fs/btrfs/transaction.c

   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
  25 static 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
  42 void 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
  81 static 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
 110 static 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
 140 static 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
 147 static 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
 154 static 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
 160 static 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  */
 168 static 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);
 174 loop:
 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  */
 294 static 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
 355 void 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
 374 int 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
 398 static 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  */
 409 static 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
 428 static 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
 439 static 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
 452 static struct btrfs_trans_handle *
 453 start_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         }
 507 again:
 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
 570 got_it:
 571         btrfs_record_root_in_trans(h, root);
 572
 573         if (!current->journal_info)
 574                 current->journal_info = h;
 575         return h;
 576
 577 join_fail:
 578         if (type & __TRANS_FREEZABLE)
 579                 sb_end_intwrite(fs_info->sb);
 580         kmem_cache_free(btrfs_trans_handle_cachep, h);
 581 alloc_fail:
 582         if (num_bytes)
 583                 btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
 584                                         num_bytes);
 585 reserve_fail:
 586         btrfs_qgroup_free_meta_pertrans(root, qgroup_reserved);
 587         return ERR_PTR(ret);
 588 }
 589
 590 struct 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
 597 struct 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
 638 struct 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
 644 struct 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  */
 663 struct 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  */
 676 struct btrfs_trans_handle *
 677 btrfs_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 */
 690 static noinline void wait_for_commit(struct btrfs_transaction *commit)
 691 {
 692         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 693 }
 694
 695 int 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);
 749 out:
 750         return ret;
 751 }
 752
 753 void btrfs_throttle(struct btrfs_fs_info *fs_info)
 754 {
 755         wait_current_trans(fs_info);
 756 }
 757
 758 static 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
 768 int 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
 790 static 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
 811 static 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         cond_wake_up(&cur_trans->writer_wait);
 881         btrfs_put_transaction(cur_trans);
 882
 883         if (current->journal_info == trans)
 884                 current->journal_info = NULL;
 885
 886         if (throttle)
 887                 btrfs_run_delayed_iputs(info);
 888
 889         if (trans->aborted ||
 890             test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
 891                 wake_up_process(info->transaction_kthread);
 892                 err = -EIO;
 893         }
 894
 895         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 896         if (must_run_delayed_refs) {
 897                 btrfs_async_run_delayed_refs(info, cur, transid,
 898                                              must_run_delayed_refs == 1);
 899         }
 900         return err;
 901 }
 902
 903 int btrfs_end_transaction(struct btrfs_trans_handle *trans)
 904 {
 905         return __btrfs_end_transaction(trans, 0);
 906 }
 907
 908 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
 909 {
 910         return __btrfs_end_transaction(trans, 1);
 911 }
 912
 913 /*
 914  * when btree blocks are allocated, they have some corresponding bits set for
 915  * them in one of two extent_io trees.  This is used to make sure all of
 916  * those extents are sent to disk but does not wait on them
 917  */
 918 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
 919                                struct extent_io_tree *dirty_pages, int mark)
 920 {
 921         int err = 0;
 922         int werr = 0;
 923         struct address_space *mapping = fs_info->btree_inode->i_mapping;
 924         struct extent_state *cached_state = NULL;
 925         u64 start = 0;
 926         u64 end;
 927
 928         atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers);
 929         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 930                                       mark, &cached_state)) {
 931                 bool wait_writeback = false;
 932
 933                 err = convert_extent_bit(dirty_pages, start, end,
 934                                          EXTENT_NEED_WAIT,
 935                                          mark, &cached_state);
 936                 /*
 937                  * convert_extent_bit can return -ENOMEM, which is most of the
 938                  * time a temporary error. So when it happens, ignore the error
 939                  * and wait for writeback of this range to finish - because we
 940                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
 941                  * to __btrfs_wait_marked_extents() would not know that
 942                  * writeback for this range started and therefore wouldn't
 943                  * wait for it to finish - we don't want to commit a
 944                  * superblock that points to btree nodes/leafs for which
 945                  * writeback hasn't finished yet (and without errors).
 946                  * We cleanup any entries left in the io tree when committing
 947                  * the transaction (through clear_btree_io_tree()).
 948                  */
 949                 if (err == -ENOMEM) {
 950                         err = 0;
 951                         wait_writeback = true;
 952                 }
 953                 if (!err)
 954                         err = filemap_fdatawrite_range(mapping, start, end);
 955                 if (err)
 956                         werr = err;
 957                 else if (wait_writeback)
 958                         werr = filemap_fdatawait_range(mapping, start, end);
 959                 free_extent_state(cached_state);
 960                 cached_state = NULL;
 961                 cond_resched();
 962                 start = end + 1;
 963         }
 964         atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers);
 965         return werr;
 966 }
 967
 968 /*
 969  * when btree blocks are allocated, they have some corresponding bits set for
 970  * them in one of two extent_io trees.  This is used to make sure all of
 971  * those extents are on disk for transaction or log commit.  We wait
 972  * on all the pages and clear them from the dirty pages state tree
 973  */
 974 static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
 975                                        struct extent_io_tree *dirty_pages)
 976 {
 977         int err = 0;
 978         int werr = 0;
 979         struct address_space *mapping = fs_info->btree_inode->i_mapping;
 980         struct extent_state *cached_state = NULL;
 981         u64 start = 0;
 982         u64 end;
 983
 984         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 985                                       EXTENT_NEED_WAIT, &cached_state)) {
 986                 /*
 987                  * Ignore -ENOMEM errors returned by clear_extent_bit().
 988                  * When committing the transaction, we'll remove any entries
 989                  * left in the io tree. For a log commit, we don't remove them
 990                  * after committing the log because the tree can be accessed
 991                  * concurrently - we do it only at transaction commit time when
 992                  * it's safe to do it (through clear_btree_io_tree()).
