1/*
   2 * Copyright (C) 2007 Oracle.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/fs.h>
  20#include <linux/slab.h>
  21#include <linux/sched.h>
  22#include <linux/writeback.h>
  23#include <linux/pagemap.h>
  24#include <linux/blkdev.h>
  25#include <linux/uuid.h>
  26#include "ctree.h"
  27#include "disk-io.h"
  28#include "transaction.h"
  29#include "locking.h"
  30#include "tree-log.h"
  31#include "inode-map.h"
  32#include "volumes.h"
  33#include "dev-replace.h"
  34#include "qgroup.h"
  35
  36#define BTRFS_ROOT_TRANS_TAG 0
  37
  38static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
  39	[TRANS_STATE_RUNNING]		= 0U,
  40	[TRANS_STATE_BLOCKED]		= (__TRANS_USERSPACE |
  41					   __TRANS_START),
  42	[TRANS_STATE_COMMIT_START]	= (__TRANS_USERSPACE |
  43					   __TRANS_START |
  44					   __TRANS_ATTACH),
  45	[TRANS_STATE_COMMIT_DOING]	= (__TRANS_USERSPACE |
  46					   __TRANS_START |
  47					   __TRANS_ATTACH |
  48					   __TRANS_JOIN),
  49	[TRANS_STATE_UNBLOCKED]		= (__TRANS_USERSPACE |
  50					   __TRANS_START |
  51					   __TRANS_ATTACH |
  52					   __TRANS_JOIN |
  53					   __TRANS_JOIN_NOLOCK),
  54	[TRANS_STATE_COMPLETED]		= (__TRANS_USERSPACE |
  55					   __TRANS_START |
  56					   __TRANS_ATTACH |
  57					   __TRANS_JOIN |
  58					   __TRANS_JOIN_NOLOCK),
  59};
  60
  61void btrfs_put_transaction(struct btrfs_transaction *transaction)
  62{
  63	WARN_ON(atomic_read(&transaction->use_count) == 0);
  64	if (atomic_dec_and_test(&transaction->use_count)) {
  65		BUG_ON(!list_empty(&transaction->list));
  66		WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
  67		if (transaction->delayed_refs.pending_csums)
  68			btrfs_err(transaction->fs_info,
  69				  "pending csums is %llu",
  70				  transaction->delayed_refs.pending_csums);
  71		while (!list_empty(&transaction->pending_chunks)) {
  72			struct extent_map *em;
  73
  74			em = list_first_entry(&transaction->pending_chunks,
  75					      struct extent_map, list);
  76			list_del_init(&em->list);
  77			free_extent_map(em);
  78		}
  79		/*
  80		 * If any block groups are found in ->deleted_bgs then it's
  81		 * because the transaction was aborted and a commit did not
  82		 * happen (things failed before writing the new superblock
  83		 * and calling btrfs_finish_extent_commit()), so we can not
  84		 * discard the physical locations of the block groups.
  85		 */
  86		while (!list_empty(&transaction->deleted_bgs)) {
  87			struct btrfs_block_group_cache *cache;
  88
  89			cache = list_first_entry(&transaction->deleted_bgs,
  90						 struct btrfs_block_group_cache,
  91						 bg_list);
  92			list_del_init(&cache->bg_list);
  93			btrfs_put_block_group_trimming(cache);
  94			btrfs_put_block_group(cache);
  95		}
  96		kmem_cache_free(btrfs_transaction_cachep, transaction);
  97	}
  98}
  99
 100static void clear_btree_io_tree(struct extent_io_tree *tree)
 101{
 102	spin_lock(&tree->lock);
 103	/*
 104	 * Do a single barrier for the waitqueue_active check here, the state
 105	 * of the waitqueue should not change once clear_btree_io_tree is
 106	 * called.
 107	 */
 108	smp_mb();
 109	while (!RB_EMPTY_ROOT(&tree->state)) {
 110		struct rb_node *node;
 111		struct extent_state *state;
 112
 113		node = rb_first(&tree->state);
 114		state = rb_entry(node, struct extent_state, rb_node);
 115		rb_erase(&state->rb_node, &tree->state);
 116		RB_CLEAR_NODE(&state->rb_node);
 117		/*
 118		 * btree io trees aren't supposed to have tasks waiting for
 119		 * changes in the flags of extent states ever.
 120		 */
 121		ASSERT(!waitqueue_active(&state->wq));
 122		free_extent_state(state);
 123
 124		cond_resched_lock(&tree->lock);
 125	}
 126	spin_unlock(&tree->lock);
 127}
 128
 129static noinline void switch_commit_roots(struct btrfs_transaction *trans,
 130					 struct btrfs_fs_info *fs_info)
 131{
 132	struct btrfs_root *root, *tmp;
 133
 134	down_write(&fs_info->commit_root_sem);
 135	list_for_each_entry_safe(root, tmp, &trans->switch_commits,
 136				 dirty_list) {
 137		list_del_init(&root->dirty_list);
 138		free_extent_buffer(root->commit_root);
 139		root->commit_root = btrfs_root_node(root);
 140		if (is_fstree(root->objectid))
 141			btrfs_unpin_free_ino(root);
 142		clear_btree_io_tree(&root->dirty_log_pages);
 143	}
 144
 145	/* We can free old roots now. */
 146	spin_lock(&trans->dropped_roots_lock);
 147	while (!list_empty(&trans->dropped_roots)) {
 148		root = list_first_entry(&trans->dropped_roots,
 149					struct btrfs_root, root_list);
 150		list_del_init(&root->root_list);
 151		spin_unlock(&trans->dropped_roots_lock);
 152		btrfs_drop_and_free_fs_root(fs_info, root);
 153		spin_lock(&trans->dropped_roots_lock);
 154	}
 155	spin_unlock(&trans->dropped_roots_lock);
 156	up_write(&fs_info->commit_root_sem);
 157}
 158
 159static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 160					 unsigned int type)
 161{
 162	if (type & TRANS_EXTWRITERS)
 163		atomic_inc(&trans->num_extwriters);
 164}
 165
 166static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 167					 unsigned int type)
 168{
 169	if (type & TRANS_EXTWRITERS)
 170		atomic_dec(&trans->num_extwriters);
 171}
 172
 173static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 174					  unsigned int type)
 175{
 176	atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 177}
 178
 179static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 180{
 181	return atomic_read(&trans->num_extwriters);
 182}
 183
 184/*
 185 * either allocate a new transaction or hop into the existing one
 186 */
 187static noinline int join_transaction(struct btrfs_fs_info *fs_info,
 188				     unsigned int type)
 189{
 190	struct btrfs_transaction *cur_trans;
 
 191
 192	spin_lock(&fs_info->trans_lock);
 193loop:
 194	/* The file system has been taken offline. No new transactions. */
 195	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 196		spin_unlock(&fs_info->trans_lock);
 197		return -EROFS;
 198	}
 199
 200	cur_trans = fs_info->running_transaction;
 201	if (cur_trans) {
 202		if (cur_trans->aborted) {
 203			spin_unlock(&fs_info->trans_lock);
 204			return cur_trans->aborted;
 205		}
 206		if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 207			spin_unlock(&fs_info->trans_lock);
 208			return -EBUSY;
 209		}
 210		atomic_inc(&cur_trans->use_count);
 211		atomic_inc(&cur_trans->num_writers);
 212		extwriter_counter_inc(cur_trans, type);
 213		spin_unlock(&fs_info->trans_lock);
 214		return 0;
 215	}
 216	spin_unlock(&fs_info->trans_lock);
 217
 218	/*
 219	 * If we are ATTACH, we just want to catch the current transaction,
 220	 * and commit it. If there is no transaction, just return ENOENT.
 221	 */
 222	if (type == TRANS_ATTACH)
 223		return -ENOENT;
 224
 225	/*
 226	 * JOIN_NOLOCK only happens during the transaction commit, so
 227	 * it is impossible that ->running_transaction is NULL
 228	 */
 229	BUG_ON(type == TRANS_JOIN_NOLOCK);
 230
 231	cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 232	if (!cur_trans)
 233		return -ENOMEM;
 234
 235	spin_lock(&fs_info->trans_lock);
 236	if (fs_info->running_transaction) {
 237		/*
 238		 * someone started a transaction after we unlocked.  Make sure
 239		 * to redo the checks above
 240		 */
 241		kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 242		goto loop;
 243	} else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 244		spin_unlock(&fs_info->trans_lock);
 245		kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 246		return -EROFS;
 247	}
 248
 249	cur_trans->fs_info = fs_info;
 250	atomic_set(&cur_trans->num_writers, 1);
 251	extwriter_counter_init(cur_trans, type);
 252	init_waitqueue_head(&cur_trans->writer_wait);
 253	init_waitqueue_head(&cur_trans->commit_wait);
 254	init_waitqueue_head(&cur_trans->pending_wait);
 255	cur_trans->state = TRANS_STATE_RUNNING;
 256	/*
 257	 * One for this trans handle, one so it will live on until we
 258	 * commit the transaction.
 259	 */
 260	atomic_set(&cur_trans->use_count, 2);
 261	atomic_set(&cur_trans->pending_ordered, 0);
 262	cur_trans->flags = 0;
 263	cur_trans->start_time = get_seconds();
 264
 265	memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
 266
 267	cur_trans->delayed_refs.href_root = RB_ROOT;
 268	cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
 269	atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 270
 271	/*
 272	 * although the tree mod log is per file system and not per transaction,
 273	 * the log must never go across transaction boundaries.
 274	 */
 275	smp_mb();
 276	if (!list_empty(&fs_info->tree_mod_seq_list))
 277		WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
 
 278	if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 279		WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
 
