fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30 #include "inode-map.h"
  31 #include "volumes.h"
  32
  33 #define BTRFS_ROOT_TRANS_TAG 0
  34
  35 void put_transaction(struct btrfs_transaction *transaction)
  36 {
  37         WARN_ON(atomic_read(&transaction->use_count) == 0);
  38         if (atomic_dec_and_test(&transaction->use_count)) {
  39                 BUG_ON(!list_empty(&transaction->list));
  40                 WARN_ON(transaction->delayed_refs.root.rb_node);
  41                 WARN_ON(!list_empty(&transaction->delayed_refs.seq_head));
  42                 memset(transaction, 0, sizeof(*transaction));
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static noinline void switch_commit_root(struct btrfs_root *root)
  48 {
  49         free_extent_buffer(root->commit_root);
  50         root->commit_root = btrfs_root_node(root);
  51 }
  52
  53 /*
  54  * either allocate a new transaction or hop into the existing one
  55  */
  56 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  57 {
  58         struct btrfs_transaction *cur_trans;
  59         struct btrfs_fs_info *fs_info = root->fs_info;
  60
  61         spin_lock(&fs_info->trans_lock);
  62 loop:
  63         /* The file system has been taken offline. No new transactions. */
  64         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  65                 spin_unlock(&fs_info->trans_lock);
  66                 return -EROFS;
  67         }
  68
  69         if (fs_info->trans_no_join) {
  70                 if (!nofail) {
  71                         spin_unlock(&fs_info->trans_lock);
  72                         return -EBUSY;
  73                 }
  74         }
  75
  76         cur_trans = fs_info->running_transaction;
  77         if (cur_trans) {
  78                 if (cur_trans->aborted) {
  79                         spin_unlock(&fs_info->trans_lock);
  80                         return cur_trans->aborted;
  81                 }
  82                 atomic_inc(&cur_trans->use_count);
  83                 atomic_inc(&cur_trans->num_writers);
  84                 cur_trans->num_joined++;
  85                 spin_unlock(&fs_info->trans_lock);
  86                 return 0;
  87         }
  88         spin_unlock(&fs_info->trans_lock);
  89
  90         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  91         if (!cur_trans)
  92                 return -ENOMEM;
  93
  94         spin_lock(&fs_info->trans_lock);
  95         if (fs_info->running_transaction) {
  96                 /*
  97                  * someone started a transaction after we unlocked.  Make sure
  98                  * to redo the trans_no_join checks above
  99                  */
 100                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 101                 cur_trans = fs_info->running_transaction;
 102                 goto loop;
 103         } else if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 104                 spin_unlock(&root->fs_info->trans_lock);
 105                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 106                 return -EROFS;
 107         }
 108
 109         atomic_set(&cur_trans->num_writers, 1);
 110         cur_trans->num_joined = 0;
 111         init_waitqueue_head(&cur_trans->writer_wait);
 112         init_waitqueue_head(&cur_trans->commit_wait);
 113         cur_trans->in_commit = 0;
 114         cur_trans->blocked = 0;
 115         /*
 116          * One for this trans handle, one so it will live on until we
 117          * commit the transaction.
 118          */
 119         atomic_set(&cur_trans->use_count, 2);
 120         cur_trans->commit_done = 0;
 121         cur_trans->start_time = get_seconds();
 122
 123         cur_trans->delayed_refs.root = RB_ROOT;
 124         cur_trans->delayed_refs.num_entries = 0;
 125         cur_trans->delayed_refs.num_heads_ready = 0;
 126         cur_trans->delayed_refs.num_heads = 0;
 127         cur_trans->delayed_refs.flushing = 0;
 128         cur_trans->delayed_refs.run_delayed_start = 0;
 129         cur_trans->delayed_refs.seq = 1;
 130
 131         /*
 132          * although the tree mod log is per file system and not per transaction,
 133          * the log must never go across transaction boundaries.
 134          */
 135         smp_mb();
 136         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 137                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 138                         "creating a fresh transaction\n");
 139                 WARN_ON(1);
 140         }
 141         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 142                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 143                         "creating a fresh transaction\n");
 144                 WARN_ON(1);
 145         }
 146         atomic_set(&fs_info->tree_mod_seq, 0);
 147
 148         init_waitqueue_head(&cur_trans->delayed_refs.seq_wait);
 149         spin_lock_init(&cur_trans->commit_lock);
 150         spin_lock_init(&cur_trans->delayed_refs.lock);
 151         INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head);
 152
 153         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 154         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 155         extent_io_tree_init(&cur_trans->dirty_pages,
 156                              fs_info->btree_inode->i_mapping);
 157         fs_info->generation++;
 158         cur_trans->transid = fs_info->generation;
 159         fs_info->running_transaction = cur_trans;
 160         cur_trans->aborted = 0;
 161         spin_unlock(&fs_info->trans_lock);
 162
 163         return 0;
 164 }
 165
 166 /*
 167  * this does all the record keeping required to make sure that a reference
 168  * counted root is properly recorded in a given transaction.  This is required
 169  * to make sure the old root from before we joined the transaction is deleted
 170  * when the transaction commits
 171  */
 172 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 173                                struct btrfs_root *root)
 174 {
 175         if (root->ref_cows && root->last_trans < trans->transid) {
 176                 WARN_ON(root == root->fs_info->extent_root);
 177                 WARN_ON(root->commit_root != root->node);
 178
 179                 /*
 180                  * see below for in_trans_setup usage rules
 181                  * we have the reloc mutex held now, so there
 182                  * is only one writer in this function
 183                  */
 184                 root->in_trans_setup = 1;
 185
 186                 /* make sure readers find in_trans_setup before
 187                  * they find our root->last_trans update
 188                  */
 189                 smp_wmb();
 190
 191                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 192                 if (root->last_trans == trans->transid) {
 193                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 194                         return 0;
 195                 }
 196                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 197                            (unsigned long)root->root_key.objectid,
 198                            BTRFS_ROOT_TRANS_TAG);
 199                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 200                 root->last_trans = trans->transid;
 201
 202                 /* this is pretty tricky.  We don't want to
 203                  * take the relocation lock in btrfs_record_root_in_trans
 204                  * unless we're really doing the first setup for this root in
 205                  * this transaction.