 993                  */
 994                 err = clear_extent_bit(dirty_pages, start, end,
 995                                        EXTENT_NEED_WAIT, 0, 0, &cached_state);
 996                 if (err == -ENOMEM)
 997                         err = 0;
 998                 if (!err)
 999                         err = filemap_fdatawait_range(mapping, start, end);
1000                 if (err)
1001                         werr = err;
1002                 free_extent_state(cached_state);
1003                 cached_state = NULL;
1004                 cond_resched();
1005                 start = end + 1;
1006         }
1007         if (err)
1008                 werr = err;
1009         return werr;
1010 }
1011
1012 int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1013                        struct extent_io_tree *dirty_pages)
1014 {
1015         bool errors = false;
1016         int err;
1017
1018         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1019         if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1020                 errors = true;
1021
1022         if (errors && !err)
1023                 err = -EIO;
1024         return err;
1025 }
1026
1027 int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1028 {
1029         struct btrfs_fs_info *fs_info = log_root->fs_info;
1030         struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1031         bool errors = false;
1032         int err;
1033
1034         ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1035
1036         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1037         if ((mark & EXTENT_DIRTY) &&
1038             test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1039                 errors = true;
1040
1041         if ((mark & EXTENT_NEW) &&
1042             test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1043                 errors = true;
1044
1045         if (errors && !err)
1046                 err = -EIO;
1047         return err;
1048 }
1049
1050 /*
1051  * When btree blocks are allocated the corresponding extents are marked dirty.
1052  * This function ensures such extents are persisted on disk for transaction or
1053  * log commit.
1054  *
1055  * @trans: transaction whose dirty pages we'd like to write
1056  */
1057 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1058 {
1059         int ret;
1060         int ret2;
1061         struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1062         struct btrfs_fs_info *fs_info = trans->fs_info;
1063         struct blk_plug plug;
1064
1065         blk_start_plug(&plug);
1066         ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1067         blk_finish_plug(&plug);
1068         ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1069
1070         clear_btree_io_tree(&trans->transaction->dirty_pages);
1071
1072         if (ret)
1073                 return ret;
1074         else if (ret2)
1075                 return ret2;
1076         else
1077                 return 0;
1078 }
1079
1080 /*
1081  * this is used to update the root pointer in the tree of tree roots.
1082  *
1083  * But, in the case of the extent allocation tree, updating the root
1084  * pointer may allocate blocks which may change the root of the extent
1085  * allocation tree.
1086  *
1087  * So, this loops and repeats and makes sure the cowonly root didn't
1088  * change while the root pointer was being updated in the metadata.
1089  */
1090 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1091                                struct btrfs_root *root)
1092 {
1093         int ret;
1094         u64 old_root_bytenr;
1095         u64 old_root_used;
1096         struct btrfs_fs_info *fs_info = root->fs_info;
1097         struct btrfs_root *tree_root = fs_info->tree_root;
1098
1099         old_root_used = btrfs_root_used(&root->root_item);
1100
1101         while (1) {
1102                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1103                 if (old_root_bytenr == root->node->start &&
1104                     old_root_used == btrfs_root_used(&root->root_item))
1105                         break;
1106
1107                 btrfs_set_root_node(&root->root_item, root->node);
1108                 ret = btrfs_update_root(trans, tree_root,
1109                                         &root->root_key,
1110                                         &root->root_item);
1111                 if (ret)
1112                         return ret;
1113
1114                 old_root_used = btrfs_root_used(&root->root_item);
1115         }
1116
1117         return 0;
1118 }
1119
1120 /*
1121  * update all the cowonly tree roots on disk
1122  *
1123  * The error handling in this function may not be obvious. Any of the
1124  * failures will cause the file system to go offline. We still need
1125  * to clean up the delayed refs.
1126  */
1127 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1128 {
1129         struct btrfs_fs_info *fs_info = trans->fs_info;
1130         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1131         struct list_head *io_bgs = &trans->transaction->io_bgs;
1132         struct list_head *next;
1133         struct extent_buffer *eb;
1134         int ret;
1135
1136         eb = btrfs_lock_root_node(fs_info->tree_root);
1137         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1138                               0, &eb);
1139         btrfs_tree_unlock(eb);
1140         free_extent_buffer(eb);
1141
1142         if (ret)
1143                 return ret;
1144
1145         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1146         if (ret)
1147                 return ret;
1148
1149         ret = btrfs_run_dev_stats(trans, fs_info);
1150         if (ret)
1151                 return ret;
1152         ret = btrfs_run_dev_replace(trans, fs_info);
1153         if (ret)
1154                 return ret;
1155         ret = btrfs_run_qgroups(trans, fs_info);
1156         if (ret)
1157                 return ret;
1158
1159         ret = btrfs_setup_space_cache(trans, fs_info);
1160         if (ret)
1161                 return ret;
1162
1163         /* run_qgroups might have added some more refs */
1164         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1165         if (ret)
1166                 return ret;
1167 again:
1168         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1169                 struct btrfs_root *root;
1170                 next = fs_info->dirty_cowonly_roots.next;
1171                 list_del_init(next);
1172                 root = list_entry(next, struct btrfs_root, dirty_list);
1173                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1174
1175                 if (root != fs_info->extent_root)
1176                         list_add_tail(&root->dirty_list,
1177                                       &trans->transaction->switch_commits);
1178                 ret = update_cowonly_root(trans, root);
1179                 if (ret)
1180                         return ret;
1181                 ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1182                 if (ret)
1183                         return ret;
1184         }
1185
1186         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1187                 ret = btrfs_write_dirty_block_groups(trans, fs_info);
1188                 if (ret)
1189                         return ret;
1190                 ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1191                 if (ret)
1192                         return ret;
1193         }
1194
1195         if (!list_empty(&fs_info->dirty_cowonly_roots))
1196                 goto again;
1197
1198         list_add_tail(&fs_info->extent_root->dirty_list,
1199                       &trans->transaction->switch_commits);
1200         btrfs_after_dev_replace_commit(fs_info);
1201
1202         return 0;
1203 }
1204
1205 /*
1206  * dead roots are old snapshots that need to be deleted.  This allocates
1207  * a dirty root struct and adds it into the list of dead roots that need to
1208  * be deleted
1209  */
1210 void btrfs_add_dead_root(struct btrfs_root *root)
1211 {
1212         struct btrfs_fs_info *fs_info = root->fs_info;
1213
1214         spin_lock(&fs_info->trans_lock);
1215         if (list_empty(&root->root_list))
1216                 list_add_tail(&root->root_list, &fs_info->dead_roots);
1217         spin_unlock(&fs_info->trans_lock);
1218 }
1219
1220 /*
1221  * update all the cowonly tree roots on disk
1222  */
1223 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1224 {
1225         struct btrfs_fs_info *fs_info = trans->fs_info;
1226         struct btrfs_root *gang[8];
1227         int i;
1228         int ret;
1229         int err = 0;
1230
1231         spin_lock(&fs_info->fs_roots_radix_lock);
1232         while (1) {
1233                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1234                                                  (void **)gang, 0,
1235                                                  ARRAY_SIZE(gang),
1236                                                  BTRFS_ROOT_TRANS_TAG);
1237                 if (ret == 0)
1238                         break;
1239                 for (i = 0; i < ret; i++) {
1240                         struct btrfs_root *root = gang[i];
1241                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1242                                         (unsigned long)root->root_key.objectid,
1243                                         BTRFS_ROOT_TRANS_TAG);
1244                         spin_unlock(&fs_info->fs_roots_radix_lock);
1245
1246                         btrfs_free_log(trans, root);
1247                         btrfs_update_reloc_root(trans, root);
1248
1249                         btrfs_save_ino_cache(root, trans);
1250
1251                         /* see comments in should_cow_block() */
1252                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1253                         smp_mb__after_atomic();
1254
1255                         if (root->commit_root != root->node) {
1256                                 list_add_tail(&root->dirty_list,
1257                                         &trans->transaction->switch_commits);
1258                                 btrfs_set_root_node(&root->root_item,
1259                                                     root->node);
1260                         }
1261
1262                         err = btrfs_update_root(trans, fs_info->tree_root,
1263                                                 &root->root_key,
1264                                                 &root->root_item);
1265                         spin_lock(&fs_info->fs_roots_radix_lock);
1266                         if (err)
1267                                 break;
1268                         btrfs_qgroup_free_meta_all_pertrans(root);
1269                 }
1270         }
1271         spin_unlock(&fs_info->fs_roots_radix_lock);
1272         return err;
1273 }
1274
1275 /*
1276  * defrag a given btree.
