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v6.8
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   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 "zoned.h"
  27#include "fs.h"
  28#include "accessors.h"
  29#include "extent-tree.h"
  30#include "root-tree.h"
  31#include "defrag.h"
  32#include "dir-item.h"
  33#include "uuid-tree.h"
  34#include "ioctl.h"
  35#include "relocation.h"
  36#include "scrub.h"
  37
  38static struct kmem_cache *btrfs_trans_handle_cachep;
  39
  40/*
  41 * Transaction states and transitions
  42 *
  43 * No running transaction (fs tree blocks are not modified)
  44 * |
  45 * | To next stage:
  46 * |  Call start_transaction() variants. Except btrfs_join_transaction_nostart().
  47 * V
  48 * Transaction N [[TRANS_STATE_RUNNING]]
  49 * |
  50 * | New trans handles can be attached to transaction N by calling all
  51 * | start_transaction() variants.
  52 * |
  53 * | To next stage:
  54 * |  Call btrfs_commit_transaction() on any trans handle attached to
  55 * |  transaction N
  56 * V
  57 * Transaction N [[TRANS_STATE_COMMIT_PREP]]
  58 * |
  59 * | If there are simultaneous calls to btrfs_commit_transaction() one will win
  60 * | the race and the rest will wait for the winner to commit the transaction.
  61 * |
  62 * | The winner will wait for previous running transaction to completely finish
  63 * | if there is one.
  64 * |
  65 * Transaction N [[TRANS_STATE_COMMIT_START]]
  66 * |
  67 * | Then one of the following happens:
 
 
 
  68 * | - Wait for all other trans handle holders to release.
  69 * |   The btrfs_commit_transaction() caller will do the commit work.
  70 * | - Wait for current transaction to be committed by others.
  71 * |   Other btrfs_commit_transaction() caller will do the commit work.
  72 * |
  73 * | At this stage, only btrfs_join_transaction*() variants can attach
  74 * | to this running transaction.
  75 * | All other variants will wait for current one to finish and attach to
  76 * | transaction N+1.
  77 * |
  78 * | To next stage:
  79 * |  Caller is chosen to commit transaction N, and all other trans handle
  80 * |  haven been released.
  81 * V
  82 * Transaction N [[TRANS_STATE_COMMIT_DOING]]
  83 * |
  84 * | The heavy lifting transaction work is started.
  85 * | From running delayed refs (modifying extent tree) to creating pending
  86 * | snapshots, running qgroups.
  87 * | In short, modify supporting trees to reflect modifications of subvolume
  88 * | trees.
  89 * |
  90 * | At this stage, all start_transaction() calls will wait for this
  91 * | transaction to finish and attach to transaction N+1.
  92 * |
  93 * | To next stage:
  94 * |  Until all supporting trees are updated.
  95 * V
  96 * Transaction N [[TRANS_STATE_UNBLOCKED]]
  97 * |						    Transaction N+1
  98 * | All needed trees are modified, thus we only    [[TRANS_STATE_RUNNING]]
  99 * | need to write them back to disk and update	    |
 100 * | super blocks.				    |
 101 * |						    |
 102 * | At this stage, new transaction is allowed to   |
 103 * | start.					    |
 104 * | All new start_transaction() calls will be	    |
 105 * | attached to transid N+1.			    |
 106 * |						    |
 107 * | To next stage:				    |
 108 * |  Until all tree blocks are super blocks are    |
 109 * |  written to block devices			    |
 110 * V						    |
 111 * Transaction N [[TRANS_STATE_COMPLETED]]	    V
 112 *   All tree blocks and super blocks are written.  Transaction N+1
 113 *   This transaction is finished and all its	    [[TRANS_STATE_COMMIT_START]]
 114 *   data structures will be cleaned up.	    | Life goes on
 115 */
 116static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
 117	[TRANS_STATE_RUNNING]		= 0U,
 118	[TRANS_STATE_COMMIT_PREP]	= 0U,
 119	[TRANS_STATE_COMMIT_START]	= (__TRANS_START | __TRANS_ATTACH),
 120	[TRANS_STATE_COMMIT_DOING]	= (__TRANS_START |
 121					   __TRANS_ATTACH |
 122					   __TRANS_JOIN |
 123					   __TRANS_JOIN_NOSTART),
 124	[TRANS_STATE_UNBLOCKED]		= (__TRANS_START |
 125					   __TRANS_ATTACH |
 126					   __TRANS_JOIN |
 127					   __TRANS_JOIN_NOLOCK |
 128					   __TRANS_JOIN_NOSTART),
 129	[TRANS_STATE_SUPER_COMMITTED]	= (__TRANS_START |
 130					   __TRANS_ATTACH |
 131					   __TRANS_JOIN |
 132					   __TRANS_JOIN_NOLOCK |
 133					   __TRANS_JOIN_NOSTART),
 134	[TRANS_STATE_COMPLETED]		= (__TRANS_START |
 135					   __TRANS_ATTACH |
 136					   __TRANS_JOIN |
 137					   __TRANS_JOIN_NOLOCK |
 138					   __TRANS_JOIN_NOSTART),
 139};
 140
 141void btrfs_put_transaction(struct btrfs_transaction *transaction)
 142{
 143	WARN_ON(refcount_read(&transaction->use_count) == 0);
 144	if (refcount_dec_and_test(&transaction->use_count)) {
 145		BUG_ON(!list_empty(&transaction->list));
 146		WARN_ON(!RB_EMPTY_ROOT(
 147				&transaction->delayed_refs.href_root.rb_root));
 148		WARN_ON(!RB_EMPTY_ROOT(
 149				&transaction->delayed_refs.dirty_extent_root));
 150		if (transaction->delayed_refs.pending_csums)
 151			btrfs_err(transaction->fs_info,
 152				  "pending csums is %llu",
 153				  transaction->delayed_refs.pending_csums);
 154		/*
 155		 * If any block groups are found in ->deleted_bgs then it's
 156		 * because the transaction was aborted and a commit did not
 157		 * happen (things failed before writing the new superblock
 158		 * and calling btrfs_finish_extent_commit()), so we can not
 159		 * discard the physical locations of the block groups.
 160		 */
 161		while (!list_empty(&transaction->deleted_bgs)) {
 162			struct btrfs_block_group *cache;
 163
 164			cache = list_first_entry(&transaction->deleted_bgs,
 165						 struct btrfs_block_group,
 166						 bg_list);
 167			list_del_init(&cache->bg_list);
 168			btrfs_unfreeze_block_group(cache);
 169			btrfs_put_block_group(cache);
 170		}
 171		WARN_ON(!list_empty(&transaction->dev_update_list));
 172		kfree(transaction);
 173	}
 174}
 175
 176static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
 177{
 178	struct btrfs_transaction *cur_trans = trans->transaction;
 179	struct btrfs_fs_info *fs_info = trans->fs_info;
 180	struct btrfs_root *root, *tmp;
 181
 182	/*
 183	 * At this point no one can be using this transaction to modify any tree
 184	 * and no one can start another transaction to modify any tree either.
 185	 */
 186	ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING);
 187
 188	down_write(&fs_info->commit_root_sem);
 189
 190	if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
 191		fs_info->last_reloc_trans = trans->transid;
 192
 193	list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
 194				 dirty_list) {
 195		list_del_init(&root->dirty_list);
 196		free_extent_buffer(root->commit_root);
 197		root->commit_root = btrfs_root_node(root);
 198		extent_io_tree_release(&root->dirty_log_pages);
 199		btrfs_qgroup_clean_swapped_blocks(root);
 200	}
 201
 202	/* We can free old roots now. */
 203	spin_lock(&cur_trans->dropped_roots_lock);
 204	while (!list_empty(&cur_trans->dropped_roots)) {
 205		root = list_first_entry(&cur_trans->dropped_roots,
 206					struct btrfs_root, root_list);
 207		list_del_init(&root->root_list);
 208		spin_unlock(&cur_trans->dropped_roots_lock);
 209		btrfs_free_log(trans, root);
 210		btrfs_drop_and_free_fs_root(fs_info, root);
 211		spin_lock(&cur_trans->dropped_roots_lock);
 212	}
 213	spin_unlock(&cur_trans->dropped_roots_lock);
 214
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 215	up_write(&fs_info->commit_root_sem);
 216}
 217
 218static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 219					 unsigned int type)
 220{
 221	if (type & TRANS_EXTWRITERS)
 222		atomic_inc(&trans->num_extwriters);
 223}
 224
 225static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 226					 unsigned int type)
 227{
 228	if (type & TRANS_EXTWRITERS)
 229		atomic_dec(&trans->num_extwriters);
 230}
 231
 232static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 233					  unsigned int type)
 234{
 235	atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 236}
 237
 238static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 239{
 240	return atomic_read(&trans->num_extwriters);
 241}
 242
 243/*
 244 * To be called after doing the chunk btree updates right after allocating a new
 245 * chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a
 246 * chunk after all chunk btree updates and after finishing the second phase of
 247 * chunk allocation (btrfs_create_pending_block_groups()) in case some block
 248 * group had its chunk item insertion delayed to the second phase.
 249 */
 250void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
 251{
 252	struct btrfs_fs_info *fs_info = trans->fs_info;
 253
 254	if (!trans->chunk_bytes_reserved)
 255		return;
 256
 257	btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,
 258				trans->chunk_bytes_reserved, NULL);
 259	trans->chunk_bytes_reserved = 0;
 260}
 261
 262/*
 263 * either allocate a new transaction or hop into the existing one
 264 */
 265static noinline int join_transaction(struct btrfs_fs_info *fs_info,
 266				     unsigned int type)
 267{
 268	struct btrfs_transaction *cur_trans;
 269
 270	spin_lock(&fs_info->trans_lock);
 271loop:
 272	/* The file system has been taken offline. No new transactions. */
 273	if (BTRFS_FS_ERROR(fs_info)) {
 274		spin_unlock(&fs_info->trans_lock);
 275		return -EROFS;
 276	}
 277
 278	cur_trans = fs_info->running_transaction;
 279	if (cur_trans) {
 280		if (TRANS_ABORTED(cur_trans)) {
 281			spin_unlock(&fs_info->trans_lock);
 282			return cur_trans->aborted;
 283		}
 284		if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 285			spin_unlock(&fs_info->trans_lock);
 286			return -EBUSY;
 287		}
 288		refcount_inc(&cur_trans->use_count);
 289		atomic_inc(&cur_trans->num_writers);
 290		extwriter_counter_inc(cur_trans, type);
 291		spin_unlock(&fs_info->trans_lock);
 292		btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
 293		btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
 294		return 0;
 295	}
 296	spin_unlock(&fs_info->trans_lock);
 297
 298	/*
 299	 * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the
 300	 * current transaction, and commit it. If there is no transaction, just
 301	 * return ENOENT.
 302	 */
 303	if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)
 304		return -ENOENT;
 305
 306	/*
 307	 * JOIN_NOLOCK only happens during the transaction commit, so
 308	 * it is impossible that ->running_transaction is NULL
 309	 */
 310	BUG_ON(type == TRANS_JOIN_NOLOCK);
 311
 312	cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
 313	if (!cur_trans)
 314		return -ENOMEM;
 315
 316	btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);
 317	btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters);
 318
 319	spin_lock(&fs_info->trans_lock);
 320	if (fs_info->running_transaction) {
 321		/*
 322		 * someone started a transaction after we unlocked.  Make sure
 323		 * to redo the checks above
 324		 */
 325		btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
 326		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
 327		kfree(cur_trans);
 328		goto loop;
 329	} else if (BTRFS_FS_ERROR(fs_info)) {
 330		spin_unlock(&fs_info->trans_lock);
 331		btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
 332		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
 333		kfree(cur_trans);
 334		return -EROFS;
 335	}
 336
 337	cur_trans->fs_info = fs_info;
 338	atomic_set(&cur_trans->pending_ordered, 0);
 339	init_waitqueue_head(&cur_trans->pending_wait);
 340	atomic_set(&cur_trans->num_writers, 1);
 341	extwriter_counter_init(cur_trans, type);
 342	init_waitqueue_head(&cur_trans->writer_wait);
 343	init_waitqueue_head(&cur_trans->commit_wait);
 344	cur_trans->state = TRANS_STATE_RUNNING;
 345	/*
 346	 * One for this trans handle, one so it will live on until we
 347	 * commit the transaction.
 348	 */
 349	refcount_set(&cur_trans->use_count, 2);
 350	cur_trans->flags = 0;
 351	cur_trans->start_time = ktime_get_seconds();
 352
 353	memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
 354
 355	cur_trans->delayed_refs.href_root = RB_ROOT_CACHED;
 356	cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
 357	atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 358
 359	/*
 360	 * although the tree mod log is per file system and not per transaction,
 361	 * the log must never go across transaction boundaries.
 362	 */
 363	smp_mb();
 364	if (!list_empty(&fs_info->tree_mod_seq_list))
 365		WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
 366	if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 367		WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
 368	atomic64_set(&fs_info->tree_mod_seq, 0);
 369
 370	spin_lock_init(&cur_trans->delayed_refs.lock);
 371
 372	INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 373	INIT_LIST_HEAD(&cur_trans->dev_update_list);
 374	INIT_LIST_HEAD(&cur_trans->switch_commits);
 375	INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 376	INIT_LIST_HEAD(&cur_trans->io_bgs);
 377	INIT_LIST_HEAD(&cur_trans->dropped_roots);
 378	mutex_init(&cur_trans->cache_write_mutex);
 379	spin_lock_init(&cur_trans->dirty_bgs_lock);
 380	INIT_LIST_HEAD(&cur_trans->deleted_bgs);
 381	spin_lock_init(&cur_trans->dropped_roots_lock);
 
 
 382	list_add_tail(&cur_trans->list, &fs_info->trans_list);
 383	extent_io_tree_init(fs_info, &cur_trans->dirty_pages,
 384			IO_TREE_TRANS_DIRTY_PAGES);
 385	extent_io_tree_init(fs_info, &cur_trans->pinned_extents,
 386			IO_TREE_FS_PINNED_EXTENTS);
 387	btrfs_set_fs_generation(fs_info, fs_info->generation + 1);
 388	cur_trans->transid = fs_info->generation;
 389	fs_info->running_transaction = cur_trans;
 390	cur_trans->aborted = 0;
 391	spin_unlock(&fs_info->trans_lock);
 392
 393	return 0;
 394}
 395
 396/*
 397 * This does all the record keeping required to make sure that a shareable root
 398 * is properly recorded in a given transaction.  This is required to make sure
 399 * the old root from before we joined the transaction is deleted when the
 400 * transaction commits.
 401 */
 402static int record_root_in_trans(struct btrfs_trans_handle *trans,
 403			       struct btrfs_root *root,
 404			       int force)
 405{
 406	struct btrfs_fs_info *fs_info = root->fs_info;
 407	int ret = 0;
 408
 409	if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 410	    root->last_trans < trans->transid) || force) {
 
 411		WARN_ON(!force && root->commit_root != root->node);
 412
 413		/*
 414		 * see below for IN_TRANS_SETUP usage rules
 415		 * we have the reloc mutex held now, so there
 416		 * is only one writer in this function
 417		 */
 418		set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 419
 420		/* make sure readers find IN_TRANS_SETUP before
 421		 * they find our root->last_trans update
 422		 */
 423		smp_wmb();
 424
 425		spin_lock(&fs_info->fs_roots_radix_lock);
 426		if (root->last_trans == trans->transid && !force) {
 427			spin_unlock(&fs_info->fs_roots_radix_lock);
 428			return 0;
 429		}
 430		radix_tree_tag_set(&fs_info->fs_roots_radix,
 431				   (unsigned long)root->root_key.objectid,
 432				   BTRFS_ROOT_TRANS_TAG);
 433		spin_unlock(&fs_info->fs_roots_radix_lock);
 434		root->last_trans = trans->transid;
 435
 436		/* this is pretty tricky.  We don't want to
 437		 * take the relocation lock in btrfs_record_root_in_trans
 438		 * unless we're really doing the first setup for this root in
 439		 * this transaction.
 440		 *
 441		 * Normally we'd use root->last_trans as a flag to decide
 442		 * if we want to take the expensive mutex.
 443		 *
 444		 * But, we have to set root->last_trans before we
 445		 * init the relocation root, otherwise, we trip over warnings
 446		 * in ctree.c.  The solution used here is to flag ourselves
 447		 * with root IN_TRANS_SETUP.  When this is 1, we're still
 448		 * fixing up the reloc trees and everyone must wait.
 449		 *
 450		 * When this is zero, they can trust root->last_trans and fly
 451		 * through btrfs_record_root_in_trans without having to take the
 452		 * lock.  smp_wmb() makes sure that all the writes above are
 453		 * done before we pop in the zero below
 454		 */
 455		ret = btrfs_init_reloc_root(trans, root);
 456		smp_mb__before_atomic();
 457		clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 458	}
 459	return ret;
 460}
 461
 462
 463void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
 464			    struct btrfs_root *root)
 465{
 466	struct btrfs_fs_info *fs_info = root->fs_info;
 467	struct btrfs_transaction *cur_trans = trans->transaction;
 468
 469	/* Add ourselves to the transaction dropped list */
 470	spin_lock(&cur_trans->dropped_roots_lock);
 471	list_add_tail(&root->root_list, &cur_trans->dropped_roots);
 472	spin_unlock(&cur_trans->dropped_roots_lock);
 473
 474	/* Make sure we don't try to update the root at commit time */
 475	spin_lock(&fs_info->fs_roots_radix_lock);
 476	radix_tree_tag_clear(&fs_info->fs_roots_radix,
 477			     (unsigned long)root->root_key.objectid,
 478			     BTRFS_ROOT_TRANS_TAG);
 479	spin_unlock(&fs_info->fs_roots_radix_lock);
 480}
 481
 482int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 483			       struct btrfs_root *root)
 484{
 485	struct btrfs_fs_info *fs_info = root->fs_info;
 486	int ret;
 487
 488	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 489		return 0;
 490
 491	/*
 492	 * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 493	 * and barriers
 494	 */
 495	smp_rmb();
 496	if (root->last_trans == trans->transid &&
 497	    !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 498		return 0;
 499
 500	mutex_lock(&fs_info->reloc_mutex);
 501	ret = record_root_in_trans(trans, root, 0);
 502	mutex_unlock(&fs_info->reloc_mutex);
 503
 504	return ret;
 505}
 506
 507static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 508{
 509	return (trans->state >= TRANS_STATE_COMMIT_START &&
 510		trans->state < TRANS_STATE_UNBLOCKED &&
 511		!TRANS_ABORTED(trans));
 512}
 513
 514/* wait for commit against the current transaction to become unblocked
 515 * when this is done, it is safe to start a new transaction, but the current
 516 * transaction might not be fully on disk.
 517 */
 518static void wait_current_trans(struct btrfs_fs_info *fs_info)
 519{
 520	struct btrfs_transaction *cur_trans;
 521
 522	spin_lock(&fs_info->trans_lock);
 523	cur_trans = fs_info->running_transaction;
 524	if (cur_trans && is_transaction_blocked(cur_trans)) {
 525		refcount_inc(&cur_trans->use_count);
 526		spin_unlock(&fs_info->trans_lock);
 527
 528		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
 529		wait_event(fs_info->transaction_wait,
 530			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 531			   TRANS_ABORTED(cur_trans));
 532		btrfs_put_transaction(cur_trans);
 533	} else {
 534		spin_unlock(&fs_info->trans_lock);
 535	}
 536}
 537
 538static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
 539{
 540	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
 541		return 0;
 542
 543	if (type == TRANS_START)
 544		return 1;
 545
 546	return 0;
 547}
 548
 549static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 550{
 551	struct btrfs_fs_info *fs_info = root->fs_info;
 552
 553	if (!fs_info->reloc_ctl ||
 554	    !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
 555	    root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 556	    root->reloc_root)
 557		return false;
 558
 559	return true;
 560}
 561
 562static int btrfs_reserve_trans_metadata(struct btrfs_fs_info *fs_info,
 563					enum btrfs_reserve_flush_enum flush,
 564					u64 num_bytes,
 565					u64 *delayed_refs_bytes)
 566{
 567	struct btrfs_space_info *si = fs_info->trans_block_rsv.space_info;
 568	u64 bytes = num_bytes + *delayed_refs_bytes;
 569	int ret;
 570
 571	/*
 572	 * We want to reserve all the bytes we may need all at once, so we only
 573	 * do 1 enospc flushing cycle per transaction start.
 574	 */
 575	ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
 576
 577	/*
 578	 * If we are an emergency flush, which can steal from the global block
 579	 * reserve, then attempt to not reserve space for the delayed refs, as
 580	 * we will consume space for them from the global block reserve.
 581	 */
 582	if (ret && flush == BTRFS_RESERVE_FLUSH_ALL_STEAL) {
 583		bytes -= *delayed_refs_bytes;
 584		*delayed_refs_bytes = 0;
 585		ret = btrfs_reserve_metadata_bytes(fs_info, si, bytes, flush);
 586	}
 587
 588	return ret;
 589}
 590
 591static struct btrfs_trans_handle *
 592start_transaction(struct btrfs_root *root, unsigned int num_items,
 593		  unsigned int type, enum btrfs_reserve_flush_enum flush,
 594		  bool enforce_qgroups)
 595{
 596	struct btrfs_fs_info *fs_info = root->fs_info;
 597	struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
 598	struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
 599	struct btrfs_trans_handle *h;
 600	struct btrfs_transaction *cur_trans;
 601	u64 num_bytes = 0;
 602	u64 qgroup_reserved = 0;
 603	u64 delayed_refs_bytes = 0;
 604	bool reloc_reserved = false;
 605	bool do_chunk_alloc = false;
 606	int ret;
 607
 608	if (BTRFS_FS_ERROR(fs_info))
 609		return ERR_PTR(-EROFS);
 610
 611	if (current->journal_info) {
 612		WARN_ON(type & TRANS_EXTWRITERS);
 613		h = current->journal_info;
 614		refcount_inc(&h->use_count);
 615		WARN_ON(refcount_read(&h->use_count) > 2);
 616		h->orig_rsv = h->block_rsv;
 617		h->block_rsv = NULL;
 618		goto got_it;
 619	}
 620
 621	/*
 622	 * Do the reservation before we join the transaction so we can do all
 623	 * the appropriate flushing if need be.
 624	 */
 625	if (num_items && root != fs_info->chunk_root) {
 
 
 