 280	atomic64_set(&fs_info->tree_mod_seq, 0);
 281
 282	spin_lock_init(&cur_trans->delayed_refs.lock);
 283
 284	INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 285	INIT_LIST_HEAD(&cur_trans->pending_chunks);
 286	INIT_LIST_HEAD(&cur_trans->switch_commits);
 287	INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 288	INIT_LIST_HEAD(&cur_trans->io_bgs);
 289	INIT_LIST_HEAD(&cur_trans->dropped_roots);
 290	mutex_init(&cur_trans->cache_write_mutex);
 291	cur_trans->num_dirty_bgs = 0;
 292	spin_lock_init(&cur_trans->dirty_bgs_lock);
 293	INIT_LIST_HEAD(&cur_trans->deleted_bgs);
 294	spin_lock_init(&cur_trans->dropped_roots_lock);
 295	list_add_tail(&cur_trans->list, &fs_info->trans_list);
 296	extent_io_tree_init(&cur_trans->dirty_pages,
 297			     fs_info->btree_inode->i_mapping);
 298	fs_info->generation++;
 299	cur_trans->transid = fs_info->generation;
 300	fs_info->running_transaction = cur_trans;
 301	cur_trans->aborted = 0;
 302	spin_unlock(&fs_info->trans_lock);
 303
 304	return 0;
 305}
 306
 307/*
 308 * this does all the record keeping required to make sure that a reference
 309 * counted root is properly recorded in a given transaction.  This is required
 310 * to make sure the old root from before we joined the transaction is deleted
 311 * when the transaction commits
 312 */
 313static int record_root_in_trans(struct btrfs_trans_handle *trans,
 314			       struct btrfs_root *root,
 315			       int force)
 316{
 317	struct btrfs_fs_info *fs_info = root->fs_info;
 318
 319	if ((test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 320	    root->last_trans < trans->transid) || force) {
 321		WARN_ON(root == fs_info->extent_root);
 322		WARN_ON(root->commit_root != root->node);
 323
 324		/*
 325		 * see below for IN_TRANS_SETUP usage rules
 326		 * we have the reloc mutex held now, so there
 327		 * is only one writer in this function
 328		 */
 329		set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 330
 331		/* make sure readers find IN_TRANS_SETUP before
 332		 * they find our root->last_trans update
 333		 */
 334		smp_wmb();
 335
 336		spin_lock(&fs_info->fs_roots_radix_lock);
 337		if (root->last_trans == trans->transid && !force) {
 338			spin_unlock(&fs_info->fs_roots_radix_lock);
 339			return 0;
 340		}
 341		radix_tree_tag_set(&fs_info->fs_roots_radix,
 342				   (unsigned long)root->root_key.objectid,
 343				   BTRFS_ROOT_TRANS_TAG);
 344		spin_unlock(&fs_info->fs_roots_radix_lock);
 345		root->last_trans = trans->transid;
 346
 347		/* this is pretty tricky.  We don't want to
 348		 * take the relocation lock in btrfs_record_root_in_trans
 349		 * unless we're really doing the first setup for this root in
 350		 * this transaction.
 351		 *
 352		 * Normally we'd use root->last_trans as a flag to decide
 353		 * if we want to take the expensive mutex.
 354		 *
 355		 * But, we have to set root->last_trans before we
 356		 * init the relocation root, otherwise, we trip over warnings
 357		 * in ctree.c.  The solution used here is to flag ourselves
 358		 * with root IN_TRANS_SETUP.  When this is 1, we're still
 359		 * fixing up the reloc trees and everyone must wait.
 360		 *
 361		 * When this is zero, they can trust root->last_trans and fly
 362		 * through btrfs_record_root_in_trans without having to take the
 363		 * lock.  smp_wmb() makes sure that all the writes above are
 364		 * done before we pop in the zero below
 365		 */
 366		btrfs_init_reloc_root(trans, root);
 367		smp_mb__before_atomic();
 368		clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 369	}
 370	return 0;
 371}
 372
 373
 374void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
 375			    struct btrfs_root *root)
 376{
 377	struct btrfs_fs_info *fs_info = root->fs_info;
 378	struct btrfs_transaction *cur_trans = trans->transaction;
 379
 380	/* Add ourselves to the transaction dropped list */
 381	spin_lock(&cur_trans->dropped_roots_lock);
 382	list_add_tail(&root->root_list, &cur_trans->dropped_roots);
 383	spin_unlock(&cur_trans->dropped_roots_lock);
 384
 385	/* Make sure we don't try to update the root at commit time */
 386	spin_lock(&fs_info->fs_roots_radix_lock);
 387	radix_tree_tag_clear(&fs_info->fs_roots_radix,
 388			     (unsigned long)root->root_key.objectid,
 389			     BTRFS_ROOT_TRANS_TAG);
 390	spin_unlock(&fs_info->fs_roots_radix_lock);
 391}
 392
 393int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 394			       struct btrfs_root *root)
 395{
 396	struct btrfs_fs_info *fs_info = root->fs_info;
 397
 398	if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 399		return 0;
 400
 401	/*
 402	 * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 403	 * and barriers
 404	 */
 405	smp_rmb();
 406	if (root->last_trans == trans->transid &&
 407	    !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 408		return 0;
 409
 410	mutex_lock(&fs_info->reloc_mutex);
 411	record_root_in_trans(trans, root, 0);
 412	mutex_unlock(&fs_info->reloc_mutex);
 413
 414	return 0;
 415}
 416
 417static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 418{
 419	return (trans->state >= TRANS_STATE_BLOCKED &&
 420		trans->state < TRANS_STATE_UNBLOCKED &&
 421		!trans->aborted);
 422}
 423
 424/* wait for commit against the current transaction to become unblocked
 425 * when this is done, it is safe to start a new transaction, but the current
 426 * transaction might not be fully on disk.
 427 */
 428static void wait_current_trans(struct btrfs_fs_info *fs_info)
 429{
 430	struct btrfs_transaction *cur_trans;
 431
 432	spin_lock(&fs_info->trans_lock);
 433	cur_trans = fs_info->running_transaction;
 434	if (cur_trans && is_transaction_blocked(cur_trans)) {
 435		atomic_inc(&cur_trans->use_count);
 436		spin_unlock(&fs_info->trans_lock);
 437
 438		wait_event(fs_info->transaction_wait,
 439			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 440			   cur_trans->aborted);
 441		btrfs_put_transaction(cur_trans);
 442	} else {
 443		spin_unlock(&fs_info->trans_lock);
 444	}
 445}
 446
 447static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
 448{
 449	if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
 450		return 0;
 451
 452	if (type == TRANS_USERSPACE)
 453		return 1;
 454
 455	if (type == TRANS_START &&
 456	    !atomic_read(&fs_info->open_ioctl_trans))
 457		return 1;
 458
 459	return 0;
 460}
 461
 462static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 463{
 464	struct btrfs_fs_info *fs_info = root->fs_info;
 465
 466	if (!fs_info->reloc_ctl ||
 467	    !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
 468	    root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 469	    root->reloc_root)
 470		return false;
 471
 472	return true;
 473}
 474
 475static struct btrfs_trans_handle *
 476start_transaction(struct btrfs_root *root, unsigned int num_items,
 477		  unsigned int type, enum btrfs_reserve_flush_enum flush)
 478{
 479	struct btrfs_fs_info *fs_info = root->fs_info;
 480
 481	struct btrfs_trans_handle *h;
 482	struct btrfs_transaction *cur_trans;
 483	u64 num_bytes = 0;
 484	u64 qgroup_reserved = 0;
 485	bool reloc_reserved = false;
 486	int ret;
 487
 488	/* Send isn't supposed to start transactions. */
 489	ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
 490
 491	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
 492		return ERR_PTR(-EROFS);
 493
 494	if (current->journal_info) {
 495		WARN_ON(type & TRANS_EXTWRITERS);
 496		h = current->journal_info;
 497		h->use_count++;
 498		WARN_ON(h->use_count > 2);
 499		h->orig_rsv = h->block_rsv;
 500		h->block_rsv = NULL;
 501		goto got_it;
 502	}
 503
 504	/*
 505	 * Do the reservation before we join the transaction so we can do all
 506	 * the appropriate flushing if need be.
 507	 */
 508	if (num_items > 0 && root != fs_info->chunk_root) {
 509		qgroup_reserved = num_items * fs_info->nodesize;
 510		ret = btrfs_qgroup_reserve_meta(root, qgroup_reserved);
 511		if (ret)
 512			return ERR_PTR(ret);
 513
 514		num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
 515		/*
 516		 * Do the reservation for the relocation root creation
 517		 */
 518		if (need_reserve_reloc_root(root)) {
 519			num_bytes += fs_info->nodesize;
 520			reloc_reserved = true;
 521		}
 522
 523		ret = btrfs_block_rsv_add(root, &fs_info->trans_block_rsv,
 
 524					  num_bytes, flush);
 525		if (ret)
 526			goto reserve_fail;
 527	}
 528again:
 529	h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
 530	if (!h) {
 531		ret = -ENOMEM;
 532		goto alloc_fail;
 533	}
 534
 535	/*
 536	 * If we are JOIN_NOLOCK we're already committing a transaction and
 537	 * waiting on this guy, so we don't need to do the sb_start_intwrite
 538	 * because we're already holding a ref.  We need this because we could
 539	 * have raced in and did an fsync() on a file which can kick a commit
 540	 * and then we deadlock with somebody doing a freeze.
 541	 *
 542	 * If we are ATTACH, it means we just want to catch the current
 543	 * transaction and commit it, so we needn't do sb_start_intwrite(). 
 544	 */
 545	if (type & __TRANS_FREEZABLE)
 546		sb_start_intwrite(fs_info->sb);
 547
 548	if (may_wait_transaction(fs_info, type))
 549		wait_current_trans(fs_info);
 550
 551	do {
 552		ret = join_transaction(fs_info, type);
 553		if (ret == -EBUSY) {
 554			wait_current_trans(fs_info);
 555			if (unlikely(type == TRANS_ATTACH))
 556				ret = -ENOENT;
 557		}
 558	} while (ret == -EBUSY);
 559
 560	if (ret < 0)
 
 
 561		goto join_fail;
 