1277  * Every leaf in the btree is read and defragged.
1278  */
1279 int btrfs_defrag_root(struct btrfs_root *root)
1280 {
1281         struct btrfs_fs_info *info = root->fs_info;
1282         struct btrfs_trans_handle *trans;
1283         int ret;
1284
1285         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1286                 return 0;
1287
1288         while (1) {
1289                 trans = btrfs_start_transaction(root, 0);
1290                 if (IS_ERR(trans))
1291                         return PTR_ERR(trans);
1292
1293                 ret = btrfs_defrag_leaves(trans, root);
1294
1295                 btrfs_end_transaction(trans);
1296                 btrfs_btree_balance_dirty(info);
1297                 cond_resched();
1298
1299                 if (btrfs_fs_closing(info) || ret != -EAGAIN)
1300                         break;
1301
1302                 if (btrfs_defrag_cancelled(info)) {
1303                         btrfs_debug(info, "defrag_root cancelled");
1304                         ret = -EAGAIN;
1305                         break;
1306                 }
1307         }
1308         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1309         return ret;
1310 }
1311
1312 /*
1313  * Do all special snapshot related qgroup dirty hack.
1314  *
1315  * Will do all needed qgroup inherit and dirty hack like switch commit
1316  * roots inside one transaction and write all btree into disk, to make
1317  * qgroup works.
1318  */
1319 static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1320                                    struct btrfs_root *src,
1321                                    struct btrfs_root *parent,
1322                                    struct btrfs_qgroup_inherit *inherit,
1323                                    u64 dst_objectid)
1324 {
1325         struct btrfs_fs_info *fs_info = src->fs_info;
1326         int ret;
1327
1328         /*
1329          * Save some performance in the case that qgroups are not
1330          * enabled. If this check races with the ioctl, rescan will
1331          * kick in anyway.
1332          */
1333         if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
1334                 return 0;
1335
1336         /*
1337          * Ensure dirty @src will be commited.  Or, after comming
1338          * commit_fs_roots() and switch_commit_roots(), any dirty but not
1339          * recorded root will never be updated again, causing an outdated root
1340          * item.
1341          */
1342         record_root_in_trans(trans, src, 1);
1343
1344         /*
1345          * We are going to commit transaction, see btrfs_commit_transaction()
1346          * comment for reason locking tree_log_mutex
1347          */
1348         mutex_lock(&fs_info->tree_log_mutex);
1349
1350         ret = commit_fs_roots(trans);
1351         if (ret)
1352                 goto out;
1353         ret = btrfs_qgroup_account_extents(trans);
1354         if (ret < 0)
1355                 goto out;
1356
1357         /* Now qgroup are all updated, we can inherit it to new qgroups */
1358         ret = btrfs_qgroup_inherit(trans, fs_info,
1359                                    src->root_key.objectid, dst_objectid,
1360                                    inherit);
1361         if (ret < 0)
1362                 goto out;
1363
1364         /*
1365          * Now we do a simplified commit transaction, which will:
1366          * 1) commit all subvolume and extent tree
1367          *    To ensure all subvolume and extent tree have a valid
1368          *    commit_root to accounting later insert_dir_item()
1369          * 2) write all btree blocks onto disk
1370          *    This is to make sure later btree modification will be cowed
1371          *    Or commit_root can be populated and cause wrong qgroup numbers
1372          * In this simplified commit, we don't really care about other trees
1373          * like chunk and root tree, as they won't affect qgroup.
1374          * And we don't write super to avoid half committed status.
1375          */
1376         ret = commit_cowonly_roots(trans);
1377         if (ret)
1378                 goto out;
1379         switch_commit_roots(trans->transaction);
1380         ret = btrfs_write_and_wait_transaction(trans);
1381         if (ret)
1382                 btrfs_handle_fs_error(fs_info, ret,
1383                         "Error while writing out transaction for qgroup");
1384
1385 out:
1386         mutex_unlock(&fs_info->tree_log_mutex);
1387
1388         /*
1389          * Force parent root to be updated, as we recorded it before so its
1390          * last_trans == cur_transid.
1391          * Or it won't be committed again onto disk after later
1392          * insert_dir_item()
1393          */
1394         if (!ret)
1395                 record_root_in_trans(trans, parent, 1);
1396         return ret;
1397 }
1398
1399 /*
1400  * new snapshots need to be created at a very specific time in the
1401  * transaction commit.  This does the actual creation.
1402  *
1403  * Note:
1404  * If the error which may affect the commitment of the current transaction
1405  * happens, we should return the error number. If the error which just affect
1406  * the creation of the pending snapshots, just return 0.