 626		qgroup_reserved = num_items * fs_info->nodesize;
 627		/*
 628		 * Use prealloc for now, as there might be a currently running
 629		 * transaction that could free this reserved space prematurely
 630		 * by committing.
 631		 */
 632		ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserved,
 633							 enforce_qgroups, false);
 634		if (ret)
 635			return ERR_PTR(ret);
 636
 637		num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);
 638		/*
 639		 * If we plan to insert/update/delete "num_items" from a btree,
 640		 * we will also generate delayed refs for extent buffers in the
 641		 * respective btree paths, so reserve space for the delayed refs
 642		 * that will be generated by the caller as it modifies btrees.
 643		 * Try to reserve them to avoid excessive use of the global
 644		 * block reserve.
 645		 */
 646		delayed_refs_bytes = btrfs_calc_delayed_ref_bytes(fs_info, num_items);
 
 
 
 
 
 647
 648		/*
 649		 * Do the reservation for the relocation root creation
 650		 */
 651		if (need_reserve_reloc_root(root)) {
 652			num_bytes += fs_info->nodesize;
 653			reloc_reserved = true;
 654		}
 655
 656		ret = btrfs_reserve_trans_metadata(fs_info, flush, num_bytes,
 657						   &delayed_refs_bytes);
 658		if (ret)
 659			goto reserve_fail;
 
 
 
 
 
 660
 661		btrfs_block_rsv_add_bytes(trans_rsv, num_bytes, true);
 662
 663		if (trans_rsv->space_info->force_alloc)
 664			do_chunk_alloc = true;
 665	} else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&
 666		   !btrfs_block_rsv_full(delayed_refs_rsv)) {
 667		/*
 668		 * Some people call with btrfs_start_transaction(root, 0)
 669		 * because they can be throttled, but have some other mechanism
 670		 * for reserving space.  We still want these guys to refill the
 671		 * delayed block_rsv so just add 1 items worth of reservation
 672		 * here.
 673		 */
 674		ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);
 675		if (ret)
 676			goto reserve_fail;
 677	}
 678again:
 679	h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
 680	if (!h) {
 681		ret = -ENOMEM;
 682		goto alloc_fail;
 683	}
 684
 685	/*
 686	 * If we are JOIN_NOLOCK we're already committing a transaction and
 687	 * waiting on this guy, so we don't need to do the sb_start_intwrite
 688	 * because we're already holding a ref.  We need this because we could
 689	 * have raced in and did an fsync() on a file which can kick a commit
 690	 * and then we deadlock with somebody doing a freeze.
 691	 *
 692	 * If we are ATTACH, it means we just want to catch the current
 693	 * transaction and commit it, so we needn't do sb_start_intwrite(). 
 694	 */
 695	if (type & __TRANS_FREEZABLE)
 696		sb_start_intwrite(fs_info->sb);
 697
 698	if (may_wait_transaction(fs_info, type))
 699		wait_current_trans(fs_info);
 700
 701	do {
 702		ret = join_transaction(fs_info, type);
 703		if (ret == -EBUSY) {
 704			wait_current_trans(fs_info);
 705			if (unlikely(type == TRANS_ATTACH ||
 706				     type == TRANS_JOIN_NOSTART))
 707				ret = -ENOENT;
 708		}
 709	} while (ret == -EBUSY);
 710
 711	if (ret < 0)
 712		goto join_fail;
 713
 714	cur_trans = fs_info->running_transaction;
 715
 716	h->transid = cur_trans->transid;
 717	h->transaction = cur_trans;
 
 718	refcount_set(&h->use_count, 1);
 719	h->fs_info = root->fs_info;
 720
 721	h->type = type;
 722	INIT_LIST_HEAD(&h->new_bgs);
 723	btrfs_init_metadata_block_rsv(fs_info, &h->delayed_rsv, BTRFS_BLOCK_RSV_DELOPS);
 724
 725	smp_mb();
 726	if (cur_trans->state >= TRANS_STATE_COMMIT_START &&
 727	    may_wait_transaction(fs_info, type)) {
 728		current->journal_info = h;
 729		btrfs_commit_transaction(h);
 730		goto again;
 731	}
 732
 733	if (num_bytes) {
 734		trace_btrfs_space_reservation(fs_info, "transaction",
 735					      h->transid, num_bytes, 1);
 736		h->block_rsv = trans_rsv;
 737		h->bytes_reserved = num_bytes;
 738		if (delayed_refs_bytes > 0) {
 739			trace_btrfs_space_reservation(fs_info,
 740						      "local_delayed_refs_rsv",
 741						      h->transid,
 742						      delayed_refs_bytes, 1);
 743			h->delayed_refs_bytes_reserved = delayed_refs_bytes;
 744			btrfs_block_rsv_add_bytes(&h->delayed_rsv, delayed_refs_bytes, true);
 745			delayed_refs_bytes = 0;
 746		}
 747		h->reloc_reserved = reloc_reserved;
 748	}
 749
 750	/*
 751	 * Now that we have found a transaction to be a part of, convert the
 752	 * qgroup reservation from prealloc to pertrans. A different transaction
 753	 * can't race in and free our pertrans out from under us.
 754	 */
 755	if (qgroup_reserved)
 756		btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved);
 757
 758got_it:
 759	if (!current->journal_info)
 760		current->journal_info = h;
 761
 762	/*
 763	 * If the space_info is marked ALLOC_FORCE then we'll get upgraded to
 764	 * ALLOC_FORCE the first run through, and then we won't allocate for
 765	 * anybody else who races in later.  We don't care about the return
 766	 * value here.
 767	 */
 768	if (do_chunk_alloc && num_bytes) {
 769		u64 flags = h->block_rsv->space_info->flags;
 770
 771		btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),
 772				  CHUNK_ALLOC_NO_FORCE);
 773	}
 774
 775	/*
 776	 * btrfs_record_root_in_trans() needs to alloc new extents, and may
 777	 * call btrfs_join_transaction() while we're also starting a
 778	 * transaction.
 779	 *
 780	 * Thus it need to be called after current->journal_info initialized,
 781	 * or we can deadlock.
 782	 */
 783	ret = btrfs_record_root_in_trans(h, root);
 784	if (ret) {
 785		/*
 786		 * The transaction handle is fully initialized and linked with
 787		 * other structures so it needs to be ended in case of errors,
 788		 * not just freed.
 789		 */
 790		btrfs_end_transaction(h);
 791		return ERR_PTR(ret);
 792	}
 793
 794	return h;
 795
 796join_fail:
 797	if (type & __TRANS_FREEZABLE)
 798		sb_end_intwrite(fs_info->sb);
 799	kmem_cache_free(btrfs_trans_handle_cachep, h);
 800alloc_fail:
 801	if (num_bytes)
 802		btrfs_block_rsv_release(fs_info, trans_rsv, num_bytes, NULL);
 803	if (delayed_refs_bytes)
 804		btrfs_space_info_free_bytes_may_use(fs_info, trans_rsv->space_info,
 805						    delayed_refs_bytes);
 806reserve_fail:
 807	btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved);
 808	return ERR_PTR(ret);
 809}
 810
 811struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 812						   unsigned int num_items)
 813{
 814	return start_transaction(root, num_items, TRANS_START,
 815				 BTRFS_RESERVE_FLUSH_ALL, true);
 816}
 817
 818struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 819					struct btrfs_root *root,
 820					unsigned int num_items)
 821{
 822	return start_transaction(root, num_items, TRANS_START,
 823				 BTRFS_RESERVE_FLUSH_ALL_STEAL, false);
 824}
 825
 826struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 827{
 828	return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
 829				 true);
 830}
 831
 832struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)
 833{
 834	return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
 835				 BTRFS_RESERVE_NO_FLUSH, true);
 836}
 837
 838/*
 839 * Similar to regular join but it never starts a transaction when none is
 840 * running or when there's a running one at a state >= TRANS_STATE_UNBLOCKED.
 841 * This is similar to btrfs_attach_transaction() but it allows the join to
 842 * happen if the transaction commit already started but it's not yet in the
 843 * "doing" phase (the state is < TRANS_STATE_COMMIT_DOING).
 844 */
 845struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)
 846{
 847	return start_transaction(root, 0, TRANS_JOIN_NOSTART,
 848				 BTRFS_RESERVE_NO_FLUSH, true);
 849}
 850
 851/*
 852 * Catch the running transaction.
 853 *
 854 * It is used when we want to commit the current the transaction, but
 855 * don't want to start a new one.
 856 *
 857 * Note: If this function return -ENOENT, it just means there is no
 858 * running transaction. But it is possible that the inactive transaction
 859 * is still in the memory, not fully on disk. If you hope there is no
 860 * inactive transaction in the fs when -ENOENT is returned, you should
 861 * invoke
 862 *     btrfs_attach_transaction_barrier()
 863 */
 864struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 865{
 866	return start_transaction(root, 0, TRANS_ATTACH,
 867				 BTRFS_RESERVE_NO_FLUSH, true);
 868}
 869
 870/*
 871 * Catch the running transaction.
 872 *
 873 * It is similar to the above function, the difference is this one
 874 * will wait for all the inactive transactions until they fully
 875 * complete.
 876 */
 877struct btrfs_trans_handle *
 878btrfs_attach_transaction_barrier(struct btrfs_root *root)
 879{
 880	struct btrfs_trans_handle *trans;
 881
 882	trans = start_transaction(root, 0, TRANS_ATTACH,
 883				  BTRFS_RESERVE_NO_FLUSH, true);
 884	if (trans == ERR_PTR(-ENOENT)) {
 885		int ret;
 886
 887		ret = btrfs_wait_for_commit(root->fs_info, 0);
 888		if (ret)
 889			return ERR_PTR(ret);
 890	}
 891
 892	return trans;
 893}
 894
 895/* Wait for a transaction commit to reach at least the given state. */
 896static noinline void wait_for_commit(struct btrfs_transaction *commit,
 897				     const enum btrfs_trans_state min_state)
 898{
 899	struct btrfs_fs_info *fs_info = commit->fs_info;
 900	u64 transid = commit->transid;
 901	bool put = false;
 902
 903	/*
 904	 * At the moment this function is called with min_state either being
 905	 * TRANS_STATE_COMPLETED or TRANS_STATE_SUPER_COMMITTED.
 906	 */
 907	if (min_state == TRANS_STATE_COMPLETED)
 908		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
 909	else
 910		btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
 911
 912	while (1) {
 913		wait_event(commit->commit_wait, commit->state >= min_state);
 914		if (put)
 915			btrfs_put_transaction(commit);
 916
 917		if (min_state < TRANS_STATE_COMPLETED)
 918			break;
 919
 920		/*
 921		 * A transaction isn't really completed until all of the
 922		 * previous transactions are completed, but with fsync we can
 923		 * end up with SUPER_COMMITTED transactions before a COMPLETED
 924		 * transaction. Wait for those.
 925		 */
 926
 927		spin_lock(&fs_info->trans_lock);
 928		commit = list_first_entry_or_null(&fs_info->trans_list,
 929						  struct btrfs_transaction,
 930						  list);
 931		if (!commit || commit->transid > transid) {
 932			spin_unlock(&fs_info->trans_lock);
 933			break;
 934		}
 935		refcount_inc(&commit->use_count);
 936		put = true;
 937		spin_unlock(&fs_info->trans_lock);
 938	}
 939}
 940
 941int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
 942{
 943	struct btrfs_transaction *cur_trans = NULL, *t;
 944	int ret = 0;
 945
 946	if (transid) {
 947		if (transid <= btrfs_get_last_trans_committed(fs_info))
 948			goto out;
 949
 950		/* find specified transaction */
 951		spin_lock(&fs_info->trans_lock);
 952		list_for_each_entry(t, &fs_info->trans_list, list) {
 953			if (t->transid == transid) {
 954				cur_trans = t;
 955				refcount_inc(&cur_trans->use_count);
 956				ret = 0;
 957				break;
 958			}
 959			if (t->transid > transid) {
 960				ret = 0;
 961				break;
 962			}
 963		}
 964		spin_unlock(&fs_info->trans_lock);
 965
 966		/*
 967		 * The specified transaction doesn't exist, or we
 968		 * raced with btrfs_commit_transaction
 969		 */
 970		if (!cur_trans) {
 971			if (transid > btrfs_get_last_trans_committed(fs_info))
 972				ret = -EINVAL;
 973			goto out;
 974		}
 975	} else {
 976		/* find newest transaction that is committing | committed */
 977		spin_lock(&fs_info->trans_lock);
 978		list_for_each_entry_reverse(t, &fs_info->trans_list,
 979					    list) {
 980			if (t->state >= TRANS_STATE_COMMIT_START) {
 981				if (t->state == TRANS_STATE_COMPLETED)
 982					break;
 983				cur_trans = t;
 984				refcount_inc(&cur_trans->use_count);
 985				break;
 986			}
 987		}
 988		spin_unlock(&fs_info->trans_lock);
 989		if (!cur_trans)
 990			goto out;  /* nothing committing|committed */
 991	}
 992
 993	wait_for_commit(cur_trans, TRANS_STATE_COMPLETED);
 994	ret = cur_trans->aborted;
 995	btrfs_put_transaction(cur_trans);
 996out:
 997	return ret;
 998}
 999
1000void btrfs_throttle(struct btrfs_fs_info *fs_info)
1001{
1002	wait_current_trans(fs_info);
1003}
1004
 
 
 
 
 
 
 
 
 
 
1005bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
1006{
1007	struct btrfs_transaction *cur_trans = trans->transaction;
1008
1009	if (cur_trans->state >= TRANS_STATE_COMMIT_START ||
1010	    test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags))
1011		return true;
1012
1013	if (btrfs_check_space_for_delayed_refs(trans->fs_info))
1014		return true;
1015
1016	return !!btrfs_block_rsv_check(&trans->fs_info->global_block_rsv, 50);
1017}
1018
1019static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
1020
1021{
1022	struct btrfs_fs_info *fs_info = trans->fs_info;
1023
1024	if (!trans->block_rsv) {
1025		ASSERT(!trans->bytes_reserved);
1026		ASSERT(!trans->delayed_refs_bytes_reserved);
1027		return;
1028	}
1029
1030	if (!trans->bytes_reserved) {
1031		ASSERT(!trans->delayed_refs_bytes_reserved);
1032		return;
1033	}
1034
1035	ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
1036	trace_btrfs_space_reservation(fs_info, "transaction",
1037				      trans->transid, trans->bytes_reserved, 0);
1038	btrfs_block_rsv_release(fs_info, trans->block_rsv,
1039				trans->bytes_reserved, NULL);
1040	trans->bytes_reserved = 0;
1041
1042	if (!trans->delayed_refs_bytes_reserved)
1043		return;
1044
1045	trace_btrfs_space_reservation(fs_info, "local_delayed_refs_rsv",
1046				      trans->transid,
1047				      trans->delayed_refs_bytes_reserved, 0);
1048	btrfs_block_rsv_release(fs_info, &trans->delayed_rsv,
1049				trans->delayed_refs_bytes_reserved, NULL);
1050	trans->delayed_refs_bytes_reserved = 0;
1051}
1052
1053static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
1054				   int throttle)
1055{
1056	struct btrfs_fs_info *info = trans->fs_info;
1057	struct btrfs_transaction *cur_trans = trans->transaction;
1058	int err = 0;
1059
1060	if (refcount_read(&trans->use_count) > 1) {
1061		refcount_dec(&trans->use_count);
1062		trans->block_rsv = trans->orig_rsv;
1063		return 0;
1064	}
1065
1066	btrfs_trans_release_metadata(trans);
1067	trans->block_rsv = NULL;
1068
1069	btrfs_create_pending_block_groups(trans);
1070
1071	btrfs_trans_release_chunk_metadata(trans);
1072
1073	if (trans->type & __TRANS_FREEZABLE)
1074		sb_end_intwrite(info->sb);
1075
1076	WARN_ON(cur_trans != info->running_transaction);
1077	WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
1078	atomic_dec(&cur_trans->num_writers);
1079	extwriter_counter_dec(cur_trans, trans->type);
1080
1081	cond_wake_up(&cur_trans->writer_wait);
1082
1083	btrfs_lockdep_release(info, btrfs_trans_num_extwriters);
1084	btrfs_lockdep_release(info, btrfs_trans_num_writers);
1085
1086	btrfs_put_transaction(cur_trans);
1087
1088	if (current->journal_info == trans)
1089		current->journal_info = NULL;
1090
1091	if (throttle)
1092		btrfs_run_delayed_iputs(info);
1093
1094	if (TRANS_ABORTED(trans) || BTRFS_FS_ERROR(info)) {
 
1095		wake_up_process(info->transaction_kthread);
1096		if (TRANS_ABORTED(trans))
1097			err = trans->aborted;
1098		else
1099			err = -EROFS;
1100	}
1101
1102	kmem_cache_free(btrfs_trans_handle_cachep, trans);
1103	return err;
1104}
1105
1106int btrfs_end_transaction(struct btrfs_trans_handle *trans)
1107{
1108	return __btrfs_end_transaction(trans, 0);
1109}
1110
1111int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
1112{
1113	return __btrfs_end_transaction(trans, 1);
1114}
1115
1116/*
1117 * when btree blocks are allocated, they have some corresponding bits set for
1118 * them in one of two extent_io trees.  This is used to make sure all of
1119 * those extents are sent to disk but does not wait on them
1120 */
1121int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
1122			       struct extent_io_tree *dirty_pages, int mark)
1123{
1124	int err = 0;
1125	int werr = 0;
1126	struct address_space *mapping = fs_info->btree_inode->i_mapping;
1127	struct extent_state *cached_state = NULL;
1128	u64 start = 0;
1129	u64 end;
1130
1131	while (find_first_extent_bit(dirty_pages, start, &start, &end,
1132				     mark, &cached_state)) {
 
1133		bool wait_writeback = false;
1134
1135		err = convert_extent_bit(dirty_pages, start, end,
1136					 EXTENT_NEED_WAIT,
1137					 mark, &cached_state);
1138		/*
1139		 * convert_extent_bit can return -ENOMEM, which is most of the
1140		 * time a temporary error. So when it happens, ignore the error
1141		 * and wait for writeback of this range to finish - because we
1142		 * failed to set the bit EXTENT_NEED_WAIT for the range, a call
1143		 * to __btrfs_wait_marked_extents() would not know that
1144		 * writeback for this range started and therefore wouldn't
1145		 * wait for it to finish - we don't want to commit a
1146		 * superblock that points to btree nodes/leafs for which
1147		 * writeback hasn't finished yet (and without errors).
1148		 * We cleanup any entries left in the io tree when committing
1149		 * the transaction (through extent_io_tree_release()).
1150		 */
1151		if (err == -ENOMEM) {
1152			err = 0;
1153			wait_writeback = true;
1154		}
1155		if (!err)
1156			err = filemap_fdatawrite_range(mapping, start, end);
1157		if (err)
1158			werr = err;
1159		else if (wait_writeback)
1160			werr = filemap_fdatawait_range(mapping, start, end);
1161		free_extent_state(cached_state);
1162		cached_state = NULL;
1163		cond_resched();
1164		start = end + 1;
1165	}
 
1166	return werr;
1167}
1168
1169/*
1170 * when btree blocks are allocated, they have some corresponding bits set for
1171 * them in one of two extent_io trees.  This is used to make sure all of
1172 * those extents are on disk for transaction or log commit.  We wait
1173 * on all the pages and clear them from the dirty pages state tree
1174 */
1175static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
1176				       struct extent_io_tree *dirty_pages)
1177{
1178	int err = 0;
1179	int werr = 0;
1180	struct address_space *mapping = fs_info->btree_inode->i_mapping;
1181	struct extent_state *cached_state = NULL;
1182	u64 start = 0;
1183	u64 end;
1184
1185	while (find_first_extent_bit(dirty_pages, start, &start, &end,
1186				     EXTENT_NEED_WAIT, &cached_state)) {
1187		/*
1188		 * Ignore -ENOMEM errors returned by clear_extent_bit().
1189		 * When committing the transaction, we'll remove any entries
1190		 * left in the io tree. For a log commit, we don't remove them
1191		 * after committing the log because the tree can be accessed
1192		 * concurrently - we do it only at transaction commit time when
1193		 * it's safe to do it (through extent_io_tree_release()).
1194		 */
1195		err = clear_extent_bit(dirty_pages, start, end,
1196				       EXTENT_NEED_WAIT, &cached_state);
1197		if (err == -ENOMEM)
1198			err = 0;
1199		if (!err)
1200			err = filemap_fdatawait_range(mapping, start, end);
1201		if (err)
1202			werr = err;
1203		free_extent_state(cached_state);
1204		cached_state = NULL;
1205		cond_resched();
1206		start = end + 1;
1207	}
1208	if (err)
1209		werr = err;
1210	return werr;
1211}
1212
1213static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1214		       struct extent_io_tree *dirty_pages)
1215{
1216	bool errors = false;
1217	int err;
1218
1219	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1220	if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1221		errors = true;
1222
1223	if (errors && !err)
1224		err = -EIO;
1225	return err;
1226}
1227
1228int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1229{
1230	struct btrfs_fs_info *fs_info = log_root->fs_info;
1231	struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1232	bool errors = false;
1233	int err;
1234
1235	ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1236
1237	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1238	if ((mark & EXTENT_DIRTY) &&
1239	    test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1240		errors = true;
1241
1242	if ((mark & EXTENT_NEW) &&
1243	    test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1244		errors = true;
1245
1246	if (errors && !err)
1247		err = -EIO;
1248	return err;
1249}
1250
1251/*
1252 * When btree blocks are allocated the corresponding extents are marked dirty.
1253 * This function ensures such extents are persisted on disk for transaction or
1254 * log commit.
1255 *
1256 * @trans: transaction whose dirty pages we'd like to write
1257 */
1258static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1259{
1260	int ret;
1261	int ret2;
1262	struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1263	struct btrfs_fs_info *fs_info = trans->fs_info;
1264	struct blk_plug plug;
1265
1266	blk_start_plug(&plug);
1267	ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1268	blk_finish_plug(&plug);
1269	ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1270
1271	extent_io_tree_release(&trans->transaction->dirty_pages);
1272
1273	if (ret)
1274		return ret;
1275	else if (ret2)
1276		return ret2;
1277	else
1278		return 0;
1279}
1280
1281/*
1282 * this is used to update the root pointer in the tree of tree roots.
1283 *
1284 * But, in the case of the extent allocation tree, updating the root
1285 * pointer may allocate blocks which may change the root of the extent
1286 * allocation tree.
1287 *
1288 * So, this loops and repeats and makes sure the cowonly root didn't
1289 * change while the root pointer was being updated in the metadata.
1290 */
1291static int update_cowonly_root(struct btrfs_trans_handle *trans,
1292			       struct btrfs_root *root)
1293{
1294	int ret;
1295	u64 old_root_bytenr;
1296	u64 old_root_used;
1297	struct btrfs_fs_info *fs_info = root->fs_info;
1298	struct btrfs_root *tree_root = fs_info->tree_root;
1299
1300	old_root_used = btrfs_root_used(&root->root_item);
1301
1302	while (1) {
1303		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1304		if (old_root_bytenr == root->node->start &&
1305		    old_root_used == btrfs_root_used(&root->root_item))
1306			break;
1307
1308		btrfs_set_root_node(&root->root_item, root->node);
1309		ret = btrfs_update_root(trans, tree_root,
1310					&root->root_key,
1311					&root->root_item);
1312		if (ret)
1313			return ret;
1314
1315		old_root_used = btrfs_root_used(&root->root_item);
1316	}
1317
1318	return 0;
1319}
1320
1321/*
1322 * update all the cowonly tree roots on disk
1323 *
1324 * The error handling in this function may not be obvious. Any of the
1325 * failures will cause the file system to go offline. We still need
1326 * to clean up the delayed refs.
1327 */
1328static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1329{
1330	struct btrfs_fs_info *fs_info = trans->fs_info;
1331	struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1332	struct list_head *io_bgs = &trans->transaction->io_bgs;
1333	struct list_head *next;
1334	struct extent_buffer *eb;
1335	int ret;
1336
1337	/*
1338	 * At this point no one can be using this transaction to modify any tree
1339	 * and no one can start another transaction to modify any tree either.
1340	 */
1341	ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
1342
1343	eb = btrfs_lock_root_node(fs_info->tree_root);
1344	ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1345			      0, &eb, BTRFS_NESTING_COW);
1346	btrfs_tree_unlock(eb);
1347	free_extent_buffer(eb);
1348
1349	if (ret)
1350		return ret;
1351
1352	ret = btrfs_run_dev_stats(trans);
1353	if (ret)
1354		return ret;
1355	ret = btrfs_run_dev_replace(trans);
1356	if (ret)
1357		return ret;
1358	ret = btrfs_run_qgroups(trans);
1359	if (ret)
1360		return ret;
1361
1362	ret = btrfs_setup_space_cache(trans);
1363	if (ret)
1364		return ret;
1365
1366again:
1367	while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1368		struct btrfs_root *root;
1369		next = fs_info->dirty_cowonly_roots.next;
1370		list_del_init(next);
1371		root = list_entry(next, struct btrfs_root, dirty_list);
1372		clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1373
1374		list_add_tail(&root->dirty_list,
1375			      &trans->transaction->switch_commits);
 
