/*1384		 * We're writing the dirty block groups, which could generate1385		 * delayed refs, which could generate more dirty block groups,1386		 * so we want to keep this flushing in this loop to make sure1387		 * everything gets run.1388		 */1389		ret = btrfs_run_delayed_refs(trans, U64_MAX);1390		if (ret)1391			return ret;1392	}1393 1394	if (!list_empty(&fs_info->dirty_cowonly_roots))1395		goto again;1396 1397	/* Update dev-replace pointer once everything is committed */1398	fs_info->dev_replace.committed_cursor_left =1399		fs_info->dev_replace.cursor_left_last_write_of_item;1400 1401	return 0;1402}1403 1404/*1405 * If we had a pending drop we need to see if there are any others left in our1406 * dead roots list, and if not clear our bit and wake any waiters.1407 */1408void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info)1409{1410	/*1411	 * We put the drop in progress roots at the front of the list, so if the1412	 * first entry doesn't have UNFINISHED_DROP set we can wake everybody1413	 * up.1414	 */1415	spin_lock(&fs_info->trans_lock);1416	if (!list_empty(&fs_info->dead_roots)) {1417		struct btrfs_root *root = list_first_entry(&fs_info->dead_roots,1418							   struct btrfs_root,1419							   root_list);1420		if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) {1421			spin_unlock(&fs_info->trans_lock);1422			return;1423		}1424	}1425	spin_unlock(&fs_info->trans_lock);1426 1427	btrfs_wake_unfinished_drop(fs_info);1428}1429 1430/*1431 * dead roots are old snapshots that need to be deleted.  This allocates1432 * a dirty root struct and adds it into the list of dead roots that need to1433 * be deleted1434 */1435void btrfs_add_dead_root(struct btrfs_root *root)1436{1437	struct btrfs_fs_info *fs_info = root->fs_info;1438 1439	spin_lock(&fs_info->trans_lock);1440	if (list_empty(&root->root_list)) {1441		btrfs_grab_root(root);1442 1443		/* We want to process the partially complete drops first. */1444		if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state))1445			list_add(&root->root_list, &fs_info->dead_roots);1446		else1447			list_add_tail(&root->root_list, &fs_info->dead_roots);1448	}1449	spin_unlock(&fs_info->trans_lock);1450}1451 1452/*1453 * Update each subvolume root and its relocation root, if it exists, in the tree1454 * of tree roots. Also free log roots if they exist.1455 */1456static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)1457{1458	struct btrfs_fs_info *fs_info = trans->fs_info;1459	struct btrfs_root *gang[8];1460	int i;1461	int ret;1462 1463	/*1464	 * At this point no one can be using this transaction to modify any tree1465	 * and no one can start another transaction to modify any tree either.1466	 */1467	ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);1468 1469	spin_lock(&fs_info->fs_roots_radix_lock);1470	while (1) {1471		ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,1472						 (void **)gang, 0,1473						 ARRAY_SIZE(gang),1474						 BTRFS_ROOT_TRANS_TAG);1475		if (ret == 0)1476			break;1477		for (i = 0; i < ret; i++) {1478			struct btrfs_root *root = gang[i];1479			int ret2;1480 1481			/*1482			 * At this point we can neither have tasks logging inodes1483			 * from a root nor trying to commit a log tree.1484			 */1485			ASSERT(atomic_read(&root->log_writers) == 0);1486			ASSERT(atomic_read(&root->log_commit[0]) == 0);1487			ASSERT(atomic_read(&root->log_commit[1]) == 0);1488 1489			radix_tree_tag_clear(&fs_info->fs_roots_radix,1490					(unsigned long)btrfs_root_id(root),1491					BTRFS_ROOT_TRANS_TAG);1492			btrfs_qgroup_free_meta_all_pertrans(root);1493			spin_unlock(&fs_info->fs_roots_radix_lock);1494 1495			btrfs_free_log(trans, root);1496			ret2 = btrfs_update_reloc_root(trans, root);1497			if (ret2)1498				return ret2;1499 1500			/* see comments in should_cow_block() */1501			clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);1502			smp_mb__after_atomic();1503 1504			if (root->commit_root != root->node) {1505				list_add_tail(&root->dirty_list,1506					&trans->transaction->switch_commits);1507				btrfs_set_root_node(&root->root_item,1508						    root->node);1509			}1510 1511			ret2 = btrfs_update_root(trans, fs_info->tree_root,1512						&root->root_key,1513						&root->root_item);1514			if (ret2)1515				return ret2;1516			spin_lock(&fs_info->fs_roots_radix_lock);1517		}1518	}1519	spin_unlock(&fs_info->fs_roots_radix_lock);1520	return 0;1521}1522 1523/*1524 * Do all special snapshot related qgroup dirty hack.1525 *1526 * Will do all needed qgroup inherit and dirty hack like switch commit1527 * roots inside one transaction and write all btree into disk, to make1528 * qgroup works.1529 */1530static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,1531				   struct btrfs_root *src,1532				   struct btrfs_root *parent,1533				   struct btrfs_qgroup_inherit *inherit,1534				   u64 dst_objectid)1535{1536	struct btrfs_fs_info *fs_info = src->fs_info;1537	int ret;1538 1539	/*1540	 * Save some performance in the case that qgroups are not enabled. If1541	 * this check races with the ioctl, rescan will kick in anyway.1542	 */1543	if (!btrfs_qgroup_full_accounting(fs_info))1544		return 0;1545 1546	/*1547	 * Ensure dirty @src will be committed.  