1407  */
1408 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1409                                    struct btrfs_pending_snapshot *pending)
1410 {
1411
1412         struct btrfs_fs_info *fs_info = trans->fs_info;
1413         struct btrfs_key key;
1414         struct btrfs_root_item *new_root_item;
1415         struct btrfs_root *tree_root = fs_info->tree_root;
1416         struct btrfs_root *root = pending->root;
1417         struct btrfs_root *parent_root;
1418         struct btrfs_block_rsv *rsv;
1419         struct inode *parent_inode;
1420         struct btrfs_path *path;
1421         struct btrfs_dir_item *dir_item;
1422         struct dentry *dentry;
1423         struct extent_buffer *tmp;
1424         struct extent_buffer *old;
1425         struct timespec64 cur_time;
1426         int ret = 0;
1427         u64 to_reserve = 0;
1428         u64 index = 0;
1429         u64 objectid;
1430         u64 root_flags;
1431         uuid_le new_uuid;
1432
1433         ASSERT(pending->path);
1434         path = pending->path;
1435
1436         ASSERT(pending->root_item);
1437         new_root_item = pending->root_item;
1438
1439         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1440         if (pending->error)
1441                 goto no_free_objectid;
1442
1443         /*
1444          * Make qgroup to skip current new snapshot's qgroupid, as it is
1445          * accounted by later btrfs_qgroup_inherit().
1446          */
1447         btrfs_set_skip_qgroup(trans, objectid);
1448
1449         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1450
1451         if (to_reserve > 0) {
1452                 pending->error = btrfs_block_rsv_add(root,
1453                                                      &pending->block_rsv,
1454                                                      to_reserve,
1455                                                      BTRFS_RESERVE_NO_FLUSH);
1456                 if (pending->error)
1457                         goto clear_skip_qgroup;
1458         }
1459
1460         key.objectid = objectid;
1461         key.offset = (u64)-1;
1462         key.type = BTRFS_ROOT_ITEM_KEY;
1463
1464         rsv = trans->block_rsv;
1465         trans->block_rsv = &pending->block_rsv;
1466         trans->bytes_reserved = trans->block_rsv->reserved;
1467         trace_btrfs_space_reservation(fs_info, "transaction",
1468                                       trans->transid,
1469                                       trans->bytes_reserved, 1);
1470         dentry = pending->dentry;
1471         parent_inode = pending->dir;
1472         parent_root = BTRFS_I(parent_inode)->root;
1473         record_root_in_trans(trans, parent_root, 0);
1474
1475         cur_time = current_time(parent_inode);
1476
1477         /*
1478          * insert the directory item
1479          */
1480         ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1481         BUG_ON(ret); /* -ENOMEM */
1482
1483         /* check if there is a file/dir which has the same name. */
1484         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1485                                          btrfs_ino(BTRFS_I(parent_inode)),
1486                                          dentry->d_name.name,
1487                                          dentry->d_name.len, 0);
1488         if (dir_item != NULL && !IS_ERR(dir_item)) {
1489                 pending->error = -EEXIST;
1490                 goto dir_item_existed;
1491         } else if (IS_ERR(dir_item)) {
1492                 ret = PTR_ERR(dir_item);
1493                 btrfs_abort_transaction(trans, ret);
1494                 goto fail;
1495         }
1496         btrfs_release_path(path);
1497
1498         /*
1499          * pull in the delayed directory update
1500          * and the delayed inode item
1501          * otherwise we corrupt the FS during
1502          * snapshot
1503          */
1504         ret = btrfs_run_delayed_items(trans);
1505         if (ret) {      /* Transaction aborted */
1506                 btrfs_abort_transaction(trans, ret);
1507                 goto fail;
1508         }
1509
1510         record_root_in_trans(trans, root, 0);
1511         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1512         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1513         btrfs_check_and_init_root_item(new_root_item);
1514
1515         root_flags = btrfs_root_flags(new_root_item);
1516         if (pending->readonly)
1517                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1518         else
1519                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1520         btrfs_set_root_flags(new_root_item, root_flags);
1521
1522         btrfs_set_root_generation_v2(new_root_item,
1523                         trans->transid);
1524         uuid_le_gen(&new_uuid);
1525         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1526         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1527                         BTRFS_UUID_SIZE);
1528         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1529                 memset(new_root_item->received_uuid, 0,
1530                        sizeof(new_root_item->received_uuid));
1531                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1532                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1533                 btrfs_set_root_stransid(new_root_item, 0);
1534                 btrfs_set_root_rtransid(new_root_item, 0);
1535         }
1536         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1537         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1538         btrfs_set_root_otransid(new_root_item, trans->transid);
1539
1540         old = btrfs_lock_root_node(root);
1541         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1542         if (ret) {
1543                 btrfs_tree_unlock(old);
1544                 free_extent_buffer(old);
1545                 btrfs_abort_transaction(trans, ret);
1546                 goto fail;
1547         }
1548
1549         btrfs_set_lock_blocking(old);
1550
1551         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1552         /* clean up in any case */
1553         btrfs_tree_unlock(old);
1554         free_extent_buffer(old);
1555         if (ret) {
1556                 btrfs_abort_transaction(trans, ret);
1557                 goto fail;
1558         }
1559         /* see comments in should_cow_block() */
1560         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1561         smp_wmb();
1562
1563         btrfs_set_root_node(new_root_item, tmp);
1564         /* record when the snapshot was created in key.offset */
1565         key.offset = trans->transid;
1566         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1567         btrfs_tree_unlock(tmp);
1568         free_extent_buffer(tmp);
1569         if (ret) {
1570                 btrfs_abort_transaction(trans, ret);
1571                 goto fail;
1572         }
1573
1574         /*
1575          * insert root back/forward references
1576          */
1577         ret = btrfs_add_root_ref(trans, fs_info, objectid,
1578                                  parent_root->root_key.objectid,
1579                                  btrfs_ino(BTRFS_I(parent_inode)), index,
1580                                  dentry->d_name.name, dentry->d_name.len);
1581         if (ret) {
1582                 btrfs_abort_transaction(trans, ret);
1583                 goto fail;
1584         }
1585
1586         key.offset = (u64)-1;
1587         pending->snap = btrfs_read_fs_root_no_name(fs_info, &key);
1588         if (IS_ERR(pending->snap)) {
1589                 ret = PTR_ERR(pending->snap);
1590                 btrfs_abort_transaction(trans, ret);
1591                 goto fail;
1592         }
1593
1594         ret = btrfs_reloc_post_snapshot(trans, pending);
1595         if (ret) {
1596                 btrfs_abort_transaction(trans, ret);
1597                 goto fail;
1598         }
1599
1600         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1601         if (ret) {
1602                 btrfs_abort_transaction(trans, ret);
1603                 goto fail;
1604         }
1605
1606         /*
1607          * Do special qgroup accounting for snapshot, as we do some qgroup
1608          * snapshot hack to do fast snapshot.
1609          * To co-operate with that hack, we do hack again.