1376		ret = update_cowonly_root(trans, root);
1377		if (ret)
1378			return ret;
1379	}
1380
1381	/* Now flush any delayed refs generated by updating all of the roots */
1382	ret = btrfs_run_delayed_refs(trans, U64_MAX);
1383	if (ret)
1384		return ret;
1385
1386	while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1387		ret = btrfs_write_dirty_block_groups(trans);
1388		if (ret)
1389			return ret;
1390
1391		/*
1392		 * We're writing the dirty block groups, which could generate
1393		 * delayed refs, which could generate more dirty block groups,
1394		 * so we want to keep this flushing in this loop to make sure
1395		 * everything gets run.
1396		 */
1397		ret = btrfs_run_delayed_refs(trans, U64_MAX);
1398		if (ret)
1399			return ret;
1400	}
1401
1402	if (!list_empty(&fs_info->dirty_cowonly_roots))
1403		goto again;
1404
 
 
 
1405	/* Update dev-replace pointer once everything is committed */
1406	fs_info->dev_replace.committed_cursor_left =
1407		fs_info->dev_replace.cursor_left_last_write_of_item;
1408
1409	return 0;
1410}
1411
1412/*
1413 * If we had a pending drop we need to see if there are any others left in our
1414 * dead roots list, and if not clear our bit and wake any waiters.
1415 */
1416void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info)
1417{
1418	/*
1419	 * We put the drop in progress roots at the front of the list, so if the
1420	 * first entry doesn't have UNFINISHED_DROP set we can wake everybody
1421	 * up.
1422	 */
1423	spin_lock(&fs_info->trans_lock);
1424	if (!list_empty(&fs_info->dead_roots)) {
1425		struct btrfs_root *root = list_first_entry(&fs_info->dead_roots,
1426							   struct btrfs_root,
1427							   root_list);
1428		if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) {
1429			spin_unlock(&fs_info->trans_lock);
1430			return;
1431		}
1432	}
1433	spin_unlock(&fs_info->trans_lock);
1434
1435	btrfs_wake_unfinished_drop(fs_info);
1436}
1437
1438/*
1439 * dead roots are old snapshots that need to be deleted.  This allocates
1440 * a dirty root struct and adds it into the list of dead roots that need to
1441 * be deleted
1442 */
1443void btrfs_add_dead_root(struct btrfs_root *root)
1444{
1445	struct btrfs_fs_info *fs_info = root->fs_info;
1446
1447	spin_lock(&fs_info->trans_lock);
1448	if (list_empty(&root->root_list)) {
1449		btrfs_grab_root(root);
1450
1451		/* We want to process the partially complete drops first. */
1452		if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state))
1453			list_add(&root->root_list, &fs_info->dead_roots);
1454		else
1455			list_add_tail(&root->root_list, &fs_info->dead_roots);
1456	}
1457	spin_unlock(&fs_info->trans_lock);
1458}
1459
1460/*
1461 * Update each subvolume root and its relocation root, if it exists, in the tree
1462 * of tree roots. Also free log roots if they exist.
1463 */
1464static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1465{
1466	struct btrfs_fs_info *fs_info = trans->fs_info;
1467	struct btrfs_root *gang[8];
1468	int i;
1469	int ret;
1470
1471	/*
1472	 * At this point no one can be using this transaction to modify any tree
1473	 * and no one can start another transaction to modify any tree either.
1474	 */
1475	ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING);
1476
1477	spin_lock(&fs_info->fs_roots_radix_lock);
1478	while (1) {
1479		ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1480						 (void **)gang, 0,
1481						 ARRAY_SIZE(gang),
1482						 BTRFS_ROOT_TRANS_TAG);
1483		if (ret == 0)
1484			break;
1485		for (i = 0; i < ret; i++) {
1486			struct btrfs_root *root = gang[i];
1487			int ret2;
1488
1489			/*
1490			 * At this point we can neither have tasks logging inodes
1491			 * from a root nor trying to commit a log tree.
1492			 */
1493			ASSERT(atomic_read(&root->log_writers) == 0);
1494			ASSERT(atomic_read(&root->log_commit[0]) == 0);
1495			ASSERT(atomic_read(&root->log_commit[1]) == 0);
1496
1497			radix_tree_tag_clear(&fs_info->fs_roots_radix,
1498					(unsigned long)root->root_key.objectid,
1499					BTRFS_ROOT_TRANS_TAG);
1500			spin_unlock(&fs_info->fs_roots_radix_lock);
1501
1502			btrfs_free_log(trans, root);
1503			ret2 = btrfs_update_reloc_root(trans, root);
1504			if (ret2)
1505				return ret2;
1506
1507			/* see comments in should_cow_block() */
1508			clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1509			smp_mb__after_atomic();
1510
1511			if (root->commit_root != root->node) {
1512				list_add_tail(&root->dirty_list,
1513					&trans->transaction->switch_commits);
1514				btrfs_set_root_node(&root->root_item,
1515						    root->node);
1516			}
1517
1518			ret2 = btrfs_update_root(trans, fs_info->tree_root,
1519						&root->root_key,
1520						&root->root_item);
1521			if (ret2)
1522				return ret2;
1523			spin_lock(&fs_info->fs_roots_radix_lock);
1524			btrfs_qgroup_free_meta_all_pertrans(root);
1525		}
1526	}
1527	spin_unlock(&fs_info->fs_roots_radix_lock);
1528	return 0;
1529}
1530
1531/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1532 * Do all special snapshot related qgroup dirty hack.
1533 *
1534 * Will do all needed qgroup inherit and dirty hack like switch commit
1535 * roots inside one transaction and write all btree into disk, to make
1536 * qgroup works.
1537 */
1538static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1539				   struct btrfs_root *src,
1540				   struct btrfs_root *parent,
1541				   struct btrfs_qgroup_inherit *inherit,
1542				   u64 dst_objectid)
1543{
1544	struct btrfs_fs_info *fs_info = src->fs_info;
1545	int ret;
1546
1547	/*
1548	 * Save some performance in the case that qgroups are not enabled. If
1549	 * this check races with the ioctl, rescan will kick in anyway.
 
1550	 */
1551	if (!btrfs_qgroup_full_accounting(fs_info))
1552		return 0;
1553
1554	/*
1555	 * Ensure dirty @src will be committed.  Or, after coming
1556	 * commit_fs_roots() and switch_commit_roots(), any dirty but not
1557	 * recorded root will never be updated again, causing an outdated root
1558	 * item.
1559	 */
1560	ret = record_root_in_trans(trans, src, 1);
1561	if (ret)
1562		return ret;
1563
1564	/*
1565	 * btrfs_qgroup_inherit relies on a consistent view of the usage for the
1566	 * src root, so we must run the delayed refs here.
1567	 *
1568	 * However this isn't particularly fool proof, because there's no
1569	 * synchronization keeping us from changing the tree after this point
1570	 * before we do the qgroup_inherit, or even from making changes while
1571	 * we're doing the qgroup_inherit.  But that's a problem for the future,
1572	 * for now flush the delayed refs to narrow the race window where the
1573	 * qgroup counters could end up wrong.
1574	 */
1575	ret = btrfs_run_delayed_refs(trans, U64_MAX);
1576	if (ret) {
1577		btrfs_abort_transaction(trans, ret);
1578		return ret;
1579	}
1580
 
 
 
 
 
 
1581	ret = commit_fs_roots(trans);
1582	if (ret)
1583		goto out;
1584	ret = btrfs_qgroup_account_extents(trans);
1585	if (ret < 0)
1586		goto out;
1587
1588	/* Now qgroup are all updated, we can inherit it to new qgroups */
1589	ret = btrfs_qgroup_inherit(trans, src->root_key.objectid, dst_objectid,
1590				   parent->root_key.objectid, inherit);
1591	if (ret < 0)
1592		goto out;
1593
1594	/*
1595	 * Now we do a simplified commit transaction, which will:
1596	 * 1) commit all subvolume and extent tree
1597	 *    To ensure all subvolume and extent tree have a valid
1598	 *    commit_root to accounting later insert_dir_item()
1599	 * 2) write all btree blocks onto disk
1600	 *    This is to make sure later btree modification will be cowed
1601	 *    Or commit_root can be populated and cause wrong qgroup numbers
1602	 * In this simplified commit, we don't really care about other trees
1603	 * like chunk and root tree, as they won't affect qgroup.
1604	 * And we don't write super to avoid half committed status.
1605	 */
1606	ret = commit_cowonly_roots(trans);
1607	if (ret)
1608		goto out;
1609	switch_commit_roots(trans);
1610	ret = btrfs_write_and_wait_transaction(trans);
1611	if (ret)
1612		btrfs_handle_fs_error(fs_info, ret,
1613			"Error while writing out transaction for qgroup");
1614
1615out:
 
 
1616	/*
1617	 * Force parent root to be updated, as we recorded it before so its
1618	 * last_trans == cur_transid.
1619	 * Or it won't be committed again onto disk after later
1620	 * insert_dir_item()
1621	 */
1622	if (!ret)
1623		ret = record_root_in_trans(trans, parent, 1);
1624	return ret;
1625}
1626
1627/*
1628 * new snapshots need to be created at a very specific time in the
1629 * transaction commit.  This does the actual creation.
1630 *
1631 * Note:
1632 * If the error which may affect the commitment of the current transaction
1633 * happens, we should return the error number. If the error which just affect
1634 * the creation of the pending snapshots, just return 0.
1635 */
1636static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1637				   struct btrfs_pending_snapshot *pending)
1638{
1639
1640	struct btrfs_fs_info *fs_info = trans->fs_info;
1641	struct btrfs_key key;
1642	struct btrfs_root_item *new_root_item;
1643	struct btrfs_root *tree_root = fs_info->tree_root;
1644	struct btrfs_root *root = pending->root;
1645	struct btrfs_root *parent_root;
1646	struct btrfs_block_rsv *rsv;
1647	struct inode *parent_inode = pending->dir;
1648	struct btrfs_path *path;
1649	struct btrfs_dir_item *dir_item;
 
1650	struct extent_buffer *tmp;
1651	struct extent_buffer *old;
1652	struct timespec64 cur_time;
1653	int ret = 0;
1654	u64 to_reserve = 0;
1655	u64 index = 0;
1656	u64 objectid;
1657	u64 root_flags;
1658	unsigned int nofs_flags;
1659	struct fscrypt_name fname;
1660
1661	ASSERT(pending->path);
1662	path = pending->path;
1663
1664	ASSERT(pending->root_item);
1665	new_root_item = pending->root_item;
1666
1667	/*
1668	 * We're inside a transaction and must make sure that any potential
1669	 * allocations with GFP_KERNEL in fscrypt won't recurse back to
1670	 * filesystem.
1671	 */
1672	nofs_flags = memalloc_nofs_save();
1673	pending->error = fscrypt_setup_filename(parent_inode,
1674						&pending->dentry->d_name, 0,
1675						&fname);
1676	memalloc_nofs_restore(nofs_flags);
1677	if (pending->error)
1678		goto free_pending;
1679
1680	pending->error = btrfs_get_free_objectid(tree_root, &objectid);
1681	if (pending->error)
1682		goto free_fname;
1683
1684	/*
1685	 * Make qgroup to skip current new snapshot's qgroupid, as it is
1686	 * accounted by later btrfs_qgroup_inherit().
1687	 */
1688	btrfs_set_skip_qgroup(trans, objectid);
1689
1690	btrfs_reloc_pre_snapshot(pending, &to_reserve);
1691
1692	if (to_reserve > 0) {
1693		pending->error = btrfs_block_rsv_add(fs_info,
1694						     &pending->block_rsv,
1695						     to_reserve,
1696						     BTRFS_RESERVE_NO_FLUSH);
1697		if (pending->error)
1698			goto clear_skip_qgroup;
1699	}
1700
1701	key.objectid = objectid;
1702	key.offset = (u64)-1;
1703	key.type = BTRFS_ROOT_ITEM_KEY;
1704
1705	rsv = trans->block_rsv;
1706	trans->block_rsv = &pending->block_rsv;
1707	trans->bytes_reserved = trans->block_rsv->reserved;
1708	trace_btrfs_space_reservation(fs_info, "transaction",
1709				      trans->transid,
1710				      trans->bytes_reserved, 1);
 
 
1711	parent_root = BTRFS_I(parent_inode)->root;
1712	ret = record_root_in_trans(trans, parent_root, 0);
1713	if (ret)
1714		goto fail;
1715	cur_time = current_time(parent_inode);
1716
1717	/*
1718	 * insert the directory item
1719	 */
1720	ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1721	if (ret) {
1722		btrfs_abort_transaction(trans, ret);
1723		goto fail;
1724	}
1725
1726	/* check if there is a file/dir which has the same name. */
1727	dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1728					 btrfs_ino(BTRFS_I(parent_inode)),
1729					 &fname.disk_name, 0);
 
1730	if (dir_item != NULL && !IS_ERR(dir_item)) {
1731		pending->error = -EEXIST;
1732		goto dir_item_existed;
1733	} else if (IS_ERR(dir_item)) {
1734		ret = PTR_ERR(dir_item);
1735		btrfs_abort_transaction(trans, ret);
1736		goto fail;
1737	}
1738	btrfs_release_path(path);
1739
1740	ret = btrfs_create_qgroup(trans, objectid);
1741	if (ret && ret != -EEXIST) {
1742		btrfs_abort_transaction(trans, ret);
1743		goto fail;
1744	}
1745
1746	/*
1747	 * pull in the delayed directory update
1748	 * and the delayed inode item
1749	 * otherwise we corrupt the FS during
1750	 * snapshot
1751	 */
1752	ret = btrfs_run_delayed_items(trans);
1753	if (ret) {	/* Transaction aborted */
1754		btrfs_abort_transaction(trans, ret);
1755		goto fail;
1756	}
1757
1758	ret = record_root_in_trans(trans, root, 0);
1759	if (ret) {
1760		btrfs_abort_transaction(trans, ret);
1761		goto fail;
1762	}
1763	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1764	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1765	btrfs_check_and_init_root_item(new_root_item);
1766
1767	root_flags = btrfs_root_flags(new_root_item);
1768	if (pending->readonly)
1769		root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1770	else
1771		root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1772	btrfs_set_root_flags(new_root_item, root_flags);
1773
1774	btrfs_set_root_generation_v2(new_root_item,
1775			trans->transid);
1776	generate_random_guid(new_root_item->uuid);
1777	memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1778			BTRFS_UUID_SIZE);
1779	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1780		memset(new_root_item->received_uuid, 0,
1781		       sizeof(new_root_item->received_uuid));
1782		memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1783		memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1784		btrfs_set_root_stransid(new_root_item, 0);
1785		btrfs_set_root_rtransid(new_root_item, 0);
1786	}
1787	btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1788	btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1789	btrfs_set_root_otransid(new_root_item, trans->transid);
1790
1791	old = btrfs_lock_root_node(root);
1792	ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,
1793			      BTRFS_NESTING_COW);
1794	if (ret) {
1795		btrfs_tree_unlock(old);
1796		free_extent_buffer(old);
1797		btrfs_abort_transaction(trans, ret);
1798		goto fail;
1799	}
1800
1801	ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1802	/* clean up in any case */
1803	btrfs_tree_unlock(old);
1804	free_extent_buffer(old);
1805	if (ret) {
1806		btrfs_abort_transaction(trans, ret);
1807		goto fail;
1808	}
1809	/* see comments in should_cow_block() */
1810	set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1811	smp_wmb();
1812
1813	btrfs_set_root_node(new_root_item, tmp);
1814	/* record when the snapshot was created in key.offset */
1815	key.offset = trans->transid;
1816	ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1817	btrfs_tree_unlock(tmp);
1818	free_extent_buffer(tmp);
1819	if (ret) {
1820		btrfs_abort_transaction(trans, ret);
1821		goto fail;
1822	}
1823
1824	/*
1825	 * insert root back/forward references
1826	 */
1827	ret = btrfs_add_root_ref(trans, objectid,
1828				 parent_root->root_key.objectid,
1829				 btrfs_ino(BTRFS_I(parent_inode)), index,
1830				 &fname.disk_name);
1831	if (ret) {
1832		btrfs_abort_transaction(trans, ret);
1833		goto fail;
1834	}
1835
1836	key.offset = (u64)-1;
1837	pending->snap = btrfs_get_new_fs_root(fs_info, objectid, &pending->anon_dev);
1838	if (IS_ERR(pending->snap)) {
1839		ret = PTR_ERR(pending->snap);
1840		pending->snap = NULL;
1841		btrfs_abort_transaction(trans, ret);
1842		goto fail;
1843	}
1844
1845	ret = btrfs_reloc_post_snapshot(trans, pending);
1846	if (ret) {
1847		btrfs_abort_transaction(trans, ret);
1848		goto fail;
1849	}
1850
1851	/*
1852	 * Do special qgroup accounting for snapshot, as we do some qgroup
1853	 * snapshot hack to do fast snapshot.
1854	 * To co-operate with that hack, we do hack again.
1855	 * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1856	 */
1857	if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL)
1858		ret = qgroup_account_snapshot(trans, root, parent_root,
1859					      pending->inherit, objectid);
1860	else if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE)
1861		ret = btrfs_qgroup_inherit(trans, root->root_key.objectid, objectid,
1862					   parent_root->root_key.objectid, pending->inherit);
1863	if (ret < 0)
1864		goto fail;
1865
1866	ret = btrfs_insert_dir_item(trans, &fname.disk_name,
1867				    BTRFS_I(parent_inode), &key, BTRFS_FT_DIR,
1868				    index);
1869	/* We have check then name at the beginning, so it is impossible. */
1870	BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1871	if (ret) {
1872		btrfs_abort_transaction(trans, ret);
1873		goto fail;
1874	}
1875
1876	btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1877						  fname.disk_name.len * 2);
1878	inode_set_mtime_to_ts(parent_inode,
1879			      inode_set_ctime_current(parent_inode));
1880	ret = btrfs_update_inode_fallback(trans, BTRFS_I(parent_inode));
1881	if (ret) {
1882		btrfs_abort_transaction(trans, ret);
1883		goto fail;
1884	}
1885	ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
1886				  BTRFS_UUID_KEY_SUBVOL,
1887				  objectid);
1888	if (ret) {
1889		btrfs_abort_transaction(trans, ret);
1890		goto fail;
1891	}
1892	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1893		ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
1894					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1895					  objectid);
1896		if (ret && ret != -EEXIST) {
1897			btrfs_abort_transaction(trans, ret);
1898			goto fail;
1899		}
1900	}
1901
1902fail:
1903	pending->error = ret;
1904dir_item_existed:
1905	trans->block_rsv = rsv;
1906	trans->bytes_reserved = 0;
1907clear_skip_qgroup:
1908	btrfs_clear_skip_qgroup(trans);
1909free_fname:
1910	fscrypt_free_filename(&fname);
1911free_pending:
1912	kfree(new_root_item);
1913	pending->root_item = NULL;
1914	btrfs_free_path(path);
1915	pending->path = NULL;
1916
1917	return ret;
1918}
1919
1920/*
1921 * create all the snapshots we've scheduled for creation
1922 */
1923static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1924{
1925	struct btrfs_pending_snapshot *pending, *next;
1926	struct list_head *head = &trans->transaction->pending_snapshots;
1927	int ret = 0;
1928
1929	list_for_each_entry_safe(pending, next, head, list) {
1930		list_del(&pending->list);
1931		ret = create_pending_snapshot(trans, pending);
1932		if (ret)
1933			break;
1934	}
1935	return ret;
1936}
1937
1938static void update_super_roots(struct btrfs_fs_info *fs_info)
1939{
1940	struct btrfs_root_item *root_item;
1941	struct btrfs_super_block *super;
1942
1943	super = fs_info->super_copy;
1944
1945	root_item = &fs_info->chunk_root->root_item;
1946	super->chunk_root = root_item->bytenr;
1947	super->chunk_root_generation = root_item->generation;
1948	super->chunk_root_level = root_item->level;
1949
1950	root_item = &fs_info->tree_root->root_item;
1951	super->root = root_item->bytenr;
1952	super->generation = root_item->generation;
1953	super->root_level = root_item->level;
1954	if (btrfs_test_opt(fs_info, SPACE_CACHE))
1955		super->cache_generation = root_item->generation;
1956	else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags))
1957		super->cache_generation = 0;
1958	if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1959		super->uuid_tree_generation = root_item->generation;
1960}
1961
1962int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1963{
1964	struct btrfs_transaction *trans;
1965	int ret = 0;
1966
1967	spin_lock(&info->trans_lock);
1968	trans = info->running_transaction;
1969	if (trans)
1970		ret = (trans->state >= TRANS_STATE_COMMIT_START);
1971	spin_unlock(&info->trans_lock);
1972	return ret;
1973}
1974
1975int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1976{
1977	struct btrfs_transaction *trans;
1978	int ret = 0;
1979
1980	spin_lock(&info->trans_lock);
1981	trans = info->running_transaction;
1982	if (trans)
1983		ret = is_transaction_blocked(trans);
1984	spin_unlock(&info->trans_lock);
1985	return ret;
1986}
1987
1988void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1989{
1990	struct btrfs_fs_info *fs_info = trans->fs_info;
 
