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 <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33
  34 #define BTRFS_ROOT_TRANS_TAG 0
  35
  36 void put_transaction(struct btrfs_transaction *transaction)
  37 {
  38         WARN_ON(atomic_read(&transaction->use_count) == 0);
  39         if (atomic_dec_and_test(&transaction->use_count)) {
  40                 BUG_ON(!list_empty(&transaction->list));
  41                 WARN_ON(transaction->delayed_refs.root.rb_node);
  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 (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 104                 spin_unlock(&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
 130         /*
 131          * although the tree mod log is per file system and not per transaction,
 132          * the log must never go across transaction boundaries.
 133          */
 134         smp_mb();
 135         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 136                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 137                         "creating a fresh transaction\n");
 138                 WARN_ON(1);
 139         }
 140         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 141                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 142                         "creating a fresh transaction\n");
 143                 WARN_ON(1);
 144         }
 145         atomic_set(&fs_info->tree_mod_seq, 0);
 146
 147         spin_lock_init(&cur_trans->commit_lock);
 148         spin_lock_init(&cur_trans->delayed_refs.lock);
 149
 150         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 151         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 152         extent_io_tree_init(&cur_trans->dirty_pages,
 153                              fs_info->btree_inode->i_mapping);
 154         fs_info->generation++;
 155         cur_trans->transid = fs_info->generation;
 156         fs_info->running_transaction = cur_trans;
 157         cur_trans->aborted = 0;
 158         spin_unlock(&fs_info->trans_lock);
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * this does all the record keeping required to make sure that a reference
 165  * counted root is properly recorded in a given transaction.  This is required
 166  * to make sure the old root from before we joined the transaction is deleted
 167  * when the transaction commits
 168  */
 169 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 170                                struct btrfs_root *root)
 171 {
 172         if (root->ref_cows && root->last_trans < trans->transid) {
 173                 WARN_ON(root == root->fs_info->extent_root);
 174                 WARN_ON(root->commit_root != root->node);
 175
 176                 /*
 177                  * see below for in_trans_setup usage rules
 178                  * we have the reloc mutex held now, so there
 179                  * is only one writer in this function
 180                  */
 181                 root->in_trans_setup = 1;
 182
 183                 /* make sure readers find in_trans_setup before
 184                  * they find our root->last_trans update
 185                  */
 186                 smp_wmb();
 187
 188                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 189                 if (root->last_trans == trans->transid) {
 190                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 191                         return 0;
 192                 }
 193                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 194                            (unsigned long)root->root_key.objectid,
 195                            BTRFS_ROOT_TRANS_TAG);
 196                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 197                 root->last_trans = trans->transid;
 198
 199                 /* this is pretty tricky.  We don't want to
 200                  * take the relocation lock in btrfs_record_root_in_trans
 201                  * unless we're really doing the first setup for this root in
 202                  * this transaction.
 203                  *
 204                  * Normally we'd use root->last_trans as a flag to decide
 205                  * if we want to take the expensive mutex.
 206                  *
 207                  * But, we have to set root->last_trans before we
 208                  * init the relocation root, otherwise, we trip over warnings
 209                  * in ctree.c.  The solution used here is to flag ourselves
 210                  * with root->in_trans_setup.  When this is 1, we're still
 211                  * fixing up the reloc trees and everyone must wait.
 212                  *
 213                  * When this is zero, they can trust root->last_trans and fly
 214                  * through btrfs_record_root_in_trans without having to take the
 215                  * lock.  smp_wmb() makes sure that all the writes above are
 216                  * done before we pop in the zero below
 217                  */
 218                 btrfs_init_reloc_root(trans, root);
 219                 smp_wmb();
 220                 root->in_trans_setup = 0;
 221         }
 222         return 0;
 223 }
 224
 225
 226 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 227                                struct btrfs_root *root)
 228 {
 229         if (!root->ref_cows)
 230                 return 0;
 231
 232         /*
 233          * see record_root_in_trans for comments about in_trans_setup usage
 234          * and barriers
 235          */
 236         smp_rmb();
 237         if (root->last_trans == trans->transid &&
 238             !root->in_trans_setup)
 239                 return 0;
 240
 241         mutex_lock(&root->fs_info->reloc_mutex);
 242         record_root_in_trans(trans, root);
 243         mutex_unlock(&root->fs_info->reloc_mutex);
 244
 245         return 0;
 246 }
 247
 248 /* wait for commit against the current transaction to become unblocked
 249  * when this is done, it is safe to start a new transaction, but the current
 250  * transaction might not be fully on disk.
 251  */
 252 static void wait_current_trans(struct btrfs_root *root)
 253 {
 254         struct btrfs_transaction *cur_trans;
 255
 256         spin_lock(&root->fs_info->trans_lock);
 257         cur_trans = root->fs_info->running_transaction;
 258         if (cur_trans && cur_trans->blocked) {
 259                 atomic_inc(&cur_trans->use_count);
 260                 spin_unlock(&root->fs_info->trans_lock);
 261
 262                 wait_event(root->fs_info->transaction_wait,
 263                            !cur_trans->blocked);
 264                 put_transaction(cur_trans);
 265         } else {
 266                 spin_unlock(&root->fs_info->trans_lock);
 267         }
 268 }
 269
 270 enum btrfs_trans_type {
 271         TRANS_START,
 272         TRANS_JOIN,
 273         TRANS_USERSPACE,
 274         TRANS_JOIN_NOLOCK,
 275 };
 276
 277 static int may_wait_transaction(struct btrfs_root *root, int type)
 278 {
 279         if (root->fs_info->log_root_recovering)
 280                 return 0;
 281
 282         if (type == TRANS_USERSPACE)
 283                 return 1;
 284
 285         if (type == TRANS_START &&
 286             !atomic_read(&root->fs_info->open_ioctl_trans))
 287                 return 1;
 288
 289         return 0;
 290 }
 291
 292 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 293                                                     u64 num_items, int type)
 294 {
 295         struct btrfs_trans_handle *h;
 296         struct btrfs_transaction *cur_trans;
 297         u64 num_bytes = 0;
 298         int ret;
 299         u64 qgroup_reserved = 0;
 300
 301         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 302                 return ERR_PTR(-EROFS);
 303
 304         if (current->journal_info) {
 305                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 306                 h = current->journal_info;
 307                 h->use_count++;
 308                 h->orig_rsv = h->block_rsv;
 309                 h->block_rsv = NULL;
 310                 goto got_it;
 311         }
 312
 313         /*
 314          * Do the reservation before we join the transaction so we can do all
 315          * the appropriate flushing if need be.