 206                  *
 207                  * Normally we'd use root->last_trans as a flag to decide
 208                  * if we want to take the expensive mutex.
 209                  *
 210                  * But, we have to set root->last_trans before we
 211                  * init the relocation root, otherwise, we trip over warnings
 212                  * in ctree.c.  The solution used here is to flag ourselves
 213                  * with root->in_trans_setup.  When this is 1, we're still
 214                  * fixing up the reloc trees and everyone must wait.
 215                  *
 216                  * When this is zero, they can trust root->last_trans and fly
 217                  * through btrfs_record_root_in_trans without having to take the
 218                  * lock.  smp_wmb() makes sure that all the writes above are
 219                  * done before we pop in the zero below
 220                  */
 221                 btrfs_init_reloc_root(trans, root);
 222                 smp_wmb();
 223                 root->in_trans_setup = 0;
 224         }
 225         return 0;
 226 }
 227
 228
 229 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 230                                struct btrfs_root *root)
 231 {
 232         if (!root->ref_cows)
 233                 return 0;
 234
 235         /*
 236          * see record_root_in_trans for comments about in_trans_setup usage
 237          * and barriers
 238          */
 239         smp_rmb();
 240         if (root->last_trans == trans->transid &&
 241             !root->in_trans_setup)
 242                 return 0;
 243
 244         mutex_lock(&root->fs_info->reloc_mutex);
 245         record_root_in_trans(trans, root);
 246         mutex_unlock(&root->fs_info->reloc_mutex);
 247
 248         return 0;
 249 }
 250
 251 /* wait for commit against the current transaction to become unblocked
 252  * when this is done, it is safe to start a new transaction, but the current
 253  * transaction might not be fully on disk.
 254  */
 255 static void wait_current_trans(struct btrfs_root *root)
 256 {
 257         struct btrfs_transaction *cur_trans;
 258
 259         spin_lock(&root->fs_info->trans_lock);
 260         cur_trans = root->fs_info->running_transaction;
 261         if (cur_trans && cur_trans->blocked) {
 262                 atomic_inc(&cur_trans->use_count);
 263                 spin_unlock(&root->fs_info->trans_lock);
 264
 265                 wait_event(root->fs_info->transaction_wait,
 266                            !cur_trans->blocked);
 267                 put_transaction(cur_trans);
 268         } else {
 269                 spin_unlock(&root->fs_info->trans_lock);
 270         }
 271 }
 272
 273 enum btrfs_trans_type {
 274         TRANS_START,
 275         TRANS_JOIN,
 276         TRANS_USERSPACE,
 277         TRANS_JOIN_NOLOCK,
 278 };
 279
 280 static int may_wait_transaction(struct btrfs_root *root, int type)
 281 {
 282         if (root->fs_info->log_root_recovering)
 283                 return 0;
 284
 285         if (type == TRANS_USERSPACE)
 286                 return 1;
 287
 288         if (type == TRANS_START &&
 289             !atomic_read(&root->fs_info->open_ioctl_trans))
 290                 return 1;
 291
 292         return 0;
 293 }
 294
 295 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 296                                                     u64 num_items, int type)
 297 {
 298         struct btrfs_trans_handle *h;
 299         struct btrfs_transaction *cur_trans;
 300         u64 num_bytes = 0;
 301         int ret;
 302
 303         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 304                 return ERR_PTR(-EROFS);
 305
 306         if (current->journal_info) {
 307                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 308                 h = current->journal_info;
 309                 h->use_count++;
 310                 h->orig_rsv = h->block_rsv;
 311                 h->block_rsv = NULL;
 312                 goto got_it;
 313         }
 314
 315         /*
 316          * Do the reservation before we join the transaction so we can do all
 317          * the appropriate flushing if need be.
 318          */
 319         if (num_items > 0 && root != root->fs_info->chunk_root) {
 320                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 321                 ret = btrfs_block_rsv_add(root,
 322                                           &root->fs_info->trans_block_rsv,
 323                                           num_bytes);
 324                 if (ret)
 325                         return ERR_PTR(ret);
 326         }
 327 again:
 328         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 329         if (!h)
 330                 return ERR_PTR(-ENOMEM);
 331
 332         if (may_wait_transaction(root, type))
 333                 wait_current_trans(root);
 334
 335         do {
 336                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 337                 if (ret == -EBUSY)
 338                         wait_current_trans(root);
 339         } while (ret == -EBUSY);
 340
 341         if (ret < 0) {
 342                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 343                 return ERR_PTR(ret);
 344         }
 345
 346         cur_trans = root->fs_info->running_transaction;
 347
 348         h->transid = cur_trans->transid;
 349         h->transaction = cur_trans;
 350         h->blocks_used = 0;
 351         h->bytes_reserved = 0;
 352         h->delayed_ref_updates = 0;
 353         h->use_count = 1;
 354         h->block_rsv = NULL;
 355         h->orig_rsv = NULL;
 356         h->aborted = 0;
 357
 358         smp_mb();
 359         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 360                 btrfs_commit_transaction(h, root);
 361                 goto again;
 362         }
 363
 364         if (num_bytes) {
 365                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 366                                               h->transid, num_bytes, 1);
 367                 h->block_rsv = &root->fs_info->trans_block_rsv;
 368                 h->bytes_reserved = num_bytes;
 369         }
 370
 371 got_it:
 372         btrfs_record_root_in_trans(h, root);
 373
 374         if (!current->journal_info && type != TRANS_USERSPACE)
 375                 current->journal_info = h;
 376         return h;
 377 }
 378
 379 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 380                                                    int num_items)
 381 {
 382         return start_transaction(root, num_items, TRANS_START);
 383 }
 384 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 385 {
 386         return start_transaction(root, 0, TRANS_JOIN);
 387 }
 388
 389 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 390 {
 391         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 392 }
 393
 394 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 395 {
 396         return start_transaction(root, 0, TRANS_USERSPACE);
 397 }
 398
 399 /* wait for a transaction commit to be fully complete */
 400 static noinline void wait_for_commit(struct btrfs_root *root,