Or, after coming1548	 * commit_fs_roots() and switch_commit_roots(), any dirty but not1549	 * recorded root will never be updated again, causing an outdated root1550	 * item.1551	 */1552	ret = record_root_in_trans(trans, src, 1);1553	if (ret)1554		return ret;1555 1556	/*1557	 * btrfs_qgroup_inherit relies on a consistent view of the usage for the1558	 * src root, so we must run the delayed refs here.1559	 *1560	 * However this isn't particularly fool proof, because there's no1561	 * synchronization keeping us from changing the tree after this point1562	 * before we do the qgroup_inherit, or even from making changes while1563	 * we're doing the qgroup_inherit.  But that's a problem for the future,1564	 * for now flush the delayed refs to narrow the race window where the1565	 * qgroup counters could end up wrong.1566	 */1567	ret = btrfs_run_delayed_refs(trans, U64_MAX);1568	if (ret) {1569		btrfs_abort_transaction(trans, ret);1570		return ret;1571	}1572 1573	ret = commit_fs_roots(trans);1574	if (ret)1575		goto out;1576	ret = btrfs_qgroup_account_extents(trans);1577	if (ret < 0)1578		goto out;1579 1580	/* Now qgroup are all updated, we can inherit it to new qgroups */1581	ret = btrfs_qgroup_inherit(trans, btrfs_root_id(src), dst_objectid,1582				   btrfs_root_id(parent), inherit);1583	if (ret < 0)1584		goto out;1585 1586	/*1587	 * Now we do a simplified commit transaction, which will:1588	 * 1) commit all subvolume and extent tree1589	 *    To ensure all subvolume and extent tree have a valid1590	 *    commit_root to accounting later insert_dir_item()1591	 * 2) write all btree blocks onto disk1592	 *    This is to make sure later btree modification will be cowed1593	 *    Or commit_root can be populated and cause wrong qgroup numbers1594	 * In this simplified commit, we don't really care about other trees1595	 * like chunk and root tree, as they won't affect qgroup.1596	 * And we don't write super to avoid half committed status.1597	 */1598	ret = commit_cowonly_roots(trans);1599	if (ret)1600		goto out;1601	switch_commit_roots(trans);1602	ret = btrfs_write_and_wait_transaction(trans);1603	if (ret)1604		btrfs_handle_fs_error(fs_info, ret,1605			"Error while writing out transaction for qgroup");1606 1607out:1608	/*1609	 * Force parent root to be updated, as we recorded it before so its1610	 * last_trans == cur_transid.1611	 * Or it won't be committed again onto disk after later1612	 * insert_dir_item()1613	 */1614	if (!ret)1615		ret = record_root_in_trans(trans, parent, 1);1616	return ret;1617}1618 1619/*1620 * new snapshots need to be created at a very specific time in the1621 * transaction commit.  This does the actual creation.1622 *1623 * Note:1624 * If the error which may affect the commitment of the current transaction1625 * happens, we should return the error number. If the error which just affect1626 * the creation of the pending snapshots, just return 0.1627 */1628static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,1629				   struct btrfs_pending_snapshot *pending)1630{1631 1632	struct btrfs_fs_info *fs_info = trans->fs_info;1633	struct btrfs_key key;1634	struct btrfs_root_item *new_root_item;1635	struct btrfs_root *tree_root = fs_info->tree_root;1636	struct btrfs_root *root = pending->root;1637	struct btrfs_root *parent_root;1638	struct btrfs_block_rsv *rsv;1639	struct inode *parent_inode = &pending->dir->vfs_inode;1640	struct btrfs_path *path;1641	struct btrfs_dir_item *dir_item;1642	struct extent_buffer *tmp;1643	struct extent_buffer *old;1644	struct timespec64 cur_time;1645	int ret = 0;1646	u64 to_reserve = 0;1647	u64 index = 0;1648	u64 objectid;1649	u64 root_flags;1650	unsigned int nofs_flags;1651	struct fscrypt_name fname;1652 1653	ASSERT(pending->path);1654	path = pending->path;1655 1656	ASSERT(pending->root_item);1657	new_root_item = pending->root_item;1658 1659	/*1660	 * We're inside a transaction and must make sure that any potential1661	 * allocations with GFP_KERNEL in fscrypt won't recurse back to1662	 * filesystem.1663	 */1664	nofs_flags = memalloc_nofs_save();1665	pending->error = fscrypt_setup_filename(parent_inode,1666						&pending->dentry->d_name, 0,1667						&fname);1668	memalloc_nofs_restore(nofs_flags);1669	if (pending->error)1670		goto free_pending;1671 1672	pending->error = btrfs_get_free_objectid(tree_root, &objectid);1673	if (pending->error)1674		goto free_fname;1675 1676	/*1677	 * Make qgroup to skip current new snapshot's qgroupid, as it is1678	 * accounted by later btrfs_qgroup_inherit().1679	 */1680	btrfs_set_skip_qgroup(trans, objectid);1681 1682	btrfs_reloc_pre_snapshot(pending, &to_reserve);1683 1684	if (to_reserve > 0) {1685		pending->error = btrfs_block_rsv_add(fs_info,1686						     &pending->block_rsv,1687						     to_reserve,1688						     BTRFS_RESERVE_NO_FLUSH);1689		if (pending->error)1690			goto clear_skip_qgroup;1691	}1692 1693	key.objectid = objectid;1694	key.offset = (u64)-1;1695	key.type = BTRFS_ROOT_ITEM_KEY;1696 1697	rsv = trans->block_rsv;1698	trans->block_rsv = &pending->block_rsv;1699	trans->bytes_reserved = trans->block_rsv->reserved;1700	trace_btrfs_space_reservation(fs_info, "transaction",1701				      trans->transid,1702				      trans->bytes_reserved, 1);1703	parent_root = BTRFS_I(parent_inode)->root;1704	ret = record_root_in_trans(trans, parent_root, 0);1705	if (ret)1706		goto fail;1707	cur_time = current_time(parent_inode);1708 1709	/*1710	 * insert the directory item1711	 */1712	ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);1713	if (ret) {1714		btrfs_abort_transaction(trans, ret);1715		goto fail;1716	}1717 1718	/* check if there is a file/dir which has the same name. */1719	dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,1720					 