Pileus Git - ~andy/linux/blob - 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                 memset(transaction, 0, sizeof(*transaction));
  42                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  43         }
  44 }
  45
  46 static noinline void switch_commit_root(struct btrfs_root *root)
  47 {
  48         free_extent_buffer(root->commit_root);
  49         root->commit_root = btrfs_root_node(root);
  50 }
  51
  52 /*
  53  * either allocate a new transaction or hop into the existing one
  54  */
  55 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  56 {
  57         struct btrfs_transaction *cur_trans;
  58         struct btrfs_fs_info *fs_info = root->fs_info;
  59
  60         spin_lock(&fs_info->trans_lock);
  61 loop:
  62         /* The file system has been taken offline. No new transactions. */
  63         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  64                 spin_unlock(&fs_info->trans_lock);
  65                 return -EROFS;
  66         }
  67
  68         if (fs_info->trans_no_join) {
  69                 if (!nofail) {
  70                         spin_unlock(&fs_info->trans_lock);
  71                         return -EBUSY;
  72                 }
  73         }
  74
  75         cur_trans = fs_info->running_transaction;
  76         if (cur_trans) {
  77                 if (cur_trans->aborted) {
  78                         spin_unlock(&fs_info->trans_lock);
  79                         return cur_trans->aborted;
  80                 }
  81                 atomic_inc(&cur_trans->use_count);
  82                 atomic_inc(&cur_trans->num_writers);
  83                 cur_trans->num_joined++;
  84                 spin_unlock(&fs_info->trans_lock);
  85                 return 0;
  86         }
  87         spin_unlock(&fs_info->trans_lock);
  88
  89         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  90         if (!cur_trans)
  91                 return -ENOMEM;
  92
  93         spin_lock(&fs_info->trans_lock);
  94         if (fs_info->running_transaction) {
  95                 /*
  96                  * someone started a transaction after we unlocked.  Make sure
  97                  * to redo the trans_no_join checks above
  98                  */
  99                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 100                 cur_trans = fs_info->running_transaction;
 101                 goto loop;
 102         } else if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 103                 spin_unlock(&root->fs_info->trans_lock);
 104                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 105                 return -EROFS;
 106         }
 107
 108         atomic_set(&cur_trans->num_writers, 1);
 109         cur_trans->num_joined = 0;
 110         init_waitqueue_head(&cur_trans->writer_wait);
 111         init_waitqueue_head(&cur_trans->commit_wait);
 112         cur_trans->in_commit = 0;
 113         cur_trans->blocked = 0;
 114         /*
 115          * One for this trans handle, one so it will live on until we
 116          * commit the transaction.
 117          */
 118         atomic_set(&cur_trans->use_count, 2);
 119         cur_trans->commit_done = 0;
 120         cur_trans->start_time = get_seconds();
 121
 122         cur_trans->delayed_refs.root = RB_ROOT;
 123         cur_trans->delayed_refs.num_entries = 0;
 124         cur_trans->delayed_refs.num_heads_ready = 0;
 125         cur_trans->delayed_refs.num_heads = 0;
 126         cur_trans->delayed_refs.flushing = 0;
 127         cur_trans->delayed_refs.run_delayed_start = 0;
 128
 129         /*
 130          * although the tree mod log is per file system and not per transaction,
 131          * the log must never go across transaction boundaries.