 401                                     struct btrfs_transaction *commit)
 402 {
 403         wait_event(commit->commit_wait, commit->commit_done);
 404 }
 405
 406 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 407 {
 408         struct btrfs_transaction *cur_trans = NULL, *t;
 409         int ret;
 410
 411         ret = 0;
 412         if (transid) {
 413                 if (transid <= root->fs_info->last_trans_committed)
 414                         goto out;
 415
 416                 /* find specified transaction */
 417                 spin_lock(&root->fs_info->trans_lock);
 418                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 419                         if (t->transid == transid) {
 420                                 cur_trans = t;
 421                                 atomic_inc(&cur_trans->use_count);
 422                                 break;
 423                         }
 424                         if (t->transid > transid)
 425                                 break;
 426                 }
 427                 spin_unlock(&root->fs_info->trans_lock);
 428                 ret = -EINVAL;
 429                 if (!cur_trans)
 430                         goto out;  /* bad transid */
 431         } else {
 432                 /* find newest transaction that is committing | committed */
 433                 spin_lock(&root->fs_info->trans_lock);
 434                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 435                                             list) {
 436                         if (t->in_commit) {
 437                                 if (t->commit_done)
 438                                         break;
 439                                 cur_trans = t;
 440                                 atomic_inc(&cur_trans->use_count);
 441                                 break;
 442                         }
 443                 }
 444                 spin_unlock(&root->fs_info->trans_lock);
 445                 if (!cur_trans)
 446                         goto out;  /* nothing committing|committed */
 447         }
 448
 449         wait_for_commit(root, cur_trans);
 450
 451         put_transaction(cur_trans);
 452         ret = 0;
 453 out:
 454         return ret;
 455 }
 456
 457 void btrfs_throttle(struct btrfs_root *root)
 458 {
 459         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 460                 wait_current_trans(root);
 461 }
 462
 463 static int should_end_transaction(struct btrfs_trans_handle *trans,
 464                                   struct btrfs_root *root)
 465 {
 466         int ret;
 467
 468         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 469         return ret ? 1 : 0;
 470 }
 471
 472 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 473                                  struct btrfs_root *root)
 474 {
 475         struct btrfs_transaction *cur_trans = trans->transaction;
 476         struct btrfs_block_rsv *rsv = trans->block_rsv;
 477         int updates;
 478         int err;
 479
 480         smp_mb();
 481         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 482                 return 1;
 483
 484         /*
 485          * We need to do this in case we're deleting csums so the global block
 486          * rsv get's used instead of the csum block rsv.
 487          */
 488         trans->block_rsv = NULL;
 489
 490         updates = trans->delayed_ref_updates;
 491         trans->delayed_ref_updates = 0;
 492         if (updates) {
 493                 err = btrfs_run_delayed_refs(trans, root, updates);
 494                 if (err) /* Error code will also eval true */
 495                         return err;
 496         }
 497
 498         trans->block_rsv = rsv;
 499
 500         return should_end_transaction(trans, root);
 501 }
 502
 503 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 504                           struct btrfs_root *root, int throttle, int lock)
 505 {
 506         struct btrfs_transaction *cur_trans = trans->transaction;
 507         struct btrfs_fs_info *info = root->fs_info;
 508         int count = 0;
 509         int err = 0;
 510
 511         if (--trans->use_count) {
 512                 trans->block_rsv = trans->orig_rsv;
 513                 return 0;
 514         }
 515
 516         btrfs_trans_release_metadata(trans, root);
 517         trans->block_rsv = NULL;
 518         while (count < 2) {
 519                 unsigned long cur = trans->delayed_ref_updates;
 520                 trans->delayed_ref_updates = 0;
 521                 if (cur &&
 522                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 523                         trans->delayed_ref_updates = 0;
 524                         btrfs_run_delayed_refs(trans, root, cur);
 525                 } else {
 526                         break;
 527                 }
 528                 count++;
 529         }
 530
 531         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 532             should_end_transaction(trans, root)) {
 533                 trans->transaction->blocked = 1;
 534                 smp_wmb();
 535         }
 536
 537         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 538                 if (throttle) {
 539                         /*
 540                          * We may race with somebody else here so end up having
 541                          * to call end_transaction on ourselves again, so inc
 542                          * our use_count.
 543                          */
 544                         trans->use_count++;
 545                         return btrfs_commit_transaction(trans, root);
 546                 } else {
 547                         wake_up_process(info->transaction_kthread);
 548                 }
 549         }
 550
 551         WARN_ON(cur_trans != info->running_transaction);
 552         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 553         atomic_dec(&cur_trans->num_writers);
 554
 555         smp_mb();
 556         if (waitqueue_active(&cur_trans->writer_wait))
 557                 wake_up(&cur_trans->writer_wait);
 558         put_transaction(cur_trans);
 559
 560         if (current->journal_info == trans)
 561                 current->journal_info = NULL;
 562
 563         if (throttle)
 564                 btrfs_run_delayed_iputs(root);
 565
 566         if (trans->aborted ||
 567             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 568                 err = -EIO;
 569         }
 570
 571         memset(trans, 0, sizeof(*trans));
 572         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 573         return err;
 574 }
 575
 576 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 577                           struct btrfs_root *root)
 578 {
 579         int ret;
 580
 581         ret = __btrfs_end_transaction(trans, root, 0, 1);
 582         if (ret)
 583                 return ret;
 584         return 0;
 585 }
 586
 587 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 588                                    struct btrfs_root *root)
 589 {
 590         int ret;
 591
 592         ret = __btrfs_end_transaction(trans, root, 1, 1);