btrfs_ino(BTRFS_I(parent_inode)),1721					 &fname.disk_name, 0);1722	if (dir_item != NULL && !IS_ERR(dir_item)) {1723		pending->error = -EEXIST;1724		goto dir_item_existed;1725	} else if (IS_ERR(dir_item)) {1726		ret = PTR_ERR(dir_item);1727		btrfs_abort_transaction(trans, ret);1728		goto fail;1729	}1730	btrfs_release_path(path);1731 1732	ret = btrfs_create_qgroup(trans, objectid);1733	if (ret && ret != -EEXIST) {1734		btrfs_abort_transaction(trans, ret);1735		goto fail;1736	}1737 1738	/*1739	 * pull in the delayed directory update1740	 * and the delayed inode item1741	 * otherwise we corrupt the FS during1742	 * snapshot1743	 */1744	ret = btrfs_run_delayed_items(trans);1745	if (ret) {	/* Transaction aborted */1746		btrfs_abort_transaction(trans, ret);1747		goto fail;1748	}1749 1750	ret = record_root_in_trans(trans, root, 0);1751	if (ret) {1752		btrfs_abort_transaction(trans, ret);1753		goto fail;1754	}1755	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);1756	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));1757	btrfs_check_and_init_root_item(new_root_item);1758 1759	root_flags = btrfs_root_flags(new_root_item);1760	if (pending->readonly)1761		root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;1762	else1763		root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;1764	btrfs_set_root_flags(new_root_item, root_flags);1765 1766	btrfs_set_root_generation_v2(new_root_item,1767			trans->transid);1768	generate_random_guid(new_root_item->uuid);1769	memcpy(new_root_item->parent_uuid, root->root_item.uuid,1770			BTRFS_UUID_SIZE);1771	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {1772		memset(new_root_item->received_uuid, 0,1773		       sizeof(new_root_item->received_uuid));1774		memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));1775		memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));1776		btrfs_set_root_stransid(new_root_item, 0);1777		btrfs_set_root_rtransid(new_root_item, 0);1778	}1779	btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);1780	btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);1781	btrfs_set_root_otransid(new_root_item, trans->transid);1782 1783	old = btrfs_lock_root_node(root);1784	ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,1785			      BTRFS_NESTING_COW);1786	if (ret) {1787		btrfs_tree_unlock(old);1788		free_extent_buffer(old);1789		btrfs_abort_transaction(trans, ret);1790		goto fail;1791	}1792 1793	ret = btrfs_copy_root(trans, root, old, &tmp, objectid);1794	/* clean up in any case */1795	btrfs_tree_unlock(old);1796	free_extent_buffer(old);1797	if (ret) {1798		btrfs_abort_transaction(trans, ret);1799		goto fail;1800	}1801	/* see comments in should_cow_block() */1802	set_bit(BTRFS_ROOT_FORCE_COW, &root->state);1803	smp_wmb();1804 1805	btrfs_set_root_node(new_root_item, tmp);1806	/* record when the snapshot was created in key.offset */1807	key.offset = trans->transid;1808	ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);1809	btrfs_tree_unlock(tmp);1810	free_extent_buffer(tmp);1811	if (ret) {1812		btrfs_abort_transaction(trans, ret);1813		goto fail;1814	}1815 1816	/*1817	 * insert root back/forward references1818	 */1819	ret = btrfs_add_root_ref(trans, objectid,1820				 btrfs_root_id(parent_root),1821				 btrfs_ino(BTRFS_I(parent_inode)), index,1822				 &fname.disk_name);1823	if (ret) {1824		btrfs_abort_transaction(trans, ret);1825		goto fail;1826	}1827 1828	key.offset = (u64)-1;1829	pending->snap = btrfs_get_new_fs_root(fs_info, objectid, &pending->anon_dev);1830	if (IS_ERR(pending->snap)) {1831		ret = PTR_ERR(pending->snap);1832		pending->snap = NULL;1833		btrfs_abort_transaction(trans, ret);1834		goto fail;1835	}1836 1837	ret = btrfs_reloc_post_snapshot(trans, pending);1838	if (ret) {1839		btrfs_abort_transaction(trans, ret);1840		goto fail;1841	}1842 1843	/*1844	 * Do special qgroup accounting for snapshot, as we do some qgroup1845	 * snapshot hack to do fast snapshot.1846	 * To co-operate with that hack, we do hack again.1847	 * Or snapshot will be greatly slowed down by a subtree qgroup rescan1848	 */1849	if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL)1850		ret = qgroup_account_snapshot(trans, root, parent_root,1851					      pending->inherit, objectid);1852	else if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE)1853		ret = btrfs_qgroup_inherit(trans, btrfs_root_id(root), objectid,1854					   btrfs_root_id(parent_root), pending->inherit);1855	if (ret < 0)1856		goto fail;1857 1858	ret = btrfs_insert_dir_item(trans, &fname.disk_name,1859				    BTRFS_I(parent_inode), &key, BTRFS_FT_DIR,1860				    index);1861	if (ret) {1862		btrfs_abort_transaction(trans, ret);1863		goto fail;1864	}1865 1866	btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +1867						  fname.disk_name.len * 2);1868	inode_set_mtime_to_ts(parent_inode,1869			      inode_set_ctime_current(parent_inode));1870	ret = btrfs_update_inode_fallback(trans, BTRFS_I(parent_inode));1871	if (ret) {1872		btrfs_abort_transaction(trans, ret);1873		goto fail;1874	}1875	ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,1876				  BTRFS_UUID_KEY_SUBVOL,1877				  objectid);1878	if (ret) {1879		btrfs_abort_transaction(trans, ret);1880		goto fail;1881	}1882	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {1883		ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,1884					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,1885					  objectid);1886		if (ret && ret != -EEXIST) {1887			btrfs_abort_transaction(trans, ret);1888			