 132          */
 133         smp_mb();
 134         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 135                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 136                         "creating a fresh transaction\n");
 137                 WARN_ON(1);
 138         }
 139         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 140                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 141                         "creating a fresh transaction\n");
 142                 WARN_ON(1);
 143         }
 144         atomic_set(&fs_info->tree_mod_seq, 0);
 145
 146         spin_lock_init(&cur_trans->commit_lock);
 147         spin_lock_init(&cur_trans->delayed_refs.lock);
 148
 149         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 150         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 151         extent_io_tree_init(&cur_trans->dirty_pages,
 152                              fs_info->btree_inode->i_mapping);
 153         fs_info->generation++;
 154         cur_trans->transid = fs_info->generation;
 155         fs_info->running_transaction = cur_trans;
 156         cur_trans->aborted = 0;
 157         spin_unlock(&fs_info->trans_lock);
 158
 159         return 0;
 160 }
 161
 162 /*
 163  * this does all the record keeping required to make sure that a reference
 164  * counted root is properly recorded in a given transaction.  This is required
 165  * to make sure the old root from before we joined the transaction is deleted
 166  * when the transaction commits
 167  */
 168 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 169                                struct btrfs_root *root)
 170 {
 171         if (root->ref_cows && root->last_trans < trans->transid) {
 172                 WARN_ON(root == root->fs_info->extent_root);
 173                 WARN_ON(root->commit_root != root->node);
 174
 175                 /*
 176                  * see below for in_trans_setup usage rules
 177                  * we have the reloc mutex held now, so there
 178                  * is only one writer in this function
 179                  */
 180                 root->in_trans_setup = 1;
 181
 182                 /* make sure readers find in_trans_setup before
 183                  * they find our root->last_trans update
 184                  */
 185                 smp_wmb();
 186
 187                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 188                 if (root->last_trans == trans->transid) {
 189                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 190                         return 0;
 191                 }
 192                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 193                            (unsigned long)root->root_key.objectid,
 194                            BTRFS_ROOT_TRANS_TAG);
 195                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 196                 root->last_trans = trans->transid;
 197
 198                 /* this is pretty tricky.  We don't want to
 199                  * take the relocation lock in btrfs_record_root_in_trans
 200                  * unless we're really doing the first setup for this root in
 201                  * this transaction.
 202                  *
 203                  * Normally we'd use root->last_trans as a flag to decide
 204                  * if we want to take the expensive mutex.
 205                  *
 206                  * But, we have to set root->last_trans before we
 207                  * init the relocation root, otherwise, we trip over warnings
 208                  * in ctree.c.  The solution used here is to flag ourselves
 209                  * with root->in_trans_setup.  When this is 1, we're still
 210                  * fixing up the reloc trees and everyone must wait.
 211                  *
 212                  * When this is zero, they can trust root->last_trans and fly
 213                  * through btrfs_record_root_in_trans without having to take the
 214                  * lock.  smp_wmb() makes sure that all the writes above are
 215                  * done before we pop in the zero below
 216                  */
 217                 btrfs_init_reloc_root(trans, root);
 218                 smp_wmb();
 219                 root->in_trans_setup = 0;
 220         }
 221         return 0;
 222 }
 223
 224
 225 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 226                                struct btrfs_root *root)
 227 {
 228         if (!root->ref_cows)
 229                 return 0;
 230
 231         /*
 232          * see record_root_in_trans for comments about in_trans_setup usage
 233          * and barriers
 234          */
 235         smp_rmb();
 236         if (root->last_trans == trans->transid &&
 237             !root->in_trans_setup)
 238                 return 0;
 239
 240         mutex_lock(&root->fs_info->reloc_mutex);
 241         record_root_in_trans(trans, root);
 242         mutex_unlock(&root->fs_info->reloc_mutex);
 243
 244         return 0;
 245 }
 246
 247 /* wait for commit against the current transaction to become unblocked
 248  * when this is done, it is safe to start a new transaction, but the current
 249  * transaction might not be fully on disk.
 250  */
 251 static void wait_current_trans(struct btrfs_root *root)
 252 {
 253         struct btrfs_transaction *cur_trans;
 254
 255         spin_lock(&root->fs_info->trans_lock);
 256         cur_trans = root->fs_info->running_transaction;
 257         if (cur_trans && cur_trans->blocked) {
 258                 atomic_inc(&cur_trans->use_count);
 259                 spin_unlock(&root->fs_info->trans_lock);
 260
 261                 wait_event(root->fs_info->transaction_wait,
 262                            !cur_trans->blocked);
 263                 put_transaction(cur_trans);
 264         } else {
 265                 spin_unlock(&root->fs_info->trans_lock);
 266         }
 267 }
 268
 269 enum btrfs_trans_type {
 270         TRANS_START,
 271         TRANS_JOIN,
 272         TRANS_USERSPACE,
 273         TRANS_JOIN_NOLOCK,
 274 };
 275
 276 static int may_wait_transaction(struct btrfs_root *root, int type)
 277 {
 278         if (root->fs_info->log_root_recovering)
 279                 return 0;
 280
 281         if (type == TRANS_USERSPACE)
 282                 return 1;
 283
 284         if (type == TRANS_START &&
 285             !atomic_read(&root->fs_info->open_ioctl_trans))
 286                 return 1;
 287
 288         return 0;
 289 }
 290
 291 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 292                                                     u64 num_items, int type)
 293 {
 294         struct btrfs_trans_handle *h;
 295         struct btrfs_transaction *cur_trans;
 296         u64 num_bytes = 0;
 297         int ret;
 298         u64 qgroup_reserved = 0;
 299
 300         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 301                 return ERR_PTR(-EROFS);
 302
 303         if (current->journal_info) {
 304                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 305                 h = current->journal_info;
 306                 h->use_count++;
 307                 h->orig_rsv = h->block_rsv;
 308                 h->block_rsv = NULL;
 309                 goto got_it;
 310         }
 311
 312         /*
 313          * Do the reservation before we join the transaction so we can do all
 314          * the appropriate flushing if need be.