 316          */
 317         if (num_items > 0 && root != root->fs_info->chunk_root) {
 318                 if (root->fs_info->quota_enabled &&
 319                     is_fstree(root->root_key.objectid)) {
 320                         qgroup_reserved = num_items * root->leafsize;
 321                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 322                         if (ret)
 323                                 return ERR_PTR(ret);
 324                 }
 325
 326                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 327                 ret = btrfs_block_rsv_add(root,
 328                                           &root->fs_info->trans_block_rsv,
 329                                           num_bytes);
 330                 if (ret)
 331                         return ERR_PTR(ret);
 332         }
 333 again:
 334         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 335         if (!h)
 336                 return ERR_PTR(-ENOMEM);
 337
 338         sb_start_intwrite(root->fs_info->sb);
 339
 340         if (may_wait_transaction(root, type))
 341                 wait_current_trans(root);
 342
 343         do {
 344                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 345                 if (ret == -EBUSY)
 346                         wait_current_trans(root);
 347         } while (ret == -EBUSY);
 348
 349         if (ret < 0) {
 350                 sb_end_intwrite(root->fs_info->sb);
 351                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 352                 return ERR_PTR(ret);
 353         }
 354
 355         cur_trans = root->fs_info->running_transaction;
 356
 357         h->transid = cur_trans->transid;
 358         h->transaction = cur_trans;
 359         h->blocks_used = 0;
 360         h->bytes_reserved = 0;
 361         h->root = root;
 362         h->delayed_ref_updates = 0;
 363         h->use_count = 1;
 364         h->adding_csums = 0;
 365         h->block_rsv = NULL;
 366         h->orig_rsv = NULL;
 367         h->aborted = 0;
 368         h->qgroup_reserved = qgroup_reserved;
 369         h->delayed_ref_elem.seq = 0;
 370         INIT_LIST_HEAD(&h->qgroup_ref_list);
 371
 372         smp_mb();
 373         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 374                 btrfs_commit_transaction(h, root);
 375                 goto again;
 376         }
 377
 378         if (num_bytes) {
 379                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 380                                               h->transid, num_bytes, 1);
 381                 h->block_rsv = &root->fs_info->trans_block_rsv;
 382                 h->bytes_reserved = num_bytes;
 383         }
 384
 385 got_it:
 386         btrfs_record_root_in_trans(h, root);
 387
 388         if (!current->journal_info && type != TRANS_USERSPACE)
 389                 current->journal_info = h;
 390         return h;
 391 }
 392
 393 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 394                                                    int num_items)
 395 {
 396         return start_transaction(root, num_items, TRANS_START);
 397 }
 398 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 399 {
 400         return start_transaction(root, 0, TRANS_JOIN);
 401 }
 402
 403 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 404 {
 405         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 406 }
 407
 408 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 409 {
 410         return start_transaction(root, 0, TRANS_USERSPACE);
 411 }
 412
 413 /* wait for a transaction commit to be fully complete */
 414 static noinline void wait_for_commit(struct btrfs_root *root,
 415                                     struct btrfs_transaction *commit)
 416 {
 417         wait_event(commit->commit_wait, commit->commit_done);
 418 }
 419
 420 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 421 {
 422         struct btrfs_transaction *cur_trans = NULL, *t;
 423         int ret;
 424
 425         ret = 0;
 426         if (transid) {
 427                 if (transid <= root->fs_info->last_trans_committed)
 428                         goto out;
 429
 430                 /* find specified transaction */
 431                 spin_lock(&root->fs_info->trans_lock);
 432                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 433                         if (t->transid == transid) {
 434                                 cur_trans = t;
 435                                 atomic_inc(&cur_trans->use_count);
 436                                 break;
 437                         }
 438                         if (t->transid > transid)
 439                                 break;
 440                 }
 441                 spin_unlock(&root->fs_info->trans_lock);
 442                 ret = -EINVAL;
 443                 if (!cur_trans)
 444                         goto out;  /* bad transid */
 445         } else {
 446                 /* find newest transaction that is committing | committed */
 447                 spin_lock(&root->fs_info->trans_lock);
 448                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 449                                             list) {
 450                         if (t->in_commit) {
 451                                 if (t->commit_done)
 452                                         break;
 453                                 cur_trans = t;
 454                                 atomic_inc(&cur_trans->use_count);
 455                                 break;
 456                         }
 457                 }
 458                 spin_unlock(&root->fs_info->trans_lock);
 459                 if (!cur_trans)
 460                         goto out;  /* nothing committing|committed */
 461         }
 462
 463         wait_for_commit(root, cur_trans);
 464
 465         put_transaction(cur_trans);
 466         ret = 0;
 467 out:
 468         return ret;
 469 }
 470
 471 void btrfs_throttle(struct btrfs_root *root)
 472 {
 473         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 474                 wait_current_trans(root);
 475 }
 476
 477 static int should_end_transaction(struct btrfs_trans_handle *trans,
 478                                   struct btrfs_root *root)
 479 {
 480         int ret;
 481
 482         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 483         return ret ? 1 : 0;
 484 }
 485
 486 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 487                                  struct btrfs_root *root)
 488 {
 489         struct btrfs_transaction *cur_trans = trans->transaction;
 490         int updates;
 491         int err;
 492
 493         smp_mb();
 494         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 495                 return 1;
 496
 497         updates = trans->delayed_ref_updates;
 498         trans->delayed_ref_updates = 0;
 499         if (updates) {
 500                 err = btrfs_run_delayed_refs(trans, root, updates);
 501                 if (err) /* Error code will also eval true */
 502                         return err;
 503         }
 504
 505         return should_end_transaction(trans, root);
 506 }
 507
 508 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 509                           struct btrfs_root *root, int throttle, int lock)
 510 {
 511         struct btrfs_transaction *cur_trans = trans->transaction;
 512         struct btrfs_fs_info *info = root->fs_info;
 513         int count = 0;
 514         int err = 0;
 515
 516         if (--trans->use_count) {
 517                 trans->block_rsv = trans->orig_rsv;
 518                 return 0;
 519         }
 520
 521         /*
 522          * do the qgroup accounting as early as possible
 523          */
 524         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 525
 526         btrfs_trans_release_metadata(trans, root);
 527         trans->block_rsv = NULL;
 528         /*
 529          * the same root has to be passed to start_transaction and
 530          * end_transaction. Subvolume quota depends on this.