goto fail;1889		}1890	}1891 1892fail:1893	pending->error = ret;1894dir_item_existed:1895	trans->block_rsv = rsv;1896	trans->bytes_reserved = 0;1897clear_skip_qgroup:1898	btrfs_clear_skip_qgroup(trans);1899free_fname:1900	fscrypt_free_filename(&fname);1901free_pending:1902	kfree(new_root_item);1903	pending->root_item = NULL;1904	btrfs_free_path(path);1905	pending->path = NULL;1906 1907	return ret;1908}1909 1910/*1911 * create all the snapshots we've scheduled for creation1912 */1913static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)1914{1915	struct btrfs_pending_snapshot *pending, *next;1916	struct list_head *head = &trans->transaction->pending_snapshots;1917	int ret = 0;1918 1919	list_for_each_entry_safe(pending, next, head, list) {1920		list_del(&pending->list);1921		ret = create_pending_snapshot(trans, pending);1922		if (ret)1923			break;1924	}1925	return ret;1926}1927 1928static void update_super_roots(struct btrfs_fs_info *fs_info)1929{1930	struct btrfs_root_item *root_item;1931	struct btrfs_super_block *super;1932 1933	super = fs_info->super_copy;1934 1935	root_item = &fs_info->chunk_root->root_item;1936	super->chunk_root = root_item->bytenr;1937	super->chunk_root_generation = root_item->generation;1938	super->chunk_root_level = root_item->level;1939 1940	root_item = &fs_info->tree_root->root_item;1941	super->root = root_item->bytenr;1942	super->generation = root_item->generation;1943	super->root_level = root_item->level;1944	if (btrfs_test_opt(fs_info, SPACE_CACHE))1945		super->cache_generation = root_item->generation;1946	else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags))1947		super->cache_generation = 0;1948	if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))1949		super->uuid_tree_generation = root_item->generation;1950}1951 1952int btrfs_transaction_blocked(struct btrfs_fs_info *info)1953{1954	struct btrfs_transaction *trans;1955	int ret = 0;1956 1957	spin_lock(&info->trans_lock);1958	trans = info->running_transaction;1959	if (trans)1960		ret = is_transaction_blocked(trans);1961	spin_unlock(&info->trans_lock);1962	return ret;1963}1964 1965void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)1966{1967	struct btrfs_fs_info *fs_info = trans->fs_info;1968	struct btrfs_transaction *cur_trans;1969 1970	/* Kick the transaction kthread. */1971	set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);1972	wake_up_process(fs_info->transaction_kthread);1973 1974	/* take transaction reference */1975	cur_trans = trans->transaction;1976	refcount_inc(&cur_trans->use_count);1977 1978	btrfs_end_transaction(trans);1979 1980	/*1981	 * Wait for the current transaction commit to start and block1982	 * subsequent transaction joins1983	 */1984	btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);1985	wait_event(fs_info->transaction_blocked_wait,1986		   cur_trans->state >= TRANS_STATE_COMMIT_START ||1987		   TRANS_ABORTED(cur_trans));1988	btrfs_put_transaction(cur_trans);1989}1990 1991/*1992 * If there is a running transaction commit it or if it's already committing,1993 * wait for its commit to complete. Does not start and commit a new transaction1994 * if there isn't any running.1995 */1996int btrfs_commit_current_transaction(struct btrfs_root *root)1997{1998	struct btrfs_trans_handle *trans;1999 2000	trans = btrfs_attach_transaction_barrier(root);2001	if (IS_ERR(trans)) {2002		int ret = PTR_ERR(trans);2003 2004		return (ret == -ENOENT) ? 0 : ret;2005	}2006 2007	return btrfs_commit_transaction(trans);2008}2009 2010static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)2011{2012	struct btrfs_fs_info *fs_info = trans->fs_info;2013	struct btrfs_transaction *cur_trans = trans->transaction;2014 2015	WARN_ON(refcount_read(&trans->use_count) > 1);2016 2017	btrfs_abort_transaction(trans, err);2018 2019	spin_lock(&fs_info->trans_lock);2020 2021	/*2022	 * If the transaction is removed from the list, it means this2023	 * transaction has been committed successfully, so it is impossible2024	 * to call the cleanup function.2025	 */2026	BUG_ON(list_empty(&cur_trans->list));2027 2028	if (cur_trans == fs_info->running_transaction) {2029		cur_trans->state = TRANS_STATE_COMMIT_DOING;2030		spin_unlock(&fs_info->trans_lock);2031 2032		/*2033		 * The thread has already released the lockdep map as reader2034		 * already in btrfs_commit_transaction().2035		 */2036		btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);2037		wait_event(cur_trans->writer_wait,2038			   atomic_read(&cur_trans->num_writers) == 1);2039 2040		spin_lock(&fs_info->trans_lock);2041	}2042 2043	/*2044	 * Now that we know no one else is still using the transaction we can2045	 * remove the transaction from the list of transactions. This avoids2046	 * the transaction kthread from cleaning up the transaction while some2047	 * other task is still using it, which could result in a use-after-free2048	 * on things like log trees, as it forces the transaction kthread to2049	 * wait for this transaction to be cleaned up by us.2050	 */2051	list_del_init(&cur_trans->list);2052 2053	spin_unlock(&fs_info->trans_lock);2054 2055	btrfs_cleanup_one_transaction(trans->transaction, fs_info);2056 2057	spin_lock(&fs_info->trans_lock);2058	if (cur_trans == fs_info->running_transaction)2059		fs_info->running_transaction = NULL;2060	spin_unlock(&fs_info->trans_lock);2061 2062	if (trans->type & __TRANS_FREEZABLE)2063		sb_end_intwrite(fs_info->sb);2064	btrfs_put_transaction(cur_trans);2065	