 315          */
 316         if (num_items > 0 && root != root->fs_info->chunk_root) {
 317                 if (root->fs_info->quota_enabled &&
 318                     is_fstree(root->root_key.objectid)) {
 319                         qgroup_reserved = num_items * root->leafsize;
 320                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 321                         if (ret)
 322                                 return ERR_PTR(ret);
 323                 }
 324
 325                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 326                 ret = btrfs_block_rsv_add(root,
 327                                           &root->fs_info->trans_block_rsv,
 328                                           num_bytes);
 329                 if (ret)
 330                         return ERR_PTR(ret);
 331         }
 332 again:
 333         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 334         if (!h)
 335                 return ERR_PTR(-ENOMEM);
 336
 337         if (may_wait_transaction(root, type))
 338                 wait_current_trans(root);
 339
 340         do {
 341                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 342                 if (ret == -EBUSY)
 343                         wait_current_trans(root);
 344         } while (ret == -EBUSY);
 345
 346         if (ret < 0) {
 347                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 348                 return ERR_PTR(ret);
 349         }
 350
 351         cur_trans = root->fs_info->running_transaction;
 352
 353         h->transid = cur_trans->transid;
 354         h->transaction = cur_trans;
 355         h->blocks_used = 0;
 356         h->bytes_reserved = 0;
 357         h->root = root;
 358         h->delayed_ref_updates = 0;
 359         h->use_count = 1;
 360         h->block_rsv = NULL;
 361         h->orig_rsv = NULL;
 362         h->aborted = 0;
 363         h->qgroup_reserved = qgroup_reserved;
 364         h->delayed_ref_elem.seq = 0;
 365         INIT_LIST_HEAD(&h->qgroup_ref_list);
 366
 367         smp_mb();
 368         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 369                 btrfs_commit_transaction(h, root);
 370                 goto again;
 371         }
 372
 373         if (num_bytes) {
 374                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 375                                               h->transid, num_bytes, 1);
 376                 h->block_rsv = &root->fs_info->trans_block_rsv;
 377                 h->bytes_reserved = num_bytes;
 378         }
 379
 380 got_it:
 381         btrfs_record_root_in_trans(h, root);
 382
 383         if (!current->journal_info && type != TRANS_USERSPACE)
 384                 current->journal_info = h;
 385         return h;
 386 }
 387
 388 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 389                                                    int num_items)
 390 {
 391         return start_transaction(root, num_items, TRANS_START);
 392 }
 393 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 394 {
 395         return start_transaction(root, 0, TRANS_JOIN);
 396 }
 397
 398 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 399 {
 400         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 401 }
 402
 403 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 404 {
 405         return start_transaction(root, 0, TRANS_USERSPACE);
 406 }
 407
 408 /* wait for a transaction commit to be fully complete */
 409 static noinline void wait_for_commit(struct btrfs_root *root,
 410                                     struct btrfs_transaction *commit)
 411 {
 412         wait_event(commit->commit_wait, commit->commit_done);
 413 }
 414
 415 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 416 {
 417         struct btrfs_transaction *cur_trans = NULL, *t;
 418         int ret;
 419
 420         ret = 0;
 421         if (transid) {
 422                 if (transid <= root->fs_info->last_trans_committed)
 423                         goto out;
 424
 425                 /* find specified transaction */
 426                 spin_lock(&root->fs_info->trans_lock);
 427                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 428                         if (t->transid == transid) {
 429                                 cur_trans = t;
 430                                 atomic_inc(&cur_trans->use_count);
 431                                 break;
 432                         }
 433                         if (t->transid > transid)
 434                                 break;
 435                 }
 436                 spin_unlock(&root->fs_info->trans_lock);
 437                 ret = -EINVAL;
 438                 if (!cur_trans)
 439                         goto out;  /* bad transid */
 440         } else {
 441                 /* find newest transaction that is committing | committed */
 442                 spin_lock(&root->fs_info->trans_lock);