 531          */
 532         WARN_ON(trans->root != root);
 533
 534         if (trans->qgroup_reserved) {
 535                 btrfs_qgroup_free(root, trans->qgroup_reserved);
 536                 trans->qgroup_reserved = 0;
 537         }
 538
 539         while (count < 2) {
 540                 unsigned long cur = trans->delayed_ref_updates;
 541                 trans->delayed_ref_updates = 0;
 542                 if (cur &&
 543                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 544                         trans->delayed_ref_updates = 0;
 545                         btrfs_run_delayed_refs(trans, root, cur);
 546                 } else {
 547                         break;
 548                 }
 549                 count++;
 550         }
 551         btrfs_trans_release_metadata(trans, root);
 552         trans->block_rsv = NULL;
 553
 554         sb_end_intwrite(root->fs_info->sb);
 555
 556         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 557             should_end_transaction(trans, root)) {
 558                 trans->transaction->blocked = 1;
 559                 smp_wmb();
 560         }
 561
 562         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 563                 if (throttle) {
 564                         /*
 565                          * We may race with somebody else here so end up having
 566                          * to call end_transaction on ourselves again, so inc
 567                          * our use_count.
 568                          */
 569                         trans->use_count++;
 570                         return btrfs_commit_transaction(trans, root);
 571                 } else {
 572                         wake_up_process(info->transaction_kthread);
 573                 }
 574         }
 575
 576         WARN_ON(cur_trans != info->running_transaction);
 577         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 578         atomic_dec(&cur_trans->num_writers);
 579
 580         smp_mb();
 581         if (waitqueue_active(&cur_trans->writer_wait))
 582                 wake_up(&cur_trans->writer_wait);
 583         put_transaction(cur_trans);
 584
 585         if (current->journal_info == trans)
 586                 current->journal_info = NULL;
 587
 588         if (throttle)
 589                 btrfs_run_delayed_iputs(root);
 590
 591         if (trans->aborted ||
 592             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 593                 err = -EIO;
 594         }
 595         assert_qgroups_uptodate(trans);
 596
 597         memset(trans, 0, sizeof(*trans));
 598         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 599         return err;
 600 }
 601
 602 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 603                           struct btrfs_root *root)
 604 {
 605         int ret;
 606
 607         ret = __btrfs_end_transaction(trans, root, 0, 1);
 608         if (ret)
 609                 return ret;
 610         return 0;
 611 }
 612
 613 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 614                                    struct btrfs_root *root)
 615 {
 616         int ret;
 617
 618         ret = __btrfs_end_transaction(trans, root, 1, 1);
 619         if (ret)
 620                 return ret;
 621         return 0;
 622 }
 623
 624 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 625                                  struct btrfs_root *root)
 626 {
 627         int ret;
 628
 629         ret = __btrfs_end_transaction(trans, root, 0, 0);
 630         if (ret)
 631                 return ret;
 632         return 0;
 633 }
 634
 635 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 636                                 struct btrfs_root *root)
 637 {
 638         return __btrfs_end_transaction(trans, root, 1, 1);
 639 }
 640
 641 /*
 642  * when btree blocks are allocated, they have some corresponding bits set for
 643  * them in one of two extent_io trees.  This is used to make sure all of
 644  * those extents are sent to disk but does not wait on them
 645  */
 646 int btrfs_write_marked_extents(struct btrfs_root *root,
 647                                struct extent_io_tree *dirty_pages, int mark)
 648 {
 649         int err = 0;
 650         int werr = 0;
 651         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 652         u64 start = 0;
 653         u64 end;
 654
 655         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 656                                       mark)) {
 657                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 658                                    GFP_NOFS);
 659                 err = filemap_fdatawrite_range(mapping, start, end);
 660                 if (err)
 661                         werr = err;
 662                 cond_resched();
 663                 start = end + 1;
 664         }
 665         if (err)
 666                 werr = err;
 667         return werr;
 668 }
 669
 670 /*
 671  * when btree blocks are allocated, they have some corresponding bits set for
 672  * them in one of two extent_io trees.  This is used to make sure all of
 673  * those extents are on disk for transaction or log commit.  We wait
 674  * on all the pages and clear them from the dirty pages state tree
 675  */
 676 int btrfs_wait_marked_extents(struct btrfs_root *root,
 677                               struct extent_io_tree *dirty_pages, int mark)
 678 {
 679         int err = 0;
 680         int werr = 0;
 681         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 682         u64 start = 0;
 683         u64 end;
 684
 685         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 686                                       EXTENT_NEED_WAIT)) {
 687                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 688                 err = filemap_fdatawait_range(mapping, start, end);
 689                 if (err)
 690                         werr = err;
 691                 cond_resched();
 692                 start = end + 1;
 693         }
 694         if (err)
 695                 werr = err;
 696         return werr;
 697 }
 698
 699 /*
 700  * when btree blocks are allocated, they have some corresponding bits set for
 701  * them in one of two extent_io trees.  This is used to make sure all of
 702  * those extents are on disk for transaction or log commit
 703  */
 704 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 705                                 struct extent_io_tree *dirty_pages, int mark)
 706 {
 707         int ret;
 708         int ret2;
 709
 710         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 711         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 712
 713         if (ret)
 714                 return ret;
 715         if (ret2)
 716                 return ret2;
 717         return 0;
 718 }
 719
 720 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 721                                      struct btrfs_root *root)
 722 {
 723         if (!trans || !trans->transaction) {
 724                 struct inode *btree_inode;
 725                 btree_inode = root->fs_info->btree_inode;
 726                 return filemap_write_and_wait(btree_inode->i_mapping);
 727         }
 728         return btrfs_write_and_wait_marked_extents(root,
 729                                            &trans->transaction->dirty_pages,
 730                                            EXTENT_DIRTY);
 731 }
 732
 733 /*
 734  * this is used to update the root pointer in the tree of tree roots.
