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