1991	struct btrfs_transaction *cur_trans;
1992
1993	/* Kick the transaction kthread. */
1994	set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
1995	wake_up_process(fs_info->transaction_kthread);
 
 
 
 
 
 
 
 
1996
1997	/* take transaction reference */
1998	cur_trans = trans->transaction;
1999	refcount_inc(&cur_trans->use_count);
2000
2001	btrfs_end_transaction(trans);
2002
2003	/*
 
 
 
 
 
 
 
 
2004	 * Wait for the current transaction commit to start and block
2005	 * subsequent transaction joins
2006	 */
2007	btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2008	wait_event(fs_info->transaction_blocked_wait,
2009		   cur_trans->state >= TRANS_STATE_COMMIT_START ||
2010		   TRANS_ABORTED(cur_trans));
 
 
 
2011	btrfs_put_transaction(cur_trans);
 
2012}
2013
 
2014static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
2015{
2016	struct btrfs_fs_info *fs_info = trans->fs_info;
2017	struct btrfs_transaction *cur_trans = trans->transaction;
2018
2019	WARN_ON(refcount_read(&trans->use_count) > 1);
2020
2021	btrfs_abort_transaction(trans, err);
2022
2023	spin_lock(&fs_info->trans_lock);
2024
2025	/*
2026	 * If the transaction is removed from the list, it means this
2027	 * transaction has been committed successfully, so it is impossible
2028	 * to call the cleanup function.
2029	 */
2030	BUG_ON(list_empty(&cur_trans->list));
2031
2032	if (cur_trans == fs_info->running_transaction) {
2033		cur_trans->state = TRANS_STATE_COMMIT_DOING;
2034		spin_unlock(&fs_info->trans_lock);
2035
2036		/*
2037		 * The thread has already released the lockdep map as reader
2038		 * already in btrfs_commit_transaction().
2039		 */
2040		btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
2041		wait_event(cur_trans->writer_wait,
2042			   atomic_read(&cur_trans->num_writers) == 1);
2043
2044		spin_lock(&fs_info->trans_lock);
2045	}
2046
2047	/*
2048	 * Now that we know no one else is still using the transaction we can
2049	 * remove the transaction from the list of transactions. This avoids
2050	 * the transaction kthread from cleaning up the transaction while some
2051	 * other task is still using it, which could result in a use-after-free
2052	 * on things like log trees, as it forces the transaction kthread to
2053	 * wait for this transaction to be cleaned up by us.
2054	 */
2055	list_del_init(&cur_trans->list);
2056
2057	spin_unlock(&fs_info->trans_lock);
2058
2059	btrfs_cleanup_one_transaction(trans->transaction, fs_info);
2060
2061	spin_lock(&fs_info->trans_lock);
2062	if (cur_trans == fs_info->running_transaction)
2063		fs_info->running_transaction = NULL;
2064	spin_unlock(&fs_info->trans_lock);
2065
2066	if (trans->type & __TRANS_FREEZABLE)
2067		sb_end_intwrite(fs_info->sb);
2068	btrfs_put_transaction(cur_trans);
2069	btrfs_put_transaction(cur_trans);
2070
2071	trace_btrfs_transaction_commit(fs_info);
2072
2073	if (current->journal_info == trans)
2074		current->journal_info = NULL;
2075
2076	/*
2077	 * If relocation is running, we can't cancel scrub because that will
2078	 * result in a deadlock. Before relocating a block group, relocation
2079	 * pauses scrub, then starts and commits a transaction before unpausing
2080	 * scrub. If the transaction commit is being done by the relocation
2081	 * task or triggered by another task and the relocation task is waiting
2082	 * for the commit, and we end up here due to an error in the commit
2083	 * path, then calling btrfs_scrub_cancel() will deadlock, as we are
2084	 * asking for scrub to stop while having it asked to be paused higher
2085	 * above in relocation code.
2086	 */
2087	if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
2088		btrfs_scrub_cancel(fs_info);
2089
2090	kmem_cache_free(btrfs_trans_handle_cachep, trans);
2091}
2092
2093/*
2094 * Release reserved delayed ref space of all pending block groups of the
2095 * transaction and remove them from the list
2096 */
2097static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
2098{
2099       struct btrfs_fs_info *fs_info = trans->fs_info;
2100       struct btrfs_block_group *block_group, *tmp;
2101
2102       list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
2103               btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info);
2104               list_del_init(&block_group->bg_list);
2105       }
2106}
2107
2108static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
2109{
2110	/*
2111	 * We use try_to_writeback_inodes_sb() here because if we used
2112	 * btrfs_start_delalloc_roots we would deadlock with fs freeze.
2113	 * Currently are holding the fs freeze lock, if we do an async flush
2114	 * we'll do btrfs_join_transaction() and deadlock because we need to
2115	 * wait for the fs freeze lock.  Using the direct flushing we benefit
2116	 * from already being in a transaction and our join_transaction doesn't
2117	 * have to re-take the fs freeze lock.
2118	 *
2119	 * Note that try_to_writeback_inodes_sb() will only trigger writeback
2120	 * if it can read lock sb->s_umount. It will always be able to lock it,
2121	 * except when the filesystem is being unmounted or being frozen, but in
2122	 * those cases sync_filesystem() is called, which results in calling
2123	 * writeback_inodes_sb() while holding a write lock on sb->s_umount.
2124	 * Note that we don't call writeback_inodes_sb() directly, because it
2125	 * will emit a warning if sb->s_umount is not locked.
2126	 */
2127	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2128		try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
2129	return 0;
2130}
2131
2132static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
2133{
2134	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2135		btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
2136}
2137
2138/*
2139 * Add a pending snapshot associated with the given transaction handle to the
2140 * respective handle. This must be called after the transaction commit started
2141 * and while holding fs_info->trans_lock.
2142 * This serves to guarantee a caller of btrfs_commit_transaction() that it can
2143 * safely free the pending snapshot pointer in case btrfs_commit_transaction()
2144 * returns an error.
2145 */
2146static void add_pending_snapshot(struct btrfs_trans_handle *trans)
2147{
2148	struct btrfs_transaction *cur_trans = trans->transaction;
2149
2150	if (!trans->pending_snapshot)
2151		return;
2152
2153	lockdep_assert_held(&trans->fs_info->trans_lock);
2154	ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_PREP);
2155
2156	list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);
2157}
2158
2159static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval)
2160{
2161	fs_info->commit_stats.commit_count++;
2162	fs_info->commit_stats.last_commit_dur = interval;
2163	fs_info->commit_stats.max_commit_dur =
2164			max_t(u64, fs_info->commit_stats.max_commit_dur, interval);
2165	fs_info->commit_stats.total_commit_dur += interval;
2166}
2167
2168int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
2169{
2170	struct btrfs_fs_info *fs_info = trans->fs_info;
2171	struct btrfs_transaction *cur_trans = trans->transaction;
2172	struct btrfs_transaction *prev_trans = NULL;
2173	int ret;
2174	ktime_t start_time;
2175	ktime_t interval;
2176
2177	ASSERT(refcount_read(&trans->use_count) == 1);
2178	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2179
2180	clear_bit(BTRFS_FS_NEED_TRANS_COMMIT, &fs_info->flags);
2181
2182	/* Stop the commit early if ->aborted is set */
2183	if (TRANS_ABORTED(cur_trans)) {
2184		ret = cur_trans->aborted;
2185		goto lockdep_trans_commit_start_release;
 
2186	}
2187
2188	btrfs_trans_release_metadata(trans);
2189	trans->block_rsv = NULL;
2190
2191	/*
2192	 * We only want one transaction commit doing the flushing so we do not
2193	 * waste a bunch of time on lock contention on the extent root node.
2194	 */
2195	if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING,
2196			      &cur_trans->delayed_refs.flags)) {
2197		/*
2198		 * Make a pass through all the delayed refs we have so far.
2199		 * Any running threads may add more while we are here.
2200		 */
2201		ret = btrfs_run_delayed_refs(trans, 0);
2202		if (ret)
2203			goto lockdep_trans_commit_start_release;
 
 
2204	}
2205
2206	btrfs_create_pending_block_groups(trans);
2207
2208	if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
2209		int run_it = 0;
2210
2211		/* this mutex is also taken before trying to set
2212		 * block groups readonly.  We need to make sure
2213		 * that nobody has set a block group readonly
2214		 * after a extents from that block group have been
2215		 * allocated for cache files.  btrfs_set_block_group_ro
2216		 * will wait for the transaction to commit if it
2217		 * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2218		 *
2219		 * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2220		 * only one process starts all the block group IO.  It wouldn't
2221		 * hurt to have more than one go through, but there's no
2222		 * real advantage to it either.
2223		 */
2224		mutex_lock(&fs_info->ro_block_group_mutex);
2225		if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2226				      &cur_trans->flags))
2227			run_it = 1;
2228		mutex_unlock(&fs_info->ro_block_group_mutex);
2229
2230		if (run_it) {
2231			ret = btrfs_start_dirty_block_groups(trans);
2232			if (ret)
2233				goto lockdep_trans_commit_start_release;
 
 
2234		}
2235	}
2236
2237	spin_lock(&fs_info->trans_lock);
2238	if (cur_trans->state >= TRANS_STATE_COMMIT_PREP) {
2239		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2240
2241		add_pending_snapshot(trans);
2242
2243		spin_unlock(&fs_info->trans_lock);
2244		refcount_inc(&cur_trans->use_count);
2245
2246		if (trans->in_fsync)
2247			want_state = TRANS_STATE_SUPER_COMMITTED;
2248
2249		btrfs_trans_state_lockdep_release(fs_info,
2250						  BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2251		ret = btrfs_end_transaction(trans);
2252		wait_for_commit(cur_trans, want_state);
2253
2254		if (TRANS_ABORTED(cur_trans))
2255			ret = cur_trans->aborted;
2256
2257		btrfs_put_transaction(cur_trans);
2258
2259		return ret;
2260	}
2261
2262	cur_trans->state = TRANS_STATE_COMMIT_PREP;
2263	wake_up(&fs_info->transaction_blocked_wait);
2264	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2265
2266	if (cur_trans->list.prev != &fs_info->trans_list) {
2267		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2268
2269		if (trans->in_fsync)
2270			want_state = TRANS_STATE_SUPER_COMMITTED;
2271
2272		prev_trans = list_entry(cur_trans->list.prev,
2273					struct btrfs_transaction, list);
2274		if (prev_trans->state < want_state) {
2275			refcount_inc(&prev_trans->use_count);
2276			spin_unlock(&fs_info->trans_lock);
2277
2278			wait_for_commit(prev_trans, want_state);
2279
2280			ret = READ_ONCE(prev_trans->aborted);
2281
2282			btrfs_put_transaction(prev_trans);
2283			if (ret)
2284				goto lockdep_release;
2285			spin_lock(&fs_info->trans_lock);
 
2286		}
2287	} else {
 
2288		/*
2289		 * The previous transaction was aborted and was already removed
2290		 * from the list of transactions at fs_info->trans_list. So we
2291		 * abort to prevent writing a new superblock that reflects a
2292		 * corrupt state (pointing to trees with unwritten nodes/leafs).
2293		 */
2294		if (BTRFS_FS_ERROR(fs_info)) {
2295			spin_unlock(&fs_info->trans_lock);
2296			ret = -EROFS;
2297			goto lockdep_release;
2298		}
2299	}
2300
2301	cur_trans->state = TRANS_STATE_COMMIT_START;
2302	wake_up(&fs_info->transaction_blocked_wait);
2303	spin_unlock(&fs_info->trans_lock);
2304
2305	/*
2306	 * Get the time spent on the work done by the commit thread and not
2307	 * the time spent waiting on a previous commit
2308	 */
2309	start_time = ktime_get_ns();
2310
2311	extwriter_counter_dec(cur_trans, trans->type);
2312
2313	ret = btrfs_start_delalloc_flush(fs_info);
2314	if (ret)
2315		goto lockdep_release;
2316
2317	ret = btrfs_run_delayed_items(trans);
2318	if (ret)
2319		goto lockdep_release;
2320
2321	/*
2322	 * The thread has started/joined the transaction thus it holds the
2323	 * lockdep map as a reader. It has to release it before acquiring the
2324	 * lockdep map as a writer.
2325	 */
2326	btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
2327	btrfs_might_wait_for_event(fs_info, btrfs_trans_num_extwriters);
2328	wait_event(cur_trans->writer_wait,
2329		   extwriter_counter_read(cur_trans) == 0);
2330
2331	/* some pending stuffs might be added after the previous flush. */
2332	ret = btrfs_run_delayed_items(trans);
2333	if (ret) {
2334		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2335		goto cleanup_transaction;
2336	}
2337
2338	btrfs_wait_delalloc_flush(fs_info);
2339
2340	/*
2341	 * Wait for all ordered extents started by a fast fsync that joined this
2342	 * transaction. Otherwise if this transaction commits before the ordered
2343	 * extents complete we lose logged data after a power failure.
2344	 */
2345	btrfs_might_wait_for_event(fs_info, btrfs_trans_pending_ordered);
2346	wait_event(cur_trans->pending_wait,
2347		   atomic_read(&cur_trans->pending_ordered) == 0);
2348
2349	btrfs_scrub_pause(fs_info);
2350	/*
2351	 * Ok now we need to make sure to block out any other joins while we
2352	 * commit the transaction.  We could have started a join before setting
2353	 * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2354	 */
2355	spin_lock(&fs_info->trans_lock);
2356	add_pending_snapshot(trans);
2357	cur_trans->state = TRANS_STATE_COMMIT_DOING;
2358	spin_unlock(&fs_info->trans_lock);
2359
2360	/*
2361	 * The thread has started/joined the transaction thus it holds the
2362	 * lockdep map as a reader. It has to release it before acquiring the
2363	 * lockdep map as a writer.
2364	 */
2365	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2366	btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);
2367	wait_event(cur_trans->writer_wait,
2368		   atomic_read(&cur_trans->num_writers) == 1);
2369
2370	/*
2371	 * Make lockdep happy by acquiring the state locks after
2372	 * btrfs_trans_num_writers is released. If we acquired the state locks
2373	 * before releasing the btrfs_trans_num_writers lock then lockdep would
2374	 * complain because we did not follow the reverse order unlocking rule.
2375	 */
2376	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2377	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2378	btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2379
2380	/*
2381	 * We've started the commit, clear the flag in case we were triggered to
2382	 * do an async commit but somebody else started before the transaction
2383	 * kthread could do the work.
2384	 */
2385	clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags);
2386
2387	if (TRANS_ABORTED(cur_trans)) {
2388		ret = cur_trans->aborted;
2389		btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2390		goto scrub_continue;
2391	}
2392	/*
2393	 * the reloc mutex makes sure that we stop
2394	 * the balancing code from coming in and moving
2395	 * extents around in the middle of the commit
2396	 */
2397	mutex_lock(&fs_info->reloc_mutex);
2398
2399	/*
2400	 * We needn't worry about the delayed items because we will
2401	 * deal with them in create_pending_snapshot(), which is the
2402	 * core function of the snapshot creation.
2403	 */
2404	ret = create_pending_snapshots(trans);
2405	if (ret)
2406		goto unlock_reloc;
2407
2408	/*
2409	 * We insert the dir indexes of the snapshots and update the inode
2410	 * of the snapshots' parents after the snapshot creation, so there
2411	 * are some delayed items which are not dealt with. Now deal with
2412	 * them.
2413	 *
2414	 * We needn't worry that this operation will corrupt the snapshots,
2415	 * because all the tree which are snapshoted will be forced to COW
2416	 * the nodes and leaves.
2417	 */
2418	ret = btrfs_run_delayed_items(trans);
2419	if (ret)
2420		goto unlock_reloc;
2421
2422	ret = btrfs_run_delayed_refs(trans, U64_MAX);
2423	if (ret)
2424		goto unlock_reloc;
2425
2426	/*
2427	 * make sure none of the code above managed to slip in a
2428	 * delayed item
2429	 */
2430	btrfs_assert_delayed_root_empty(fs_info);
2431
2432	WARN_ON(cur_trans != trans->transaction);
2433
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2434	ret = commit_fs_roots(trans);
2435	if (ret)
2436		goto unlock_reloc;
 
 
 
 
 
 
2437
2438	/* commit_fs_roots gets rid of all the tree log roots, it is now
2439	 * safe to free the root of tree log roots
2440	 */
2441	btrfs_free_log_root_tree(trans, fs_info);
2442
2443	/*
2444	 * Since fs roots are all committed, we can get a quite accurate
2445	 * new_roots. So let's do quota accounting.
2446	 */
2447	ret = btrfs_qgroup_account_extents(trans);
2448	if (ret < 0)
2449		goto unlock_reloc;
2450
2451	ret = commit_cowonly_roots(trans);
2452	if (ret)
2453		goto unlock_reloc;
2454
2455	/*
2456	 * The tasks which save the space cache and inode cache may also
2457	 * update ->aborted, check it.
2458	 */
2459	if (TRANS_ABORTED(cur_trans)) {
2460		ret = cur_trans->aborted;
2461		goto unlock_reloc;
2462	}
2463
2464	cur_trans = fs_info->running_transaction;
2465
2466	btrfs_set_root_node(&fs_info->tree_root->root_item,
2467			    fs_info->tree_root->node);
2468	list_add_tail(&fs_info->tree_root->dirty_list,
2469		      &cur_trans->switch_commits);
2470
2471	btrfs_set_root_node(&fs_info->chunk_root->root_item,
2472			    fs_info->chunk_root->node);
2473	list_add_tail(&fs_info->chunk_root->dirty_list,
2474		      &cur_trans->switch_commits);
2475
2476	if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
2477		btrfs_set_root_node(&fs_info->block_group_root->root_item,
2478				    fs_info->block_group_root->node);
2479		list_add_tail(&fs_info->block_group_root->dirty_list,
2480			      &cur_trans->switch_commits);
2481	}
2482
2483	switch_commit_roots(trans);
2484
2485	ASSERT(list_empty(&cur_trans->dirty_bgs));
2486	ASSERT(list_empty(&cur_trans->io_bgs));
2487	update_super_roots(fs_info);
2488
2489	btrfs_set_super_log_root(fs_info->super_copy, 0);
2490	btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2491	memcpy(fs_info->super_for_commit, fs_info->super_copy,
2492	       sizeof(*fs_info->super_copy));
2493
2494	btrfs_commit_device_sizes(cur_trans);
2495
2496	clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2497	clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2498
2499	btrfs_trans_release_chunk_metadata(trans);
2500
2501	/*
2502	 * Before changing the transaction state to TRANS_STATE_UNBLOCKED and
2503	 * setting fs_info->running_transaction to NULL, lock tree_log_mutex to
2504	 * make sure that before we commit our superblock, no other task can
2505	 * start a new transaction and commit a log tree before we commit our
2506	 * superblock. Anyone trying to commit a log tree locks this mutex before
2507	 * writing its superblock.
2508	 */
2509	mutex_lock(&fs_info->tree_log_mutex);
2510
2511	spin_lock(&fs_info->trans_lock);
2512	cur_trans->state = TRANS_STATE_UNBLOCKED;
2513	fs_info->running_transaction = NULL;
2514	spin_unlock(&fs_info->trans_lock);
2515	mutex_unlock(&fs_info->reloc_mutex);
2516
2517	wake_up(&fs_info->transaction_wait);
2518	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2519
2520	/* If we have features changed, wake up the cleaner to update sysfs. */
2521	if (test_bit(BTRFS_FS_FEATURE_CHANGED, &fs_info->flags) &&
2522	    fs_info->cleaner_kthread)
2523		wake_up_process(fs_info->cleaner_kthread);
2524
2525	ret = btrfs_write_and_wait_transaction(trans);
2526	if (ret) {
2527		btrfs_handle_fs_error(fs_info, ret,
2528				      "Error while writing out transaction");
 
 
 
 
2529		mutex_unlock(&fs_info->tree_log_mutex);
2530		goto scrub_continue;
2531	}
2532
 
 
 
 
 
 
 
2533	ret = write_all_supers(fs_info, 0);
2534	/*
2535	 * the super is written, we can safely allow the tree-loggers
2536	 * to go about their business
2537	 */
2538	mutex_unlock(&fs_info->tree_log_mutex);
2539	if (ret)
2540		goto scrub_continue;
2541
2542	/*
2543	 * We needn't acquire the lock here because there is no other task
2544	 * which can change it.
2545	 */
2546	cur_trans->state = TRANS_STATE_SUPER_COMMITTED;
2547	wake_up(&cur_trans->commit_wait);
2548	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2549
2550	btrfs_finish_extent_commit(trans);
2551
2552	if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2553		btrfs_clear_space_info_full(fs_info);
2554
2555	btrfs_set_last_trans_committed(fs_info, cur_trans->transid);
2556	/*
2557	 * We needn't acquire the lock here because there is no other task
2558	 * which can change it.
2559	 */
2560	cur_trans->state = TRANS_STATE_COMPLETED;
2561	wake_up(&cur_trans->commit_wait);
2562	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2563
2564	spin_lock(&fs_info->trans_lock);
2565	list_del_init(&cur_trans->list);
2566	spin_unlock(&fs_info->trans_lock);
2567
2568	btrfs_put_transaction(cur_trans);
2569	btrfs_put_transaction(cur_trans);
2570
2571	if (trans->type & __TRANS_FREEZABLE)
2572		sb_end_intwrite(fs_info->sb);
2573
2574	trace_btrfs_transaction_commit(fs_info);
2575
2576	interval = ktime_get_ns() - start_time;
2577
2578	btrfs_scrub_continue(fs_info);
2579
2580	if (current->journal_info == trans)
2581		current->journal_info = NULL;
2582
2583	kmem_cache_free(btrfs_trans_handle_cachep, trans);
2584
2585	update_commit_stats(fs_info, interval);
2586
2587	return ret;
2588
 