 562
 563	cur_trans = fs_info->running_transaction;
 564
 565	h->transid = cur_trans->transid;
 566	h->transaction = cur_trans;
 567	h->root = root;
 568	h->use_count = 1;
 569	h->fs_info = root->fs_info;
 570
 571	h->type = type;
 572	h->can_flush_pending_bgs = true;
 573	INIT_LIST_HEAD(&h->qgroup_ref_list);
 574	INIT_LIST_HEAD(&h->new_bgs);
 575
 576	smp_mb();
 577	if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 578	    may_wait_transaction(fs_info, type)) {
 579		current->journal_info = h;
 580		btrfs_commit_transaction(h);
 581		goto again;
 582	}
 583
 584	if (num_bytes) {
 585		trace_btrfs_space_reservation(fs_info, "transaction",
 586					      h->transid, num_bytes, 1);
 587		h->block_rsv = &fs_info->trans_block_rsv;
 588		h->bytes_reserved = num_bytes;
 589		h->reloc_reserved = reloc_reserved;
 590	}
 591
 592got_it:
 593	btrfs_record_root_in_trans(h, root);
 594
 595	if (!current->journal_info && type != TRANS_USERSPACE)
 596		current->journal_info = h;
 597	return h;
 598
 599join_fail:
 600	if (type & __TRANS_FREEZABLE)
 601		sb_end_intwrite(fs_info->sb);
 602	kmem_cache_free(btrfs_trans_handle_cachep, h);
 603alloc_fail:
 604	if (num_bytes)
 605		btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
 606					num_bytes);
 607reserve_fail:
 608	btrfs_qgroup_free_meta(root, qgroup_reserved);
 609	return ERR_PTR(ret);
 610}
 611
 612struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 613						   unsigned int num_items)
 614{
 615	return start_transaction(root, num_items, TRANS_START,
 616				 BTRFS_RESERVE_FLUSH_ALL);
 617}
 618struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 619					struct btrfs_root *root,
 620					unsigned int num_items,
 621					int min_factor)
 622{
 623	struct btrfs_fs_info *fs_info = root->fs_info;
 624	struct btrfs_trans_handle *trans;
 625	u64 num_bytes;
 626	int ret;
 627
 628	trans = btrfs_start_transaction(root, num_items);
 629	if (!IS_ERR(trans) || PTR_ERR(trans) != -ENOSPC)
 630		return trans;
 631
 632	trans = btrfs_start_transaction(root, 0);
 633	if (IS_ERR(trans))
 634		return trans;
 635
 636	num_bytes = btrfs_calc_trans_metadata_size(fs_info, num_items);
 637	ret = btrfs_cond_migrate_bytes(fs_info, &fs_info->trans_block_rsv,
 638				       num_bytes, min_factor);
 
 
 639	if (ret) {
 640		btrfs_end_transaction(trans);
 641		return ERR_PTR(ret);
 642	}
 643
 644	trans->block_rsv = &fs_info->trans_block_rsv;
 645	trans->bytes_reserved = num_bytes;
 646	trace_btrfs_space_reservation(fs_info, "transaction",
 647				      trans->transid, num_bytes, 1);
 648
 649	return trans;
 650}
 651
 652struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 653					struct btrfs_root *root,
 654					unsigned int num_items)
 655{
 656	return start_transaction(root, num_items, TRANS_START,
 657				 BTRFS_RESERVE_FLUSH_LIMIT);
 658}
 659
 660struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 661{
 662	return start_transaction(root, 0, TRANS_JOIN,
 663				 BTRFS_RESERVE_NO_FLUSH);
 664}
 665
 666struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 667{
 668	return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
 669				 BTRFS_RESERVE_NO_FLUSH);
 670}
 671
 672struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 673{
 674	return start_transaction(root, 0, TRANS_USERSPACE,
 675				 BTRFS_RESERVE_NO_FLUSH);
 676}
 677
 678/*
 679 * btrfs_attach_transaction() - catch the running transaction
 680 *
 681 * It is used when we want to commit the current the transaction, but
 682 * don't want to start a new one.
 683 *
 684 * Note: If this function return -ENOENT, it just means there is no
 685 * running transaction. But it is possible that the inactive transaction
 686 * is still in the memory, not fully on disk. If you hope there is no
 687 * inactive transaction in the fs when -ENOENT is returned, you should
 688 * invoke
 689 *     btrfs_attach_transaction_barrier()
 690 */
 691struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 692{
 693	return start_transaction(root, 0, TRANS_ATTACH,
 694				 BTRFS_RESERVE_NO_FLUSH);
 695}
 696
 697/*
 698 * btrfs_attach_transaction_barrier() - catch the running transaction
 699 *
 700 * It is similar to the above function, the differentia is this one
 701 * will wait for all the inactive transactions until they fully
 702 * complete.
 703 */
 704struct btrfs_trans_handle *
 705btrfs_attach_transaction_barrier(struct btrfs_root *root)
 706{
 707	struct btrfs_trans_handle *trans;
 708
 709	trans = start_transaction(root, 0, TRANS_ATTACH,
 710				  BTRFS_RESERVE_NO_FLUSH);
 711	if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 712		btrfs_wait_for_commit(root->fs_info, 0);
 713
 714	return trans;
 715}
 716
 717/* wait for a transaction commit to be fully complete */
 718static noinline void wait_for_commit(struct btrfs_transaction *commit)
 
 719{
 720	wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 721}
 722
 723int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
 724{
 725	struct btrfs_transaction *cur_trans = NULL, *t;
 726	int ret = 0;
 727
 728	if (transid) {
 729		if (transid <= fs_info->last_trans_committed)
 730			goto out;
 731
 732		/* find specified transaction */
 733		spin_lock(&fs_info->trans_lock);
 734		list_for_each_entry(t, &fs_info->trans_list, list) {
 735			if (t->transid == transid) {
 736				cur_trans = t;
 737				atomic_inc(&cur_trans->use_count);
 738				ret = 0;
 739				break;
 740			}
 741			if (t->transid > transid) {
 742				ret = 0;
 743				break;
 744			}
 745		}
 746		spin_unlock(&fs_info->trans_lock);
 747
 748		/*
 749		 * The specified transaction doesn't exist, or we
 750		 * raced with btrfs_commit_transaction
 751		 */
 752		if (!cur_trans) {
 753			if (transid > fs_info->last_trans_committed)
 754				ret = -EINVAL;
 755			goto out;
 756		}
 757	} else {
 758		/* find newest transaction that is committing | committed */
 759		spin_lock(&fs_info->trans_lock);
 760		list_for_each_entry_reverse(t, &fs_info->trans_list,
 761					    list) {
 762			if (t->state >= TRANS_STATE_COMMIT_START) {
 763				if (t->state == TRANS_STATE_COMPLETED)
 764					break;
 765				cur_trans = t;
 766				atomic_inc(&cur_trans->use_count);
 767				break;
 768			}
 769		}
 770		spin_unlock(&fs_info->trans_lock);
 771		if (!cur_trans)
 772			goto out;  /* nothing committing|committed */
 773	}
 774
 775	wait_for_commit(cur_trans);
 776	btrfs_put_transaction(cur_trans);
 777out:
 778	return ret;
 779}
 780
 781void btrfs_throttle(struct btrfs_fs_info *fs_info)
 782{
 783	if (!atomic_read(&fs_info->open_ioctl_trans))
 784		wait_current_trans(fs_info);
 785}
 786
 787static int should_end_transaction(struct btrfs_trans_handle *trans)
 
 788{
 789	struct btrfs_fs_info *fs_info = trans->fs_info;
 790
 791	if (fs_info->global_block_rsv.space_info->full &&
 792	    btrfs_check_space_for_delayed_refs(trans, fs_info))
 793		return 1;
 794
 795	return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5);
 796}
 797
 798int btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
 
 799{
 800	struct btrfs_transaction *cur_trans = trans->transaction;
 801	struct btrfs_fs_info *fs_info = trans->fs_info;
 802	int updates;
 803	int err;
 804
 805	smp_mb();
 806	if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 807	    cur_trans->delayed_refs.flushing)
 808		return 1;
 809
 810	updates = trans->delayed_ref_updates;
 811	trans->delayed_ref_updates = 0;
 812	if (updates) {
 813		err = btrfs_run_delayed_refs(trans, fs_info, updates * 2);
 814		if (err) /* Error code will also eval true */
 815			return err;
 816	}
 817
 818	return should_end_transaction(trans);
 819}
 820
 821static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 822				   int throttle)
 823{
 824	struct btrfs_fs_info *info = trans->fs_info;
 825	struct btrfs_transaction *cur_trans = trans->transaction;
 826	u64 transid = trans->transid;
 827	unsigned long cur = trans->delayed_ref_updates;
 828	int lock = (trans->type != TRANS_JOIN_NOLOCK);
 829	int err = 0;
 830	int must_run_delayed_refs = 0;
 831
 832	if (trans->use_count > 1) {
 833		trans->use_count--;
 834		trans->block_rsv = trans->orig_rsv;
 835		return 0;
 836	}
 837
 838	btrfs_trans_release_metadata(trans, info);
 839	trans->block_rsv = NULL;
 840
 841	if (!list_empty(&trans->new_bgs))
 842		btrfs_create_pending_block_groups(trans, info);
 843
 844	trans->delayed_ref_updates = 0;
 845	if (!trans->sync) {
 846		must_run_delayed_refs =
 847			btrfs_should_throttle_delayed_refs(trans, info);
 848		cur = max_t(unsigned long, cur, 32);
 849
 850		/*
 851		 * don't make the caller wait if they are from a NOLOCK
 852		 * or ATTACH transaction, it will deadlock with commit
 853		 */
 854		if (must_run_delayed_refs == 1 &&
 855		    (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
 856			must_run_delayed_refs = 2;
 857	}
 858
 859	btrfs_trans_release_metadata(trans, info);
 860	trans->block_rsv = NULL;
 861
 862	if (!list_empty(&trans->new_bgs))
 863		btrfs_create_pending_block_groups(trans, info);
 864
 865	btrfs_trans_release_chunk_metadata(trans);
 866
 867	if (lock && !atomic_read(&info->open_ioctl_trans) &&
 868	    should_end_transaction(trans) &&
 869	    ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 870		spin_lock(&info->trans_lock);
 871		if (cur_trans->state == TRANS_STATE_RUNNING)
 872			cur_trans->state = TRANS_STATE_BLOCKED;
 873		spin_unlock(&info->trans_lock);
 874	}
 875
 876	if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 877		if (throttle)
 878			return btrfs_commit_transaction(trans);
 879		else
 880			wake_up_process(info->transaction_kthread);
 881	}
 882
 883	if (trans->type & __TRANS_FREEZABLE)
 884		sb_end_intwrite(info->sb);
 885
 886	WARN_ON(cur_trans != info->running_transaction);
 887	WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 888	atomic_dec(&cur_trans->num_writers);
 889	extwriter_counter_dec(cur_trans, trans->type);
 890
 891	/*
 892	 * Make sure counter is updated before we wake up waiters.
 893	 */
 894	smp_mb();
 895	if (waitqueue_active(&cur_trans->writer_wait))
 896		wake_up(&cur_trans->writer_wait);
 897	btrfs_put_transaction(cur_trans);
 898
 899	if (current->journal_info == trans)
 900		current->journal_info = NULL;
 901
 902	if (throttle)
 903		btrfs_run_delayed_iputs(info);
 904
 905	if (trans->aborted ||
 906	    test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
 907		wake_up_process(info->transaction_kthread);
 908		err = -EIO;
 909	}
 910	assert_qgroups_uptodate(trans);
 911
 912	kmem_cache_free(btrfs_trans_handle_cachep, trans);
 913	if (must_run_delayed_refs) {
 914		btrfs_async_run_delayed_refs(info, cur, transid,
 915					     must_run_delayed_refs == 1);
 916	}
 917	return err;
 918}
 919
 920int btrfs_end_transaction(struct btrfs_trans_handle *trans)
 