 593         if (ret)
 594                 return ret;
 595         return 0;
 596 }
 597
 598 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 599                                  struct btrfs_root *root)
 600 {
 601         int ret;
 602
 603         ret = __btrfs_end_transaction(trans, root, 0, 0);
 604         if (ret)
 605                 return ret;
 606         return 0;
 607 }
 608
 609 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 610                                 struct btrfs_root *root)
 611 {
 612         return __btrfs_end_transaction(trans, root, 1, 1);
 613 }
 614
 615 /*
 616  * when btree blocks are allocated, they have some corresponding bits set for
 617  * them in one of two extent_io trees.  This is used to make sure all of
 618  * those extents are sent to disk but does not wait on them
 619  */
 620 int btrfs_write_marked_extents(struct btrfs_root *root,
 621                                struct extent_io_tree *dirty_pages, int mark)
 622 {
 623         int err = 0;
 624         int werr = 0;
 625         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 626         u64 start = 0;
 627         u64 end;
 628
 629         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 630                                       mark)) {
 631                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 632                                    GFP_NOFS);
 633                 err = filemap_fdatawrite_range(mapping, start, end);
 634                 if (err)
 635                         werr = err;
 636                 cond_resched();
 637                 start = end + 1;
 638         }
 639         if (err)
 640                 werr = err;
 641         return werr;
 642 }
 643
 644 /*
 645  * when btree blocks are allocated, they have some corresponding bits set for
 646  * them in one of two extent_io trees.  This is used to make sure all of
 647  * those extents are on disk for transaction or log commit.  We wait
 648  * on all the pages and clear them from the dirty pages state tree
 649  */
 650 int btrfs_wait_marked_extents(struct btrfs_root *root,
 651                               struct extent_io_tree *dirty_pages, int mark)
 652 {
 653         int err = 0;
 654         int werr = 0;
 655         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 656         u64 start = 0;
 657         u64 end;
 658
 659         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 660                                       EXTENT_NEED_WAIT)) {
 661                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 662                 err = filemap_fdatawait_range(mapping, start, end);
 663                 if (err)
 664                         werr = err;
 665                 cond_resched();
 666                 start = end + 1;
 667         }
 668         if (err)
 669                 werr = err;
 670         return werr;
 671 }
 672
 673 /*
 674  * when btree blocks are allocated, they have some corresponding bits set for
 675  * them in one of two extent_io trees.  This is used to make sure all of
 676  * those extents are on disk for transaction or log commit
 677  */
 678 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 679                                 struct extent_io_tree *dirty_pages, int mark)
 680 {
 681         int ret;
 682         int ret2;
 683
 684         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 685         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 686
 687         if (ret)
 688                 return ret;
 689         if (ret2)
 690                 return ret2;
 691         return 0;
 692 }
 693
 694 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 695                                      struct btrfs_root *root)
 696 {
 697         if (!trans || !trans->transaction) {
 698                 struct inode *btree_inode;
 699                 btree_inode = root->fs_info->btree_inode;
 700                 return filemap_write_and_wait(btree_inode->i_mapping);
 701         }
 702         return btrfs_write_and_wait_marked_extents(root,
 703                                            &trans->transaction->dirty_pages,
 704                                            EXTENT_DIRTY);
 705 }
 706
 707 /*
 708  * this is used to update the root pointer in the tree of tree roots.
 709  *
 710  * But, in the case of the extent allocation tree, updating the root
 711  * pointer may allocate blocks which may change the root of the extent
 712  * allocation tree.
 713  *
 714  * So, this loops and repeats and makes sure the cowonly root didn't
 715  * change while the root pointer was being updated in the metadata.
 716  */
 717 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 718                                struct btrfs_root *root)
 719 {
 720         int ret;
 721         u64 old_root_bytenr;
 722         u64 old_root_used;
 723         struct btrfs_root *tree_root = root->fs_info->tree_root;
 724
 725         old_root_used = btrfs_root_used(&root->root_item);
 726         btrfs_write_dirty_block_groups(trans, root);
 727
 728         while (1) {
 729                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 730                 if (old_root_bytenr == root->node->start &&
 731                     old_root_used == btrfs_root_used(&root->root_item))
 732                         break;
 733
 734                 btrfs_set_root_node(&root->root_item, root->node);
 735                 ret = btrfs_update_root(trans, tree_root,
 736                                         &root->root_key,
 737                                         &root->root_item);
 738                 if (ret)
 739                         return ret;
 740
 741                 old_root_used = btrfs_root_used(&root->root_item);
 742                 ret = btrfs_write_dirty_block_groups(trans, root);
 743                 if (ret)
 744                         return ret;
 745         }
 746
 747         if (root != root->fs_info->extent_root)
 748                 switch_commit_root(root);
 749
 750         return 0;
 751 }
 752
 753 /*
 754  * update all the cowonly tree roots on disk
 755  *
 756  * The error handling in this function may not be obvious. Any of the
 757  * failures will cause the file system to go offline. We still need
 758  * to clean up the delayed refs.
 759  */
 760 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 761                                          struct btrfs_root *root)
 762 {
 763         struct btrfs_fs_info *fs_info = root->fs_info;
 764         struct list_head *next;
 765         struct extent_buffer *eb;
 766         int ret;
 767
 768         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 769         if (ret)
 770                 return ret;
 771
 772         eb = btrfs_lock_root_node(fs_info->tree_root);
 773         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 774                               0, &eb);
 775         btrfs_tree_unlock(eb);
 776         free_extent_buffer(eb);
 777
 778         if (ret)
 779                 return ret;
 780
 781         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 782         if (ret)
 783                 return ret;