 735  *
 736  * But, in the case of the extent allocation tree, updating the root
 737  * pointer may allocate blocks which may change the root of the extent
 738  * allocation tree.
 739  *
 740  * So, this loops and repeats and makes sure the cowonly root didn't
 741  * change while the root pointer was being updated in the metadata.
 742  */
 743 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 744                                struct btrfs_root *root)
 745 {
 746         int ret;
 747         u64 old_root_bytenr;
 748         u64 old_root_used;
 749         struct btrfs_root *tree_root = root->fs_info->tree_root;
 750
 751         old_root_used = btrfs_root_used(&root->root_item);
 752         btrfs_write_dirty_block_groups(trans, root);
 753
 754         while (1) {
 755                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 756                 if (old_root_bytenr == root->node->start &&
 757                     old_root_used == btrfs_root_used(&root->root_item))
 758                         break;
 759
 760                 btrfs_set_root_node(&root->root_item, root->node);
 761                 ret = btrfs_update_root(trans, tree_root,
 762                                         &root->root_key,
 763                                         &root->root_item);
 764                 if (ret)
 765                         return ret;
 766
 767                 old_root_used = btrfs_root_used(&root->root_item);
 768                 ret = btrfs_write_dirty_block_groups(trans, root);
 769                 if (ret)
 770                         return ret;
 771         }
 772
 773         if (root != root->fs_info->extent_root)
 774                 switch_commit_root(root);
 775
 776         return 0;
 777 }
 778
 779 /*
 780  * update all the cowonly tree roots on disk
 781  *
 782  * The error handling in this function may not be obvious. Any of the
 783  * failures will cause the file system to go offline. We still need
 784  * to clean up the delayed refs.
 785  */
 786 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 787                                          struct btrfs_root *root)
 788 {
 789         struct btrfs_fs_info *fs_info = root->fs_info;
 790         struct list_head *next;
 791         struct extent_buffer *eb;
 792         int ret;
 793
 794         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 795         if (ret)
 796                 return ret;
 797
 798         eb = btrfs_lock_root_node(fs_info->tree_root);
 799         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 800                               0, &eb);
 801         btrfs_tree_unlock(eb);
 802         free_extent_buffer(eb);
 803
 804         if (ret)
 805                 return ret;
 806
 807         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 808         if (ret)
 809                 return ret;
 810
 811         ret = btrfs_run_dev_stats(trans, root->fs_info);
 812         BUG_ON(ret);
 813
 814         ret = btrfs_run_qgroups(trans, root->fs_info);
 815         BUG_ON(ret);
 816
 817         /* run_qgroups might have added some more refs */
 818         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 819         BUG_ON(ret);
 820
 821         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 822                 next = fs_info->dirty_cowonly_roots.next;
 823                 list_del_init(next);
 824                 root = list_entry(next, struct btrfs_root, dirty_list);
 825
 826                 ret = update_cowonly_root(trans, root);
 827                 if (ret)
 828                         return ret;
 829         }
 830
 831         down_write(&fs_info->extent_commit_sem);
 832         switch_commit_root(fs_info->extent_root);
 833         up_write(&fs_info->extent_commit_sem);
 834
 835         return 0;
 836 }
 837
 838 /*
 839  * dead roots are old snapshots that need to be deleted.  This allocates
 840  * a dirty root struct and adds it into the list of dead roots that need to
 841  * be deleted
 842  */
 843 int btrfs_add_dead_root(struct btrfs_root *root)
 844 {
 845         spin_lock(&root->fs_info->trans_lock);
 846         list_add(&root->root_list, &root->fs_info->dead_roots);
 847         spin_unlock(&root->fs_info->trans_lock);
 848         return 0;
 849 }
 850
 851 /*
 852  * update all the cowonly tree roots on disk
 853  */
 854 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 855                                     struct btrfs_root *root)
 856 {
 857         struct btrfs_root *gang[8];
 858         struct btrfs_fs_info *fs_info = root->fs_info;
 859         int i;
 860         int ret;
 861         int err = 0;
 862
 863         spin_lock(&fs_info->fs_roots_radix_lock);
 864         while (1) {
 865                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 866                                                  (void **)gang, 0,
 867                                                  ARRAY_SIZE(gang),
 868                                                  BTRFS_ROOT_TRANS_TAG);
 869                 if (ret == 0)
 870                         break;
 871                 for (i = 0; i < ret; i++) {
 872                         root = gang[i];
 873                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 874                                         (unsigned long)root->root_key.objectid,
 875                                         BTRFS_ROOT_TRANS_TAG);
 876                         spin_unlock(&fs_info->fs_roots_radix_lock);
 877
 878                         btrfs_free_log(trans, root);
 879                         btrfs_update_reloc_root(trans, root);
 880                         btrfs_orphan_commit_root(trans, root);
 881
 882                         btrfs_save_ino_cache(root, trans);
 883
 884                         /* see comments in should_cow_block() */
 885                         root->force_cow = 0;
 886                         smp_wmb();
 887
 888                         if (root->commit_root != root->node) {
 889                                 mutex_lock(&root->fs_commit_mutex);
 890                                 switch_commit_root(root);
 891                                 btrfs_unpin_free_ino(root);
 892                                 mutex_unlock(&root->fs_commit_mutex);
 893
 894                                 btrfs_set_root_node(&root->root_item,
 895                                                     root->node);
 896                         }
 897
 898                         err = btrfs_update_root(trans, fs_info->tree_root,
 899                                                 &root->root_key,
 900                                                 &root->root_item);
 901                         spin_lock(&fs_info->fs_roots_radix_lock);
 902                         if (err)
 903                                 break;
 904                 }
 905         }
 906         spin_unlock(&fs_info->fs_roots_radix_lock);
 907         return err;
 908 }
 909
 910 /*
 911  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 912  * otherwise every leaf in the btree is read and defragged.