 
2589unlock_reloc:
2590	mutex_unlock(&fs_info->reloc_mutex);
2591	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED);
2592scrub_continue:
2593	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED);
2594	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED);
2595	btrfs_scrub_continue(fs_info);
2596cleanup_transaction:
2597	btrfs_trans_release_metadata(trans);
2598	btrfs_cleanup_pending_block_groups(trans);
2599	btrfs_trans_release_chunk_metadata(trans);
2600	trans->block_rsv = NULL;
2601	btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2602	if (current->journal_info == trans)
2603		current->journal_info = NULL;
2604	cleanup_transaction(trans, ret);
2605
2606	return ret;
2607
2608lockdep_release:
2609	btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters);
2610	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);
2611	goto cleanup_transaction;
2612
2613lockdep_trans_commit_start_release:
2614	btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_PREP);
2615	btrfs_end_transaction(trans);
2616	return ret;
2617}
2618
2619/*
2620 * return < 0 if error
2621 * 0 if there are no more dead_roots at the time of call
2622 * 1 there are more to be processed, call me again
2623 *
2624 * The return value indicates there are certainly more snapshots to delete, but
2625 * if there comes a new one during processing, it may return 0. We don't mind,
2626 * because btrfs_commit_super will poke cleaner thread and it will process it a
2627 * few seconds later.
2628 */
2629int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info)
2630{
2631	struct btrfs_root *root;
2632	int ret;
 
2633
2634	spin_lock(&fs_info->trans_lock);
2635	if (list_empty(&fs_info->dead_roots)) {
2636		spin_unlock(&fs_info->trans_lock);
2637		return 0;
2638	}
2639	root = list_first_entry(&fs_info->dead_roots,
2640			struct btrfs_root, root_list);
2641	list_del_init(&root->root_list);
2642	spin_unlock(&fs_info->trans_lock);
2643
2644	btrfs_debug(fs_info, "cleaner removing %llu", root->root_key.objectid);
2645
2646	btrfs_kill_all_delayed_nodes(root);
2647
2648	if (btrfs_header_backref_rev(root->node) <
2649			BTRFS_MIXED_BACKREF_REV)
2650		ret = btrfs_drop_snapshot(root, 0, 0);
2651	else
2652		ret = btrfs_drop_snapshot(root, 1, 0);
2653
2654	btrfs_put_root(root);
2655	return (ret < 0) ? 0 : 1;
2656}
2657
2658/*
2659 * We only mark the transaction aborted and then set the file system read-only.
2660 * This will prevent new transactions from starting or trying to join this
2661 * one.
2662 *
2663 * This means that error recovery at the call site is limited to freeing
2664 * any local memory allocations and passing the error code up without
2665 * further cleanup. The transaction should complete as it normally would
2666 * in the call path but will return -EIO.
2667 *
2668 * We'll complete the cleanup in btrfs_end_transaction and
2669 * btrfs_commit_transaction.
2670 */
2671void __cold __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
2672				      const char *function,
2673				      unsigned int line, int error, bool first_hit)
2674{
2675	struct btrfs_fs_info *fs_info = trans->fs_info;
2676
2677	WRITE_ONCE(trans->aborted, error);
2678	WRITE_ONCE(trans->transaction->aborted, error);
2679	if (first_hit && error == -ENOSPC)
2680		btrfs_dump_space_info_for_trans_abort(fs_info);
2681	/* Wake up anybody who may be waiting on this transaction */
2682	wake_up(&fs_info->transaction_wait);
2683	wake_up(&fs_info->transaction_blocked_wait);
2684	__btrfs_handle_fs_error(fs_info, function, line, error, NULL);
2685}
2686
2687int __init btrfs_transaction_init(void)
2688{
2689	btrfs_trans_handle_cachep = kmem_cache_create("btrfs_trans_handle",
2690			sizeof(struct btrfs_trans_handle), 0,
2691			SLAB_TEMPORARY | SLAB_MEM_SPREAD, NULL);
2692	if (!btrfs_trans_handle_cachep)
2693		return -ENOMEM;
2694	return 0;
2695}
2696
2697void __cold btrfs_transaction_exit(void)
2698{
2699	kmem_cache_destroy(btrfs_trans_handle_cachep);
 
 
 
 
 
2700}
v5.14.15
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   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/writeback.h>
  10#include <linux/pagemap.h>
  11#include <linux/blkdev.h>
  12#include <linux/uuid.h>
 
  13#include "misc.h"
  14#include "ctree.h"
  15#include "disk-io.h"
  16#include "transaction.h"
  17#include "locking.h"
  18#include "tree-log.h"
  19#include "volumes.h"
  20#include "dev-replace.h"
  21#include "qgroup.h"
  22#include "block-group.h"
  23#include "space-info.h"
  24#include "zoned.h"
 
 
 
 
 
 
 
 
 
 
  25
  26#define BTRFS_ROOT_TRANS_TAG 0
  27
  28/*
  29 * Transaction states and transitions
  30 *
  31 * No running transaction (fs tree blocks are not modified)
  32 * |
  33 * | To next stage:
  34 * |  Call start_transaction() variants. Except btrfs_join_transaction_nostart().
  35 * V
  36 * Transaction N [[TRANS_STATE_RUNNING]]
  37 * |
  38 * | New trans handles can be attached to transaction N by calling all
  39 * | start_transaction() variants.
  40 * |
  41 * | To next stage:
  42 * |  Call btrfs_commit_transaction() on any trans handle attached to
  43 * |  transaction N
  44 * V
 
 
 
 
 
 
 
 
  45 * Transaction N [[TRANS_STATE_COMMIT_START]]
  46 * |
  47 * | Will wait for previous running transaction to completely finish if there
  48 * | is one
  49 * |
  50 * | Then one of the following happes:
  51 * | - Wait for all other trans handle holders to release.
  52 * |   The btrfs_commit_transaction() caller will do the commit work.
  53 * | - Wait for current transaction to be committed by others.
  54 * |   Other btrfs_commit_transaction() caller will do the commit work.
  55 * |
  56 * | At this stage, only btrfs_join_transaction*() variants can attach
  57 * | to this running transaction.
  58 * | All other variants will wait for current one to finish and attach to
  59 * | transaction N+1.
  60 * |
  61 * | To next stage:
  62 * |  Caller is chosen to commit transaction N, and all other trans handle
  63 * |  haven been released.
  64 * V
  65 * Transaction N [[TRANS_STATE_COMMIT_DOING]]
  66 * |
  67 * | The heavy lifting transaction work is started.
  68 * | From running delayed refs (modifying extent tree) to creating pending
  69 * | snapshots, running qgroups.
  70 * | In short, modify supporting trees to reflect modifications of subvolume
  71 * | trees.
  72 * |
  73 * | At this stage, all start_transaction() calls will wait for this
  74 * | transaction to finish and attach to transaction N+1.
  75 * |
  76 * | To next stage:
  77 * |  Until all supporting trees are updated.
  78 * V
  79 * Transaction N [[TRANS_STATE_UNBLOCKED]]
  80 * |						    Transaction N+1
  81 * | All needed trees are modified, thus we only    [[TRANS_STATE_RUNNING]]
  82 * | need to write them back to disk and update	    |
  83 * | super blocks.				    |
  84 * |						    |
  85 * | At this stage, new transaction is allowed to   |
  86 * | start.					    |
  87 * | All new start_transaction() calls will be	    |
  88 * | attached to transid N+1.			    |
  89 * |						    |
  90 * | To next stage:				    |
  91 * |  Until all tree blocks are super blocks are    |
  92 * |  written to block devices			    |
  93 * V						    |
  94 * Transaction N [[TRANS_STATE_COMPLETED]]	    V
  95 *   All tree blocks and super blocks are written.  Transaction N+1
  96 *   This transaction is finished and all its	    [[TRANS_STATE_COMMIT_START]]
  97 *   data structures will be cleaned up.	    | Life goes on
  98 */
  99static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
 100	[TRANS_STATE_RUNNING]		= 0U,
 
 101	[TRANS_STATE_COMMIT_START]	= (__TRANS_START | __TRANS_ATTACH),
 102	[TRANS_STATE_COMMIT_DOING]	= (__TRANS_START |
 103					   __TRANS_ATTACH |
 104					   __TRANS_JOIN |
 105					   __TRANS_JOIN_NOSTART),
 106	[TRANS_STATE_UNBLOCKED]		= (__TRANS_START |
 107					   __TRANS_ATTACH |
 108					   __TRANS_JOIN |
 109					   __TRANS_JOIN_NOLOCK |
 110					   __TRANS_JOIN_NOSTART),
 111	[TRANS_STATE_SUPER_COMMITTED]	= (__TRANS_START |
 112					   __TRANS_ATTACH |
 113					   __TRANS_JOIN |
 114					   __TRANS_JOIN_NOLOCK |
 115					   __TRANS_JOIN_NOSTART),
 116	[TRANS_STATE_COMPLETED]		= (__TRANS_START |
 117					   __TRANS_ATTACH |
 118					   __TRANS_JOIN |
 119					   __TRANS_JOIN_NOLOCK |
 120					   __TRANS_JOIN_NOSTART),
 121};
 122
 123void btrfs_put_transaction(struct btrfs_transaction *transaction)
 124{
 125	WARN_ON(refcount_read(&transaction->use_count) == 0);
 126	if (refcount_dec_and_test(&transaction->use_count)) {
 127		BUG_ON(!list_empty(&transaction->list));
 128		WARN_ON(!RB_EMPTY_ROOT(
 129				&transaction->delayed_refs.href_root.rb_root));
 130		WARN_ON(!RB_EMPTY_ROOT(
 131				&transaction->delayed_refs.dirty_extent_root));
 132		if (transaction->delayed_refs.pending_csums)
 133			btrfs_err(transaction->fs_info,
 134				  "pending csums is %llu",
 135				  transaction->delayed_refs.pending_csums);
 136		/*
 137		 * If any block groups are found in ->deleted_bgs then it's
 138		 * because the transaction was aborted and a commit did not
 139		 * happen (things failed before writing the new superblock
 140		 * and calling btrfs_finish_extent_commit()), so we can not
 141		 * discard the physical locations of the block groups.
 142		 */
 143		while (!list_empty(&transaction->deleted_bgs)) {
 144			struct btrfs_block_group *cache;
 145
 146			cache = list_first_entry(&transaction->deleted_bgs,
 147						 struct btrfs_block_group,
 148						 bg_list);
 149			list_del_init(&cache->bg_list);
 150			btrfs_unfreeze_block_group(cache);
 151			btrfs_put_block_group(cache);
 152		}
 153		WARN_ON(!list_empty(&transaction->dev_update_list));
 154		kfree(transaction);
 155	}
 156}
 157
 158static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
 159{
 160	struct btrfs_transaction *cur_trans = trans->transaction;
 161	struct btrfs_fs_info *fs_info = trans->fs_info;
 162	struct btrfs_root *root, *tmp;
 163	struct btrfs_caching_control *caching_ctl, *next;
 
 
 
 
 
 164
 165	down_write(&fs_info->commit_root_sem);
 
 
 
 
 166	list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
 167				 dirty_list) {
 168		list_del_init(&root->dirty_list);
 169		free_extent_buffer(root->commit_root);
 170		root->commit_root = btrfs_root_node(root);
 171		extent_io_tree_release(&root->dirty_log_pages);
 172		btrfs_qgroup_clean_swapped_blocks(root);
 173	}
 174
 175	/* We can free old roots now. */
 176	spin_lock(&cur_trans->dropped_roots_lock);
 177	while (!list_empty(&cur_trans->dropped_roots)) {
 178		root = list_first_entry(&cur_trans->dropped_roots,
 179					struct btrfs_root, root_list);
 180		list_del_init(&root->root_list);
 181		spin_unlock(&cur_trans->dropped_roots_lock);
 182		btrfs_free_log(trans, root);
 183		btrfs_drop_and_free_fs_root(fs_info, root);
 184		spin_lock(&cur_trans->dropped_roots_lock);
 185	}
 186	spin_unlock(&cur_trans->dropped_roots_lock);
 187
 188	/*
 189	 * We have to update the last_byte_to_unpin under the commit_root_sem,
 190	 * at the same time we swap out the commit roots.
 191	 *
 192	 * This is because we must have a real view of the last spot the caching
 193	 * kthreads were while caching.  Consider the following views of the
 194	 * extent tree for a block group
 195	 *
 196	 * commit root
 197	 * +----+----+----+----+----+----+----+
 198	 * |\\\\|    |\\\\|\\\\|    |\\\\|\\\\|
 199	 * +----+----+----+----+----+----+----+
 200	 * 0    1    2    3    4    5    6    7
 201	 *
 202	 * new commit root
 203	 * +----+----+----+----+----+----+----+
 204	 * |    |    |    |\\\\|    |    |\\\\|
 205	 * +----+----+----+----+----+----+----+
 206	 * 0    1    2    3    4    5    6    7
 207	 *
 208	 * If the cache_ctl->progress was at 3, then we are only allowed to
 209	 * unpin [0,1) and [2,3], because the caching thread has already
 210	 * processed those extents.  We are not allowed to unpin [5,6), because
 211	 * the caching thread will re-start it's search from 3, and thus find
 212	 * the hole from [4,6) to add to the free space cache.
 213	 */
 214	spin_lock(&fs_info->block_group_cache_lock);
 215	list_for_each_entry_safe(caching_ctl, next,
 216				 &fs_info->caching_block_groups, list) {
 217		struct btrfs_block_group *cache = caching_ctl->block_group;
 218
 219		if (btrfs_block_group_done(cache)) {
 220			cache->last_byte_to_unpin = (u64)-1;
 221			list_del_init(&caching_ctl->list);
 222			btrfs_put_caching_control(caching_ctl);
 223		} else {
 224			cache->last_byte_to_unpin = caching_ctl->progress;
 225		}
 226	}
 227	spin_unlock(&fs_info->block_group_cache_lock);
 228	up_write(&fs_info->commit_root_sem);
 229}
 230
 231static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 232					 unsigned int type)
 233{
 234	if (type & TRANS_EXTWRITERS)
 235		atomic_inc(&trans->num_extwriters);
 236}
 237
 238static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 239					 unsigned int type)
 240{
 241	if (type & TRANS_EXTWRITERS)
 242		atomic_dec(&trans->num_extwriters);
 243}
 244
 245static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 246					  unsigned int type)
 247{
 248	atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 249}
 250
 251static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 252{
 253	return atomic_read(&trans->num_extwriters);
 254}
 255
 256/*
 257 * To be called after doing the chunk btree updates right after allocating a new
 258 * chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a
 259 * chunk after all chunk btree updates and after finishing the second phase of
 260 * chunk allocation (btrfs_create_pending_block_groups()) in case some block
 261 * group had its chunk item insertion delayed to the second phase.
 262 */
 263void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
 264{
 265	struct btrfs_fs_info *fs_info = trans->fs_info;
 266
 267	if (!trans->chunk_bytes_reserved)
 268		return;
 269
 270	btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,
 271				trans->chunk_bytes_reserved, NULL);
 272	trans->chunk_bytes_reserved = 0;
 273}
 274
 275/*
 276 * either allocate a new transaction or hop into the existing one
 277 */
 278static noinline int join_transaction(struct btrfs_fs_info *fs_info,
 279				     unsigned int type)
 280{
 281	struct btrfs_transaction *cur_trans;
 282
 283	spin_lock(&fs_info->trans_lock);
 284loop:
 285	/* The file system has been taken offline. No new transactions. */
 286	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 287		spin_unlock(&fs_info->trans_lock);
 288		return -EROFS;
 289	}
 290
 291	cur_trans = fs_info->running_transaction;
 292	if (cur_trans) {
 293		if (TRANS_ABORTED(cur_trans)) {
 294			spin_unlock(&fs_info->trans_lock);
 295			return cur_trans->aborted;
 296		}
 297		if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 298			spin_unlock(&fs_info->trans_lock);
 299			return -EBUSY;
 300		}
 301		refcount_inc(&cur_trans->use_count);
 302		atomic_inc(&cur_trans->num_writers);
 303		extwriter_counter_inc(cur_trans, type);
 304		spin_unlock(&fs_info->trans_lock);
 
 
 305		return 0;
 306	}
 307	spin_unlock(&fs_info->trans_lock);
 308
 309	/*
 310	 * If we are ATTACH, we just want to catch the current transaction,
 311	 * and commit it. If there is no transaction, just return ENOENT.
 
 312	 */
 313	if (type == TRANS_ATTACH)
 314		return -ENOENT;
 315
 316	/*
 317	 * JOIN_NOLOCK only happens during the transaction commit, so
 318	 * it is impossible that ->running_transaction is NULL
 319	 */
 320	BUG_ON(type == TRANS_JOIN_NOLOCK);
 321
 322	cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
 323	if (!cur_trans)
 324		return -ENOMEM;
 325
 
 
 
 326	spin_lock(&fs_info->trans_lock);
 327	if (fs_info->running_transaction) {
 328		/*
 329		 * someone started a transaction after we unlocked.  Make sure
 330		 * to redo the checks above
 331		 */
 
 
 332		kfree(cur_trans);
 333		goto loop;
 334	} else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 335		spin_unlock(&fs_info->trans_lock);
 
 
 336		kfree(cur_trans);
 337		return -EROFS;
 338	}
 339
 340	cur_trans->fs_info = fs_info;
 341	atomic_set(&cur_trans->pending_ordered, 0);
 342	init_waitqueue_head(&cur_trans->pending_wait);
 343	atomic_set(&cur_trans->num_writers, 1);
 344	extwriter_counter_init(cur_trans, type);
 345	init_waitqueue_head(&cur_trans->writer_wait);
 346	init_waitqueue_head(&cur_trans->commit_wait);
 347	cur_trans->state = TRANS_STATE_RUNNING;
 348	/*
 349	 * One for this trans handle, one so it will live on until we
 350	 * commit the transaction.
 351	 */
 352	refcount_set(&cur_trans->use_count, 2);
 353	cur_trans->flags = 0;
 354	cur_trans->start_time = ktime_get_seconds();
 355
 356	memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
 357
 358	cur_trans->delayed_refs.href_root = RB_ROOT_CACHED;
 359	cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
 360	atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 361
 362	/*
 363	 * although the tree mod log is per file system and not per transaction,
 364	 * the log must never go across transaction boundaries.
 365	 */
 366	smp_mb();
 367	if (!list_empty(&fs_info->tree_mod_seq_list))
 368		WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
 369	if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 370		WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
 371	atomic64_set(&fs_info->tree_mod_seq, 0);
 372
 373	spin_lock_init(&cur_trans->delayed_refs.lock);
 374
 375	INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 376	INIT_LIST_HEAD(&cur_trans->dev_update_list);
 377	INIT_LIST_HEAD(&cur_trans->switch_commits);
 378	INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 379	INIT_LIST_HEAD(&cur_trans->io_bgs);
 380	INIT_LIST_HEAD(&cur_trans->dropped_roots);
 381	mutex_init(&cur_trans->cache_write_mutex);
 382	spin_lock_init(&cur_trans->dirty_bgs_lock);
 383	INIT_LIST_HEAD(&cur_trans->deleted_bgs);
 384	spin_lock_init(&cur_trans->dropped_roots_lock);
 385	INIT_LIST_HEAD(&cur_trans->releasing_ebs);
 386	spin_lock_init(&cur_trans->releasing_ebs_lock);
 387	list_add_tail(&cur_trans->list, &fs_info->trans_list);
 388	extent_io_tree_init(fs_info, &cur_trans->dirty_pages,
 389			IO_TREE_TRANS_DIRTY_PAGES, fs_info->btree_inode);
 390	extent_io_tree_init(fs_info, &cur_trans->pinned_extents,
 391			IO_TREE_FS_PINNED_EXTENTS, NULL);
 392	fs_info->generation++;
 393	cur_trans->transid = fs_info->generation;
 394	fs_info->running_transaction = cur_trans;
 395	cur_trans->aborted = 0;
 396	spin_unlock(&fs_info->trans_lock);
 397
 398	return 0;
 399}
 400
 401/*
 402 * This does all the record keeping required to make sure that a shareable root
 403 * is properly recorded in a given transaction.  This is required to make sure
 404 * the old root from before we joined the transaction is deleted when the
 405 * transaction commits.
 406 */
 407static int record_root_in_trans(struct btrfs_trans_handle *trans,
 408			       struct btrfs_root *root,
 409			       int force)
 410{
 411	struct btrfs_fs_info *fs_info = root->fs_info;
 412	int ret = 0;
 413
 414	if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 415	    root->last_trans < trans->transid) || force) {
 416		WARN_ON(root == fs_info->extent_root);
 417		WARN_ON(!force && root->commit_root != root->node);
 418
 419		/*
 420		 * see below for IN_TRANS_SETUP usage rules
 421		 * we have the reloc mutex held now, so there
 422		 * is only one writer in this function
 423		 */
 424		set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 425
 426		/* make sure readers find IN_TRANS_SETUP before
 427		 * they find our root->last_trans update
 428		 */
 429		smp_wmb();
 430
 431		spin_lock(&fs_info->fs_roots_radix_lock);
 432		if (root->last_trans == trans->transid && !force) {
 433			spin_unlock(&fs_info->fs_roots_radix_lock);
 434			return 0;
 435		}
 436		radix_tree_tag_set(&fs_info->fs_roots_radix,
 437				   (unsigned long)root->root_key.objectid,
 438				   BTRFS_ROOT_TRANS_TAG);
 439		spin_unlock(&fs_info->fs_roots_radix_lock);
 440		root->last_trans = trans->transid;
 441
 442		/* this is pretty tricky.  We don't want to
 443		 * take the relocation lock in btrfs_record_root_in_trans
 444		 * unless we're really doing the first setup for this root in
 445		 * this transaction.
 446		 *
 447		 * Normally we'd use root->last_trans as a flag to decide
 448		 * if we want to take the expensive mutex.
 449		 *
 450		 * But, we have to set root->last_trans before we
 451		 * init the relocation root, otherwise, we trip over warnings
 452		 * in ctree.c.  The solution used here is to flag ourselves
 453		 * with root IN_TRANS_SETUP.  When this is 1, we're still
 454		 * fixing up the reloc trees and everyone must wait.
 455		 *
 456		 * When this is zero, they can trust root->last_trans and fly
 457		 * through btrfs_record_root_in_trans without having to take the
 458		 * lock.  smp_wmb() makes sure that all the writes above are
 459		 * done before we pop in the zero below
 460		 */
 461		ret = btrfs_init_reloc_root(trans, root);
 462		smp_mb__before_atomic();
 463		clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 464	}
 465	return ret;
 466}
 467
 468
 469void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
 470			    struct btrfs_root *root)
 471{
 472	struct btrfs_fs_info *fs_info = root->fs_info;
 473	struct btrfs_transaction *cur_trans = trans->transaction;
 474
 475	/* Add ourselves to the transaction dropped list */
 476	spin_lock(&cur_trans->dropped_roots_lock);
 477	list_add_tail(&root->root_list, &cur_trans->dropped_roots);
 478	spin_unlock(&cur_trans->dropped_roots_lock);
 479
 480	/* Make sure we don't try to update the root at commit time */
 481	spin_lock(&fs_info->fs_roots_radix_lock);
 482	radix_tree_tag_clear(&fs_info->fs_roots_radix,
 483			     (unsigned long)root->root_key.objectid,
 484			     BTRFS_ROOT_TRANS_TAG);
 485	spin_unlock(&fs_info->fs_roots_radix_lock);
 486}
 487
 488int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 489			       struct btrfs_root *root)
 490{
 491	struct btrfs_fs_info *fs_info = root->fs_info;
 492	int ret;
 493
 494	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 495		return 0;
 496
 497	/*
 498	 * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 499	 * and barriers
 500	 */
 501	smp_rmb();
 502	if (root->last_trans == trans->transid &&
 503	    !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 504		return 0;
 505
 506	mutex_lock(&fs_info->reloc_mutex);
 507	ret = record_root_in_trans(trans, root, 0);
 508	mutex_unlock(&fs_info->reloc_mutex);
 509
 510	return ret;
 511}
 512
 513static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 514{
 515	return (trans->state >= TRANS_STATE_COMMIT_START &&
 516		trans->state < TRANS_STATE_UNBLOCKED &&
 517		!TRANS_ABORTED(trans));
 518}
 519
 520/* wait for commit against the current transaction to become unblocked
 521 * when this is done, it is safe to start a new transaction, but the current
 522 * transaction might not be fully on disk.
 523 */
 524static void wait_current_trans(struct btrfs_fs_info *fs_info)
 525{
 526	struct btrfs_transaction *cur_trans;
 527
 528	spin_lock(&fs_info->trans_lock);
 529	cur_trans = fs_info->running_transaction;
 530	if (cur_trans && is_transaction_blocked(cur_trans)) {
 531		refcount_inc(&cur_trans->use_count);
 532		spin_unlock(&fs_info->trans_lock);
 533
 