 784
 785         ret = btrfs_run_dev_stats(trans, root->fs_info);
 786         BUG_ON(ret);
 787
 788         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 789                 next = fs_info->dirty_cowonly_roots.next;
 790                 list_del_init(next);
 791                 root = list_entry(next, struct btrfs_root, dirty_list);
 792
 793                 ret = update_cowonly_root(trans, root);
 794                 if (ret)
 795                         return ret;
 796         }
 797
 798         down_write(&fs_info->extent_commit_sem);
 799         switch_commit_root(fs_info->extent_root);
 800         up_write(&fs_info->extent_commit_sem);
 801
 802         return 0;
 803 }
 804
 805 /*
 806  * dead roots are old snapshots that need to be deleted.  This allocates
 807  * a dirty root struct and adds it into the list of dead roots that need to
 808  * be deleted
 809  */
 810 int btrfs_add_dead_root(struct btrfs_root *root)
 811 {
 812         spin_lock(&root->fs_info->trans_lock);
 813         list_add(&root->root_list, &root->fs_info->dead_roots);
 814         spin_unlock(&root->fs_info->trans_lock);
 815         return 0;
 816 }
 817
 818 /*
 819  * update all the cowonly tree roots on disk
 820  */
 821 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 822                                     struct btrfs_root *root)
 823 {
 824         struct btrfs_root *gang[8];
 825         struct btrfs_fs_info *fs_info = root->fs_info;
 826         int i;
 827         int ret;
 828         int err = 0;
 829
 830         spin_lock(&fs_info->fs_roots_radix_lock);
 831         while (1) {
 832                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 833                                                  (void **)gang, 0,
 834                                                  ARRAY_SIZE(gang),
 835                                                  BTRFS_ROOT_TRANS_TAG);
 836                 if (ret == 0)
 837                         break;
 838                 for (i = 0; i < ret; i++) {
 839                         root = gang[i];
 840                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 841                                         (unsigned long)root->root_key.objectid,
 842                                         BTRFS_ROOT_TRANS_TAG);
 843                         spin_unlock(&fs_info->fs_roots_radix_lock);
 844
 845                         btrfs_free_log(trans, root);
 846                         btrfs_update_reloc_root(trans, root);
 847                         btrfs_orphan_commit_root(trans, root);
 848
 849                         btrfs_save_ino_cache(root, trans);
 850
 851                         /* see comments in should_cow_block() */
 852                         root->force_cow = 0;
 853                         smp_wmb();
 854
 855                         if (root->commit_root != root->node) {
 856                                 mutex_lock(&root->fs_commit_mutex);
 857                                 switch_commit_root(root);
 858                                 btrfs_unpin_free_ino(root);
 859                                 mutex_unlock(&root->fs_commit_mutex);
 860
 861                                 btrfs_set_root_node(&root->root_item,
 862                                                     root->node);
 863                         }
 864
 865                         err = btrfs_update_root(trans, fs_info->tree_root,
 866                                                 &root->root_key,
 867                                                 &root->root_item);
 868                         spin_lock(&fs_info->fs_roots_radix_lock);
 869                         if (err)
 870                                 break;
 871                 }
 872         }
 873         spin_unlock(&fs_info->fs_roots_radix_lock);
 874         return err;
 875 }
 876
 877 /*
 878  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 879  * otherwise every leaf in the btree is read and defragged.
 880  */
 881 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 882 {
 883         struct btrfs_fs_info *info = root->fs_info;
 884         struct btrfs_trans_handle *trans;
 885         int ret;
 886         unsigned long nr;
 887
 888         if (xchg(&root->defrag_running, 1))
 889                 return 0;
 890
 891         while (1) {
 892                 trans = btrfs_start_transaction(root, 0);
 893                 if (IS_ERR(trans))
 894                         return PTR_ERR(trans);
 895
 896                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 897
 898                 nr = trans->blocks_used;
 899                 btrfs_end_transaction(trans, root);
 900                 btrfs_btree_balance_dirty(info->tree_root, nr);
 901                 cond_resched();
 902
 903                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 904                         break;
 905         }
 906         root->defrag_running = 0;
 907         return ret;
 908 }
 909
 910 /*
 911  * new snapshots need to be created at a very specific time in the
 912  * transaction commit.  This does the actual creation
 913  */
 914 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 915                                    struct btrfs_fs_info *fs_info,
 916                                    struct btrfs_pending_snapshot *pending)
 917 {
 918         struct btrfs_key key;
 919         struct btrfs_root_item *new_root_item;
 920         struct btrfs_root *tree_root = fs_info->tree_root;
 921         struct btrfs_root *root = pending->root;
 922         struct btrfs_root *parent_root;
 923         struct btrfs_block_rsv *rsv;
 924         struct inode *parent_inode;
 925         struct dentry *parent;
 926         struct dentry *dentry;
 927         struct extent_buffer *tmp;
 928         struct extent_buffer *old;
 929         int ret;
 930         u64 to_reserve = 0;
 931         u64 index = 0;
 932         u64 objectid;
 933         u64 root_flags;
 934
 935         rsv = trans->block_rsv;
 936
 937         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 938         if (!new_root_item) {
 939                 ret = pending->error = -ENOMEM;
 940                 goto fail;
 941         }
 942
 943         ret = btrfs_find_free_objectid(tree_root, &objectid);
 944         if (ret) {
 945                 pending->error = ret;
 946                 goto fail;
 947         }
 948
 949         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 950
 951         if (to_reserve > 0) {
 952                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
 953                                                   to_reserve);
 954                 if (ret) {
 955                         pending->error = ret;
 956                         goto fail;
 957                 }
 958         }
 959
 960         key.objectid = objectid;
 961         key.offset = (u64)-1;
 962         key.type = BTRFS_ROOT_ITEM_KEY;
 963
 964         trans->block_rsv = &pending->block_rsv;
 965
 966         dentry = pending->dentry;
 967         parent = dget_parent(dentry);
 968         parent_inode = parent->d_inode;
 969         parent_root = BTRFS_I(parent_inode)->root;