 913  */
 914 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 915 {
 916         struct btrfs_fs_info *info = root->fs_info;
 917         struct btrfs_trans_handle *trans;
 918         int ret;
 919         unsigned long nr;
 920
 921         if (xchg(&root->defrag_running, 1))
 922                 return 0;
 923
 924         while (1) {
 925                 trans = btrfs_start_transaction(root, 0);
 926                 if (IS_ERR(trans))
 927                         return PTR_ERR(trans);
 928
 929                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 930
 931                 nr = trans->blocks_used;
 932                 btrfs_end_transaction(trans, root);
 933                 btrfs_btree_balance_dirty(info->tree_root, nr);
 934                 cond_resched();
 935
 936                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 937                         break;
 938         }
 939         root->defrag_running = 0;
 940         return ret;
 941 }
 942
 943 /*
 944  * new snapshots need to be created at a very specific time in the
 945  * transaction commit.  This does the actual creation
 946  */
 947 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 948                                    struct btrfs_fs_info *fs_info,
 949                                    struct btrfs_pending_snapshot *pending)
 950 {
 951         struct btrfs_key key;
 952         struct btrfs_root_item *new_root_item;
 953         struct btrfs_root *tree_root = fs_info->tree_root;
 954         struct btrfs_root *root = pending->root;
 955         struct btrfs_root *parent_root;
 956         struct btrfs_block_rsv *rsv;
 957         struct inode *parent_inode;
 958         struct dentry *parent;
 959         struct dentry *dentry;
 960         struct extent_buffer *tmp;
 961         struct extent_buffer *old;
 962         struct timespec cur_time = CURRENT_TIME;
 963         int ret;
 964         u64 to_reserve = 0;
 965         u64 index = 0;
 966         u64 objectid;
 967         u64 root_flags;
 968         uuid_le new_uuid;
 969
 970         rsv = trans->block_rsv;
 971
 972         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 973         if (!new_root_item) {
 974                 ret = pending->error = -ENOMEM;
 975                 goto fail;
 976         }
 977
 978         ret = btrfs_find_free_objectid(tree_root, &objectid);
 979         if (ret) {
 980                 pending->error = ret;
 981                 goto fail;
 982         }
 983
 984         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 985
 986         if (to_reserve > 0) {
 987                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
 988                                                   to_reserve);
 989                 if (ret) {
 990                         pending->error = ret;
 991                         goto fail;
 992                 }
 993         }
 994
 995         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
 996                                    objectid, pending->inherit);
 997         kfree(pending->inherit);
 998         if (ret) {
 999                 pending->error = ret;
1000                 goto fail;
1001         }
1002
1003         key.objectid = objectid;
1004         key.offset = (u64)-1;
1005         key.type = BTRFS_ROOT_ITEM_KEY;
1006
1007         trans->block_rsv = &pending->block_rsv;
1008
1009         dentry = pending->dentry;
1010         parent = dget_parent(dentry);
1011         parent_inode = parent->d_inode;
1012         parent_root = BTRFS_I(parent_inode)->root;
1013         record_root_in_trans(trans, parent_root);
1014
1015         /*
1016          * insert the directory item
1017          */
1018         ret = btrfs_set_inode_index(parent_inode, &index);
1019         BUG_ON(ret); /* -ENOMEM */
1020         ret = btrfs_insert_dir_item(trans, parent_root,
1021                                 dentry->d_name.name, dentry->d_name.len,
1022                                 parent_inode, &key,
1023                                 BTRFS_FT_DIR, index);
1024         if (ret == -EEXIST) {
1025                 pending->error = -EEXIST;
1026                 dput(parent);
1027                 goto fail;
1028         } else if (ret) {
1029                 goto abort_trans_dput;
1030         }
1031
1032         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1033                                          dentry->d_name.len * 2);
1034         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1035         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1036         if (ret)
1037                 goto abort_trans_dput;
1038
1039         /*
1040          * pull in the delayed directory update
1041          * and the delayed inode item
1042          * otherwise we corrupt the FS during
1043          * snapshot
1044          */
1045         ret = btrfs_run_delayed_items(trans, root);
1046         if (ret) { /* Transaction aborted */
1047                 dput(parent);
1048                 goto fail;
1049         }
1050
1051         record_root_in_trans(trans, root);
1052         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1053         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1054         btrfs_check_and_init_root_item(new_root_item);
1055
1056         root_flags = btrfs_root_flags(new_root_item);
1057         if (pending->readonly)
1058                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1059         else
1060                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1061         btrfs_set_root_flags(new_root_item, root_flags);
1062
1063         btrfs_set_root_generation_v2(new_root_item,
1064                         trans->transid);
1065         uuid_le_gen(&new_uuid);
1066         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1067         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1068                         BTRFS_UUID_SIZE);
1069         new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1070         new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1071         btrfs_set_root_otransid(new_root_item, trans->transid);
1072         memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1073         memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1074         btrfs_set_root_stransid(new_root_item, 0);
1075         btrfs_set_root_rtransid(new_root_item, 0);
1076
1077         old = btrfs_lock_root_node(root);
1078         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1079         if (ret) {
1080                 btrfs_tree_unlock(old);
1081                 free_extent_buffer(old);
1082                 goto abort_trans_dput;
1083         }
1084
1085         btrfs_set_lock_blocking(old);
1086
1087         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1088         /* clean up in any case */
1089         btrfs_tree_unlock(old);
1090         free_extent_buffer(old);
1091         if (ret)
1092                 goto abort_trans_dput;
1093
1094         /* see comments in should_cow_block() */
1095         root->force_cow = 1;
1096         smp_wmb();
1097
1098         btrfs_set_root_node(new_root_item, tmp);
1099         /* record when the snapshot was created in key.offset */
1100         key.offset = trans->transid;
1101         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1102         btrfs_tree_unlock(tmp);
1103         free_extent_buffer(tmp);
1104         if (ret)
1105                 goto abort_trans_dput;
1106
1107         /*
1108          * insert root back/forward references
1109          */
1110         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1111                                  parent_root->root_key.objectid,
1112                                  btrfs_ino(parent_inode), index,
1113                                  dentry->d_name.name, dentry->d_name.len);
1114         dput(parent);
1115         if (ret)
1116                 goto fail;
1117
1118         key.offset = (u64)-1;
1119         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1120         if (IS_ERR(pending->snap)) {