 921{
 922	return __btrfs_end_transaction(trans, 0);
 923}
 924
 925int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
 
 926{
 927	return __btrfs_end_transaction(trans, 1);
 928}
 929
 930/*
 931 * when btree blocks are allocated, they have some corresponding bits set for
 932 * them in one of two extent_io trees.  This is used to make sure all of
 933 * those extents are sent to disk but does not wait on them
 934 */
 935int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
 936			       struct extent_io_tree *dirty_pages, int mark)
 937{
 938	int err = 0;
 939	int werr = 0;
 940	struct address_space *mapping = fs_info->btree_inode->i_mapping;
 941	struct extent_state *cached_state = NULL;
 942	u64 start = 0;
 943	u64 end;
 944
 945	while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 946				      mark, &cached_state)) {
 947		bool wait_writeback = false;
 948
 949		err = convert_extent_bit(dirty_pages, start, end,
 950					 EXTENT_NEED_WAIT,
 951					 mark, &cached_state);
 952		/*
 953		 * convert_extent_bit can return -ENOMEM, which is most of the
 954		 * time a temporary error. So when it happens, ignore the error
 955		 * and wait for writeback of this range to finish - because we
 956		 * failed to set the bit EXTENT_NEED_WAIT for the range, a call
 957		 * to __btrfs_wait_marked_extents() would not know that
 958		 * writeback for this range started and therefore wouldn't
 959		 * wait for it to finish - we don't want to commit a
 960		 * superblock that points to btree nodes/leafs for which
 961		 * writeback hasn't finished yet (and without errors).
 962		 * We cleanup any entries left in the io tree when committing
 963		 * the transaction (through clear_btree_io_tree()).
 964		 */
 965		if (err == -ENOMEM) {
 966			err = 0;
 967			wait_writeback = true;
 968		}
 969		if (!err)
 970			err = filemap_fdatawrite_range(mapping, start, end);
 971		if (err)
 972			werr = err;
 973		else if (wait_writeback)
 974			werr = filemap_fdatawait_range(mapping, start, end);
 975		free_extent_state(cached_state);
 976		cached_state = NULL;
 977		cond_resched();
 978		start = end + 1;
 979	}
 980	return werr;
 981}
 982
 983/*
 984 * when btree blocks are allocated, they have some corresponding bits set for
 985 * them in one of two extent_io trees.  This is used to make sure all of
 986 * those extents are on disk for transaction or log commit.  We wait
 987 * on all the pages and clear them from the dirty pages state tree
 988 */
 989static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
 990				       struct extent_io_tree *dirty_pages)
 991{
 992	int err = 0;
 993	int werr = 0;
 994	struct address_space *mapping = fs_info->btree_inode->i_mapping;
 995	struct extent_state *cached_state = NULL;
 996	u64 start = 0;
 997	u64 end;
 
 
 998
 999	while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1000				      EXTENT_NEED_WAIT, &cached_state)) {
1001		/*
1002		 * Ignore -ENOMEM errors returned by clear_extent_bit().
1003		 * When committing the transaction, we'll remove any entries
1004		 * left in the io tree. For a log commit, we don't remove them
1005		 * after committing the log because the tree can be accessed
1006		 * concurrently - we do it only at transaction commit time when
1007		 * it's safe to do it (through clear_btree_io_tree()).
1008		 */
1009		err = clear_extent_bit(dirty_pages, start, end,
1010				       EXTENT_NEED_WAIT,
1011				       0, 0, &cached_state, GFP_NOFS);
1012		if (err == -ENOMEM)
1013			err = 0;
1014		if (!err)
1015			err = filemap_fdatawait_range(mapping, start, end);
1016		if (err)
1017			werr = err;
1018		free_extent_state(cached_state);
1019		cached_state = NULL;
1020		cond_resched();
1021		start = end + 1;
1022	}
1023	if (err)
1024		werr = err;
1025	return werr;
1026}
1027
1028int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1029		       struct extent_io_tree *dirty_pages)
1030{
1031	bool errors = false;
1032	int err;
1033
1034	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1035	if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1036		errors = true;
1037
1038	if (errors && !err)
1039		err = -EIO;
1040	return err;
1041}
1042
1043int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1044{
1045	struct btrfs_fs_info *fs_info = log_root->fs_info;
1046	struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1047	bool errors = false;
1048	int err;
1049
1050	ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1051
1052	err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1053	if ((mark & EXTENT_DIRTY) &&
1054	    test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1055		errors = true;
1056
1057	if ((mark & EXTENT_NEW) &&
1058	    test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1059		errors = true;
1060
1061	if (errors && !err)
1062		err = -EIO;
1063	return err;
1064}
1065
1066/*
1067 * when btree blocks are allocated, they have some corresponding bits set for
1068 * them in one of two extent_io trees.  This is used to make sure all of
1069 * those extents are on disk for transaction or log commit
1070 */
1071static int btrfs_write_and_wait_marked_extents(struct btrfs_fs_info *fs_info,
1072				struct extent_io_tree *dirty_pages, int mark)
1073{
1074	int ret;
1075	int ret2;
1076	struct blk_plug plug;
1077
1078	blk_start_plug(&plug);
1079	ret = btrfs_write_marked_extents(fs_info, dirty_pages, mark);
1080	blk_finish_plug(&plug);
1081	ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1082
1083	if (ret)
1084		return ret;
1085	if (ret2)
1086		return ret2;
1087	return 0;
1088}
1089
1090static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
1091					    struct btrfs_fs_info *fs_info)
1092{
1093	int ret;
1094
1095	ret = btrfs_write_and_wait_marked_extents(fs_info,
1096					   &trans->transaction->dirty_pages,
1097					   EXTENT_DIRTY);
1098	clear_btree_io_tree(&trans->transaction->dirty_pages);
1099
1100	return ret;
1101}
1102
1103/*
1104 * this is used to update the root pointer in the tree of tree roots.
1105 *
1106 * But, in the case of the extent allocation tree, updating the root
1107 * pointer may allocate blocks which may change the root of the extent
1108 * allocation tree.
1109 *
1110 * So, this loops and repeats and makes sure the cowonly root didn't
1111 * change while the root pointer was being updated in the metadata.
1112 */
1113static int update_cowonly_root(struct btrfs_trans_handle *trans,
1114			       struct btrfs_root *root)
1115{
1116	int ret;
1117	u64 old_root_bytenr;
1118	u64 old_root_used;
1119	struct btrfs_fs_info *fs_info = root->fs_info;
1120	struct btrfs_root *tree_root = fs_info->tree_root;
1121
1122	old_root_used = btrfs_root_used(&root->root_item);
1123
1124	while (1) {
1125		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1126		if (old_root_bytenr == root->node->start &&
1127		    old_root_used == btrfs_root_used(&root->root_item))
1128			break;
1129
1130		btrfs_set_root_node(&root->root_item, root->node);
1131		ret = btrfs_update_root(trans, tree_root,
1132					&root->root_key,
1133					&root->root_item);
1134		if (ret)
1135			return ret;
1136
1137		old_root_used = btrfs_root_used(&root->root_item);
1138	}
1139
1140	return 0;
1141}
1142
1143/*
1144 * update all the cowonly tree roots on disk
1145 *
1146 * The error handling in this function may not be obvious. Any of the
1147 * failures will cause the file system to go offline. We still need
1148 * to clean up the delayed refs.
1149 */
1150static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
1151					 struct btrfs_fs_info *fs_info)
1152{
 
1153	struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1154	struct list_head *io_bgs = &trans->transaction->io_bgs;
1155	struct list_head *next;
1156	struct extent_buffer *eb;
1157	int ret;
1158
1159	eb = btrfs_lock_root_node(fs_info->tree_root);
1160	ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1161			      0, &eb);
1162	btrfs_tree_unlock(eb);
1163	free_extent_buffer(eb);
1164
1165	if (ret)
1166		return ret;
1167
1168	ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1169	if (ret)
1170		return ret;
1171
1172	ret = btrfs_run_dev_stats(trans, fs_info);
1173	if (ret)
1174		return ret;
1175	ret = btrfs_run_dev_replace(trans, fs_info);
1176	if (ret)
1177		return ret;
1178	ret = btrfs_run_qgroups(trans, fs_info);
1179	if (ret)
1180		return ret;
1181
1182	ret = btrfs_setup_space_cache(trans, fs_info);
1183	if (ret)
1184		return ret;
1185
1186	/* run_qgroups might have added some more refs */
1187	ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1188	if (ret)
1189		return ret;
1190again:
1191	while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1192		struct btrfs_root *root;
1193		next = fs_info->dirty_cowonly_roots.next;
1194		list_del_init(next);
1195		root = list_entry(next, struct btrfs_root, dirty_list);
1196		clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1197
1198		if (root != fs_info->extent_root)
1199			list_add_tail(&root->dirty_list,
1200				      &trans->transaction->switch_commits);
1201		ret = update_cowonly_root(trans, root);
1202		if (ret)
1203			return ret;
1204		ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1205		if (ret)
1206			return ret;
1207	}
1208
1209	while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1210		ret = btrfs_write_dirty_block_groups(trans, fs_info);
1211		if (ret)
1212			return ret;
1213		ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1214		if (ret)
1215			return ret;
1216	}
1217
1218	if (!list_empty(&fs_info->dirty_cowonly_roots))
1219		goto again;
1220
1221	list_add_tail(&fs_info->extent_root->dirty_list,
1222		      &trans->transaction->switch_commits);
1223	btrfs_after_dev_replace_commit(fs_info);
1224
1225	return 0;
1226}
1227
1228/*
1229 * dead roots are old snapshots that need to be deleted.  This allocates
1230 * a dirty root struct and adds it into the list of dead roots that need to
1231 * be deleted
1232 */
1233void btrfs_add_dead_root(struct btrfs_root *root)
1234{
1235	struct btrfs_fs_info *fs_info = root->fs_info;
1236
1237	spin_lock(&fs_info->trans_lock);
1238	if (list_empty(&root->root_list))
1239		list_add_tail(&root->root_list, &fs_info->dead_roots);
1240	spin_unlock(&fs_info->trans_lock);
1241}
1242
1243/*
1244 * update all the cowonly tree roots on disk
1245 */
1246static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1247				    struct btrfs_fs_info *fs_info)
1248{
1249	struct btrfs_root *gang[8];
 