 970         record_root_in_trans(trans, parent_root);
 971
 972         /*
 973          * insert the directory item
 974          */
 975         ret = btrfs_set_inode_index(parent_inode, &index);
 976         BUG_ON(ret); /* -ENOMEM */
 977         ret = btrfs_insert_dir_item(trans, parent_root,
 978                                 dentry->d_name.name, dentry->d_name.len,
 979                                 parent_inode, &key,
 980                                 BTRFS_FT_DIR, index);
 981         if (ret == -EEXIST) {
 982                 pending->error = -EEXIST;
 983                 dput(parent);
 984                 goto fail;
 985         } else if (ret) {
 986                 goto abort_trans_dput;
 987         }
 988
 989         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 990                                          dentry->d_name.len * 2);
 991         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 992         if (ret)
 993                 goto abort_trans_dput;
 994
 995         /*
 996          * pull in the delayed directory update
 997          * and the delayed inode item
 998          * otherwise we corrupt the FS during
 999          * snapshot
1000          */
1001         ret = btrfs_run_delayed_items(trans, root);
1002         if (ret) { /* Transaction aborted */
1003                 dput(parent);
1004                 goto fail;
1005         }
1006
1007         record_root_in_trans(trans, root);
1008         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1009         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1010         btrfs_check_and_init_root_item(new_root_item);
1011
1012         root_flags = btrfs_root_flags(new_root_item);
1013         if (pending->readonly)
1014                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1015         else
1016                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1017         btrfs_set_root_flags(new_root_item, root_flags);
1018
1019         old = btrfs_lock_root_node(root);
1020         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1021         if (ret) {
1022                 btrfs_tree_unlock(old);
1023                 free_extent_buffer(old);
1024                 goto abort_trans_dput;
1025         }
1026
1027         btrfs_set_lock_blocking(old);
1028
1029         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1030         /* clean up in any case */
1031         btrfs_tree_unlock(old);
1032         free_extent_buffer(old);
1033         if (ret)
1034                 goto abort_trans_dput;
1035
1036         /* see comments in should_cow_block() */
1037         root->force_cow = 1;
1038         smp_wmb();
1039
1040         btrfs_set_root_node(new_root_item, tmp);
1041         /* record when the snapshot was created in key.offset */
1042         key.offset = trans->transid;
1043         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1044         btrfs_tree_unlock(tmp);
1045         free_extent_buffer(tmp);
1046         if (ret)
1047                 goto abort_trans_dput;
1048
1049         /*
1050          * insert root back/forward references
1051          */
1052         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1053                                  parent_root->root_key.objectid,
1054                                  btrfs_ino(parent_inode), index,
1055                                  dentry->d_name.name, dentry->d_name.len);
1056         dput(parent);
1057         if (ret)
1058                 goto fail;
1059
1060         key.offset = (u64)-1;
1061         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1062         if (IS_ERR(pending->snap)) {
1063                 ret = PTR_ERR(pending->snap);
1064                 goto abort_trans;
1065         }
1066
1067         ret = btrfs_reloc_post_snapshot(trans, pending);
1068         if (ret)
1069                 goto abort_trans;
1070         ret = 0;
1071 fail:
1072         kfree(new_root_item);
1073         trans->block_rsv = rsv;
1074         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1075         return ret;
1076
1077 abort_trans_dput:
1078         dput(parent);
1079 abort_trans:
1080         btrfs_abort_transaction(trans, root, ret);
1081         goto fail;
1082 }
1083
1084 /*
1085  * create all the snapshots we've scheduled for creation
1086  */
1087 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1088                                              struct btrfs_fs_info *fs_info)
1089 {
1090         struct btrfs_pending_snapshot *pending;
1091         struct list_head *head = &trans->transaction->pending_snapshots;
1092
1093         list_for_each_entry(pending, head, list)
1094                 create_pending_snapshot(trans, fs_info, pending);
1095         return 0;
1096 }
1097
1098 static void update_super_roots(struct btrfs_root *root)
1099 {
1100         struct btrfs_root_item *root_item;
1101         struct btrfs_super_block *super;
1102
1103         super = root->fs_info->super_copy;
1104
1105         root_item = &root->fs_info->chunk_root->root_item;
1106         super->chunk_root = root_item->bytenr;
1107         super->chunk_root_generation = root_item->generation;
1108         super->chunk_root_level = root_item->level;
1109
1110         root_item = &root->fs_info->tree_root->root_item;
1111         super->root = root_item->bytenr;
1112         super->generation = root_item->generation;
1113         super->root_level = root_item->level;
1114         if (btrfs_test_opt(root, SPACE_CACHE))
1115                 super->cache_generation = root_item->generation;
1116 }
1117
1118 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1119 {
1120         int ret = 0;
1121         spin_lock(&info->trans_lock);
1122         if (info->running_transaction)
1123                 ret = info->running_transaction->in_commit;
1124         spin_unlock(&info->trans_lock);
1125         return ret;
1126 }
1127
1128 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1129 {
1130         int ret = 0;
1131         spin_lock(&info->trans_lock);
1132         if (info->running_transaction)
1133                 ret = info->running_transaction->blocked;
1134         spin_unlock(&info->trans_lock);
1135         return ret;
1136 }
1137
1138 /*
1139  * wait for the current transaction commit to start and block subsequent
1140  * transaction joins
1141  */
1142 static void wait_current_trans_commit_start(struct btrfs_root *root,
1143                                             struct btrfs_transaction *trans)
1144 {
1145         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1146 }
1147
1148 /*
1149  * wait for the current transaction to start and then become unblocked.
1150  * caller holds ref.
1151  */
1152 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1153                                          struct btrfs_transaction *trans)
1154 {
1155         wait_event(root->fs_info->transaction_wait,
1156                    trans->commit_done || (trans->in_commit && !trans->blocked));
1157 }
1158
1159 /*
1160  * commit transactions asynchronously. once btrfs_commit_transaction_async
1161  * returns, any subsequent transaction will not be allowed to join.