btrfs_put_transaction(cur_trans);2066 2067	trace_btrfs_transaction_commit(fs_info);2068 2069	if (current->journal_info == trans)2070		current->journal_info = NULL;2071 2072	/*2073	 * If relocation is running, we can't cancel scrub because that will2074	 * result in a deadlock. Before relocating a block group, relocation2075	 * pauses scrub, then starts and commits a transaction before unpausing2076	 * scrub. If the transaction commit is being done by the relocation2077	 * task or triggered by another task and the relocation task is waiting2078	 * for the commit, and we end up here due to an error in the commit2079	 * path, then calling btrfs_scrub_cancel() will deadlock, as we are2080	 * asking for scrub to stop while having it asked to be paused higher2081	 * above in relocation code.2082	 */2083	if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))2084		btrfs_scrub_cancel(fs_info);2085 2086	kmem_cache_free(btrfs_trans_handle_cachep, trans);2087}2088 2089/*2090 * Release reserved delayed ref space of all pending block groups of the2091 * transaction and remove them from the list2092 */2093static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)2094{2095       struct btrfs_fs_info *fs_info = trans->fs_info;2096       struct btrfs_block_group *block_group, *tmp;2097 2098       list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {2099               btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info);2100               list_del_init(&block_group->bg_list);2101       }2102}2103 2104static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)2105{2106	/*2107	 * We use try_to_writeback_inodes_sb() here because if we used2108	 * btrfs_start_delalloc_roots we would deadlock with fs freeze.2109	 * Currently are holding the fs freeze lock, if we do an async flush2110	 * we'll do btrfs_join_transaction() and deadlock because we need to2111	 * wait for the fs freeze lock.  Using the direct flushing we benefit2112	 * from already being in a transaction and our join_transaction doesn't2113	 * have to re-take the fs freeze lock.2114	 *2115	 * Note that try_to_writeback_inodes_sb() will only trigger writeback2116	 * if it can read lock sb->s_umount. It will always be able to lock it,2117	 * except when the filesystem is being unmounted or being frozen, but in2118	 * those cases sync_filesystem() is called, which results in calling2119	 * writeback_inodes_sb() while holding a write lock on sb->s_umount.2120	 * Note that we don't call writeback_inodes_sb() directly, because it2121	 * will emit a warning if sb->s_umount is not locked.2122	 */2123	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))2124		try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);2125	return 0;2126}2127 2128static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)2129{2130	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))2131		btrfs_wait_ordered_roots(fs_info, U64_MAX, NULL);2132}2133 2134/*2135 * Add a pending snapshot associated with the given transaction handle to the2136 * respective handle. This must be called after the transaction commit started2137 * and while holding fs_info->trans_lock.2138 * This serves to guarantee a caller of btrfs_commit_transaction() that it can2139 * safely free the pending snapshot pointer in case btrfs_commit_transaction()2140 * returns an error.2141 */2142static void add_pending_snapshot(struct btrfs_trans_handle *trans)2143{2144	struct btrfs_transaction *cur_trans = trans->transaction;2145 2146	if (!trans->pending_snapshot)2147		return;2148 2149	lockdep_assert_held(&trans->fs_info->trans_lock);2150	ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_PREP);2151 2152	list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);2153}2154 2155static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval)2156{2157	fs_info->commit_stats.commit_count++;2158	fs_info->commit_stats.last_commit_dur = interval;2159	fs_info->commit_stats.max_commit_dur =2160			max_t(u64, fs_info->commit_stats.max_commit_dur, interval);2161	fs_info->commit_stats.total_commit_dur += interval;2162}2163 2164int btrfs_commit_transaction(struct btrfs_trans_handle *trans)2165{2166	struct btrfs_fs_info *fs_info = trans->fs_info;2167	struct btrfs_transaction *cur_trans = trans->transaction;2168	struct btrfs_transaction *prev_trans = NULL;2169	int ret;2170	ktime_t start_time;2171	ktime_t interval;2172 2173	ASSERT(refcount_read(&trans->use_count) == 1);2174	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);2175 2176	clear_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);2177 2178	/* Stop the commit early if ->aborted is set */2179	if (TRANS_ABORTED(cur_trans)) {2180		ret = cur_trans->aborted;2181		goto lockdep_trans_commit_start_release;2182	}2183 2184	btrfs_trans_release_metadata(trans);2185	trans->block_rsv = NULL;2186 2187	/*2188	 * We only want one transaction commit doing the flushing so we do not2189	 * waste a bunch of time on lock contention on the extent root node.2190	 */2191	if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING,2192			      &cur_trans->delayed_refs.flags)) {2193		/*2194		 * Make a pass through all the delayed refs we have so far.2195		 * Any running threads may add more while we are here.2196		 */2197		ret = btrfs_run_delayed_refs(trans, 0);2198		if (ret)2199			goto lockdep_trans_commit_start_release;2200	}2201 2202	btrfs_create_pending_block_groups(trans);2203 2204	if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {2205		int run_it = 0;2206 2207		/* this mutex is also taken before trying to set2208		 * block groups readonly.  