1250	int i;
1251	int ret;
1252	int err = 0;
1253
1254	spin_lock(&fs_info->fs_roots_radix_lock);
1255	while (1) {
1256		ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1257						 (void **)gang, 0,
1258						 ARRAY_SIZE(gang),
1259						 BTRFS_ROOT_TRANS_TAG);
1260		if (ret == 0)
1261			break;
1262		for (i = 0; i < ret; i++) {
1263			struct btrfs_root *root = gang[i];
1264			radix_tree_tag_clear(&fs_info->fs_roots_radix,
1265					(unsigned long)root->root_key.objectid,
1266					BTRFS_ROOT_TRANS_TAG);
1267			spin_unlock(&fs_info->fs_roots_radix_lock);
1268
1269			btrfs_free_log(trans, root);
1270			btrfs_update_reloc_root(trans, root);
1271			btrfs_orphan_commit_root(trans, root);
1272
1273			btrfs_save_ino_cache(root, trans);
1274
1275			/* see comments in should_cow_block() */
1276			clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1277			smp_mb__after_atomic();
1278
1279			if (root->commit_root != root->node) {
1280				list_add_tail(&root->dirty_list,
1281					&trans->transaction->switch_commits);
1282				btrfs_set_root_node(&root->root_item,
1283						    root->node);
1284			}
1285
1286			err = btrfs_update_root(trans, fs_info->tree_root,
1287						&root->root_key,
1288						&root->root_item);
1289			spin_lock(&fs_info->fs_roots_radix_lock);
1290			if (err)
1291				break;
1292			btrfs_qgroup_free_meta_all(root);
1293		}
1294	}
1295	spin_unlock(&fs_info->fs_roots_radix_lock);
1296	return err;
1297}
1298
1299/*
1300 * defrag a given btree.
1301 * Every leaf in the btree is read and defragged.
1302 */
1303int btrfs_defrag_root(struct btrfs_root *root)
1304{
1305	struct btrfs_fs_info *info = root->fs_info;
1306	struct btrfs_trans_handle *trans;
1307	int ret;
1308
1309	if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1310		return 0;
1311
1312	while (1) {
1313		trans = btrfs_start_transaction(root, 0);
1314		if (IS_ERR(trans))
1315			return PTR_ERR(trans);
1316
1317		ret = btrfs_defrag_leaves(trans, root);
1318
1319		btrfs_end_transaction(trans);
1320		btrfs_btree_balance_dirty(info);
1321		cond_resched();
1322
1323		if (btrfs_fs_closing(info) || ret != -EAGAIN)
1324			break;
1325
1326		if (btrfs_defrag_cancelled(info)) {
1327			btrfs_debug(info, "defrag_root cancelled");
1328			ret = -EAGAIN;
1329			break;
1330		}
1331	}
1332	clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1333	return ret;
1334}
1335
1336/*
1337 * Do all special snapshot related qgroup dirty hack.
1338 *
1339 * Will do all needed qgroup inherit and dirty hack like switch commit
1340 * roots inside one transaction and write all btree into disk, to make
1341 * qgroup works.
1342 */
1343static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1344				   struct btrfs_root *src,
1345				   struct btrfs_root *parent,
1346				   struct btrfs_qgroup_inherit *inherit,
1347				   u64 dst_objectid)
1348{
1349	struct btrfs_fs_info *fs_info = src->fs_info;
1350	int ret;
1351
1352	/*
1353	 * Save some performance in the case that qgroups are not
1354	 * enabled. If this check races with the ioctl, rescan will
1355	 * kick in anyway.
1356	 */
1357	mutex_lock(&fs_info->qgroup_ioctl_lock);
1358	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
1359		mutex_unlock(&fs_info->qgroup_ioctl_lock);
1360		return 0;
1361	}
1362	mutex_unlock(&fs_info->qgroup_ioctl_lock);
1363
1364	/*
1365	 * We are going to commit transaction, see btrfs_commit_transaction()
1366	 * comment for reason locking tree_log_mutex
1367	 */
1368	mutex_lock(&fs_info->tree_log_mutex);
1369
1370	ret = commit_fs_roots(trans, fs_info);
1371	if (ret)
1372		goto out;
1373	ret = btrfs_qgroup_prepare_account_extents(trans, fs_info);
1374	if (ret < 0)
1375		goto out;
1376	ret = btrfs_qgroup_account_extents(trans, fs_info);
1377	if (ret < 0)
1378		goto out;
1379
1380	/* Now qgroup are all updated, we can inherit it to new qgroups */
1381	ret = btrfs_qgroup_inherit(trans, fs_info,
1382				   src->root_key.objectid, dst_objectid,
1383				   inherit);
1384	if (ret < 0)
1385		goto out;
1386
1387	/*
1388	 * Now we do a simplified commit transaction, which will:
1389	 * 1) commit all subvolume and extent tree
1390	 *    To ensure all subvolume and extent tree have a valid
1391	 *    commit_root to accounting later insert_dir_item()
1392	 * 2) write all btree blocks onto disk
1393	 *    This is to make sure later btree modification will be cowed
1394	 *    Or commit_root can be populated and cause wrong qgroup numbers
1395	 * In this simplified commit, we don't really care about other trees
1396	 * like chunk and root tree, as they won't affect qgroup.
1397	 * And we don't write super to avoid half committed status.
1398	 */
1399	ret = commit_cowonly_roots(trans, fs_info);
1400	if (ret)
1401		goto out;
1402	switch_commit_roots(trans->transaction, fs_info);
1403	ret = btrfs_write_and_wait_transaction(trans, fs_info);
1404	if (ret)
1405		btrfs_handle_fs_error(fs_info, ret,
1406			"Error while writing out transaction for qgroup");
1407
1408out:
1409	mutex_unlock(&fs_info->tree_log_mutex);
1410
1411	/*
1412	 * Force parent root to be updated, as we recorded it before so its
1413	 * last_trans == cur_transid.
1414	 * Or it won't be committed again onto disk after later
1415	 * insert_dir_item()
1416	 */
1417	if (!ret)
1418		record_root_in_trans(trans, parent, 1);
1419	return ret;
1420}
1421
1422/*
1423 * new snapshots need to be created at a very specific time in the
1424 * transaction commit.  This does the actual creation.
1425 *
1426 * Note:
1427 * If the error which may affect the commitment of the current transaction
1428 * happens, we should return the error number. If the error which just affect
1429 * the creation of the pending snapshots, just return 0.
1430 */
1431static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1432				   struct btrfs_fs_info *fs_info,
1433				   struct btrfs_pending_snapshot *pending)
1434{
1435	struct btrfs_key key;
1436	struct btrfs_root_item *new_root_item;
1437	struct btrfs_root *tree_root = fs_info->tree_root;
1438	struct btrfs_root *root = pending->root;
1439	struct btrfs_root *parent_root;
1440	struct btrfs_block_rsv *rsv;
1441	struct inode *parent_inode;
1442	struct btrfs_path *path;
1443	struct btrfs_dir_item *dir_item;
1444	struct dentry *dentry;
1445	struct extent_buffer *tmp;
1446	struct extent_buffer *old;
1447	struct timespec cur_time;
1448	int ret = 0;
1449	u64 to_reserve = 0;
1450	u64 index = 0;
1451	u64 objectid;
1452	u64 root_flags;
1453	uuid_le new_uuid;
1454
1455	ASSERT(pending->path);
1456	path = pending->path;
1457
1458	ASSERT(pending->root_item);
1459	new_root_item = pending->root_item;
1460
1461	pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1462	if (pending->error)
1463		goto no_free_objectid;
1464
1465	/*
1466	 * Make qgroup to skip current new snapshot's qgroupid, as it is
1467	 * accounted by later btrfs_qgroup_inherit().
1468	 */
1469	btrfs_set_skip_qgroup(trans, objectid);
1470
1471	btrfs_reloc_pre_snapshot(pending, &to_reserve);
1472
1473	if (to_reserve > 0) {
1474		pending->error = btrfs_block_rsv_add(root,
1475						     &pending->block_rsv,
1476						     to_reserve,
1477						     BTRFS_RESERVE_NO_FLUSH);
1478		if (pending->error)
1479			goto clear_skip_qgroup;
1480	}
1481
1482	key.objectid = objectid;
1483	key.offset = (u64)-1;
1484	key.type = BTRFS_ROOT_ITEM_KEY;
1485
1486	rsv = trans->block_rsv;
1487	trans->block_rsv = &pending->block_rsv;
1488	trans->bytes_reserved = trans->block_rsv->reserved;
1489	trace_btrfs_space_reservation(fs_info, "transaction",
1490				      trans->transid,
1491				      trans->bytes_reserved, 1);
1492	dentry = pending->dentry;
1493	parent_inode = pending->dir;
1494	parent_root = BTRFS_I(parent_inode)->root;
1495	record_root_in_trans(trans, parent_root, 0);
1496
1497	cur_time = current_time(parent_inode);
1498
1499	/*
1500	 * insert the directory item
1501	 */
1502	ret = btrfs_set_inode_index(parent_inode, &index);
1503	BUG_ON(ret); /* -ENOMEM */
1504
1505	/* check if there is a file/dir which has the same name. */
1506	dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1507					 btrfs_ino(parent_inode),
1508					 dentry->d_name.name,
1509					 dentry->d_name.len, 0);
1510	if (dir_item != NULL && !IS_ERR(dir_item)) {
1511		pending->error = -EEXIST;
1512		goto dir_item_existed;
1513	} else if (IS_ERR(dir_item)) {
1514		ret = PTR_ERR(dir_item);
1515		btrfs_abort_transaction(trans, ret);
1516		goto fail;
1517	}
1518	btrfs_release_path(path);
1519
1520	/*
1521	 * pull in the delayed directory update
1522	 * and the delayed inode item
1523	 * otherwise we corrupt the FS during
1524	 * snapshot
1525	 */
1526	ret = btrfs_run_delayed_items(trans, fs_info);
1527	if (ret) {	/* Transaction aborted */
1528		btrfs_abort_transaction(trans, ret);
1529		goto fail;
1530	}
1531
1532	record_root_in_trans(trans, root, 0);
1533	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1534	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1535	btrfs_check_and_init_root_item(new_root_item);
1536
1537	root_flags = btrfs_root_flags(new_root_item);
1538	if (pending->readonly)
1539		root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1540	else
1541		root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1542	btrfs_set_root_flags(new_root_item, root_flags);
1543
1544	btrfs_set_root_generation_v2(new_root_item,
1545			trans->transid);
1546	uuid_le_gen(&new_uuid);
1547	memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1548	memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1549			BTRFS_UUID_SIZE);
1550	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1551		memset(new_root_item->received_uuid, 0,
1552		       sizeof(new_root_item->received_uuid));
1553		memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1554		memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1555		btrfs_set_root_stransid(new_root_item, 0);
1556		btrfs_set_root_rtransid(new_root_item, 0);
1557	}
1558	btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1559	btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1560	btrfs_set_root_otransid(new_root_item, trans->transid);
1561
1562	old = btrfs_lock_root_node(root);
1563	ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1564	if (ret) {
1565		btrfs_tree_unlock(old);
1566		free_extent_buffer(old);
1567		btrfs_abort_transaction(trans, ret);
1568		goto fail;
1569	}
1570
1571	btrfs_set_lock_blocking(old);
1572
1573	ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1574	/* clean up in any case */
1575	btrfs_tree_unlock(old);
1576	free_extent_buffer(old);
1577	if (ret) {
1578		btrfs_abort_transaction(trans, ret);
1579		goto fail;
1580	}
1581	/* see comments in should_cow_block() */
1582	set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1583	smp_wmb();
1584
1585	btrfs_set_root_node(new_root_item, tmp);
1586	/* record when the snapshot was created in key.offset */
1587	key.offset = trans->transid;
1588	ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1589	btrfs_tree_unlock(tmp);
1590	free_extent_buffer(tmp);
1591	if (ret) {
1592		btrfs_abort_transaction(trans, ret);
1593		goto fail;
1594	}
1595
1596	/*
1597	 * insert root back/forward references
1598	 */
1599	ret = btrfs_add_root_ref(trans, fs_info, objectid,
1600				 parent_root->root_key.objectid,
1601				 btrfs_ino(parent_inode), index,
1602				 dentry->d_name.name, dentry->d_name.len);
1603	if (ret) {
1604		btrfs_abort_transaction(trans, ret);
1605		goto fail;
1606	}
1607
1608	key.offset = (u64)-1;
1609	pending->snap = btrfs_read_fs_root_no_name(fs_info, &key);
1610	if (IS_ERR(pending->snap)) {
1611		ret = PTR_ERR(pending->snap);
1612		btrfs_abort_transaction(trans, ret);
1613		goto fail;
1614	}
1615
1616	ret = btrfs_reloc_post_snapshot(trans, pending);
1617	if (ret) {
1618		btrfs_abort_transaction(trans, ret);
1619		goto fail;
1620	}
1621
1622	ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
1623	if (ret) {
1624		btrfs_abort_transaction(trans, ret);
1625		goto fail;
1626	}
1627
1628	/*
1629	 * Do special qgroup accounting for snapshot, as we do some qgroup
1630	 * snapshot hack to do fast snapshot.
1631	 * To co-operate with that hack, we do hack again.
1632	 * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1633	 */
1634	ret = qgroup_account_snapshot(trans, root, parent_root,
1635				      pending->inherit, objectid);
1636	if (ret < 0)
1637		goto fail;
1638
1639	ret = btrfs_insert_dir_item(trans, parent_root,
1640				    dentry->d_name.name, dentry->d_name.len,
1641				    parent_inode, &key,
1642				    BTRFS_FT_DIR, index);
1643	/* We have check then name at the beginning, so it is impossible. */
1644	BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1645	if (ret) {
1646		btrfs_abort_transaction(trans, ret);
1647		goto fail;
1648	}
1649
1650	btrfs_i_size_write(parent_inode, parent_inode->i_size +
1651					 dentry->d_name.len * 2);
1652	parent_inode->i_mtime = parent_inode->i_ctime =
1653		current_time(parent_inode);
1654	ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1655	if (ret) {
1656		btrfs_abort_transaction(trans, ret);
1657		goto fail;
1658	}
1659	ret = btrfs_uuid_tree_add(trans, fs_info, new_uuid.b,
1660				  BTRFS_UUID_KEY_SUBVOL, objectid);
1661	if (ret) {
1662		btrfs_abort_transaction(trans, ret);
1663		goto fail;
1664	}
1665	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1666		ret = btrfs_uuid_tree_add(trans, fs_info,
1667					  new_root_item->received_uuid,
1668					  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1669					  objectid);
1670		if (ret && ret != -EEXIST) {
1671			btrfs_abort_transaction(trans, ret);
1672			goto fail;
1673		}
1674	}
1675
1676	ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1677	if (ret) {
1678		btrfs_abort_transaction(trans, ret);
1679		goto fail;
1680	}
1681
1682fail:
1683	pending->error = ret;
1684dir_item_existed:
1685	trans->block_rsv = rsv;
1686	trans->bytes_reserved = 0;
1687clear_skip_qgroup:
1688	btrfs_clear_skip_qgroup(trans);
1689no_free_objectid:
1690	kfree(new_root_item);
1691	pending->root_item = NULL;
1692	btrfs_free_path(path);
1693	pending->path = NULL;
1694
1695	return ret;
1696}
1697
1698/*
1699 * create all the snapshots we've scheduled for creation
1700 */
1701static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1702					     struct btrfs_fs_info *fs_info)
1703{
1704	struct btrfs_pending_snapshot *pending, *next;
1705	struct list_head *head = &trans->transaction->pending_snapshots;
1706	int ret = 0;
1707
1708	list_for_each_entry_safe(pending, next, head, list) {
1709		list_del(&pending->list);
1710		ret = create_pending_snapshot(trans, fs_info, pending);
1711		if (ret)
1712			break;
1713	}
1714	return ret;
1715}
1716
1717static void update_super_roots(struct btrfs_fs_info *fs_info)
1718{
1719	struct btrfs_root_item *root_item;
1720	struct btrfs_super_block *super;
1721
1722	super = fs_info->super_copy;
1723
1724	root_item = &fs_info->chunk_root->root_item;
1725	super->chunk_root = root_item->bytenr;
1726	super->chunk_root_generation = root_item->generation;
1727	super->chunk_root_level = root_item->level;
1728
1729	root_item = &fs_info->tree_root->root_item;
1730	super->root = root_item->bytenr;
1731	super->generation = root_item->generation;
1732	super->root_level = root_item->level;
1733	if (btrfs_test_opt(fs_info, SPACE_CACHE))
1734		super->cache_generation = root_item->generation;
1735	if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1736		super->uuid_tree_generation = root_item->generation;
1737}
1738
1739int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1740{
1741	struct btrfs_transaction *trans;
1742	int ret = 0;
1743
1744	spin_lock(&info->trans_lock);
1745	trans = info->running_transaction;
1746	if (trans)
1747		ret = (trans->state >= TRANS_STATE_COMMIT_START);
1748	spin_unlock(&info->trans_lock);
1749	return ret;
1750}
1751
1752int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1753{
1754	struct btrfs_transaction *trans;
1755	int ret = 0;
1756
1757	spin_lock(&info->trans_lock);
1758	trans = info->running_transaction;
1759	if (trans)
1760		ret = is_transaction_blocked(trans);
1761	spin_unlock(&info->trans_lock);
1762	return ret;
1763}
1764
1765/*
1766 * wait for the current transaction commit to start and block subsequent
1767 * transaction joins
1768 */
1769static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
1770					    struct btrfs_transaction *trans)
1771{
1772	wait_event(fs_info->transaction_blocked_wait,
1773		   trans->state >= TRANS_STATE_COMMIT_START || trans->aborted);
 