1610          * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1611          */
1612         ret = qgroup_account_snapshot(trans, root, parent_root,
1613                                       pending->inherit, objectid);
1614         if (ret < 0)
1615                 goto fail;
1616
1617         ret = btrfs_insert_dir_item(trans, parent_root,
1618                                     dentry->d_name.name, dentry->d_name.len,
1619                                     BTRFS_I(parent_inode), &key,
1620                                     BTRFS_FT_DIR, index);
1621         /* We have check then name at the beginning, so it is impossible. */
1622         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1623         if (ret) {
1624                 btrfs_abort_transaction(trans, ret);
1625                 goto fail;
1626         }
1627
1628         btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1629                                          dentry->d_name.len * 2);
1630         parent_inode->i_mtime = parent_inode->i_ctime =
1631                 current_time(parent_inode);
1632         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1633         if (ret) {
1634                 btrfs_abort_transaction(trans, ret);
1635                 goto fail;
1636         }
1637         ret = btrfs_uuid_tree_add(trans, new_uuid.b, BTRFS_UUID_KEY_SUBVOL,
1638                                   objectid);
1639         if (ret) {
1640                 btrfs_abort_transaction(trans, ret);
1641                 goto fail;
1642         }
1643         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1644                 ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
1645                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1646                                           objectid);
1647                 if (ret && ret != -EEXIST) {
1648                         btrfs_abort_transaction(trans, ret);
1649                         goto fail;
1650                 }
1651         }
1652
1653         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1654         if (ret) {
1655                 btrfs_abort_transaction(trans, ret);
1656                 goto fail;
1657         }
1658
1659 fail:
1660         pending->error = ret;
1661 dir_item_existed:
1662         trans->block_rsv = rsv;
1663         trans->bytes_reserved = 0;
1664 clear_skip_qgroup:
1665         btrfs_clear_skip_qgroup(trans);
1666 no_free_objectid:
1667         kfree(new_root_item);
1668         pending->root_item = NULL;
1669         btrfs_free_path(path);
1670         pending->path = NULL;
1671
1672         return ret;
1673 }
1674
1675 /*
1676  * create all the snapshots we've scheduled for creation
1677  */
1678 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1679 {
1680         struct btrfs_pending_snapshot *pending, *next;
1681         struct list_head *head = &trans->transaction->pending_snapshots;
1682         int ret = 0;
1683
1684         list_for_each_entry_safe(pending, next, head, list) {
1685                 list_del(&pending->list);
1686                 ret = create_pending_snapshot(trans, pending);
1687                 if (ret)
1688                         break;
1689         }
1690         return ret;
1691 }
1692
1693 static void update_super_roots(struct btrfs_fs_info *fs_info)
1694 {
1695         struct btrfs_root_item *root_item;
1696         struct btrfs_super_block *super;
1697
1698         super = fs_info->super_copy;
1699
1700         root_item = &fs_info->chunk_root->root_item;
1701         super->chunk_root = root_item->bytenr;
1702         super->chunk_root_generation = root_item->generation;
1703         super->chunk_root_level = root_item->level;
1704
1705         root_item = &fs_info->tree_root->root_item;
1706         super->root = root_item->bytenr;
1707         super->generation = root_item->generation;
1708         super->root_level = root_item->level;
1709         if (btrfs_test_opt(fs_info, SPACE_CACHE))
1710                 super->cache_generation = root_item->generation;
1711         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1712                 super->uuid_tree_generation = root_item->generation;
1713 }
1714
1715 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1716 {
1717         struct btrfs_transaction *trans;
1718         int ret = 0;
1719
1720         spin_lock(&info->trans_lock);
1721         trans = info->running_transaction;
1722         if (trans)
1723                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1724         spin_unlock(&info->trans_lock);
1725         return ret;
1726 }
1727
1728 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1729 {
1730         struct btrfs_transaction *trans;
1731         int ret = 0;
1732
1733         spin_lock(&info->trans_lock);
1734         trans = info->running_transaction;
1735         if (trans)
1736                 ret = is_transaction_blocked(trans);
1737         spin_unlock(&info->trans_lock);
1738         return ret;
1739 }
1740
1741 /*
1742  * wait for the current transaction commit to start and block subsequent
1743  * transaction joins
1744  */
1745 static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
1746                                             struct btrfs_transaction *trans)
1747 {
1748         wait_event(fs_info->transaction_blocked_wait,
1749                    trans->state >= TRANS_STATE_COMMIT_START || trans->aborted);
1750 }
1751
1752 /*
1753  * wait for the current transaction to start and then become unblocked.
1754  * caller holds ref.
1755  */
1756 static void wait_current_trans_commit_start_and_unblock(
1757                                         struct btrfs_fs_info *fs_info,
1758                                         struct btrfs_transaction *trans)
1759 {
1760         wait_event(fs_info->transaction_wait,
1761                    trans->state >= TRANS_STATE_UNBLOCKED || trans->aborted);
1762 }
1763
1764 /*
1765  * commit transactions asynchronously. once btrfs_commit_transaction_async
1766  * returns, any subsequent transaction will not be allowed to join.
1767  */
1768 struct btrfs_async_commit {
1769         struct btrfs_trans_handle *newtrans;
1770         struct work_struct work;
1771 };
1772
1773 static void do_async_commit(struct work_struct *work)
1774 {
1775         struct btrfs_async_commit *ac =
1776                 container_of(work, struct btrfs_async_commit, work);
1777
1778         /*
1779          * We've got freeze protection passed with the transaction.
1780          * Tell lockdep about it.
1781          */
1782         if (ac->newtrans->type & __TRANS_FREEZABLE)
1783                 __sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1784
1785         current->journal_info = ac->newtrans;
1786
1787         btrfs_commit_transaction(ac->newtrans);
1788         kfree(ac);
1789 }
1790
1791 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1792                                    int wait_for_unblock)
1793 {
1794         struct btrfs_fs_info *fs_info = trans->fs_info;
1795         struct btrfs_async_commit *ac;
1796         struct btrfs_transaction *cur_trans;
1797
1798         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1799         if (!ac)
1800                 return -ENOMEM;
1801
1802         INIT_WORK(&ac->work, do_async_commit);
1803         ac->newtrans = btrfs_join_transaction(trans->root);
1804         if (IS_ERR(ac->newtrans)) {
1805                 int err = PTR_ERR(ac->newtrans);
1806                 kfree(ac);
1807                 return err;
1808         }
1809
1810         /* take transaction reference */
1811         cur_trans = trans->transaction;
1812         refcount_inc(&cur_trans->use_count);
1813
1814         btrfs_end_transaction(trans);
1815
1816         /*
1817          * Tell lockdep we've released the freeze rwsem, since the
1818          * async commit thread will be the one to unlock it.