We need to make sure2209		 * that nobody has set a block group readonly2210		 * after a extents from that block group have been2211		 * allocated for cache files.  btrfs_set_block_group_ro2212		 * will wait for the transaction to commit if it2213		 * finds BTRFS_TRANS_DIRTY_BG_RUN set.2214		 *2215		 * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure2216		 * only one process starts all the block group IO.  It wouldn't2217		 * hurt to have more than one go through, but there's no2218		 * real advantage to it either.2219		 */2220		mutex_lock(&fs_info->ro_block_group_mutex);2221		if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,2222				      &cur_trans->flags))2223			run_it = 1;2224		mutex_unlock(&fs_info->ro_block_group_mutex);2225 2226		if (run_it) {2227			ret = btrfs_start_dirty_block_groups(trans);2228			if (ret)2229				goto lockdep_trans_commit_start_release;2230		}2231	}2232 2233	spin_lock(&fs_info->trans_lock);2234	if (cur_trans->state >= TRANS_STATE_COMMIT_PREP) {2235		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;2236 2237		add_pending_snapshot(trans);2238 2239		spin_unlock(&fs_info->trans_lock);2240		refcount_inc(&cur_trans->use_count);2241 2242		if (trans->in_fsync)2243			want_state = TRANS_STATE_SUPER_COMMITTED;2244 2245		btrfs_trans_state_lockdep_release(fs_info,2246						  BTRFS_LOCKDEP_TRANS_COMMIT_PREP);2247		ret = btrfs_end_transaction(trans);2248		wait_for_commit(cur_trans, want_state);2249 2250		if (TRANS_ABORTED(cur_trans))2251			ret = cur_trans->aborted;2252 2253		btrfs_put_transaction(cur_trans);2254 2255		return ret;2256	}2257 2258	cur_trans->state = TRANS_STATE_COMMIT_PREP;2259	wake_up(&fs_info->transaction_blocked_wait);2260	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);2261 2262	if (cur_trans->list.prev != &fs_info->trans_list) {2263		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;2264 2265		if (trans->in_fsync)2266			want_state = TRANS_STATE_SUPER_COMMITTED;2267 2268		prev_trans = list_entry(cur_trans->list.prev,2269					struct btrfs_transaction, list);2270		if (prev_trans->state < want_state) {2271			refcount_inc(&prev_trans->use_count);2272			spin_unlock(&fs_info->trans_lock);2273 2274			wait_for_commit(prev_trans, want_state);2275 2276			ret = READ_ONCE(prev_trans->aborted);2277 2278			btrfs_put_transaction(prev_trans);2279			if (ret)2280				goto lockdep_release;2281			spin_lock(&fs_info->trans_lock);2282		}2283	} else {2284		/*2285		 * The previous transaction was aborted and was already removed2286		 * from the list of transactions at fs_info->trans_list. So we2287		 * abort to prevent writing a new superblock that reflects a2288		 * corrupt state (pointing to trees with unwritten nodes/leafs).2289		 */2290		if (BTRFS_FS_ERROR(fs_info)) {2291			spin_unlock(&fs_info->trans_lock);2292			ret = -EROFS;2293			goto lockdep_release;2294		}2295	}2296 2297	cur_trans->state = TRANS_STATE_COMMIT_START;2298	wake_up(&fs_info->transaction_blocked_wait);2299	spin_unlock(&fs_info->trans_lock);2300 2301	/*2302	 * Get the time spent on the work done by the commit thread and not2303	 * the time spent waiting on a previous commit2304	 */2305	start_time = ktime_get_ns();2306 2307	extwriter_counter_dec(cur_trans, trans->type);2308 2309	ret = btrfs_start_delalloc_flush(fs_info);2310	if (ret)2311		goto lockdep_release;2312 2313	ret = btrfs_run_delayed_items(trans);2314	if (ret)2315		goto lockdep_release;2316 2317	/*2318	 * The thread has started/joined the transaction thus it holds the2319	 * lockdep map as a reader. It has to release it before acquiring the2320	 * lockdep map as a writer.2321	 */2322	btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);2323	btrfs_might_wait_for_event(fs_info, btrfs_trans_num_extwriters);2324	wait_event(cur_trans->writer_wait,2325		   extwriter_counter_read(cur_trans) == 0);2326 2327	/* some pending stuffs might be added after the previous flush. */2328	ret = btrfs_run_delayed_items(trans);2329	if (ret) {2330		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);2331		goto cleanup_transaction;2332	}2333 2334	btrfs_wait_delalloc_flush(fs_info);2335 2336	/*2337	 * Wait for all ordered extents started by a fast fsync that joined this2338	 * transaction. Otherwise if this transaction commits before the ordered2339	 * extents complete we lose logged data after a power failure.2340	 */2341	btrfs_might_wait_for_event(fs_info, btrfs_trans_pending_ordered);2342	wait_event(cur_trans->pending_wait,2343		   atomic_read(&cur_trans->pending_ordered) == 0);2344 2345	btrfs_scrub_pause(fs_info);2346	/*2347	 * Ok now we need to make sure to block out any other joins while we2348	 * commit the transaction.  