1121                 ret = PTR_ERR(pending->snap);
1122                 goto abort_trans;
1123         }
1124
1125         ret = btrfs_reloc_post_snapshot(trans, pending);
1126         if (ret)
1127                 goto abort_trans;
1128         ret = 0;
1129 fail:
1130         kfree(new_root_item);
1131         trans->block_rsv = rsv;
1132         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1133         return ret;
1134
1135 abort_trans_dput:
1136         dput(parent);
1137 abort_trans:
1138         btrfs_abort_transaction(trans, root, ret);
1139         goto fail;
1140 }
1141
1142 /*
1143  * create all the snapshots we've scheduled for creation
1144  */
1145 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1146                                              struct btrfs_fs_info *fs_info)
1147 {
1148         struct btrfs_pending_snapshot *pending;
1149         struct list_head *head = &trans->transaction->pending_snapshots;
1150
1151         list_for_each_entry(pending, head, list)
1152                 create_pending_snapshot(trans, fs_info, pending);
1153         return 0;
1154 }
1155
1156 static void update_super_roots(struct btrfs_root *root)
1157 {
1158         struct btrfs_root_item *root_item;
1159         struct btrfs_super_block *super;
1160
1161         super = root->fs_info->super_copy;
1162
1163         root_item = &root->fs_info->chunk_root->root_item;
1164         super->chunk_root = root_item->bytenr;
1165         super->chunk_root_generation = root_item->generation;
1166         super->chunk_root_level = root_item->level;
1167
1168         root_item = &root->fs_info->tree_root->root_item;
1169         super->root = root_item->bytenr;
1170         super->generation = root_item->generation;
1171         super->root_level = root_item->level;
1172         if (btrfs_test_opt(root, SPACE_CACHE))
1173                 super->cache_generation = root_item->generation;
1174 }
1175
1176 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1177 {
1178         int ret = 0;
1179         spin_lock(&info->trans_lock);
1180         if (info->running_transaction)
1181                 ret = info->running_transaction->in_commit;
1182         spin_unlock(&info->trans_lock);
1183         return ret;
1184 }
1185
1186 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1187 {
1188         int ret = 0;
1189         spin_lock(&info->trans_lock);
1190         if (info->running_transaction)
1191                 ret = info->running_transaction->blocked;
1192         spin_unlock(&info->trans_lock);
1193         return ret;
1194 }
1195
1196 /*
1197  * wait for the current transaction commit to start and block subsequent
1198  * transaction joins
1199  */
1200 static void wait_current_trans_commit_start(struct btrfs_root *root,
1201                                             struct btrfs_transaction *trans)
1202 {
1203         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1204 }
1205
1206 /*
1207  * wait for the current transaction to start and then become unblocked.
1208  * caller holds ref.
1209  */
1210 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1211                                          struct btrfs_transaction *trans)
1212 {
1213         wait_event(root->fs_info->transaction_wait,
1214                    trans->commit_done || (trans->in_commit && !trans->blocked));
1215 }
1216
1217 /*
1218  * commit transactions asynchronously. once btrfs_commit_transaction_async
1219  * returns, any subsequent transaction will not be allowed to join.
1220  */
1221 struct btrfs_async_commit {
1222         struct btrfs_trans_handle *newtrans;
1223         struct btrfs_root *root;
1224         struct delayed_work work;
1225 };
1226
1227 static void do_async_commit(struct work_struct *work)
1228 {
1229         struct btrfs_async_commit *ac =
1230                 container_of(work, struct btrfs_async_commit, work.work);
1231
1232         btrfs_commit_transaction(ac->newtrans, ac->root);
1233         kfree(ac);
1234 }
1235
1236 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1237                                    struct btrfs_root *root,
1238                                    int wait_for_unblock)
1239 {
1240         struct btrfs_async_commit *ac;
1241         struct btrfs_transaction *cur_trans;
1242
1243         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1244         if (!ac)
1245                 return -ENOMEM;
1246
1247         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1248         ac->root = root;
1249         ac->newtrans = btrfs_join_transaction(root);
1250         if (IS_ERR(ac->newtrans)) {
1251                 int err = PTR_ERR(ac->newtrans);
1252                 kfree(ac);
1253                 return err;
1254         }
1255
1256         /* take transaction reference */
1257         cur_trans = trans->transaction;
1258         atomic_inc(&cur_trans->use_count);
1259
1260         btrfs_end_transaction(trans, root);
1261         schedule_delayed_work(&ac->work, 0);
1262
1263         /* wait for transaction to start and unblock */
1264         if (wait_for_unblock)
1265                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1266         else
1267                 wait_current_trans_commit_start(root, cur_trans);
1268
1269         if (current->journal_info == trans)
1270                 current->journal_info = NULL;
1271
1272         put_transaction(cur_trans);
1273         return 0;
1274 }
1275
1276
1277 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1278                                 struct btrfs_root *root, int err)
1279 {
1280         struct btrfs_transaction *cur_trans = trans->transaction;
1281
1282         WARN_ON(trans->use_count > 1);
1283
1284         btrfs_abort_transaction(trans, root, err);
1285
1286         spin_lock(&root->fs_info->trans_lock);
1287         list_del_init(&cur_trans->list);
1288         if (cur_trans == root->fs_info->running_transaction) {
1289                 root->fs_info->running_transaction = NULL;
1290                 root->fs_info->trans_no_join = 0;
1291         }
1292         spin_unlock(&root->fs_info->trans_lock);
1293
1294         btrfs_cleanup_one_transaction(trans->transaction, root);
1295
1296         put_transaction(cur_trans);
1297         put_transaction(cur_trans);
1298
1299         trace_btrfs_transaction_commit(root);
1300
1301         btrfs_scrub_continue(root);
1302
1303         if (current->journal_info == trans)
1304                 current->journal_info = NULL;
1305
1306         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1307 }
1308
1309 /*
1310  * btrfs_transaction state sequence:
1311  *    in_commit = 0, blocked = 0  (initial)
1312  *    in_commit = 1, blocked = 1
1313  *    blocked = 0
1314  *    commit_done = 1
1315  */
1316 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1317                              struct btrfs_root *root)
1318 {
1319         unsigned long joined = 0;
1320         struct btrfs_transaction *cur_trans = trans->transaction;
1321         struct btrfs_transaction *prev_trans = NULL;
1322         DEFINE_WAIT(wait);
1323         int ret = -EIO;
1324         int should_grow = 0;
1325         unsigned long now = get_seconds();
1326         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1327
1328         btrfs_run_ordered_operations(root, 0);
1329
1330         if (cur_trans->aborted)
1331                 goto cleanup_transaction;
1332
1333         /* make a pass through all the delayed refs we have so far
1334          * any runnings procs may add more while we are here
1335          */
1336         ret = btrfs_run_delayed_refs(trans, root, 0);
1337         if (ret)
1338                 goto cleanup_transaction;
1339
1340         btrfs_trans_release_metadata(trans, root);
1341         trans->block_rsv = NULL;
1342
1343         cur_trans = trans->transaction;
1344
1345         /*
1346          * set the flushing flag so procs in this transaction have to
1347          * start sending their work down.