1819          */
1820         if (ac->newtrans->type & __TRANS_FREEZABLE)
1821                 __sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1822
1823         schedule_work(&ac->work);
1824
1825         /* wait for transaction to start and unblock */
1826         if (wait_for_unblock)
1827                 wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
1828         else
1829                 wait_current_trans_commit_start(fs_info, cur_trans);
1830
1831         if (current->journal_info == trans)
1832                 current->journal_info = NULL;
1833
1834         btrfs_put_transaction(cur_trans);
1835         return 0;
1836 }
1837
1838
1839 static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
1840 {
1841         struct btrfs_fs_info *fs_info = trans->fs_info;
1842         struct btrfs_transaction *cur_trans = trans->transaction;
1843         DEFINE_WAIT(wait);
1844
1845         WARN_ON(refcount_read(&trans->use_count) > 1);
1846
1847         btrfs_abort_transaction(trans, err);
1848
1849         spin_lock(&fs_info->trans_lock);
1850
1851         /*
1852          * If the transaction is removed from the list, it means this
1853          * transaction has been committed successfully, so it is impossible
1854          * to call the cleanup function.
1855          */
1856         BUG_ON(list_empty(&cur_trans->list));
1857
1858         list_del_init(&cur_trans->list);
1859         if (cur_trans == fs_info->running_transaction) {
1860                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1861                 spin_unlock(&fs_info->trans_lock);
1862                 wait_event(cur_trans->writer_wait,
1863                            atomic_read(&cur_trans->num_writers) == 1);
1864
1865                 spin_lock(&fs_info->trans_lock);
1866         }
1867         spin_unlock(&fs_info->trans_lock);
1868
1869         btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1870
1871         spin_lock(&fs_info->trans_lock);
1872         if (cur_trans == fs_info->running_transaction)
1873                 fs_info->running_transaction = NULL;
1874         spin_unlock(&fs_info->trans_lock);
1875
1876         if (trans->type & __TRANS_FREEZABLE)
1877                 sb_end_intwrite(fs_info->sb);
1878         btrfs_put_transaction(cur_trans);
1879         btrfs_put_transaction(cur_trans);
1880
1881         trace_btrfs_transaction_commit(trans->root);
1882
1883         if (current->journal_info == trans)
1884                 current->journal_info = NULL;
1885         btrfs_scrub_cancel(fs_info);
1886
1887         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1888 }
1889
1890 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1891 {
1892         /*
1893          * We use writeback_inodes_sb here because if we used
1894          * btrfs_start_delalloc_roots we would deadlock with fs freeze.
1895          * Currently are holding the fs freeze lock, if we do an async flush
1896          * we'll do btrfs_join_transaction() and deadlock because we need to
1897          * wait for the fs freeze lock.  Using the direct flushing we benefit
1898          * from already being in a transaction and our join_transaction doesn't
1899          * have to re-take the fs freeze lock.
1900          */
1901         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1902                 writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
1903         return 0;
1904 }
1905
1906 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1907 {
1908         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT))
1909                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
1910 }
1911
1912 static inline void
1913 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
1914 {
1915         wait_event(cur_trans->pending_wait,
1916                    atomic_read(&cur_trans->pending_ordered) == 0);
1917 }
1918
1919 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
1920 {
1921         struct btrfs_fs_info *fs_info = trans->fs_info;
1922         struct btrfs_transaction *cur_trans = trans->transaction;
1923         struct btrfs_transaction *prev_trans = NULL;
1924         int ret;
1925
1926         /* Stop the commit early if ->aborted is set */
1927         if (unlikely(READ_ONCE(cur_trans->aborted))) {
1928                 ret = cur_trans->aborted;
1929                 btrfs_end_transaction(trans);
1930                 return ret;
1931         }
1932
1933         /* make a pass through all the delayed refs we have so far
1934          * any runnings procs may add more while we are here
1935          */
1936         ret = btrfs_run_delayed_refs(trans, 0);
1937         if (ret) {
1938                 btrfs_end_transaction(trans);
1939                 return ret;
1940         }
1941
1942         btrfs_trans_release_metadata(trans);
1943         trans->block_rsv = NULL;
1944
1945         cur_trans = trans->transaction;
1946
1947         /*
1948          * set the flushing flag so procs in this transaction have to
1949          * start sending their work down.
1950          */
1951         cur_trans->delayed_refs.flushing = 1;
1952         smp_wmb();
1953
1954         if (!list_empty(&trans->new_bgs))
1955                 btrfs_create_pending_block_groups(trans);
1956
1957         ret = btrfs_run_delayed_refs(trans, 0);
1958         if (ret) {
1959                 btrfs_end_transaction(trans);
1960                 return ret;
1961         }
1962
1963         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
1964                 int run_it = 0;
1965
1966                 /* this mutex is also taken before trying to set
1967                  * block groups readonly.  We need to make sure
1968                  * that nobody has set a block group readonly
1969                  * after a extents from that block group have been
1970                  * allocated for cache files.  btrfs_set_block_group_ro
1971                  * will wait for the transaction to commit if it
1972                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
1973                  *
1974                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
1975                  * only one process starts all the block group IO.  It wouldn't
1976                  * hurt to have more than one go through, but there's no
1977                  * real advantage to it either.