We could have started a join before setting2349	 * COMMIT_DOING so make sure to wait for num_writers to == 1 again.2350	 */2351	spin_lock(&fs_info->trans_lock);2352	add_pending_snapshot(trans);2353	cur_trans->state = TRANS_STATE_COMMIT_DOING;2354	spin_unlock(&fs_info->trans_lock);2355 2356	/*2357	 * The thread has started/joined the transaction thus it holds the2358	 * lockdep map as a reader. It has to release it before acquiring the2359	 * lockdep map as a writer.2360	 */2361	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);2362	btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);2363	wait_event(cur_trans->writer_wait,2364		   atomic_read(&cur_trans->num_writers) == 1);2365 2366	/*2367	 * Make lockdep happy by acquiring the state locks after2368	 * btrfs_trans_num_writers is released. If we acquired the state locks2369	 * before releasing the btrfs_trans_num_writers lock then lockdep would2370	 * complain because we did not follow the reverse order unlocking rule.2371	 */2372	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);2373	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);2374	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);2375 2376	/*2377	 * We've started the commit, clear the flag in case we were triggered to2378	 * do an async commit but somebody else started before the transaction2379	 * kthread could do the work.2380	 */2381	clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);2382 2383	if (TRANS_ABORTED(cur_trans)) {2384		ret = cur_trans->aborted;2385		btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);2386		goto scrub_continue;2387	}2388	/*2389	 * the reloc mutex makes sure that we stop2390	 * the balancing code from coming in and moving2391	 * extents around in the middle of the commit2392	 */2393	mutex_lock(&fs_info->reloc_mutex);2394 2395	/*2396	 * We needn't worry about the delayed items because we will2397	 * deal with them in create_pending_snapshot(), which is the2398	 * core function of the snapshot creation.2399	 */2400	ret = create_pending_snapshots(trans);2401	if (ret)2402		goto unlock_reloc;2403 2404	/*2405	 * We insert the dir indexes of the snapshots and update the inode2406	 * of the snapshots' parents after the snapshot creation, so there2407	 * are some delayed items which are not dealt with. Now deal with2408	 * them.2409	 *2410	 * We needn't worry that this operation will corrupt the snapshots,2411	 * because all the tree which are snapshoted will be forced to COW2412	 * the nodes and leaves.2413	 */2414	ret = btrfs_run_delayed_items(trans);2415	if (ret)2416		goto unlock_reloc;2417 2418	ret = btrfs_run_delayed_refs(trans, U64_MAX);2419	if (ret)2420		goto unlock_reloc;2421 2422	/*2423	 * make sure none of the code above managed to slip in a2424	 * delayed item2425	 */2426	btrfs_assert_delayed_root_empty(fs_info);2427 2428	WARN_ON(cur_trans != trans->transaction);2429 2430	ret = commit_fs_roots(trans);2431	if (ret)2432		goto unlock_reloc;2433 2434	/* commit_fs_roots gets rid of all the tree log roots, it is now2435	 * safe to free the root of tree log roots2436	 */2437	btrfs_free_log_root_tree(trans, fs_info);2438 2439	/*2440	 * Since fs roots are all committed, we can get a quite accurate2441	 * new_roots. So let's do quota accounting.2442	 */2443	ret = btrfs_qgroup_account_extents(trans);2444	if (ret < 0)2445		goto unlock_reloc;2446 2447	ret = commit_cowonly_roots(trans);2448	if (ret)2449		goto unlock_reloc;2450 2451	/*2452	 * The tasks which save the space cache and inode cache may also2453	 * update ->aborted, check it.2454	 */2455	if (TRANS_ABORTED(cur_trans)) {2456		ret = cur_trans->aborted;2457		goto unlock_reloc;2458	}2459 2460	cur_trans = fs_info->running_transaction;2461 2462	btrfs_set_root_node(&fs_info->tree_root->root_item,2463			    fs_info->tree_root->node);2464	list_add_tail(&fs_info->tree_root->dirty_list,2465		      &cur_trans->switch_commits);2466 2467	btrfs_set_root_node(&fs_info->chunk_root->root_item,2468			    fs_info->chunk_root->node);2469	list_add_tail(&fs_info->chunk_root->dirty_list,2470		      &cur_trans->switch_commits);2471 2472	if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {2473		btrfs_set_root_node(&fs_info->block_group_root->root_item,2474				    fs_info->block_group_root->node);2475		list_add_tail(&fs_info->block_group_root->dirty_list,2476			      &cur_trans->switch_commits);2477	}2478 2479	switch_commit_roots(trans);2480 2481	ASSERT(list_empty(&cur_trans->dirty_bgs));2482	ASSERT(list_empty(&cur_trans->io_bgs));2483	update_super_roots(fs_info);2484 2485	btrfs_set_super_log_root(fs_info->super_copy, 0);2486	btrfs_set_super_log_root_level(fs_info->super_copy, 0);2487	memcpy(fs_info->super_for_commit, fs_info->super_copy,2488	       sizeof(*fs_info->super_copy));2489 2490	btrfs_commit_device_sizes(cur_trans);2491 2492	clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);2493	clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);2494 2495	btrfs_trans_release_chunk_metadata(trans);2496 2497	/*2498	 * Before changing the transaction state to TRANS_STATE_UNBLOCKED and2499	 * setting fs_info->running_transaction to NULL, lock tree_log_mutex to2500	 * make sure that before we commit our superblock, no other task can2501	 * start a new transaction and commit a log tree before we commit our2502	 * superblock. Anyone trying to commit a log tree locks this mutex before2503	 * writing its superblock.2504	 */2505	mutex_lock(&fs_info->tree_log_mutex);2506 2507	spin_lock(&fs_info->trans_lock);2508	cur_trans->state = TRANS_STATE_UNBLOCKED;2509	fs_info->running_transaction = NULL;2510	spin_unlock(&fs_info->trans_lock);2511	mutex_unlock(&fs_info->reloc_mutex);2512 2513	wake_up(&fs_info->transaction_wait);2514	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);2515 2516	/* If we have features changed, wake up the cleaner to update sysfs. */2517	if (test_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags) &&2518	    fs_info->cleaner_kthread)2519		wake_up_process(fs_info->cleaner_kthread);2520 2521	ret = btrfs_write_and_wait_transaction(trans);2522	if (ret) {2523		btrfs_handle_fs_error(fs_info, ret,2524				      "Error while writing out transaction");2525		