1348          */
1349         cur_trans->delayed_refs.flushing = 1;
1350
1351         ret = btrfs_run_delayed_refs(trans, root, 0);
1352         if (ret)
1353                 goto cleanup_transaction;
1354
1355         spin_lock(&cur_trans->commit_lock);
1356         if (cur_trans->in_commit) {
1357                 spin_unlock(&cur_trans->commit_lock);
1358                 atomic_inc(&cur_trans->use_count);
1359                 ret = btrfs_end_transaction(trans, root);
1360
1361                 wait_for_commit(root, cur_trans);
1362
1363                 put_transaction(cur_trans);
1364
1365                 return ret;
1366         }
1367
1368         trans->transaction->in_commit = 1;
1369         trans->transaction->blocked = 1;
1370         spin_unlock(&cur_trans->commit_lock);
1371         wake_up(&root->fs_info->transaction_blocked_wait);
1372
1373         spin_lock(&root->fs_info->trans_lock);
1374         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1375                 prev_trans = list_entry(cur_trans->list.prev,
1376                                         struct btrfs_transaction, list);
1377                 if (!prev_trans->commit_done) {
1378                         atomic_inc(&prev_trans->use_count);
1379                         spin_unlock(&root->fs_info->trans_lock);
1380
1381                         wait_for_commit(root, prev_trans);
1382
1383                         put_transaction(prev_trans);
1384                 } else {
1385                         spin_unlock(&root->fs_info->trans_lock);
1386                 }
1387         } else {
1388                 spin_unlock(&root->fs_info->trans_lock);
1389         }
1390
1391         if (!btrfs_test_opt(root, SSD) &&
1392             (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1393                 should_grow = 1;
1394
1395         do {
1396                 int snap_pending = 0;
1397
1398                 joined = cur_trans->num_joined;
1399                 if (!list_empty(&trans->transaction->pending_snapshots))
1400                         snap_pending = 1;
1401
1402                 WARN_ON(cur_trans != trans->transaction);
1403
1404                 if (flush_on_commit || snap_pending) {
1405                         btrfs_start_delalloc_inodes(root, 1);
1406                         btrfs_wait_ordered_extents(root, 0, 1);
1407                 }
1408
1409                 ret = btrfs_run_delayed_items(trans, root);
1410                 if (ret)
1411                         goto cleanup_transaction;
1412
1413                 /*
1414                  * running the delayed items may have added new refs. account
1415                  * them now so that they hinder processing of more delayed refs
1416                  * as little as possible.
1417                  */
1418                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1419
1420                 /*
1421                  * rename don't use btrfs_join_transaction, so, once we
1422                  * set the transaction to blocked above, we aren't going
1423                  * to get any new ordered operations.  We can safely run
1424                  * it here and no for sure that nothing new will be added
1425                  * to the list
1426                  */
1427                 btrfs_run_ordered_operations(root, 1);
1428
1429                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1430                                 TASK_UNINTERRUPTIBLE);
1431
1432                 if (atomic_read(&cur_trans->num_writers) > 1)
1433                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1434                 else if (should_grow)
1435                         schedule_timeout(1);
1436
1437                 finish_wait(&cur_trans->writer_wait, &wait);
1438         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1439                  (should_grow && cur_trans->num_joined != joined));
1440
1441         /*
1442          * Ok now we need to make sure to block out any other joins while we
1443          * commit the transaction.  We could have started a join before setting
1444          * no_join so make sure to wait for num_writers to == 1 again.