1978                  */
1979                 mutex_lock(&fs_info->ro_block_group_mutex);
1980                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
1981                                       &cur_trans->flags))
1982                         run_it = 1;
1983                 mutex_unlock(&fs_info->ro_block_group_mutex);
1984
1985                 if (run_it) {
1986                         ret = btrfs_start_dirty_block_groups(trans);
1987                         if (ret) {
1988                                 btrfs_end_transaction(trans);
1989                                 return ret;
1990                         }
1991                 }
1992         }
1993
1994         spin_lock(&fs_info->trans_lock);
1995         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1996                 spin_unlock(&fs_info->trans_lock);
1997                 refcount_inc(&cur_trans->use_count);
1998                 ret = btrfs_end_transaction(trans);
1999
2000                 wait_for_commit(cur_trans);
2001
2002                 if (unlikely(cur_trans->aborted))
2003                         ret = cur_trans->aborted;
2004
2005                 btrfs_put_transaction(cur_trans);
2006
2007                 return ret;
2008         }
2009
2010         cur_trans->state = TRANS_STATE_COMMIT_START;
2011         wake_up(&fs_info->transaction_blocked_wait);
2012
2013         if (cur_trans->list.prev != &fs_info->trans_list) {
2014                 prev_trans = list_entry(cur_trans->list.prev,
2015                                         struct btrfs_transaction, list);
2016                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
2017                         refcount_inc(&prev_trans->use_count);
2018                         spin_unlock(&fs_info->trans_lock);
2019
2020                         wait_for_commit(prev_trans);
2021                         ret = prev_trans->aborted;
2022
2023                         btrfs_put_transaction(prev_trans);
2024                         if (ret)
2025                                 goto cleanup_transaction;
2026                 } else {
2027                         spin_unlock(&fs_info->trans_lock);
2028                 }
2029         } else {
2030                 spin_unlock(&fs_info->trans_lock);
2031         }
2032
2033         extwriter_counter_dec(cur_trans, trans->type);
2034
2035         ret = btrfs_start_delalloc_flush(fs_info);
2036         if (ret)
2037                 goto cleanup_transaction;
2038
2039         ret = btrfs_run_delayed_items(trans);
2040         if (ret)
2041                 goto cleanup_transaction;
2042
2043         wait_event(cur_trans->writer_wait,
2044                    extwriter_counter_read(cur_trans) == 0);
2045
2046         /* some pending stuffs might be added after the previous flush. */
2047         ret = btrfs_run_delayed_items(trans);
2048         if (ret)
2049                 goto cleanup_transaction;
2050
2051         btrfs_wait_delalloc_flush(fs_info);
2052
2053         btrfs_wait_pending_ordered(cur_trans);
2054
2055         btrfs_scrub_pause(fs_info);
2056         /*
2057          * Ok now we need to make sure to block out any other joins while we
2058          * commit the transaction.  We could have started a join before setting
2059          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2060          */
2061         spin_lock(&fs_info->trans_lock);
2062         cur_trans->state = TRANS_STATE_COMMIT_DOING;
2063         spin_unlock(&fs_info->trans_lock);
2064         wait_event(cur_trans->writer_wait,
2065                    atomic_read(&cur_trans->num_writers) == 1);
2066
2067         /* ->aborted might be set after the previous check, so check it */
2068         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2069                 ret = cur_trans->aborted;
2070                 goto scrub_continue;
2071         }
2072         /*
2073          * the reloc mutex makes sure that we stop
2074          * the balancing code from coming in and moving
2075          * extents around in the middle of the commit
2076          */
2077         mutex_lock(&fs_info->reloc_mutex);
2078
2079         /*
2080          * We needn't worry about the delayed items because we will
2081          * deal with them in create_pending_snapshot(), which is the
2082          * core function of the snapshot creation.
2083          */
2084         ret = create_pending_snapshots(trans);
2085         if (ret) {
2086                 mutex_unlock(&fs_info->reloc_mutex);
2087                 goto scrub_continue;
2088         }
2089
2090         /*
2091          * We insert the dir indexes of the snapshots and update the inode
2092          * of the snapshots' parents after the snapshot creation, so there
2093          * are some delayed items which are not dealt with. Now deal with
2094          * them.
2095          *
2096          * We needn't worry that this operation will corrupt the snapshots,
2097          * because all the tree which are snapshoted will be forced to COW
2098          * the nodes and leaves.
2099          */
2100         ret = btrfs_run_delayed_items(trans);
2101         if (ret) {
2102                 mutex_unlock(&fs_info->reloc_mutex);
2103                 goto scrub_continue;
2104         }
2105
2106         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
2107         if (ret) {
2108                 mutex_unlock(&fs_info->reloc_mutex);
2109                 goto scrub_continue;
2110         }
2111
2112         /*
2113          * make sure none of the code above managed to slip in a
2114          * delayed item
2115          */
2116         btrfs_assert_delayed_root_empty(fs_info);
2117
2118         WARN_ON(cur_trans != trans->transaction);
2119
2120         /* btrfs_commit_tree_roots is responsible for getting the
2121          * various roots consistent with each other.  Every pointer
2122          * in the tree of tree roots has to point to the most up to date
2123          * root for every subvolume and other tree.  So, we have to keep
2124          * the tree logging code from jumping in and changing any
2125          * of the trees.
2126          *
2127          * At this point in the commit, there can't be any tree-log
2128          * writers, but a little lower down we drop the trans mutex
2129          * and let new people in.  By holding the tree_log_mutex
2130          * from now until after the super is written, we avoid races
2131          * with the tree-log code.
2132          */
2133         mutex_lock(&fs_info->tree_log_mutex);
2134
2135         ret = commit_fs_roots(trans);
2136         if (ret) {
2137                 mutex_unlock(&fs_info->tree_log_mutex);
2138                 mutex_unlock(&fs_info->reloc_mutex);
2139                 goto scrub_continue;
2140         }
2141
2142         /*
2143          * Since the transaction is done, we can apply the pending changes
2144          * before the next transaction.
2145          */
2146         btrfs_apply_pending_changes(fs_info);
2147
2148         /* commit_fs_roots gets rid of all the tree log roots, it is now
2149          * safe to free the root of tree log roots
2150          */
2151         btrfs_free_log_root_tree(trans, fs_info);
2152
2153         /*
2154          * commit_fs_roots() can call btrfs_save_ino_cache(), which generates
2155          * new delayed refs. Must handle them or qgroup can be wrong.
2156          */
2157         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
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 fs roots are all committed, we can get a quite accurate
2166          * new_roots. So let's do quota accounting.
2167          */
2168         ret = btrfs_qgroup_account_extents(trans);
2169         if (ret < 0) {
2170                 mutex_unlock(&fs_info->tree_log_mutex);
2171                 mutex_unlock(&fs_info->reloc_mutex);
2172                 goto scrub_continue;
2173         }
2174
2175         ret = commit_cowonly_roots(trans);
2176         if (ret) {
2177                 mutex_unlock(&fs_info->tree_log_mutex);
2178                 mutex_unlock(&fs_info->reloc_mutex);
2179                 goto scrub_continue;
2180         }
2181
2182         /*
2183          * The tasks which save the space cache and inode cache may also
2184          * update ->aborted, check it.