1774}
1775
1776/*
1777 * wait for the current transaction to start and then become unblocked.
1778 * caller holds ref.
1779 */
1780static void wait_current_trans_commit_start_and_unblock(
1781					struct btrfs_fs_info *fs_info,
1782					struct btrfs_transaction *trans)
1783{
1784	wait_event(fs_info->transaction_wait,
1785		   trans->state >= TRANS_STATE_UNBLOCKED || trans->aborted);
 
1786}
1787
1788/*
1789 * commit transactions asynchronously. once btrfs_commit_transaction_async
1790 * returns, any subsequent transaction will not be allowed to join.
1791 */
1792struct btrfs_async_commit {
1793	struct btrfs_trans_handle *newtrans;
 
1794	struct work_struct work;
1795};
1796
1797static void do_async_commit(struct work_struct *work)
1798{
1799	struct btrfs_async_commit *ac =
1800		container_of(work, struct btrfs_async_commit, work);
1801
1802	/*
1803	 * We've got freeze protection passed with the transaction.
1804	 * Tell lockdep about it.
1805	 */
1806	if (ac->newtrans->type & __TRANS_FREEZABLE)
1807		__sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1808
1809	current->journal_info = ac->newtrans;
1810
1811	btrfs_commit_transaction(ac->newtrans);
1812	kfree(ac);
1813}
1814
1815int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
 