mutex_unlock(&fs_info->tree_log_mutex);2526		goto scrub_continue;2527	}2528 2529	ret = write_all_supers(fs_info, 0);2530	/*2531	 * the super is written, we can safely allow the tree-loggers2532	 * to go about their business2533	 */2534	mutex_unlock(&fs_info->tree_log_mutex);2535	if (ret)2536		goto scrub_continue;2537 2538	/*2539	 * We needn't acquire the lock here because there is no other task2540	 * which can change it.2541	 */2542	cur_trans->state = TRANS_STATE_SUPER_COMMITTED;2543	wake_up(&cur_trans->commit_wait);2544	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);2545 2546	btrfs_finish_extent_commit(trans);2547 2548	if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))2549		btrfs_clear_space_info_full(fs_info);2550 2551	btrfs_set_last_trans_committed(fs_info, cur_trans->transid);2552	/*2553	 * We needn't acquire the lock here because there is no other task2554	 * which can change it.2555	 */2556	cur_trans->state = TRANS_STATE_COMPLETED;2557	wake_up(&cur_trans->commit_wait);2558	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);2559 2560	spin_lock(&fs_info->trans_lock);2561	list_del_init(&cur_trans->list);2562	spin_unlock(&fs_info->trans_lock);2563 2564	btrfs_put_transaction(cur_trans);2565	btrfs_put_transaction(cur_trans);2566 2567	if (trans->type & __TRANS_FREEZABLE)2568		sb_end_intwrite(fs_info->sb);2569 2570	trace_btrfs_transaction_commit(fs_info);2571 2572	interval = ktime_get_ns() - start_time;2573 2574	btrfs_scrub_continue(fs_info);2575 2576	if (current->journal_info == trans)2577		current->journal_info = NULL;2578 2579	kmem_cache_free(btrfs_trans_handle_cachep, trans);2580 2581	update_commit_stats(fs_info, interval);2582 2583	return ret;2584 2585unlock_reloc:2586	mutex_unlock(&fs_info->reloc_mutex);2587	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);2588scrub_continue:2589	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);2590	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);2591	btrfs_scrub_continue(fs_info);2592cleanup_transaction:2593	btrfs_trans_release_metadata(trans);2594	btrfs_cleanup_pending_block_groups(trans);2595	btrfs_trans_release_chunk_metadata(trans);2596	trans->block_rsv = NULL;2597	btrfs_warn(fs_info, "Skipping commit of aborted transaction.");2598	if (current->journal_info == trans)2599		current->journal_info = NULL;2600	cleanup_transaction(trans, ret);2601 2602	return ret;2603 2604lockdep_release:2605	btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);2606	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);2607	goto cleanup_transaction;2608 2609lockdep_trans_commit_start_release:2610	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);2611	btrfs_end_transaction(trans);2612	return ret;2613}2614 2615/*2616 * return < 0 if error2617 * 0 if there are no more dead_roots at the time of call2618 * 1 there are more to be processed, call me again2619 *2620 * The return value indicates there are certainly more snapshots to delete, but2621 * if there comes a new one during processing, it may return 0. We don't mind,2622 * because btrfs_commit_super will poke cleaner thread and it will process it a2623 * few seconds later.2624 */2625int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info)2626{2627	struct btrfs_root *root;2628	int ret;2629 2630	spin_lock(&fs_info->trans_lock);2631	if (list_empty(&fs_info->dead_roots)) {2632		spin_unlock(&fs_info->trans_lock);2633		return 0;2634	}2635	root = list_first_entry(&fs_info->dead_roots,2636			struct btrfs_root, root_list);2637	list_del_init(&root->root_list);2638	spin_unlock(&fs_info->trans_lock);2639 2640	btrfs_debug(fs_info, "cleaner removing %llu", btrfs_root_id(root));2641 2642	btrfs_kill_all_delayed_nodes(root);2643 2644	if (btrfs_header_backref_rev(root->node) <2645			BTRFS_MIXED_BACKREF_REV)2646		ret = btrfs_drop_snapshot(root, 0, 0);2647	else2648		ret = btrfs_drop_snapshot(root, 1, 0);2649 2650	btrfs_put_root(root);2651	return (ret < 0) ? 0 : 1;2652}2653 2654/*2655 * We only mark the transaction aborted and then set the file system read-only.2656 * This will prevent new transactions from starting or trying to join this2657 * one.2658 *2659 * This means that error recovery at the call site is limited to freeing2660 * any local memory allocations and passing the error code up without2661 * further cleanup. The transaction should complete as it normally would2662 * in the call path but will return -EIO.2663 *2664 * We'll complete the cleanup in btrfs_end_transaction and2665 * btrfs_commit_transaction.2666 */2667void __cold __btrfs_abort_transaction(struct btrfs_trans_handle *trans,2668				      const char *function,2669				      unsigned int line, int error, bool first_hit)2670{2671	struct btrfs_fs_info *fs_info = trans->fs_info;2672 2673	WRITE_ONCE(trans->aborted, error);2674	WRITE_ONCE(trans->transaction->aborted, error);2675	if (first_hit && error == -ENOSPC)2676		btrfs_dump_space_info_for_trans_abort(fs_info);2677	/* Wake up anybody who may be waiting on this transaction */2678	wake_up(&fs_info->transaction_wait);2679	wake_up(&fs_info->transaction_blocked_wait);2680	__btrfs_handle_fs_error(fs_info, function, line, error, NULL);2681}2682 2683int __init btrfs_transaction_init(void)2684{2685	btrfs_trans_handle_cachep = KMEM_CACHE(btrfs_trans_handle, SLAB_TEMPORARY);2686	if (!btrfs_trans_handle_cachep)2687		return -ENOMEM;2688	return 0;2689}2690 2691void __cold btrfs_transaction_exit(void)2692{2693	kmem_cache_destroy(btrfs_trans_handle_cachep);2694}2695