1162  */
1163 struct btrfs_async_commit {
1164         struct btrfs_trans_handle *newtrans;
1165         struct btrfs_root *root;
1166         struct delayed_work work;
1167 };
1168
1169 static void do_async_commit(struct work_struct *work)
1170 {
1171         struct btrfs_async_commit *ac =
1172                 container_of(work, struct btrfs_async_commit, work.work);
1173
1174         btrfs_commit_transaction(ac->newtrans, ac->root);
1175         kfree(ac);
1176 }
1177
1178 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1179                                    struct btrfs_root *root,
1180                                    int wait_for_unblock)
1181 {
1182         struct btrfs_async_commit *ac;
1183         struct btrfs_transaction *cur_trans;
1184
1185         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1186         if (!ac)
1187                 return -ENOMEM;
1188
1189         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1190         ac->root = root;
1191         ac->newtrans = btrfs_join_transaction(root);
1192         if (IS_ERR(ac->newtrans)) {
1193                 int err = PTR_ERR(ac->newtrans);
1194                 kfree(ac);
1195                 return err;
1196         }
1197
1198         /* take transaction reference */
1199         cur_trans = trans->transaction;
1200         atomic_inc(&cur_trans->use_count);
1201
1202         btrfs_end_transaction(trans, root);
1203         schedule_delayed_work(&ac->work, 0);
1204
1205         /* wait for transaction to start and unblock */
1206         if (wait_for_unblock)
1207                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1208         else
1209                 wait_current_trans_commit_start(root, cur_trans);
1210
1211         if (current->journal_info == trans)
1212                 current->journal_info = NULL;
1213
1214         put_transaction(cur_trans);
1215         return 0;
1216 }
1217
1218
1219 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1220                                 struct btrfs_root *root, int err)
1221 {
1222         struct btrfs_transaction *cur_trans = trans->transaction;
1223
1224         WARN_ON(trans->use_count > 1);
1225
1226         btrfs_abort_transaction(trans, root, err);
1227
1228         spin_lock(&root->fs_info->trans_lock);
1229         list_del_init(&cur_trans->list);
1230         if (cur_trans == root->fs_info->running_transaction) {
1231                 root->fs_info->running_transaction = NULL;
1232                 root->fs_info->trans_no_join = 0;
1233         }
1234         spin_unlock(&root->fs_info->trans_lock);
1235
1236         btrfs_cleanup_one_transaction(trans->transaction, root);
1237
1238         put_transaction(cur_trans);
1239         put_transaction(cur_trans);
1240
1241         trace_btrfs_transaction_commit(root);
1242
1243         btrfs_scrub_continue(root);
1244
1245         if (current->journal_info == trans)
1246                 current->journal_info = NULL;
1247
1248         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1249 }
1250
1251 /*
1252  * btrfs_transaction state sequence:
1253  *    in_commit = 0, blocked = 0  (initial)
1254  *    in_commit = 1, blocked = 1
1255  *    blocked = 0
1256  *    commit_done = 1
1257  */
1258 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1259                              struct btrfs_root *root)
1260 {
1261         unsigned long joined = 0;
1262         struct btrfs_transaction *cur_trans = trans->transaction;
1263         struct btrfs_transaction *prev_trans = NULL;
1264         DEFINE_WAIT(wait);
1265         int ret = -EIO;
1266         int should_grow = 0;
1267         unsigned long now = get_seconds();
1268         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1269
1270         btrfs_run_ordered_operations(root, 0);
1271
1272         btrfs_trans_release_metadata(trans, root);
1273         trans->block_rsv = NULL;
1274
1275         if (cur_trans->aborted)
1276                 goto cleanup_transaction;
1277
1278         /* make a pass through all the delayed refs we have so far
1279          * any runnings procs may add more while we are here
1280          */
1281         ret = btrfs_run_delayed_refs(trans, root, 0);
1282         if (ret)
1283                 goto cleanup_transaction;
1284
1285         cur_trans = trans->transaction;
1286
1287         /*
1288          * set the flushing flag so procs in this transaction have to
1289          * start sending their work down.
1290          */
1291         cur_trans->delayed_refs.flushing = 1;
1292
1293         ret = btrfs_run_delayed_refs(trans, root, 0);
1294         if (ret)
1295                 goto cleanup_transaction;
1296
1297         spin_lock(&cur_trans->commit_lock);
1298         if (cur_trans->in_commit) {
1299                 spin_unlock(&cur_trans->commit_lock);
1300                 atomic_inc(&cur_trans->use_count);
1301                 ret = btrfs_end_transaction(trans, root);
1302
1303                 wait_for_commit(root, cur_trans);
1304
1305                 put_transaction(cur_trans);
1306
1307                 return ret;
1308         }
1309
1310         trans->transaction->in_commit = 1;
1311         trans->transaction->blocked = 1;
1312         spin_unlock(&cur_trans->commit_lock);
1313         wake_up(&root->fs_info->transaction_blocked_wait);
1314
1315         spin_lock(&root->fs_info->trans_lock);
1316         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1317                 prev_trans = list_entry(cur_trans->list.prev,
1318                                         struct btrfs_transaction, list);
1319                 if (!prev_trans->commit_done) {
1320                         atomic_inc(&prev_trans->use_count);
1321                         spin_unlock(&root->fs_info->trans_lock);
1322
1323                         wait_for_commit(root, prev_trans);
1324
1325                         put_transaction(prev_trans);
1326                 } else {
1327                         spin_unlock(&root->fs_info->trans_lock);
1328                 }
1329         } else {
1330                 spin_unlock(&root->fs_info->trans_lock);
1331         }
1332
1333         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1334                 should_grow = 1;
1335
1336         do {
1337                 int snap_pending = 0;
1338
1339                 joined = cur_trans->num_joined;
1340                 if (!list_empty(&trans->transaction->pending_snapshots))
1341                         snap_pending = 1;
1342
1343                 WARN_ON(cur_trans != trans->transaction);
1344
1345                 if (flush_on_commit || snap_pending) {
1346                         btrfs_start_delalloc_inodes(root, 1);
1347                         btrfs_wait_ordered_extents(root, 0, 1);
1348                 }
1349
1350                 ret = btrfs_run_delayed_items(trans, root);
1351                 if (ret)
1352                         goto cleanup_transaction;
1353
1354                 /*
1355                  * rename don't use btrfs_join_transaction, so, once we
1356                  * set the transaction to blocked above, we aren't going
1357                  * to get any new ordered operations.  We can safely run
1358                  * it here and no for sure that nothing new will be added
1359                  * to the list
1360                  */
1361                 btrfs_run_ordered_operations(root, 1);
1362
1363                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1364                                 TASK_UNINTERRUPTIBLE);
1365
1366                 if (atomic_read(&cur_trans->num_writers) > 1)
1367                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1368                 else if (should_grow)
1369                         schedule_timeout(1);
1370
1371                 finish_wait(&cur_trans->writer_wait, &wait);
1372         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1373                  (should_grow && cur_trans->num_joined != joined));
1374
1375         /*
1376          * Ok now we need to make sure to block out any other joins while we
1377          * commit the transaction.  We could have started a join before setting
1378          * no_join so make sure to wait for num_writers to == 1 again.