1445          */
1446         spin_lock(&root->fs_info->trans_lock);
1447         root->fs_info->trans_no_join = 1;
1448         spin_unlock(&root->fs_info->trans_lock);
1449         wait_event(cur_trans->writer_wait,
1450                    atomic_read(&cur_trans->num_writers) == 1);
1451
1452         /*
1453          * the reloc mutex makes sure that we stop
1454          * the balancing code from coming in and moving
1455          * extents around in the middle of the commit
1456          */
1457         mutex_lock(&root->fs_info->reloc_mutex);
1458
1459         ret = btrfs_run_delayed_items(trans, root);
1460         if (ret) {
1461                 mutex_unlock(&root->fs_info->reloc_mutex);
1462                 goto cleanup_transaction;
1463         }
1464
1465         ret = create_pending_snapshots(trans, root->fs_info);
1466         if (ret) {
1467                 mutex_unlock(&root->fs_info->reloc_mutex);
1468                 goto cleanup_transaction;
1469         }
1470
1471         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1472         if (ret) {
1473                 mutex_unlock(&root->fs_info->reloc_mutex);
1474                 goto cleanup_transaction;
1475         }
1476
1477         /*
1478          * make sure none of the code above managed to slip in a
1479          * delayed item
1480          */
1481         btrfs_assert_delayed_root_empty(root);
1482
1483         WARN_ON(cur_trans != trans->transaction);
1484
1485         btrfs_scrub_pause(root);
1486         /* btrfs_commit_tree_roots is responsible for getting the
1487          * various roots consistent with each other.  Every pointer
1488          * in the tree of tree roots has to point to the most up to date
1489          * root for every subvolume and other tree.  So, we have to keep
1490          * the tree logging code from jumping in and changing any
1491          * of the trees.
1492          *
1493          * At this point in the commit, there can't be any tree-log
1494          * writers, but a little lower down we drop the trans mutex
1495          * and let new people in.  By holding the tree_log_mutex
1496          * from now until after the super is written, we avoid races
1497          * with the tree-log code.
1498          */
1499         mutex_lock(&root->fs_info->tree_log_mutex);
1500
1501         ret = commit_fs_roots(trans, root);
1502         if (ret) {
1503                 mutex_unlock(&root->fs_info->tree_log_mutex);
1504                 mutex_unlock(&root->fs_info->reloc_mutex);
1505                 goto cleanup_transaction;
1506         }
1507
1508         /* commit_fs_roots gets rid of all the tree log roots, it is now
1509          * safe to free the root of tree log roots
1510          */
1511         btrfs_free_log_root_tree(trans, root->fs_info);
1512
1513         ret = commit_cowonly_roots(trans, root);
1514         if (ret) {
1515                 mutex_unlock(&root->fs_info->tree_log_mutex);
1516                 mutex_unlock(&root->fs_info->reloc_mutex);
1517                 goto cleanup_transaction;
1518         }
1519
1520         btrfs_prepare_extent_commit(trans, root);
1521
1522         cur_trans = root->fs_info->running_transaction;
1523
1524         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1525                             root->fs_info->tree_root->node);
1526         switch_commit_root(root->fs_info->tree_root);
1527
1528         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1529                             root->fs_info->chunk_root->node);
1530         switch_commit_root(root->fs_info->chunk_root);
1531
1532         assert_qgroups_uptodate(trans);
1533         update_super_roots(root);
1534
1535         if (!root->fs_info->log_root_recovering) {
1536                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1537                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1538         }
1539
1540         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1541                sizeof(*root->fs_info->super_copy));
1542
1543         trans->transaction->blocked = 0;
1544         spin_lock(&root->fs_info->trans_lock);
1545         root->fs_info->running_transaction = NULL;
1546         root->fs_info->trans_no_join = 0;
1547         spin_unlock(&root->fs_info->trans_lock);
1548         mutex_unlock(&root->fs_info->reloc_mutex);
1549
1550         wake_up(&root->fs_info->transaction_wait);
1551
1552         ret = btrfs_write_and_wait_transaction(trans, root);
1553         if (ret) {
1554                 btrfs_error(root->fs_info, ret,
1555                             "Error while writing out transaction.");
1556                 mutex_unlock(&root->fs_info->tree_log_mutex);
1557                 goto cleanup_transaction;
1558         }
1559
1560         ret = write_ctree_super(trans, root, 0);
1561         if (ret) {
1562                 mutex_unlock(&root->fs_info->tree_log_mutex);
1563                 goto cleanup_transaction;
1564         }
1565
1566         /*
1567          * the super is written, we can safely allow the tree-loggers
1568          * to go about their business
1569          */
1570         mutex_unlock(&root->fs_info->tree_log_mutex);
1571
1572         btrfs_finish_extent_commit(trans, root);
1573
1574         cur_trans->commit_done = 1;
1575
1576         root->fs_info->last_trans_committed = cur_trans->transid;
1577
1578         wake_up(&cur_trans->commit_wait);
1579
1580         spin_lock(&root->fs_info->trans_lock);
1581         list_del_init(&cur_trans->list);
1582         spin_unlock(&root->fs_info->trans_lock);
1583
1584         put_transaction(cur_trans);
1585         put_transaction(cur_trans);
1586
1587         sb_end_intwrite(root->fs_info->sb);
1588
1589         trace_btrfs_transaction_commit(root);
1590
1591         btrfs_scrub_continue(root);
1592
1593         if (current->journal_info == trans)
1594                 current->journal_info = NULL;
1595
1596         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1597
1598         if (current != root->fs_info->transaction_kthread)
1599                 btrfs_run_delayed_iputs(root);
1600
1601         return ret;
1602
1603 cleanup_transaction:
1604         btrfs_trans_release_metadata(trans, root);
1605         trans->block_rsv = NULL;
1606         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1607 //      WARN_ON(1);
1608         if (current->journal_info == trans)
1609                 current->journal_info = NULL;
1610         cleanup_transaction(trans, root, ret);
1611
1612         return ret;
1613 }
1614
1615 /*
1616  * interface function to delete all the snapshots we have scheduled for deletion
1617  */
1618 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1619 {
1620         LIST_HEAD(list);
1621         struct btrfs_fs_info *fs_info = root->fs_info;
1622
1623         spin_lock(&fs_info->trans_lock);
1624         list_splice_init(&fs_info->dead_roots, &list);
1625         spin_unlock(&fs_info->trans_lock);
1626
1627         while (!list_empty(&list)) {
1628                 int ret;
1629
1630                 root = list_entry(list.next, struct btrfs_root, root_list);
1631                 list_del(&root->root_list);
1632
1633                 btrfs_kill_all_delayed_nodes(root);
1634
1635                 if (btrfs_header_backref_rev(root->node) <
1636                     BTRFS_MIXED_BACKREF_REV)
1637                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1638                 else
1639                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1640                 BUG_ON(ret < 0);
1641         }
1642         return 0;
1643 }