 534		wait_event(fs_info->transaction_wait,
 535			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 536			   TRANS_ABORTED(cur_trans));
 537		btrfs_put_transaction(cur_trans);
 538	} else {
 539		spin_unlock(&fs_info->trans_lock);
 540	}
 541}
 542
 543static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
 544{
 545	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
 546		return 0;
 547
 548	if (type == TRANS_START)
 549		return 1;
 550
 551	return 0;
 552}
 553
 554static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 555{
 556	struct btrfs_fs_info *fs_info = root->fs_info;
 557
 558	if (!fs_info->reloc_ctl ||
 559	    !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
 560	    root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 561	    root->reloc_root)
 562		return false;
 563
 564	return true;
 565}
 566
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 567static struct btrfs_trans_handle *
 568start_transaction(struct btrfs_root *root, unsigned int num_items,
 569		  unsigned int type, enum btrfs_reserve_flush_enum flush,
 570		  bool enforce_qgroups)
 571{
 572	struct btrfs_fs_info *fs_info = root->fs_info;
 573	struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
 
 574	struct btrfs_trans_handle *h;
 575	struct btrfs_transaction *cur_trans;
 576	u64 num_bytes = 0;
 577	u64 qgroup_reserved = 0;
 
 578	bool reloc_reserved = false;
 579	bool do_chunk_alloc = false;
 580	int ret;
 581
 582	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
 583		return ERR_PTR(-EROFS);
 584
 585	if (current->journal_info) {
 586		WARN_ON(type & TRANS_EXTWRITERS);
 587		h = current->journal_info;
 588		refcount_inc(&h->use_count);
 589		WARN_ON(refcount_read(&h->use_count) > 2);
 590		h->orig_rsv = h->block_rsv;
 591		h->block_rsv = NULL;
 592		goto got_it;
 593	}
 594
 595	/*
 596	 * Do the reservation before we join the transaction so we can do all
 597	 * the appropriate flushing if need be.
 598	 */
 599	if (num_items && root != fs_info->chunk_root) {
 600		struct btrfs_block_rsv *rsv = &fs_info->trans_block_rsv;
 601		u64 delayed_refs_bytes = 0;
 602
 603		qgroup_reserved = num_items * fs_info->nodesize;
 604		ret = btrfs_qgroup_reserve_meta_pertrans(root, qgroup_reserved,
 605				enforce_qgroups);
 
 
 
 
 
 606		if (ret)
 607			return ERR_PTR(ret);
 608
 
 609		/*
 610		 * We want to reserve all the bytes we may need all at once, so
 611		 * we only do 1 enospc flushing cycle per transaction start.  We
 612		 * accomplish this by simply assuming we'll do 2 x num_items
 613		 * worth of delayed refs updates in this trans handle, and
 614		 * refill that amount for whatever is missing in the reserve.
 
 615		 */
 616		num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);
 617		if (flush == BTRFS_RESERVE_FLUSH_ALL &&
 618		    delayed_refs_rsv->full == 0) {
 619			delayed_refs_bytes = num_bytes;
 620			num_bytes <<= 1;
 621		}
 622
 623		/*
 624		 * Do the reservation for the relocation root creation
 625		 */
 626		if (need_reserve_reloc_root(root)) {
 627			num_bytes += fs_info->nodesize;
 628			reloc_reserved = true;
 629		}
 630
 631		ret = btrfs_block_rsv_add(root, rsv, num_bytes, flush);
 
 632		if (ret)
 633			goto reserve_fail;
 634		if (delayed_refs_bytes) {
 635			btrfs_migrate_to_delayed_refs_rsv(fs_info, rsv,
 636							  delayed_refs_bytes);
 637			num_bytes -= delayed_refs_bytes;
 638		}
 639
 640		if (rsv->space_info->force_alloc)
 
 
 641			do_chunk_alloc = true;
 642	} else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&
 643		   !delayed_refs_rsv->full) {
 644		/*
 645		 * Some people call with btrfs_start_transaction(root, 0)
 646		 * because they can be throttled, but have some other mechanism
 647		 * for reserving space.  We still want these guys to refill the
 648		 * delayed block_rsv so just add 1 items worth of reservation
 649		 * here.
 650		 */
 651		ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);
 652		if (ret)
 653			goto reserve_fail;
 654	}
 655again:
 656	h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
 657	if (!h) {
 658		ret = -ENOMEM;
 659		goto alloc_fail;
 660	}
 661
 662	/*
 663	 * If we are JOIN_NOLOCK we're already committing a transaction and
 664	 * waiting on this guy, so we don't need to do the sb_start_intwrite
 665	 * because we're already holding a ref.  We need this because we could
 666	 * have raced in and did an fsync() on a file which can kick a commit
 667	 * and then we deadlock with somebody doing a freeze.
 668	 *
 669	 * If we are ATTACH, it means we just want to catch the current
 670	 * transaction and commit it, so we needn't do sb_start_intwrite(). 
 671	 */
 672	if (type & __TRANS_FREEZABLE)
 673		sb_start_intwrite(fs_info->sb);
 674
 675	if (may_wait_transaction(fs_info, type))
 676		wait_current_trans(fs_info);
 677
 678	do {
 679		ret = join_transaction(fs_info, type);
 680		if (ret == -EBUSY) {
 681			wait_current_trans(fs_info);
 682			if (unlikely(type == TRANS_ATTACH ||
 683				     type == TRANS_JOIN_NOSTART))
 684				ret = -ENOENT;
 685		}
 686	} while (ret == -EBUSY);
 687
 688	if (ret < 0)
 689		goto join_fail;
 690
 691	cur_trans = fs_info->running_transaction;
 692
 693	h->transid = cur_trans->transid;
 694	h->transaction = cur_trans;
 695	h->root = root;
 696	refcount_set(&h->use_count, 1);
 697	h->fs_info = root->fs_info;
 698
 699	h->type = type;
 700	INIT_LIST_HEAD(&h->new_bgs);
 
 701
 702	smp_mb();
 703	if (cur_trans->state >= TRANS_STATE_COMMIT_START &&
 704	    may_wait_transaction(fs_info, type)) {
 705		current->journal_info = h;
 706		btrfs_commit_transaction(h);
 707		goto again;
 708	}
 709
 710	if (num_bytes) {
 711		trace_btrfs_space_reservation(fs_info, "transaction",
 712					      h->transid, num_bytes, 1);
 713		h->block_rsv = &fs_info->trans_block_rsv;
 714		h->bytes_reserved = num_bytes;
 
 
 
 
 
 
 
 
 
 715		h->reloc_reserved = reloc_reserved;
 716	}
 717
 
 
 
 
 
 
 
 
 718got_it:
 719	if (!current->journal_info)
 720		current->journal_info = h;
 721
 722	/*
 723	 * If the space_info is marked ALLOC_FORCE then we'll get upgraded to
 724	 * ALLOC_FORCE the first run through, and then we won't allocate for
 725	 * anybody else who races in later.  We don't care about the return
 726	 * value here.
 727	 */
 728	if (do_chunk_alloc && num_bytes) {
 729		u64 flags = h->block_rsv->space_info->flags;
 730
 731		btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),
 732				  CHUNK_ALLOC_NO_FORCE);
 733	}
 734
 735	/*
 736	 * btrfs_record_root_in_trans() needs to alloc new extents, and may
 737	 * call btrfs_join_transaction() while we're also starting a
 738	 * transaction.
 739	 *
 740	 * Thus it need to be called after current->journal_info initialized,
 741	 * or we can deadlock.
 742	 */
 743	ret = btrfs_record_root_in_trans(h, root);
 744	if (ret) {
 745		/*
 746		 * The transaction handle is fully initialized and linked with
 747		 * other structures so it needs to be ended in case of errors,
 748		 * not just freed.
 749		 */
 750		btrfs_end_transaction(h);
 751		return ERR_PTR(ret);
 752	}
 753
 754	return h;
 755
 756join_fail:
 757	if (type & __TRANS_FREEZABLE)
 758		sb_end_intwrite(fs_info->sb);
 759	kmem_cache_free(btrfs_trans_handle_cachep, h);
 760alloc_fail:
 761	if (num_bytes)
 762		btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
 763					num_bytes, NULL);
 
 
 764reserve_fail:
 765	btrfs_qgroup_free_meta_pertrans(root, qgroup_reserved);
 766	return ERR_PTR(ret);
 767}
 768
 769struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 770						   unsigned int num_items)
 771{
 772	return start_transaction(root, num_items, TRANS_START,
 773				 BTRFS_RESERVE_FLUSH_ALL, true);
 774}
 775
 776struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 777					struct btrfs_root *root,
 778					unsigned int num_items)
 779{
 780	return start_transaction(root, num_items, TRANS_START,
 781				 BTRFS_RESERVE_FLUSH_ALL_STEAL, false);
 782}
 783
 784struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 785{
 786	return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
 787				 true);
 788}
 789
 790struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)
 791{
 792	return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
 793				 BTRFS_RESERVE_NO_FLUSH, true);
 794}
 795
 796/*
 797 * Similar to regular join but it never starts a transaction when none is
 798 * running or after waiting for the current one to finish.
 
 
 
 799 */
 800struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)
 801{
 802	return start_transaction(root, 0, TRANS_JOIN_NOSTART,
 803				 BTRFS_RESERVE_NO_FLUSH, true);
 804}
 805
 806/*
 807 * btrfs_attach_transaction() - catch the running transaction
 808 *
 809 * It is used when we want to commit the current the transaction, but
 810 * don't want to start a new one.
 811 *
 812 * Note: If this function return -ENOENT, it just means there is no
 813 * running transaction. But it is possible that the inactive transaction
 814 * is still in the memory, not fully on disk. If you hope there is no
 815 * inactive transaction in the fs when -ENOENT is returned, you should
 816 * invoke
 817 *     btrfs_attach_transaction_barrier()
 818 */
 819struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 820{
 821	return start_transaction(root, 0, TRANS_ATTACH,
 822				 BTRFS_RESERVE_NO_FLUSH, true);
 823}
 824
 825/*
 826 * btrfs_attach_transaction_barrier() - catch the running transaction
 827 *
 828 * It is similar to the above function, the difference is this one
 829 * will wait for all the inactive transactions until they fully
 830 * complete.
 831 */
 832struct btrfs_trans_handle *
 833btrfs_attach_transaction_barrier(struct btrfs_root *root)
 834{
 835	struct btrfs_trans_handle *trans;
 836
 837	trans = start_transaction(root, 0, TRANS_ATTACH,
 838				  BTRFS_RESERVE_NO_FLUSH, true);
 839	if (trans == ERR_PTR(-ENOENT))
 840		btrfs_wait_for_commit(root->fs_info, 0);
 
 
 
 
 
 841
 842	return trans;
 843}
 844
 845/* Wait for a transaction commit to reach at least the given state. */
 846static noinline void wait_for_commit(struct btrfs_transaction *commit,
 847				     const enum btrfs_trans_state min_state)
 848{
 849	wait_event(commit->commit_wait, commit->state >= min_state);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 850}
 851
 852int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
 853{
 854	struct btrfs_transaction *cur_trans = NULL, *t;
 855	int ret = 0;
 856
 857	if (transid) {
 858		if (transid <= fs_info->last_trans_committed)
 859			goto out;
 860
 861		/* find specified transaction */
 862		spin_lock(&fs_info->trans_lock);
 863		list_for_each_entry(t, &fs_info->trans_list, list) {
 864			if (t->transid == transid) {
 865				cur_trans = t;
 866				refcount_inc(&cur_trans->use_count);
 867				ret = 0;
 868				break;
 869			}
 870			if (t->transid > transid) {
 871				ret = 0;
 872				break;
 873			}
 874		}
 875		spin_unlock(&fs_info->trans_lock);
 876
 877		/*
 878		 * The specified transaction doesn't exist, or we
 879		 * raced with btrfs_commit_transaction
 880		 */
 881		if (!cur_trans) {
 882			if (transid > fs_info->last_trans_committed)
 883				ret = -EINVAL;
 884			goto out;
 885		}
 886	} else {
 887		/* find newest transaction that is committing | committed */
 888		spin_lock(&fs_info->trans_lock);
 889		list_for_each_entry_reverse(t, &fs_info->trans_list,
 890					    list) {
 891			if (t->state >= TRANS_STATE_COMMIT_START) {
 892				if (t->state == TRANS_STATE_COMPLETED)
 893					break;
 894				cur_trans = t;
 895				refcount_inc(&cur_trans->use_count);
 896				break;
 897			}
 898		}
 899		spin_unlock(&fs_info->trans_lock);
 900		if (!cur_trans)
 901			goto out;  /* nothing committing|committed */
 902	}
 903
 904	wait_for_commit(cur_trans, TRANS_STATE_COMPLETED);
 
 905	btrfs_put_transaction(cur_trans);
 906out:
 907	return ret;
 908}
 909
 910void btrfs_throttle(struct btrfs_fs_info *fs_info)
 911{
 912	wait_current_trans(fs_info);
 913}
 914
 915static bool should_end_transaction(struct btrfs_trans_handle *trans)
 916{
 917	struct btrfs_fs_info *fs_info = trans->fs_info;
 918
 919	if (btrfs_check_space_for_delayed_refs(fs_info))
 920		return true;
 921
 922	return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5);
 923}
 924
 925bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
 926{
 927	struct btrfs_transaction *cur_trans = trans->transaction;
 928
 929	if (cur_trans->state >= TRANS_STATE_COMMIT_START ||
 930	    test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags))
 931		return true;
 932
 933	return should_end_transaction(trans);
 
 
 
 934}
 935
 936static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
 937
 938{
 939	struct btrfs_fs_info *fs_info = trans->fs_info;
 940
 941	if (!trans->block_rsv) {
 942		ASSERT(!trans->bytes_reserved);
 
 943		return;
 944	}
 945
 946	if (!trans->bytes_reserved)
 
 947		return;
 
 948
 949	ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
 950	trace_btrfs_space_reservation(fs_info, "transaction",
 951				      trans->transid, trans->bytes_reserved, 0);
 952	btrfs_block_rsv_release(fs_info, trans->block_rsv,
 953				trans->bytes_reserved, NULL);
 954	trans->bytes_reserved = 0;
 
 
 
 
 
 
 
 
 
 
 955}
 956
 957static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 958				   int throttle)
 959{
 960	struct btrfs_fs_info *info = trans->fs_info;
 961	struct btrfs_transaction *cur_trans = trans->transaction;
 962	int err = 0;
 963
 964	if (refcount_read(&trans->use_count) > 1) {
 965		refcount_dec(&trans->use_count);
 966		trans->block_rsv = trans->orig_rsv;
 967		return 0;
 968	}
 969
 970	btrfs_trans_release_metadata(trans);
 971	trans->block_rsv = NULL;
 972
 973	btrfs_create_pending_block_groups(trans);
 974
 975	btrfs_trans_release_chunk_metadata(trans);
 976
 977	if (trans->type & __TRANS_FREEZABLE)
 978		sb_end_intwrite(info->sb);
 979
 980	WARN_ON(cur_trans != info->running_transaction);
 981	WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 982	atomic_dec(&cur_trans->num_writers);
 983	extwriter_counter_dec(cur_trans, trans->type);
 984
 985	cond_wake_up(&cur_trans->writer_wait);
 
 
 
 
 986	btrfs_put_transaction(cur_trans);
 987
 988	if (current->journal_info == trans)
 989		current->journal_info = NULL;
 990
 991	if (throttle)
 992		btrfs_run_delayed_iputs(info);
 993
 994	if (TRANS_ABORTED(trans) ||
 995	    test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
 996		wake_up_process(info->transaction_kthread);
 997		if (TRANS_ABORTED(trans))
 998			err = trans->aborted;
 999		else
1000			err = -EROFS;
1001	}
1002
1003	kmem_cache_free(btrfs_trans_handle_cachep, trans);
1004	return err;
1005}
1006
1007int btrfs_end_transaction(struct btrfs_trans_handle *trans)
1008{
1009	return __btrfs_end_transaction(trans, 0);
1010}
1011
1012int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
1013{
1014	return __btrfs_end_transaction(trans, 1);
1015}
1016
1017/*
1018 * when btree blocks are allocated, they have some corresponding bits set for
1019 * them in one of two extent_io trees.  This is used to make sure all of
1020 * those extents are sent to disk but does not wait on them
1021 */
1022int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
1023			       struct extent_io_tree *dirty_pages, int mark)
1024{
1025	int err = 0;
1026	int werr = 0;
1027	struct address_space *mapping = fs_info->btree_inode->i_mapping;
1028	struct extent_state *cached_state = NULL;
1029	u64 start = 0;
1030	u64 end;
1031
1032	atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers);
1033	while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1034				      mark, &cached_state)) {
1035		bool wait_writeback = false;
1036
1037		err = convert_extent_bit(dirty_pages, start, end,
1038					 EXTENT_NEED_WAIT,
1039					 mark, &cached_state);
1040		/*
1041		 * convert_extent_bit can return -ENOMEM, which is most of the
1042		 * time a temporary error. So when it happens, ignore the error
1043		 * and wait for writeback of this range to finish - because we
1044		 * failed to set the bit EXTENT_NEED_WAIT for the range, a call
1045		 * to __btrfs_wait_marked_extents() would not know that
1046		 * writeback for this range started and therefore wouldn't
1047		 * wait for it to finish - we don't want to commit a
1048		 * superblock that points to btree nodes/leafs for which
1049		 * writeback hasn't finished yet (and without errors).
1050		 * We cleanup any entries left in the io tree when committing
1051		 * the transaction (through extent_io_tree_release()).
1052		 */
1053		if (err == -ENOMEM) {
1054			err = 0;
1055			wait_writeback = true;
1056		}
1057		if (!err)
1058			err = filemap_fdatawrite_range(mapping, start, end);
1059		if (err)
1060			werr = err;
1061		else if (wait_writeback)
1062			werr = filemap_fdatawait_range(mapping, start, end);
1063		free_extent_state(cached_state);
1064		cached_state = NULL;
1065		cond_resched();
1066		start = end + 1;
1067	}
1068	atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers);
1069	return werr;
1070}
1071
1072/*
1073 * when btree blocks are allocated, they have some corresponding bits set for
1074 * them in one of two extent_io trees.  This is used to make sure all of
1075 * those extents are on disk for transaction or log commit.  We wait
1076 * on all the pages and clear them from the dirty pages state tree
1077 */
1078static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
1079				       struct extent_io_tree *dirty_pages)
1080{
1081	int err = 0;
1082	int werr = 0;
1083	struct address_space *mapping = fs_info->btree_inode->i_mapping;
1084	struct extent_state *cached_state = NULL;
1085	u64 start = 0;
1086	u64 end;
1087
1088	while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1089				      EXTENT_NEED_WAIT, &cached_state)) {
1090		/*
1091		 * Ignore -ENOMEM errors returned by clear_extent_bit().
1092		 * When committing the transaction, we'll remove any entries
1093		 * left in the io tree. For a log commit, we don't remove them
1094		 * after committing the log because the tree can be accessed
1095		 * concurrently - we do it only at transaction commit time when
1096		 * it's safe to do it (through extent_io_tree_release()).
1097		 */
1098		err = clear_extent_bit(dirty_pages, start, end,
1099				       EXTENT_NEED_WAIT, 0, 0, &cached_state);
1100		if (err == -ENOMEM)
1101			err = 0;
1102		if (!err)
1103			err = filemap_fdatawait_range(mapping, start, end);
1104		if (err)
1105			werr = err;
1106		free_extent_state(cached_state);
1107		cached_state = NULL;
1108		cond_resched();
1109		start = end + 1;
1110	}
1111	if (err)
1112		werr = err;
1113	return werr;
1114}
1115
1116static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1117		       struct extent_io_tree *dirty_pages)
1118{
1119	bool errors = false;
1120	int err;
1121
1122	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1123	if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1124		errors = true;
1125
1126	if (errors && !err)
1127		err = -EIO;
1128	return err;
1129}
1130
1131int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1132{
1133	struct btrfs_fs_info *fs_info = log_root->fs_info;
1134	struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1135	bool errors = false;
1136	int err;
1137
1138	ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1139
1140	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1141	if ((mark & EXTENT_DIRTY) &&
1142	    test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1143		errors = true;
1144
1145	if ((mark & EXTENT_NEW) &&
1146	    test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1147		errors = true;
1148
1149	if (errors && !err)
1150		err = -EIO;
1151	return err;
1152}
1153
1154/*
1155 * When btree blocks are allocated the corresponding extents are marked dirty.
1156 * This function ensures such extents are persisted on disk for transaction or
1157 * log commit.
1158 *
1159 * @trans: transaction whose dirty pages we'd like to write
1160 */
1161static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1162{
1163	int ret;
1164	int ret2;
1165	struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1166	struct btrfs_fs_info *fs_info = trans->fs_info;
1167	struct blk_plug plug;
1168
1169	blk_start_plug(&plug);
1170	ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1171	blk_finish_plug(&plug);
1172	ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1173
1174	extent_io_tree_release(&trans->transaction->dirty_pages);
1175
1176	if (ret)
1177		return ret;
1178	else if (ret2)
1179		return ret2;
1180	else
1181		return 0;
1182}
1183
1184/*
1185 * this is used to update the root pointer in the tree of tree roots.
1186 *
1187 * But, in the case of the extent allocation tree, updating the root
1188 * pointer may allocate blocks which may change the root of the extent
1189 * allocation tree.
1190 *
1191 * So, this loops and repeats and makes sure the cowonly root didn't
1192 * change while the root pointer was being updated in the metadata.
1193 */
1194static int update_cowonly_root(struct btrfs_trans_handle *trans,
1195			       struct btrfs_root *root)
1196{
1197	int ret;
1198	u64 old_root_bytenr;
1199	u64 old_root_used;
1200	struct btrfs_fs_info *fs_info = root->fs_info;
1201	struct btrfs_root *tree_root = fs_info->tree_root;
1202
1203	old_root_used = btrfs_root_used(&root->root_item);
1204
1205	while (1) {
1206		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1207		if (old_root_bytenr == root->node->start &&
1208		    old_root_used == btrfs_root_used(&root->root_item))
1209			break;
1210
1211		btrfs_set_root_node(&root->root_item, root->node);
1212		ret = btrfs_update_root(trans, tree_root,
1213					&root->root_key,
1214					&root->root_item);
1215		if (ret)
1216			return ret;
1217
1218		old_root_used = btrfs_root_used(&root->root_item);
1219	}
1220
1221	return 0;
1222}
1223
1224/*
1225 * update all the cowonly tree roots on disk
1226 *
1227 * The error handling in this function may not be obvious. Any of the
1228 * failures will cause the file system to go offline. We still need
1229 * to clean up the delayed refs.
1230 */
1231static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1232{
1233	struct btrfs_fs_info *fs_info = trans->fs_info;
1234	struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1235	struct list_head *io_bgs = &trans->transaction->io_bgs;
1236	struct list_head *next;
1237	struct extent_buffer *eb;
1238	int ret;
1239
 