1816				   int wait_for_unblock)
1817{
1818	struct btrfs_fs_info *fs_info = trans->fs_info;
1819	struct btrfs_async_commit *ac;
1820	struct btrfs_transaction *cur_trans;
1821
1822	ac = kmalloc(sizeof(*ac), GFP_NOFS);
1823	if (!ac)
1824		return -ENOMEM;
1825
1826	INIT_WORK(&ac->work, do_async_commit);
1827	ac->newtrans = btrfs_join_transaction(trans->root);
 
1828	if (IS_ERR(ac->newtrans)) {
1829		int err = PTR_ERR(ac->newtrans);
1830		kfree(ac);
1831		return err;
1832	}
1833
1834	/* take transaction reference */
1835	cur_trans = trans->transaction;
1836	atomic_inc(&cur_trans->use_count);
1837
1838	btrfs_end_transaction(trans);
1839
1840	/*
1841	 * Tell lockdep we've released the freeze rwsem, since the
1842	 * async commit thread will be the one to unlock it.
1843	 */
1844	if (ac->newtrans->type & __TRANS_FREEZABLE)
1845		__sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1846
1847	schedule_work(&ac->work);
1848
1849	/* wait for transaction to start and unblock */
1850	if (wait_for_unblock)
1851		wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
1852	else
1853		wait_current_trans_commit_start(fs_info, cur_trans);
1854
1855	if (current->journal_info == trans)
1856		current->journal_info = NULL;
1857
1858	btrfs_put_transaction(cur_trans);
1859	return 0;
1860}
1861
1862
1863static void cleanup_transaction(struct btrfs_trans_handle *trans,
1864				struct btrfs_root *root, int err)
1865{
1866	struct btrfs_fs_info *fs_info = root->fs_info;
1867	struct btrfs_transaction *cur_trans = trans->transaction;
1868	DEFINE_WAIT(wait);
1869
1870	WARN_ON(trans->use_count > 1);
1871
1872	btrfs_abort_transaction(trans, err);
1873
1874	spin_lock(&fs_info->trans_lock);
1875
1876	/*
1877	 * If the transaction is removed from the list, it means this
1878	 * transaction has been committed successfully, so it is impossible
1879	 * to call the cleanup function.
1880	 */
1881	BUG_ON(list_empty(&cur_trans->list));
1882
1883	list_del_init(&cur_trans->list);
1884	if (cur_trans == fs_info->running_transaction) {
1885		cur_trans->state = TRANS_STATE_COMMIT_DOING;
1886		spin_unlock(&fs_info->trans_lock);
1887		wait_event(cur_trans->writer_wait,
1888			   atomic_read(&cur_trans->num_writers) == 1);
1889
1890		spin_lock(&fs_info->trans_lock);
1891	}
1892	spin_unlock(&fs_info->trans_lock);
1893
1894	btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1895
1896	spin_lock(&fs_info->trans_lock);
1897	if (cur_trans == fs_info->running_transaction)
1898		fs_info->running_transaction = NULL;
1899	spin_unlock(&fs_info->trans_lock);
1900
1901	if (trans->type & __TRANS_FREEZABLE)
1902		sb_end_intwrite(fs_info->sb);
1903	btrfs_put_transaction(cur_trans);
1904	btrfs_put_transaction(cur_trans);
1905
1906	trace_btrfs_transaction_commit(root);
1907
1908	if (current->journal_info == trans)
1909		current->journal_info = NULL;
1910	btrfs_scrub_cancel(fs_info);
1911
1912	kmem_cache_free(btrfs_trans_handle_cachep, trans);
1913}
1914
1915static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1916{
1917	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1918		return btrfs_start_delalloc_roots(fs_info, 1, -1);
1919	return 0;
1920}
1921
1922static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1923{
1924	if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1925		btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
1926}
1927
1928static inline void
1929btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
1930{
1931	wait_event(cur_trans->pending_wait,
1932		   atomic_read(&cur_trans->pending_ordered) == 0);
1933}
1934
1935int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 
1936{
1937	struct btrfs_fs_info *fs_info = trans->fs_info;
1938	struct btrfs_transaction *cur_trans = trans->transaction;
1939	struct btrfs_transaction *prev_trans = NULL;
 