1379          */
1380         spin_lock(&root->fs_info->trans_lock);
1381         root->fs_info->trans_no_join = 1;
1382         spin_unlock(&root->fs_info->trans_lock);
1383         wait_event(cur_trans->writer_wait,
1384                    atomic_read(&cur_trans->num_writers) == 1);
1385
1386         /*
1387          * the reloc mutex makes sure that we stop
1388          * the balancing code from coming in and moving
1389          * extents around in the middle of the commit
1390          */
1391         mutex_lock(&root->fs_info->reloc_mutex);
1392
1393         ret = btrfs_run_delayed_items(trans, root);
1394         if (ret) {
1395                 mutex_unlock(&root->fs_info->reloc_mutex);
1396                 goto cleanup_transaction;
1397         }
1398
1399         ret = create_pending_snapshots(trans, root->fs_info);
1400         if (ret) {
1401                 mutex_unlock(&root->fs_info->reloc_mutex);
1402                 goto cleanup_transaction;
1403         }
1404
1405         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1406         if (ret) {
1407                 mutex_unlock(&root->fs_info->reloc_mutex);
1408                 goto cleanup_transaction;
1409         }
1410
1411         /*
1412          * make sure none of the code above managed to slip in a
1413          * delayed item
1414          */
1415         btrfs_assert_delayed_root_empty(root);
1416
1417         WARN_ON(cur_trans != trans->transaction);
1418
1419         btrfs_scrub_pause(root);
1420         /* btrfs_commit_tree_roots is responsible for getting the
1421          * various roots consistent with each other.  Every pointer
1422          * in the tree of tree roots has to point to the most up to date
1423          * root for every subvolume and other tree.  So, we have to keep
1424          * the tree logging code from jumping in and changing any
1425          * of the trees.
1426          *
1427          * At this point in the commit, there can't be any tree-log
1428          * writers, but a little lower down we drop the trans mutex
1429          * and let new people in.  By holding the tree_log_mutex
1430          * from now until after the super is written, we avoid races
1431          * with the tree-log code.
1432          */
1433         mutex_lock(&root->fs_info->tree_log_mutex);
1434
1435         ret = commit_fs_roots(trans, root);
1436         if (ret) {
1437                 mutex_unlock(&root->fs_info->tree_log_mutex);
1438                 mutex_unlock(&root->fs_info->reloc_mutex);
1439                 goto cleanup_transaction;
1440         }
1441
1442         /* commit_fs_roots gets rid of all the tree log roots, it is now
1443          * safe to free the root of tree log roots
1444          */
1445         btrfs_free_log_root_tree(trans, root->fs_info);
1446
1447         ret = commit_cowonly_roots(trans, root);
1448         if (ret) {
1449                 mutex_unlock(&root->fs_info->tree_log_mutex);
1450                 mutex_unlock(&root->fs_info->reloc_mutex);
1451                 goto cleanup_transaction;
1452         }
1453
1454         btrfs_prepare_extent_commit(trans, root);
1455
1456         cur_trans = root->fs_info->running_transaction;
1457
1458         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1459                             root->fs_info->tree_root->node);
1460         switch_commit_root(root->fs_info->tree_root);
1461
1462         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1463                             root->fs_info->chunk_root->node);
1464         switch_commit_root(root->fs_info->chunk_root);
1465
1466         update_super_roots(root);
1467
1468         if (!root->fs_info->log_root_recovering) {
1469                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1470                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1471         }
1472
1473         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1474                sizeof(*root->fs_info->super_copy));
1475
1476         trans->transaction->blocked = 0;
1477         spin_lock(&root->fs_info->trans_lock);
1478         root->fs_info->running_transaction = NULL;
1479         root->fs_info->trans_no_join = 0;
1480         spin_unlock(&root->fs_info->trans_lock);
1481         mutex_unlock(&root->fs_info->reloc_mutex);
1482
1483         wake_up(&root->fs_info->transaction_wait);
1484
1485         ret = btrfs_write_and_wait_transaction(trans, root);
1486         if (ret) {
1487                 btrfs_error(root->fs_info, ret,
1488                             "Error while writing out transaction.");
1489                 mutex_unlock(&root->fs_info->tree_log_mutex);
1490                 goto cleanup_transaction;
1491         }
1492
1493         ret = write_ctree_super(trans, root, 0);
1494         if (ret) {
1495                 mutex_unlock(&root->fs_info->tree_log_mutex);
1496                 goto cleanup_transaction;
1497         }
1498
1499         /*
1500          * the super is written, we can safely allow the tree-loggers
1501          * to go about their business
1502          */
1503         mutex_unlock(&root->fs_info->tree_log_mutex);
1504
1505         btrfs_finish_extent_commit(trans, root);
1506
1507         cur_trans->commit_done = 1;
1508
1509         root->fs_info->last_trans_committed = cur_trans->transid;
1510
1511         wake_up(&cur_trans->commit_wait);
1512
1513         spin_lock(&root->fs_info->trans_lock);
1514         list_del_init(&cur_trans->list);
1515         spin_unlock(&root->fs_info->trans_lock);
1516
1517         put_transaction(cur_trans);
1518         put_transaction(cur_trans);
1519
1520         trace_btrfs_transaction_commit(root);
1521
1522         btrfs_scrub_continue(root);
1523
1524         if (current->journal_info == trans)
1525                 current->journal_info = NULL;
1526
1527         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1528
1529         if (current != root->fs_info->transaction_kthread)
1530                 btrfs_run_delayed_iputs(root);
1531
1532         return ret;
1533
1534 cleanup_transaction:
1535         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1536 //      WARN_ON(1);
1537         if (current->journal_info == trans)
1538                 current->journal_info = NULL;
1539         cleanup_transaction(trans, root, ret);
1540
1541         return ret;
1542 }
1543
1544 /*
1545  * interface function to delete all the snapshots we have scheduled for deletion
1546  */
1547 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1548 {
1549         LIST_HEAD(list);
1550         struct btrfs_fs_info *fs_info = root->fs_info;
1551
1552         spin_lock(&fs_info->trans_lock);
1553         list_splice_init(&fs_info->dead_roots, &list);
1554         spin_unlock(&fs_info->trans_lock);
1555
1556         while (!list_empty(&list)) {
1557                 int ret;
1558
1559                 root = list_entry(list.next, struct btrfs_root, root_list);
1560                 list_del(&root->root_list);
1561
1562                 btrfs_kill_all_delayed_nodes(root);
1563
1564                 if (btrfs_header_backref_rev(root->node) <
1565                     BTRFS_MIXED_BACKREF_REV)
1566                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1567                 else
1568                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1569                 BUG_ON(ret < 0);
1570         }
1571         return 0;
1572 }