 
 
 
 
 
1240	eb = btrfs_lock_root_node(fs_info->tree_root);
1241	ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1242			      0, &eb, BTRFS_NESTING_COW);
1243	btrfs_tree_unlock(eb);
1244	free_extent_buffer(eb);
1245
1246	if (ret)
1247		return ret;
1248
1249	ret = btrfs_run_dev_stats(trans);
1250	if (ret)
1251		return ret;
1252	ret = btrfs_run_dev_replace(trans);
1253	if (ret)
1254		return ret;
1255	ret = btrfs_run_qgroups(trans);
1256	if (ret)
1257		return ret;
1258
1259	ret = btrfs_setup_space_cache(trans);
1260	if (ret)
1261		return ret;
1262
1263again:
1264	while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1265		struct btrfs_root *root;
1266		next = fs_info->dirty_cowonly_roots.next;
1267		list_del_init(next);
1268		root = list_entry(next, struct btrfs_root, dirty_list);
1269		clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1270
1271		if (root != fs_info->extent_root)
1272			list_add_tail(&root->dirty_list,
1273				      &trans->transaction->switch_commits);
1274		ret = update_cowonly_root(trans, root);
1275		if (ret)
1276			return ret;
1277	}
1278
1279	/* Now flush any delayed refs generated by updating all of the roots */
1280	ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1281	if (ret)
1282		return ret;
1283
1284	while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1285		ret = btrfs_write_dirty_block_groups(trans);
1286		if (ret)
1287			return ret;
1288
1289		/*
1290		 * We're writing the dirty block groups, which could generate
1291		 * delayed refs, which could generate more dirty block groups,
1292		 * so we want to keep this flushing in this loop to make sure
1293		 * everything gets run.
1294		 */
1295		ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1296		if (ret)
1297			return ret;
1298	}
1299
1300	if (!list_empty(&fs_info->dirty_cowonly_roots))
1301		goto again;
1302
1303	list_add_tail(&fs_info->extent_root->dirty_list,
1304		      &trans->transaction->switch_commits);
1305
1306	/* Update dev-replace pointer once everything is committed */
1307	fs_info->dev_replace.committed_cursor_left =
1308		fs_info->dev_replace.cursor_left_last_write_of_item;
1309
1310	return 0;
1311}
1312
1313/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1314 * dead roots are old snapshots that need to be deleted.  This allocates
1315 * a dirty root struct and adds it into the list of dead roots that need to
1316 * be deleted
1317 */
1318void btrfs_add_dead_root(struct btrfs_root *root)
1319{
1320	struct btrfs_fs_info *fs_info = root->fs_info;
1321
1322	spin_lock(&fs_info->trans_lock);
1323	if (list_empty(&root->root_list)) {
1324		btrfs_grab_root(root);
1325		list_add_tail(&root->root_list, &fs_info->dead_roots);
 
 
 
 
 
1326	}
1327	spin_unlock(&fs_info->trans_lock);
1328}
1329
1330/*
1331 * update all the cowonly tree roots on disk
 
1332 */
1333static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1334{
1335	struct btrfs_fs_info *fs_info = trans->fs_info;
1336	struct btrfs_root *gang[8];
1337	int i;
1338	int ret;
1339
 
 
 
 
 
 
1340	spin_lock(&fs_info->fs_roots_radix_lock);
1341	while (1) {
1342		ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1343						 (void **)gang, 0,
1344						 ARRAY_SIZE(gang),
1345						 BTRFS_ROOT_TRANS_TAG);
1346		if (ret == 0)
1347			break;
1348		for (i = 0; i < ret; i++) {
1349			struct btrfs_root *root = gang[i];
1350			int ret2;
1351
 
 
 
 
 
 
 
 
1352			radix_tree_tag_clear(&fs_info->fs_roots_radix,
1353					(unsigned long)root->root_key.objectid,
1354					BTRFS_ROOT_TRANS_TAG);
1355			spin_unlock(&fs_info->fs_roots_radix_lock);
1356
1357			btrfs_free_log(trans, root);
1358			ret2 = btrfs_update_reloc_root(trans, root);
1359			if (ret2)
1360				return ret2;
1361
1362			/* see comments in should_cow_block() */
1363			clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1364			smp_mb__after_atomic();
1365
1366			if (root->commit_root != root->node) {
1367				list_add_tail(&root->dirty_list,
1368					&trans->transaction->switch_commits);
1369				btrfs_set_root_node(&root->root_item,
1370						    root->node);
1371			}
1372
1373			ret2 = btrfs_update_root(trans, fs_info->tree_root,
1374						&root->root_key,
1375						&root->root_item);
1376			if (ret2)
1377				return ret2;
1378			spin_lock(&fs_info->fs_roots_radix_lock);
1379			btrfs_qgroup_free_meta_all_pertrans(root);
1380		}
1381	}
1382	spin_unlock(&fs_info->fs_roots_radix_lock);
1383	return 0;
1384}
1385
1386/*
1387 * defrag a given btree.
1388 * Every leaf in the btree is read and defragged.
1389 */
1390int btrfs_defrag_root(struct btrfs_root *root)
1391{
1392	struct btrfs_fs_info *info = root->fs_info;
1393	struct btrfs_trans_handle *trans;
1394	int ret;
1395
1396	if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1397		return 0;
1398
1399	while (1) {
1400		trans = btrfs_start_transaction(root, 0);
1401		if (IS_ERR(trans)) {
1402			ret = PTR_ERR(trans);
1403			break;
1404		}
1405
1406		ret = btrfs_defrag_leaves(trans, root);
1407
1408		btrfs_end_transaction(trans);
1409		btrfs_btree_balance_dirty(info);
1410		cond_resched();
1411
1412		if (btrfs_fs_closing(info) || ret != -EAGAIN)
1413			break;
1414
1415		if (btrfs_defrag_cancelled(info)) {
1416			btrfs_debug(info, "defrag_root cancelled");
1417			ret = -EAGAIN;
1418			break;
1419		}
1420	}
1421	clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1422	return ret;
1423}
1424
1425/*
1426 * Do all special snapshot related qgroup dirty hack.
1427 *
1428 * Will do all needed qgroup inherit and dirty hack like switch commit
1429 * roots inside one transaction and write all btree into disk, to make
1430 * qgroup works.
1431 */
1432static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1433				   struct btrfs_root *src,
1434				   struct btrfs_root *parent,
1435				   struct btrfs_qgroup_inherit *inherit,
1436				   u64 dst_objectid)
1437{
1438	struct btrfs_fs_info *fs_info = src->fs_info;
1439	int ret;
1440
1441	/*
1442	 * Save some performance in the case that qgroups are not
1443	 * enabled. If this check races with the ioctl, rescan will
1444	 * kick in anyway.
1445	 */
1446	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
1447		return 0;
1448
1449	/*
1450	 * Ensure dirty @src will be committed.  Or, after coming
1451	 * commit_fs_roots() and switch_commit_roots(), any dirty but not
1452	 * recorded root will never be updated again, causing an outdated root
1453	 * item.
1454	 */
1455	ret = record_root_in_trans(trans, src, 1);
1456	if (ret)
1457		return ret;
1458
1459	/*
1460	 * btrfs_qgroup_inherit relies on a consistent view of the usage for the
1461	 * src root, so we must run the delayed refs here.
1462	 *
1463	 * However this isn't particularly fool proof, because there's no
1464	 * synchronization keeping us from changing the tree after this point
1465	 * before we do the qgroup_inherit, or even from making changes while
1466	 * we're doing the qgroup_inherit.  But that's a problem for the future,
1467	 * for now flush the delayed refs to narrow the race window where the
1468	 * qgroup counters could end up wrong.
1469	 */
1470	ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1471	if (ret) {
1472		btrfs_abort_transaction(trans, ret);
1473		return ret;
1474	}
1475
1476	/*
1477	 * We are going to commit transaction, see btrfs_commit_transaction()
1478	 * comment for reason locking tree_log_mutex
1479	 */
1480	mutex_lock(&fs_info->tree_log_mutex);
1481
1482	ret = commit_fs_roots(trans);
1483	if (ret)
1484		goto out;
1485	ret = btrfs_qgroup_account_extents(trans);
1486	if (ret < 0)
1487		goto out;
1488
1489	/* Now qgroup are all updated, we can inherit it to new qgroups */
1490	ret = btrfs_qgroup_inherit(trans, src->root_key.objectid, dst_objectid,
1491				   inherit);
1492	if (ret < 0)
1493		goto out;
1494
1495	/*
1496	 * Now we do a simplified commit transaction, which will:
1497	 * 1) commit all subvolume and extent tree
1498	 *    To ensure all subvolume and extent tree have a valid
1499	 *    commit_root to accounting later insert_dir_item()
1500	 * 2) write all btree blocks onto disk
1501	 *    This is to make sure later btree modification will be cowed
1502	 *    Or commit_root can be populated and cause wrong qgroup numbers
1503	 * In this simplified commit, we don't really care about other trees
1504	 * like chunk and root tree, as they won't affect qgroup.
1505	 * And we don't write super to avoid half committed status.
1506	 */
1507	ret = commit_cowonly_roots(trans);
1508	if (ret)
1509		goto out;
1510	switch_commit_roots(trans);
1511	ret = btrfs_write_and_wait_transaction(trans);
1512	if (ret)
1513		btrfs_handle_fs_error(fs_info, ret,
1514			"Error while writing out transaction for qgroup");
1515
1516out:
1517	mutex_unlock(&fs_info->tree_log_mutex);
1518
1519	/*
1520	 * Force parent root to be updated, as we recorded it before so its
1521	 * last_trans == cur_transid.
1522	 * Or it won't be committed again onto disk after later
1523	 * insert_dir_item()
1524	 */
1525	if (!ret)
1526		ret = record_root_in_trans(trans, parent, 1);
1527	return ret;
1528}
1529
1530/*
1531 * new snapshots need to be created at a very specific time in the
1532 * transaction commit.  This does the actual creation.
1533 *
1534 * Note:
1535 * If the error which may affect the commitment of the current transaction
1536 * happens, we should return the error number. If the error which just affect
1537 * the creation of the pending snapshots, just return 0.
1538 */
1539static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1540				   struct btrfs_pending_snapshot *pending)
1541{
1542
1543	struct btrfs_fs_info *fs_info = trans->fs_info;
1544	struct btrfs_key key;
1545	struct btrfs_root_item *new_root_item;
1546	struct btrfs_root *tree_root = fs_info->tree_root;
1547	struct btrfs_root *root = pending->root;
1548	struct btrfs_root *parent_root;
1549	struct btrfs_block_rsv *rsv;
1550	struct inode *parent_inode;
1551	struct btrfs_path *path;
1552	struct btrfs_dir_item *dir_item;
1553	struct dentry *dentry;
1554	struct extent_buffer *tmp;
1555	struct extent_buffer *old;
1556	struct timespec64 cur_time;
1557	int ret = 0;
1558	u64 to_reserve = 0;
1559	u64 index = 0;
1560	u64 objectid;
1561	u64 root_flags;
 
 
1562
1563	ASSERT(pending->path);
1564	path = pending->path;
1565
1566	ASSERT(pending->root_item);
1567	new_root_item = pending->root_item;
1568
 
 
 
 
 
 
 
 
 
 
 
 
 
1569	pending->error = btrfs_get_free_objectid(tree_root, &objectid);
1570	if (pending->error)
1571		goto no_free_objectid;
1572
1573	/*
1574	 * Make qgroup to skip current new snapshot's qgroupid, as it is
1575	 * accounted by later btrfs_qgroup_inherit().
1576	 */
1577	btrfs_set_skip_qgroup(trans, objectid);
1578
1579	btrfs_reloc_pre_snapshot(pending, &to_reserve);
1580
1581	if (to_reserve > 0) {
1582		pending->error = btrfs_block_rsv_add(root,
1583						     &pending->block_rsv,
1584						     to_reserve,
1585						     BTRFS_RESERVE_NO_FLUSH);
1586		if (pending->error)
1587			goto clear_skip_qgroup;
1588	}
1589
1590	key.objectid = objectid;
1591	key.offset = (u64)-1;
1592	key.type = BTRFS_ROOT_ITEM_KEY;
1593
1594	rsv = trans->block_rsv;
1595	trans->block_rsv = &pending->block_rsv;
1596	trans->bytes_reserved = trans->block_rsv->reserved;
1597	trace_btrfs_space_reservation(fs_info, "transaction",
1598				      trans->transid,
1599				      trans->bytes_reserved, 1);
1600	dentry = pending->dentry;
1601	parent_inode = pending->dir;
1602	parent_root = BTRFS_I(parent_inode)->root;
1603	ret = record_root_in_trans(trans, parent_root, 0);
1604	if (ret)
1605		goto fail;
1606	cur_time = current_time(parent_inode);
1607
1608	/*
1609	 * insert the directory item
1610	 */
1611	ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1612	BUG_ON(ret); /* -ENOMEM */
 
 
 
1613
1614	/* check if there is a file/dir which has the same name. */
1615	dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1616					 btrfs_ino(BTRFS_I(parent_inode)),
1617					 dentry->d_name.name,
1618					 dentry->d_name.len, 0);
1619	if (dir_item != NULL && !IS_ERR(dir_item)) {
1620		pending->error = -EEXIST;
1621		goto dir_item_existed;
1622	} else if (IS_ERR(dir_item)) {
1623		ret = PTR_ERR(dir_item);
1624		btrfs_abort_transaction(trans, ret);
1625		goto fail;
1626	}
1627	btrfs_release_path(path);
1628
 
 
 
 
 
 
1629	/*
1630	 * pull in the delayed directory update
1631	 * and the delayed inode item
1632	 * otherwise we corrupt the FS during
1633	 * snapshot
1634	 */
1635	ret = btrfs_run_delayed_items(trans);
1636	if (ret) {	/* Transaction aborted */
1637		btrfs_abort_transaction(trans, ret);
1638		goto fail;
1639	}
1640
1641	ret = record_root_in_trans(trans, root, 0);
1642	if (ret) {
1643		btrfs_abort_transaction(trans, ret);
1644		goto fail;
1645	}
1646	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1647	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1648	btrfs_check_and_init_root_item(new_root_item);
1649
1650	root_flags = btrfs_root_flags(new_root_item);
1651	if (pending->readonly)
1652		root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1653	else
1654		root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1655	btrfs_set_root_flags(new_root_item, root_flags);
1656
1657	btrfs_set_root_generation_v2(new_root_item,
1658			trans->transid);
1659	generate_random_guid(new_root_item->uuid);
1660	memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1661			BTRFS_UUID_SIZE);
1662	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1663		memset(new_root_item->received_uuid, 0,
1664		       sizeof(new_root_item->received_uuid));
1665		memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1666		memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1667		btrfs_set_root_stransid(new_root_item, 0);
1668		btrfs_set_root_rtransid(new_root_item, 0);
1669	}
1670	btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1671	btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1672	btrfs_set_root_otransid(new_root_item, trans->transid);
1673
1674	old = btrfs_lock_root_node(root);
1675	ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,
1676			      BTRFS_NESTING_COW);
1677	if (ret) {
1678		btrfs_tree_unlock(old);
1679		free_extent_buffer(old);
1680		btrfs_abort_transaction(trans, ret);
1681		goto fail;
1682	}
1683
1684	ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1685	/* clean up in any case */
1686	btrfs_tree_unlock(old);
1687	free_extent_buffer(old);
1688	if (ret) {
1689		btrfs_abort_transaction(trans, ret);
1690		goto fail;
1691	}
1692	/* see comments in should_cow_block() */
1693	set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1694	smp_wmb();
1695
1696	btrfs_set_root_node(new_root_item, tmp);
1697	/* record when the snapshot was created in key.offset */
1698	key.offset = trans->transid;
1699	ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1700	btrfs_tree_unlock(tmp);
1701	free_extent_buffer(tmp);
1702	if (ret) {
1703		btrfs_abort_transaction(trans, ret);
1704		goto fail;
1705	}
1706
1707	/*
1708	 * insert root back/forward references
1709	 */
1710	ret = btrfs_add_root_ref(trans, objectid,
1711				 parent_root->root_key.objectid,
1712				 btrfs_ino(BTRFS_I(parent_inode)), index,
1713				 dentry->d_name.name, dentry->d_name.len);
1714	if (ret) {
1715		btrfs_abort_transaction(trans, ret);
1716		goto fail;
1717	}
1718
1719	key.offset = (u64)-1;
1720	pending->snap = btrfs_get_new_fs_root(fs_info, objectid, pending->anon_dev);
1721	if (IS_ERR(pending->snap)) {
1722		ret = PTR_ERR(pending->snap);
1723		pending->snap = NULL;
1724		btrfs_abort_transaction(trans, ret);
1725		goto fail;
1726	}
1727
1728	ret = btrfs_reloc_post_snapshot(trans, pending);
1729	if (ret) {
1730		btrfs_abort_transaction(trans, ret);
1731		goto fail;
1732	}
1733
1734	/*
1735	 * Do special qgroup accounting for snapshot, as we do some qgroup
1736	 * snapshot hack to do fast snapshot.
1737	 * To co-operate with that hack, we do hack again.
1738	 * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1739	 */
1740	ret = qgroup_account_snapshot(trans, root, parent_root,
1741				      pending->inherit, objectid);
 
 
 
 
1742	if (ret < 0)
1743		goto fail;
1744
1745	ret = btrfs_insert_dir_item(trans, dentry->d_name.name,
1746				    dentry->d_name.len, BTRFS_I(parent_inode),
1747				    &key, BTRFS_FT_DIR, index);
1748	/* We have check then name at the beginning, so it is impossible. */
1749	BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1750	if (ret) {
1751		btrfs_abort_transaction(trans, ret);
1752		goto fail;
1753	}
1754
1755	btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1756					 dentry->d_name.len * 2);
1757	parent_inode->i_mtime = parent_inode->i_ctime =
1758		current_time(parent_inode);
1759	ret = btrfs_update_inode_fallback(trans, parent_root, BTRFS_I(parent_inode));
1760	if (ret) {
1761		btrfs_abort_transaction(trans, ret);
1762		goto fail;
1763	}
1764	ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
1765				  BTRFS_UUID_KEY_SUBVOL,
1766				  objectid);
1767	if (ret) {
1768		btrfs_abort_transaction(trans, ret);
1769		goto fail;
1770	}
1771	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1772		ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
1773					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1774					  objectid);
1775		if (ret && ret != -EEXIST) {
1776			btrfs_abort_transaction(trans, ret);
1777			goto fail;
1778		}
1779	}
1780
1781fail:
1782	pending->error = ret;
1783dir_item_existed:
1784	trans->block_rsv = rsv;
1785	trans->bytes_reserved = 0;
1786clear_skip_qgroup:
1787	btrfs_clear_skip_qgroup(trans);
1788no_free_objectid:
 