1940	int ret;
1941
1942	/* Stop the commit early if ->aborted is set */
1943	if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1944		ret = cur_trans->aborted;
1945		btrfs_end_transaction(trans);
1946		return ret;
1947	}
1948
1949	/* make a pass through all the delayed refs we have so far
1950	 * any runnings procs may add more while we are here
1951	 */
1952	ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1953	if (ret) {
1954		btrfs_end_transaction(trans);
1955		return ret;
1956	}
1957
1958	btrfs_trans_release_metadata(trans, fs_info);
1959	trans->block_rsv = NULL;
1960
1961	cur_trans = trans->transaction;
1962
1963	/*
1964	 * set the flushing flag so procs in this transaction have to
1965	 * start sending their work down.
1966	 */
1967	cur_trans->delayed_refs.flushing = 1;
1968	smp_wmb();
1969
1970	if (!list_empty(&trans->new_bgs))
1971		btrfs_create_pending_block_groups(trans, fs_info);
1972
1973	ret = btrfs_run_delayed_refs(trans, fs_info, 0);
1974	if (ret) {
1975		btrfs_end_transaction(trans);
1976		return ret;
1977	}
1978
1979	if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
1980		int run_it = 0;
1981
1982		/* this mutex is also taken before trying to set
1983		 * block groups readonly.  We need to make sure
1984		 * that nobody has set a block group readonly
1985		 * after a extents from that block group have been
1986		 * allocated for cache files.  btrfs_set_block_group_ro
1987		 * will wait for the transaction to commit if it
1988		 * finds BTRFS_TRANS_DIRTY_BG_RUN set.
1989		 *
1990		 * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
1991		 * only one process starts all the block group IO.  It wouldn't
1992		 * hurt to have more than one go through, but there's no
1993		 * real advantage to it either.
1994		 */
1995		mutex_lock(&fs_info->ro_block_group_mutex);
1996		if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
1997				      &cur_trans->flags))
1998			run_it = 1;
1999		mutex_unlock(&fs_info->ro_block_group_mutex);
2000
2001		if (run_it)
2002			ret = btrfs_start_dirty_block_groups(trans, fs_info);
2003	}
2004	if (ret) {
2005		btrfs_end_transaction(trans);
2006		return ret;
2007	}
2008
2009	spin_lock(&fs_info->trans_lock);
2010	if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
2011		spin_unlock(&fs_info->trans_lock);
2012		atomic_inc(&cur_trans->use_count);
2013		ret = btrfs_end_transaction(trans);
2014
2015		wait_for_commit(cur_trans);
2016
2017		if (unlikely(cur_trans->aborted))
2018			ret = cur_trans->aborted;
2019
2020		btrfs_put_transaction(cur_trans);
2021
2022		return ret;
2023	}
2024
2025	cur_trans->state = TRANS_STATE_COMMIT_START;
2026	wake_up(&fs_info->transaction_blocked_wait);
2027
2028	if (cur_trans->list.prev != &fs_info->trans_list) {
2029		prev_trans = list_entry(cur_trans->list.prev,
2030					struct btrfs_transaction, list);
2031		if (prev_trans->state != TRANS_STATE_COMPLETED) {
2032			atomic_inc(&prev_trans->use_count);
2033			spin_unlock(&fs_info->trans_lock);
2034
2035			wait_for_commit(prev_trans);
2036			ret = prev_trans->aborted;
2037
2038			btrfs_put_transaction(prev_trans);
2039			if (ret)
2040				goto cleanup_transaction;
2041		} else {
2042			spin_unlock(&fs_info->trans_lock);
2043		}
2044	} else {
2045		spin_unlock(&fs_info->trans_lock);
2046	}
2047
2048	extwriter_counter_dec(cur_trans, trans->type);
2049
2050	ret = btrfs_start_delalloc_flush(fs_info);
2051	if (ret)
2052		goto cleanup_transaction;
2053
2054	ret = btrfs_run_delayed_items(trans, fs_info);
2055	if (ret)
2056		goto cleanup_transaction;
2057
2058	wait_event(cur_trans->writer_wait,
2059		   extwriter_counter_read(cur_trans) == 0);
2060
2061	/* some pending stuffs might be added after the previous flush. */
2062	ret = btrfs_run_delayed_items(trans, fs_info);
2063	if (ret)
2064		goto cleanup_transaction;
2065
2066	btrfs_wait_delalloc_flush(fs_info);
2067
2068	btrfs_wait_pending_ordered(cur_trans);
2069
2070	btrfs_scrub_pause(fs_info);
2071	/*
2072	 * Ok now we need to make sure to block out any other joins while we
2073	 * commit the transaction.  We could have started a join before setting
2074	 * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2075	 */
2076	spin_lock(&fs_info->trans_lock);
2077	cur_trans->state = TRANS_STATE_COMMIT_DOING;
2078	spin_unlock(&fs_info->trans_lock);
2079	wait_event(cur_trans->writer_wait,
2080		   atomic_read(&cur_trans->num_writers) == 1);
2081
2082	/* ->aborted might be set after the previous check, so check it */
2083	if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
2084		ret = cur_trans->aborted;
2085		goto scrub_continue;
2086	}
2087	/*
2088	 * the reloc mutex makes sure that we stop
2089	 * the balancing code from coming in and moving
2090	 * extents around in the middle of the commit
2091	 */
2092	mutex_lock(&fs_info->reloc_mutex);
2093
2094	/*
2095	 * We needn't worry about the delayed items because we will
2096	 * deal with them in create_pending_snapshot(), which is the
2097	 * core function of the snapshot creation.
2098	 */
2099	ret = create_pending_snapshots(trans, fs_info);
2100	if (ret) {
2101		mutex_unlock(&fs_info->reloc_mutex);
2102		goto scrub_continue;
2103	}
2104
2105	/*
2106	 * We insert the dir indexes of the snapshots and update the inode
2107	 * of the snapshots' parents after the snapshot creation, so there
2108	 * are some delayed items which are not dealt with. Now deal with
2109	 * them.
2110	 *
2111	 * We needn't worry that this operation will corrupt the snapshots,
2112	 * because all the tree which are snapshoted will be forced to COW
2113	 * the nodes and leaves.
2114	 */
2115	ret = btrfs_run_delayed_items(trans, fs_info);
2116	if (ret) {
2117		mutex_unlock(&fs_info->reloc_mutex);
2118		goto scrub_continue;
2119	}
2120
2121	ret = btrfs_run_delayed_refs(trans, fs_info, (unsigned long)-1);
2122	if (ret) {
2123		mutex_unlock(&fs_info->reloc_mutex);
2124		goto scrub_continue;
2125	}
2126
2127	/* Reocrd old roots for later qgroup accounting */
2128	ret = btrfs_qgroup_prepare_account_extents(trans, fs_info);
2129	if (ret) {
2130		mutex_unlock(&fs_info->reloc_mutex);
2131		goto scrub_continue;
2132	}
2133
2134	/*
2135	 * make sure none of the code above managed to slip in a
2136	 * delayed item
2137	 */
2138	btrfs_assert_delayed_root_empty(fs_info);
2139
2140	WARN_ON(cur_trans != trans->transaction);
2141
2142	/* btrfs_commit_tree_roots is responsible for getting the
2143	 * various roots consistent with each other.  Every pointer
2144	 * in the tree of tree roots has to point to the most up to date
2145	 * root for every subvolume and other tree.  So, we have to keep
2146	 * the tree logging code from jumping in and changing any
2147	 * of the trees.
2148	 *
2149	 * At this point in the commit, there can't be any tree-log
2150	 * writers, but a little lower down we drop the trans mutex
2151	 * and let new people in.  By holding the tree_log_mutex
2152	 * from now until after the super is written, we avoid races
2153	 * with the tree-log code.
2154	 */
2155	mutex_lock(&fs_info->tree_log_mutex);
2156
2157	ret = commit_fs_roots(trans, fs_info);
2158	if (ret) {
2159		mutex_unlock(&fs_info->tree_log_mutex);
2160		mutex_unlock(&fs_info->reloc_mutex);
2161		goto scrub_continue;
2162	}
2163
2164	/*
2165	 * Since the transaction is done, we can apply the pending changes
2166	 * before the next transaction.
2167	 */
2168	btrfs_apply_pending_changes(fs_info);
2169
2170	/* commit_fs_roots gets rid of all the tree log roots, it is now
2171	 * safe to free the root of tree log roots
2172	 */
2173	btrfs_free_log_root_tree(trans, fs_info);
2174
2175	/*
2176	 * Since fs roots are all committed, we can get a quite accurate
2177	 * new_roots. So let's do quota accounting.
2178	 */
2179	ret = btrfs_qgroup_account_extents(trans, fs_info);
2180	if (ret < 0) {
2181		mutex_unlock(&fs_info->tree_log_mutex);
2182		mutex_unlock(&fs_info->reloc_mutex);
2183		goto scrub_continue;
2184	}
2185
2186	ret = commit_cowonly_roots(trans, fs_info);
2187	if (ret) {
2188		mutex_unlock(&fs_info->tree_log_mutex);
2189		mutex_unlock(&fs_info->reloc_mutex);
2190		goto scrub_continue;
2191	}
2192
2193	/*
2194	 * The tasks which save the space cache and inode cache may also
2195	 * update ->aborted, check it.
2196	 */
2197	if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
2198		ret = cur_trans->aborted;
2199		mutex_unlock(&fs_info->tree_log_mutex);
2200		mutex_unlock(&fs_info->reloc_mutex);
2201		goto scrub_continue;
2202	}
2203
2204	btrfs_prepare_extent_commit(trans, fs_info);
2205
2206	cur_trans = fs_info->running_transaction;
2207
2208	btrfs_set_root_node(&fs_info->tree_root->root_item,
2209			    fs_info->tree_root->node);
2210	list_add_tail(&fs_info->tree_root->dirty_list,
2211		      &cur_trans->switch_commits);
2212
2213	btrfs_set_root_node(&fs_info->chunk_root->root_item,
2214			    fs_info->chunk_root->node);
2215	list_add_tail(&fs_info->chunk_root->dirty_list,
2216		      &cur_trans->switch_commits);
2217
2218	switch_commit_roots(cur_trans, fs_info);
2219
2220	assert_qgroups_uptodate(trans);
2221	ASSERT(list_empty(&cur_trans->dirty_bgs));
2222	ASSERT(list_empty(&cur_trans->io_bgs));
2223	update_super_roots(fs_info);
2224
2225	btrfs_set_super_log_root(fs_info->super_copy, 0);
2226	btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2227	memcpy(fs_info->super_for_commit, fs_info->super_copy,
2228	       sizeof(*fs_info->super_copy));
2229
2230	btrfs_update_commit_device_size(fs_info);
2231	btrfs_update_commit_device_bytes_used(fs_info, cur_trans);
2232
2233	clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2234	clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2235
2236	btrfs_trans_release_chunk_metadata(trans);
2237
2238	spin_lock(&fs_info->trans_lock);
2239	cur_trans->state = TRANS_STATE_UNBLOCKED;
2240	fs_info->running_transaction = NULL;
2241	spin_unlock(&fs_info->trans_lock);
2242	mutex_unlock(&fs_info->reloc_mutex);
2243
2244	wake_up(&fs_info->transaction_wait);
2245
2246	ret = btrfs_write_and_wait_transaction(trans, fs_info);
2247	if (ret) {
2248		btrfs_handle_fs_error(fs_info, ret,
2249				      "Error while writing out transaction");
2250		mutex_unlock(&fs_info->tree_log_mutex);
2251		goto scrub_continue;
2252	}
2253
2254	ret = write_ctree_super(trans, fs_info, 0);
2255	if (ret) {
2256		mutex_unlock(&fs_info->tree_log_mutex);
2257		goto scrub_continue;
2258	}
2259
2260	/*
2261	 * the super is written, we can safely allow the tree-loggers
2262	 * to go about their business
2263	 */
2264	mutex_unlock(&fs_info->tree_log_mutex);
2265
2266	btrfs_finish_extent_commit(trans, fs_info);
2267
2268	if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2269		btrfs_clear_space_info_full(fs_info);
2270
2271	fs_info->last_trans_committed = cur_trans->transid;
2272	/*
2273	 * We needn't acquire the lock here because there is no other task
2274	 * which can change it.
2275	 */
2276	cur_trans->state = TRANS_STATE_COMPLETED;
2277	wake_up(&cur_trans->commit_wait);
2278
2279	spin_lock(&fs_info->trans_lock);
2280	list_del_init(&cur_trans->list);
2281	spin_unlock(&fs_info->trans_lock);
2282
2283	btrfs_put_transaction(cur_trans);
2284	btrfs_put_transaction(cur_trans);
2285
2286	if (trans->type & __TRANS_FREEZABLE)
2287		sb_end_intwrite(fs_info->sb);
2288
2289	trace_btrfs_transaction_commit(trans->root);
2290
2291	btrfs_scrub_continue(fs_info);
2292
2293	if (current->journal_info == trans)
2294		current->journal_info = NULL;
2295
2296	kmem_cache_free(btrfs_trans_handle_cachep, trans);
2297
2298	/*
2299	 * If fs has been frozen, we can not handle delayed iputs, otherwise
2300	 * it'll result in deadlock about SB_FREEZE_FS.
2301	 */
2302	if (current != fs_info->transaction_kthread &&
2303	    current != fs_info->cleaner_kthread && !fs_info->fs_frozen)
2304		btrfs_run_delayed_iputs(fs_info);
2305
2306	return ret;
2307
2308scrub_continue:
2309	btrfs_scrub_continue(fs_info);
2310cleanup_transaction:
2311	btrfs_trans_release_metadata(trans, fs_info);
2312	btrfs_trans_release_chunk_metadata(trans);
2313	trans->block_rsv = NULL;
2314	btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2315	if (current->journal_info == trans)
2316		current->journal_info = NULL;
2317	cleanup_transaction(trans, trans->root, ret);
2318
2319	return ret;
2320}
2321
2322/*
2323 * return < 0 if error
2324 * 0 if there are no more dead_roots at the time of call
2325 * 1 there are more to be processed, call me again
2326 *
2327 * The return value indicates there are certainly more snapshots to delete, but
2328 * if there comes a new one during processing, it may return 0. We don't mind,
2329 * because btrfs_commit_super will poke cleaner thread and it will process it a
2330 * few seconds later.
2331 */
2332int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2333{
2334	int ret;
2335	struct btrfs_fs_info *fs_info = root->fs_info;
2336
2337	spin_lock(&fs_info->trans_lock);
2338	if (list_empty(&fs_info->dead_roots)) {
2339		spin_unlock(&fs_info->trans_lock);
2340		return 0;
2341	}
2342	root = list_first_entry(&fs_info->dead_roots,
2343			struct btrfs_root, root_list);
2344	list_del_init(&root->root_list);
2345	spin_unlock(&fs_info->trans_lock);
2346
2347	btrfs_debug(fs_info, "cleaner removing %llu", root->objectid);
2348
2349	btrfs_kill_all_delayed_nodes(root);
2350
2351	if (btrfs_header_backref_rev(root->node) <
2352			BTRFS_MIXED_BACKREF_REV)
2353		ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2354	else
2355		ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2356
2357	return (ret < 0) ? 0 : 1;
2358}
2359
2360void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2361{
2362	unsigned long prev;
2363	unsigned long bit;
2364
2365	prev = xchg(&fs_info->pending_changes, 0);
2366	if (!prev)
2367		return;
2368
2369	bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2370	if (prev & bit)
2371		btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2372	prev &= ~bit;
2373
2374	bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2375	if (prev & bit)
2376		btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2377	prev &= ~bit;
2378
2379	bit = 1 << BTRFS_PENDING_COMMIT;
2380	if (prev & bit)
2381		btrfs_debug(fs_info, "pending commit done");
2382	prev &= ~bit;
2383
2384	if (prev)
2385		btrfs_warn(fs_info,
2386			"unknown pending changes left 0x%lx, ignoring", prev);
2387}