2185          */
2186         if (unlikely(READ_ONCE(cur_trans->aborted))) {
2187                 ret = cur_trans->aborted;
2188                 mutex_unlock(&fs_info->tree_log_mutex);
2189                 mutex_unlock(&fs_info->reloc_mutex);
2190                 goto scrub_continue;
2191         }
2192
2193         btrfs_prepare_extent_commit(fs_info);
2194
2195         cur_trans = fs_info->running_transaction;
2196
2197         btrfs_set_root_node(&fs_info->tree_root->root_item,
2198                             fs_info->tree_root->node);
2199         list_add_tail(&fs_info->tree_root->dirty_list,
2200                       &cur_trans->switch_commits);
2201
2202         btrfs_set_root_node(&fs_info->chunk_root->root_item,
2203                             fs_info->chunk_root->node);
2204         list_add_tail(&fs_info->chunk_root->dirty_list,
2205                       &cur_trans->switch_commits);
2206
2207         switch_commit_roots(cur_trans);
2208
2209         ASSERT(list_empty(&cur_trans->dirty_bgs));
2210         ASSERT(list_empty(&cur_trans->io_bgs));
2211         update_super_roots(fs_info);
2212
2213         btrfs_set_super_log_root(fs_info->super_copy, 0);
2214         btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2215         memcpy(fs_info->super_for_commit, fs_info->super_copy,
2216                sizeof(*fs_info->super_copy));
2217
2218         btrfs_update_commit_device_size(fs_info);
2219         btrfs_update_commit_device_bytes_used(cur_trans);
2220
2221         clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2222         clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2223
2224         btrfs_trans_release_chunk_metadata(trans);
2225
2226         spin_lock(&fs_info->trans_lock);
2227         cur_trans->state = TRANS_STATE_UNBLOCKED;
2228         fs_info->running_transaction = NULL;
2229         spin_unlock(&fs_info->trans_lock);
2230         mutex_unlock(&fs_info->reloc_mutex);
2231
2232         wake_up(&fs_info->transaction_wait);
2233
2234         ret = btrfs_write_and_wait_transaction(trans);
2235         if (ret) {
2236                 btrfs_handle_fs_error(fs_info, ret,
2237                                       "Error while writing out transaction");
2238                 mutex_unlock(&fs_info->tree_log_mutex);
2239                 goto scrub_continue;
2240         }
2241
2242         ret = write_all_supers(fs_info, 0);
2243         /*
2244          * the super is written, we can safely allow the tree-loggers
2245          * to go about their business
2246          */
2247         mutex_unlock(&fs_info->tree_log_mutex);
2248         if (ret)
2249                 goto scrub_continue;
2250
2251         btrfs_finish_extent_commit(trans);
2252
2253         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2254                 btrfs_clear_space_info_full(fs_info);
2255
2256         fs_info->last_trans_committed = cur_trans->transid;
2257         /*
2258          * We needn't acquire the lock here because there is no other task
2259          * which can change it.
2260          */
2261         cur_trans->state = TRANS_STATE_COMPLETED;
2262         wake_up(&cur_trans->commit_wait);
2263         clear_bit(BTRFS_FS_NEED_ASYNC_COMMIT, &fs_info->flags);
2264
2265         spin_lock(&fs_info->trans_lock);
2266         list_del_init(&cur_trans->list);
2267         spin_unlock(&fs_info->trans_lock);
2268
2269         btrfs_put_transaction(cur_trans);
2270         btrfs_put_transaction(cur_trans);
2271
2272         if (trans->type & __TRANS_FREEZABLE)
2273                 sb_end_intwrite(fs_info->sb);
2274
2275         trace_btrfs_transaction_commit(trans->root);
2276
2277         btrfs_scrub_continue(fs_info);
2278
2279         if (current->journal_info == trans)
2280                 current->journal_info = NULL;
2281
2282         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2283
2284         /*
2285          * If fs has been frozen, we can not handle delayed iputs, otherwise
2286          * it'll result in deadlock about SB_FREEZE_FS.
2287          */
2288         if (current != fs_info->transaction_kthread &&
2289             current != fs_info->cleaner_kthread &&
2290             !test_bit(BTRFS_FS_FROZEN, &fs_info->flags))
2291                 btrfs_run_delayed_iputs(fs_info);
2292
2293         return ret;
2294
2295 scrub_continue:
2296         btrfs_scrub_continue(fs_info);
2297 cleanup_transaction:
2298         btrfs_trans_release_metadata(trans);
2299         btrfs_trans_release_chunk_metadata(trans);
2300         trans->block_rsv = NULL;
2301         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2302         if (current->journal_info == trans)
2303                 current->journal_info = NULL;
2304         cleanup_transaction(trans, ret);
2305
2306         return ret;
2307 }
2308
2309 /*
2310  * return < 0 if error
2311  * 0 if there are no more dead_roots at the time of call
2312  * 1 there are more to be processed, call me again
2313  *
2314  * The return value indicates there are certainly more snapshots to delete, but
2315  * if there comes a new one during processing, it may return 0. We don't mind,
2316  * because btrfs_commit_super will poke cleaner thread and it will process it a
2317  * few seconds later.
2318  */
2319 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2320 {
2321         int ret;
2322         struct btrfs_fs_info *fs_info = root->fs_info;
2323
2324         spin_lock(&fs_info->trans_lock);
2325         if (list_empty(&fs_info->dead_roots)) {
2326                 spin_unlock(&fs_info->trans_lock);
2327                 return 0;
2328         }
2329         root = list_first_entry(&fs_info->dead_roots,
2330                         struct btrfs_root, root_list);
2331         list_del_init(&root->root_list);
2332         spin_unlock(&fs_info->trans_lock);
2333
2334         btrfs_debug(fs_info, "cleaner removing %llu", root->objectid);
2335
2336         btrfs_kill_all_delayed_nodes(root);
2337
2338         if (btrfs_header_backref_rev(root->node) <
2339                         BTRFS_MIXED_BACKREF_REV)
2340                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2341         else
2342                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2343
2344         return (ret < 0) ? 0 : 1;
2345 }
2346
2347 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2348 {
2349         unsigned long prev;
2350         unsigned long bit;
2351
2352         prev = xchg(&fs_info->pending_changes, 0);
2353         if (!prev)
2354                 return;
2355
2356         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2357         if (prev & bit)
2358                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2359         prev &= ~bit;
2360
2361         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2362         if (prev & bit)
2363                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2364         prev &= ~bit;
2365
2366         bit = 1 << BTRFS_PENDING_COMMIT;
2367         if (prev & bit)
2368                 btrfs_debug(fs_info, "pending commit done");
2369         prev &= ~bit;
2370
2371         if (prev)
2372                 btrfs_warn(fs_info,
2373                         "unknown pending changes left 0x%lx, ignoring", prev);
2374 }