 
1789	kfree(new_root_item);
1790	pending->root_item = NULL;
1791	btrfs_free_path(path);
1792	pending->path = NULL;
1793
1794	return ret;
1795}
1796
1797/*
1798 * create all the snapshots we've scheduled for creation
1799 */
1800static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1801{
1802	struct btrfs_pending_snapshot *pending, *next;
1803	struct list_head *head = &trans->transaction->pending_snapshots;
1804	int ret = 0;
1805
1806	list_for_each_entry_safe(pending, next, head, list) {
1807		list_del(&pending->list);
1808		ret = create_pending_snapshot(trans, pending);
1809		if (ret)
1810			break;
1811	}
1812	return ret;
1813}
1814
1815static void update_super_roots(struct btrfs_fs_info *fs_info)
1816{
1817	struct btrfs_root_item *root_item;
1818	struct btrfs_super_block *super;
1819
1820	super = fs_info->super_copy;
1821
1822	root_item = &fs_info->chunk_root->root_item;
1823	super->chunk_root = root_item->bytenr;
1824	super->chunk_root_generation = root_item->generation;
1825	super->chunk_root_level = root_item->level;
1826
1827	root_item = &fs_info->tree_root->root_item;
1828	super->root = root_item->bytenr;
1829	super->generation = root_item->generation;
1830	super->root_level = root_item->level;
1831	if (btrfs_test_opt(fs_info, SPACE_CACHE))
1832		super->cache_generation = root_item->generation;
1833	else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags))
1834		super->cache_generation = 0;
1835	if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1836		super->uuid_tree_generation = root_item->generation;
1837}
1838
1839int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1840{
1841	struct btrfs_transaction *trans;
1842	int ret = 0;
1843
1844	spin_lock(&info->trans_lock);
1845	trans = info->running_transaction;
1846	if (trans)
1847		ret = (trans->state >= TRANS_STATE_COMMIT_START);
1848	spin_unlock(&info->trans_lock);
1849	return ret;
1850}
1851
1852int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1853{
1854	struct btrfs_transaction *trans;
1855	int ret = 0;
1856
1857	spin_lock(&info->trans_lock);
1858	trans = info->running_transaction;
1859	if (trans)
1860		ret = is_transaction_blocked(trans);
1861	spin_unlock(&info->trans_lock);
1862	return ret;
1863}
1864
1865/*
1866 * commit transactions asynchronously. once btrfs_commit_transaction_async
1867 * returns, any subsequent transaction will not be allowed to join.
1868 */
1869struct btrfs_async_commit {
1870	struct btrfs_trans_handle *newtrans;
1871	struct work_struct work;
1872};
1873
1874static void do_async_commit(struct work_struct *work)
1875{
1876	struct btrfs_async_commit *ac =
1877		container_of(work, struct btrfs_async_commit, work);
1878
1879	/*
1880	 * We've got freeze protection passed with the transaction.
1881	 * Tell lockdep about it.
1882	 */
1883	if (ac->newtrans->type & __TRANS_FREEZABLE)
1884		__sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1885
1886	current->journal_info = ac->newtrans;
1887
1888	btrfs_commit_transaction(ac->newtrans);
1889	kfree(ac);
1890}
1891
1892int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans)
1893{
1894	struct btrfs_fs_info *fs_info = trans->fs_info;
1895	struct btrfs_async_commit *ac;
1896	struct btrfs_transaction *cur_trans;
1897
1898	ac = kmalloc(sizeof(*ac), GFP_NOFS);
1899	if (!ac)
1900		return -ENOMEM;
1901
1902	INIT_WORK(&ac->work, do_async_commit);
1903	ac->newtrans = btrfs_join_transaction(trans->root);
1904	if (IS_ERR(ac->newtrans)) {
1905		int err = PTR_ERR(ac->newtrans);
1906		kfree(ac);
1907		return err;
1908	}
1909
1910	/* take transaction reference */
1911	cur_trans = trans->transaction;
1912	refcount_inc(&cur_trans->use_count);
1913
1914	btrfs_end_transaction(trans);
1915
1916	/*
1917	 * Tell lockdep we've released the freeze rwsem, since the
1918	 * async commit thread will be the one to unlock it.
1919	 */
1920	if (ac->newtrans->type & __TRANS_FREEZABLE)
1921		__sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1922
1923	schedule_work(&ac->work);
1924	/*
1925	 * Wait for the current transaction commit to start and block
1926	 * subsequent transaction joins
1927	 */
 
1928	wait_event(fs_info->transaction_blocked_wait,
1929		   cur_trans->state >= TRANS_STATE_COMMIT_START ||
1930		   TRANS_ABORTED(cur_trans));
1931	if (current->journal_info == trans)
1932		current->journal_info = NULL;
1933
1934	btrfs_put_transaction(cur_trans);
1935	return 0;
1936}
1937
1938
1939static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
1940{
1941	struct btrfs_fs_info *fs_info = trans->fs_info;
1942	struct btrfs_transaction *cur_trans = trans->transaction;
1943
1944	WARN_ON(refcount_read(&trans->use_count) > 1);
1945
1946	btrfs_abort_transaction(trans, err);
1947
1948	spin_lock(&fs_info->trans_lock);
1949
1950	/*
1951	 * If the transaction is removed from the list, it means this
1952	 * transaction has been committed successfully, so it is impossible
1953	 * to call the cleanup function.
1954	 */
1955	BUG_ON(list_empty(&cur_trans->list));
1956
1957	if (cur_trans == fs_info->running_transaction) {
1958		cur_trans->state = TRANS_STATE_COMMIT_DOING;
1959		spin_unlock(&fs_info->trans_lock);
 
 
 
 
 
 
1960		wait_event(cur_trans->writer_wait,
1961			   atomic_read(&cur_trans->num_writers) == 1);
1962
1963		spin_lock(&fs_info->trans_lock);
1964	}
1965
1966	/*
1967	 * Now that we know no one else is still using the transaction we can
1968	 * remove the transaction from the list of transactions. This avoids
1969	 * the transaction kthread from cleaning up the transaction while some
1970	 * other task is still using it, which could result in a use-after-free
1971	 * on things like log trees, as it forces the transaction kthread to
1972	 * wait for this transaction to be cleaned up by us.
1973	 */
1974	list_del_init(&cur_trans->list);
1975
1976	spin_unlock(&fs_info->trans_lock);
1977
1978	btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1979
1980	spin_lock(&fs_info->trans_lock);
1981	if (cur_trans == fs_info->running_transaction)
1982		fs_info->running_transaction = NULL;
1983	spin_unlock(&fs_info->trans_lock);
1984
1985	if (trans->type & __TRANS_FREEZABLE)
1986		sb_end_intwrite(fs_info->sb);
1987	btrfs_put_transaction(cur_trans);
1988	btrfs_put_transaction(cur_trans);
1989
1990	trace_btrfs_transaction_commit(trans->root);
1991
1992	if (current->journal_info == trans)
1993		current->journal_info = NULL;
1994	btrfs_scrub_cancel(fs_info);
 
 
 
 
 
 
 
 
 
 
 
 
 
1995
1996	kmem_cache_free(btrfs_trans_handle_cachep, trans);
1997}
1998
1999/*
2000 * Release reserved delayed ref space of all pending block groups of the
2001 * transaction and remove them from the list
2002 */
2003static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
2004{
2005       struct btrfs_fs_info *fs_info = trans->fs_info;
2006       struct btrfs_block_group *block_group, *tmp;
2007
2008       list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
2009               btrfs_delayed_refs_rsv_release(fs_info, 1);
2010               list_del_init(&block_group->bg_list);
2011       }
2012}
2013
2014static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
2015{
2016	/*
2017	 * We use writeback_inodes_sb here because if we used
2018	 * btrfs_start_delalloc_roots we would deadlock with fs freeze.
2019	 * Currently are holding the fs freeze lock, if we do an async flush
2020	 * we'll do btrfs_join_transaction() and deadlock because we need to
2021	 * wait for the fs freeze lock.  Using the direct flushing we benefit
2022	 * from already being in a transaction and our join_transaction doesn't
2023	 * have to re-take the fs freeze lock.
 
 
 
 
 
 
 
 
2024	 */
2025	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2026		writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
2027	return 0;
2028}
2029
2030static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
2031{
2032	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
2033		btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
2034}
2035
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2036int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
2037{
2038	struct btrfs_fs_info *fs_info = trans->fs_info;
2039	struct btrfs_transaction *cur_trans = trans->transaction;
2040	struct btrfs_transaction *prev_trans = NULL;
2041	int ret;
 
 
2042
2043	ASSERT(refcount_read(&trans->use_count) == 1);
 
 
 
2044
2045	/* Stop the commit early if ->aborted is set */
2046	if (TRANS_ABORTED(cur_trans)) {
2047		ret = cur_trans->aborted;
2048		btrfs_end_transaction(trans);
2049		return ret;
2050	}
2051
2052	btrfs_trans_release_metadata(trans);
2053	trans->block_rsv = NULL;
2054
2055	/*
2056	 * We only want one transaction commit doing the flushing so we do not
2057	 * waste a bunch of time on lock contention on the extent root node.
2058	 */
2059	if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING,
2060			      &cur_trans->delayed_refs.flags)) {
2061		/*
2062		 * Make a pass through all the delayed refs we have so far.
2063		 * Any running threads may add more while we are here.
2064		 */
2065		ret = btrfs_run_delayed_refs(trans, 0);
2066		if (ret) {
2067			btrfs_end_transaction(trans);
2068			return ret;
2069		}
2070	}
2071
2072	btrfs_create_pending_block_groups(trans);
2073
2074	if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
2075		int run_it = 0;
2076
2077		/* this mutex is also taken before trying to set
2078		 * block groups readonly.  We need to make sure
2079		 * that nobody has set a block group readonly
2080		 * after a extents from that block group have been
2081		 * allocated for cache files.  btrfs_set_block_group_ro
2082		 * will wait for the transaction to commit if it
2083		 * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2084		 *
2085		 * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2086		 * only one process starts all the block group IO.  It wouldn't
2087		 * hurt to have more than one go through, but there's no
2088		 * real advantage to it either.
2089		 */
2090		mutex_lock(&fs_info->ro_block_group_mutex);
2091		if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2092				      &cur_trans->flags))
2093			run_it = 1;
2094		mutex_unlock(&fs_info->ro_block_group_mutex);
2095
2096		if (run_it) {
2097			ret = btrfs_start_dirty_block_groups(trans);
2098			if (ret) {
2099				btrfs_end_transaction(trans);
2100				return ret;
2101			}
2102		}
2103	}
2104
2105	spin_lock(&fs_info->trans_lock);
2106	if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
2107		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2108
 
 
2109		spin_unlock(&fs_info->trans_lock);
2110		refcount_inc(&cur_trans->use_count);
2111
2112		if (trans->in_fsync)
2113			want_state = TRANS_STATE_SUPER_COMMITTED;
 
 
 
2114		ret = btrfs_end_transaction(trans);
2115		wait_for_commit(cur_trans, want_state);
2116
2117		if (TRANS_ABORTED(cur_trans))
2118			ret = cur_trans->aborted;
2119
2120		btrfs_put_transaction(cur_trans);
2121
2122		return ret;
2123	}
2124
2125	cur_trans->state = TRANS_STATE_COMMIT_START;
2126	wake_up(&fs_info->transaction_blocked_wait);
 
2127
2128	if (cur_trans->list.prev != &fs_info->trans_list) {
2129		enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
2130
2131		if (trans->in_fsync)
2132			want_state = TRANS_STATE_SUPER_COMMITTED;
2133
2134		prev_trans = list_entry(cur_trans->list.prev,
2135					struct btrfs_transaction, list);
2136		if (prev_trans->state < want_state) {
2137			refcount_inc(&prev_trans->use_count);
2138			spin_unlock(&fs_info->trans_lock);
2139
2140			wait_for_commit(prev_trans, want_state);
2141
2142			ret = READ_ONCE(prev_trans->aborted);
2143
2144			btrfs_put_transaction(prev_trans);
2145			if (ret)
2146				goto cleanup_transaction;
2147		} else {
2148			spin_unlock(&fs_info->trans_lock);
2149		}
2150	} else {
2151		spin_unlock(&fs_info->trans_lock);
2152		/*
2153		 * The previous transaction was aborted and was already removed
2154		 * from the list of transactions at fs_info->trans_list. So we
2155		 * abort to prevent writing a new superblock that reflects a
2156		 * corrupt state (pointing to trees with unwritten nodes/leafs).
2157		 */
2158		if (test_bit(BTRFS_FS_STATE_TRANS_ABORTED, &fs_info->fs_state)) {
 
2159			ret = -EROFS;
2160			goto cleanup_transaction;
2161		}
2162	}
2163
 
 
 
 
 
 
 
 
 
 
2164	extwriter_counter_dec(cur_trans, trans->type);
2165
2166	ret = btrfs_start_delalloc_flush(fs_info);
2167	if (ret)
2168		goto cleanup_transaction;
2169
2170	ret = btrfs_run_delayed_items(trans);
2171	if (ret)
2172		goto cleanup_transaction;
2173
 
 
 
 
 
 
 
2174	wait_event(cur_trans->writer_wait,
2175		   extwriter_counter_read(cur_trans) == 0);
2176
2177	/* some pending stuffs might be added after the previous flush. */
2178	ret = btrfs_run_delayed_items(trans);
2179	if (ret)
 
2180		goto cleanup_transaction;
 
2181
2182	btrfs_wait_delalloc_flush(fs_info);
2183
2184	/*
2185	 * Wait for all ordered extents started by a fast fsync that joined this
2186	 * transaction. Otherwise if this transaction commits before the ordered
2187	 * extents complete we lose logged data after a power failure.
2188	 */
 
2189	wait_event(cur_trans->pending_wait,
2190		   atomic_read(&cur_trans->pending_ordered) == 0);
2191
2192	btrfs_scrub_pause(fs_info);
2193	/*
2194	 * Ok now we need to make sure to block out any other joins while we
2195	 * commit the transaction.  We could have started a join before setting
2196	 * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2197	 */
2198	spin_lock(&fs_info->trans_lock);
 
2199	cur_trans->state = TRANS_STATE_COMMIT_DOING;
2200	spin_unlock(&fs_info->trans_lock);
 
 
 
 
 
 
 
 
2201	wait_event(cur_trans->writer_wait,
2202		   atomic_read(&cur_trans->num_writers) == 1);
2203
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2204	if (TRANS_ABORTED(cur_trans)) {
2205		ret = cur_trans->aborted;
 
2206		goto scrub_continue;
2207	}
2208	/*
2209	 * the reloc mutex makes sure that we stop
2210	 * the balancing code from coming in and moving
2211	 * extents around in the middle of the commit
2212	 */
2213	mutex_lock(&fs_info->reloc_mutex);
2214
2215	/*
2216	 * We needn't worry about the delayed items because we will
2217	 * deal with them in create_pending_snapshot(), which is the
2218	 * core function of the snapshot creation.
2219	 */
2220	ret = create_pending_snapshots(trans);
2221	if (ret)
2222		goto unlock_reloc;
2223
2224	/*
2225	 * We insert the dir indexes of the snapshots and update the inode
2226	 * of the snapshots' parents after the snapshot creation, so there
2227	 * are some delayed items which are not dealt with. Now deal with
2228	 * them.
2229	 *
2230	 * We needn't worry that this operation will corrupt the snapshots,
2231	 * because all the tree which are snapshoted will be forced to COW
2232	 * the nodes and leaves.
2233	 */
2234	ret = btrfs_run_delayed_items(trans);
2235	if (ret)
2236		goto unlock_reloc;
2237
2238	ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
2239	if (ret)
2240		goto unlock_reloc;
2241
2242	/*
2243	 * make sure none of the code above managed to slip in a
2244	 * delayed item
2245	 */
2246	btrfs_assert_delayed_root_empty(fs_info);
2247
2248	WARN_ON(cur_trans != trans->transaction);
2249
2250	/* btrfs_commit_tree_roots is responsible for getting the
2251	 * various roots consistent with each other.  Every pointer
2252	 * in the tree of tree roots has to point to the most up to date
2253	 * root for every subvolume and other tree.  So, we have to keep
2254	 * the tree logging code from jumping in and changing any
2255	 * of the trees.
2256	 *
2257	 * At this point in the commit, there can't be any tree-log
2258	 * writers, but a little lower down we drop the trans mutex
2259	 * and let new people in.  By holding the tree_log_mutex
2260	 * from now until after the super is written, we avoid races
2261	 * with the tree-log code.
2262	 */
2263	mutex_lock(&fs_info->tree_log_mutex);
2264
2265	ret = commit_fs_roots(trans);
2266	if (ret)
2267		goto unlock_tree_log;
2268
2269	/*
2270	 * Since the transaction is done, we can apply the pending changes
2271	 * before the next transaction.
2272	 */
2273	btrfs_apply_pending_changes(fs_info);
2274
2275	/* commit_fs_roots gets rid of all the tree log roots, it is now
2276	 * safe to free the root of tree log roots
2277	 */
2278	btrfs_free_log_root_tree(trans, fs_info);
2279
2280	/*
2281	 * Since fs roots are all committed, we can get a quite accurate
2282	 * new_roots. So let's do quota accounting.
2283	 */
2284	ret = btrfs_qgroup_account_extents(trans);
2285	if (ret < 0)
2286		goto unlock_tree_log;
2287
2288	ret = commit_cowonly_roots(trans);
2289	if (ret)
2290		goto unlock_tree_log;
2291
2292	/*
2293	 * The tasks which save the space cache and inode cache may also
2294	 * update ->aborted, check it.
2295	 */
2296	if (TRANS_ABORTED(cur_trans)) {
2297		ret = cur_trans->aborted;
2298		goto unlock_tree_log;
2299	}
2300
2301	cur_trans = fs_info->running_transaction;
2302
2303	btrfs_set_root_node(&fs_info->tree_root->root_item,
2304			    fs_info->tree_root->node);
2305	list_add_tail(&fs_info->tree_root->dirty_list,
2306		      &cur_trans->switch_commits);
2307
2308	btrfs_set_root_node(&fs_info->chunk_root->root_item,
2309			    fs_info->chunk_root->node);
2310	list_add_tail(&fs_info->chunk_root->dirty_list,
2311		      &cur_trans->switch_commits);
2312
 
 
 
 
 
 
 
2313	switch_commit_roots(trans);
2314
2315	ASSERT(list_empty(&cur_trans->dirty_bgs));
2316	ASSERT(list_empty(&cur_trans->io_bgs));
2317	update_super_roots(fs_info);
2318
2319	btrfs_set_super_log_root(fs_info->super_copy, 0);
2320	btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2321	memcpy(fs_info->super_for_commit, fs_info->super_copy,
2322	       sizeof(*fs_info->super_copy));
2323
2324	btrfs_commit_device_sizes(cur_trans);
2325
2326	clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2327	clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2328
2329	btrfs_trans_release_chunk_metadata(trans);
2330
 
 
 
 
 
 
 
 
 
 
2331	spin_lock(&fs_info->trans_lock);
2332	cur_trans->state = TRANS_STATE_UNBLOCKED;
2333	fs_info->running_transaction = NULL;
2334	spin_unlock(&fs_info->trans_lock);
2335	mutex_unlock(&fs_info->reloc_mutex);
2336
2337	wake_up(&fs_info->transaction_wait);
 
 
 
 
 
 
2338
2339	ret = btrfs_write_and_wait_transaction(trans);
2340	if (ret) {
2341		btrfs_handle_fs_error(fs_info, ret,
2342				      "Error while writing out transaction");
2343		/*
2344		 * reloc_mutex has been unlocked, tree_log_mutex is still held
2345		 * but we can't jump to unlock_tree_log causing double unlock
2346		 */
2347		mutex_unlock(&fs_info->tree_log_mutex);
2348		goto scrub_continue;
2349	}
2350
2351	/*
2352	 * At this point, we should have written all the tree blocks allocated
2353	 * in this transaction. So it's now safe to free the redirtyied extent
2354	 * buffers.
2355	 */
2356	btrfs_free_redirty_list(cur_trans);
2357
2358	ret = write_all_supers(fs_info, 0);
2359	/*
2360	 * the super is written, we can safely allow the tree-loggers
2361	 * to go about their business
2362	 */
2363	mutex_unlock(&fs_info->tree_log_mutex);
2364	if (ret)
2365		goto scrub_continue;
2366
2367	/*
2368	 * We needn't acquire the lock here because there is no other task
2369	 * which can change it.
2370	 */
2371	cur_trans->state = TRANS_STATE_SUPER_COMMITTED;
2372	wake_up(&cur_trans->commit_wait);
 
2373
2374	btrfs_finish_extent_commit(trans);
2375
2376	if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2377		btrfs_clear_space_info_full(fs_info);
2378
2379	fs_info->last_trans_committed = cur_trans->transid;
2380	/*
2381	 * We needn't acquire the lock here because there is no other task
2382	 * which can change it.
2383	 */
2384	cur_trans->state = TRANS_STATE_COMPLETED;
2385	wake_up(&cur_trans->commit_wait);
 
2386
2387	spin_lock(&fs_info->trans_lock);
2388	list_del_init(&cur_trans->list);
2389	spin_unlock(&fs_info->trans_lock);
2390
2391	btrfs_put_transaction(cur_trans);
2392	btrfs_put_transaction(cur_trans);
2393
2394	if (trans->type & __TRANS_FREEZABLE)
2395		sb_end_intwrite(fs_info->sb);
2396
2397	trace_btrfs_transaction_commit(trans->root);
 
 
2398
2399	btrfs_scrub_continue(fs_info);
2400
2401	if (current->journal_info == trans)
2402		current->journal_info = NULL;
2403
2404	kmem_cache_free(btrfs_trans_handle_cachep, trans);
2405
 
 
2406	return ret;
2407
2408unlock_tree_log:
2409	mutex_unlock(&fs_info->tree_log_mutex);
2410unlock_reloc:
2411	mutex_unlock(&fs_info->reloc_mutex);
 
2412scrub_continue:
 
 
2413	btrfs_scrub_continue(fs_info);
2414cleanup_transaction:
2415	btrfs_trans_release_metadata(trans);
2416	btrfs_cleanup_pending_block_groups(trans);
2417	btrfs_trans_release_chunk_metadata(trans);
2418	trans->block_rsv = NULL;
2419	btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2420	if (current->journal_info == trans)
2421		current->journal_info = NULL;
2422	cleanup_transaction(trans, ret);
2423
2424	return ret;
 
 
 
 
 
 
 
 
 
 
2425}
2426
2427/*
2428 * return < 0 if error
2429 * 0 if there are no more dead_roots at the time of call
2430 * 1 there are more to be processed, call me again
2431 *
2432 * The return value indicates there are certainly more snapshots to delete, but
2433 * if there comes a new one during processing, it may return 0. We don't mind,
2434 * because btrfs_commit_super will poke cleaner thread and it will process it a
2435 * few seconds later.
2436 */
2437int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2438{
 
2439	int ret;
2440	struct btrfs_fs_info *fs_info = root->fs_info;
2441
2442	spin_lock(&fs_info->trans_lock);
2443	if (list_empty(&fs_info->dead_roots)) {
2444		spin_unlock(&fs_info->trans_lock);
2445		return 0;
2446	}
2447	root = list_first_entry(&fs_info->dead_roots,
2448			struct btrfs_root, root_list);
2449	list_del_init(&root->root_list);
2450	spin_unlock(&fs_info->trans_lock);
2451
2452	btrfs_debug(fs_info, "cleaner removing %llu", root->root_key.objectid);
2453
2454	btrfs_kill_all_delayed_nodes(root);
2455
2456	if (btrfs_header_backref_rev(root->node) <
2457			BTRFS_MIXED_BACKREF_REV)
2458		ret = btrfs_drop_snapshot(root, 0, 0);
2459	else
2460		ret = btrfs_drop_snapshot(root, 1, 0);
2461
2462	btrfs_put_root(root);
2463	return (ret < 0) ? 0 : 1;
2464}
2465
2466void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2467{
2468	unsigned long prev;
2469	unsigned long bit;
 
 
 
 
 
 
 
 
 
2470
2471	prev = xchg(&fs_info->pending_changes, 0);
2472	if (!prev)
2473		return;
 
 
 
 
 
 
2474
2475	bit = 1 << BTRFS_PENDING_COMMIT;
2476	if (prev & bit)
2477		btrfs_debug(fs_info, "pending commit done");
2478	prev &= ~bit;
2479
2480	if (prev)
2481		btrfs_warn(fs_info,
2482			"unknown pending changes left 0x%lx, ignoring", prev);
2483}