 443                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 444                                             list) {
 445                         if (t->in_commit) {
 446                                 if (t->commit_done)
 447                                         break;
 448                                 cur_trans = t;
 449                                 atomic_inc(&cur_trans->use_count);
 450                                 break;
 451                         }
 452                 }
 453                 spin_unlock(&root->fs_info->trans_lock);
 454                 if (!cur_trans)
 455                         goto out;  /* nothing committing|committed */
 456         }
 457
 458         wait_for_commit(root, cur_trans);
 459
 460         put_transaction(cur_trans);
 461         ret = 0;
 462 out:
 463         return ret;
 464 }
 465
 466 void btrfs_throttle(struct btrfs_root *root)
 467 {
 468         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 469                 wait_current_trans(root);
 470 }
 471
 472 static int should_end_transaction(struct btrfs_trans_handle *trans,
 473                                   struct btrfs_root *root)
 474 {
 475         int ret;
 476
 477         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 478         return ret ? 1 : 0;
 479 }
 480
 481 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 482                                  struct btrfs_root *root)
 483 {
 484         struct btrfs_transaction *cur_trans = trans->transaction;
 485         struct btrfs_block_rsv *rsv = trans->block_rsv;
 486         int updates;
 487         int err;
 488
 489         smp_mb();
 490         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 491                 return 1;
 492
 493         /*
 494          * We need to do this in case we're deleting csums so the global block
 495          * rsv get's used instead of the csum block rsv.
 496          */
 497         trans->block_rsv = NULL;
 498
 499         updates = trans->delayed_ref_updates;
 500         trans->delayed_ref_updates = 0;
 501         if (updates) {
 502                 err = btrfs_run_delayed_refs(trans, root, updates);
 503                 if (err) /* Error code will also eval true */
 504                         return err;
 505         }
 506
 507         trans->block_rsv = rsv;
 508
 509         return should_end_transaction(trans, root);
 510 }
 511
 512 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 513                           struct btrfs_root *root, int throttle, int lock)
 514 {
 515         struct btrfs_transaction *cur_trans = trans->transaction;
 516         struct btrfs_fs_info *info = root->fs_info;
 517         int count = 0;
 518         int err = 0;
 519
 520         if (--trans->use_count) {
 521                 trans->block_rsv = trans->orig_rsv;
 522                 return 0;
 523         }
 524
 525         /*
 526          * do the qgroup accounting as early as possible
 527          */
 528         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 529
 530         btrfs_trans_release_metadata(trans, root);
 531         trans->block_rsv = NULL;
 532         /*
 533          * the same root has to be passed to start_transaction and
 534          * end_transaction. Subvolume quota depends on this.
 535          */
 536         WARN_ON(trans->root != root);
 537
 538         if (trans->qgroup_reserved) {
 539                 btrfs_qgroup_free(root, trans->qgroup_reserved);
 540                 trans->qgroup_reserved = 0;
 541         }
 542
 543         while (count < 2) {
 544                 unsigned long cur = trans->delayed_ref_updates;
 545                 trans->delayed_ref_updates = 0;
 546                 if (cur &&
 547                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 548                         trans->delayed_ref_updates = 0;
 549                         btrfs_run_delayed_refs(trans, root, cur);
 550                 } else {
 551                         break;
 552                 }
 553                 count++;
 554         }
 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         int ret;
 963         u64 to_reserve = 0;
 964         u64 index = 0;
 965         u64 objectid;
 966         u64 root_flags;
 967
 968         rsv = trans->block_rsv;
 969
 970         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 971         if (!new_root_item) {
 972                 ret = pending->error = -ENOMEM;
 973                 goto fail;
 974         }
 975
 976         ret = btrfs_find_free_objectid(tree_root, &objectid);
 977         if (ret) {
 978                 pending->error = ret;
 979                 goto fail;
 980         }
 981
 982         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 983
 984         if (to_reserve > 0) {
 985                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
 986                                                   to_reserve);
 987                 if (ret) {
 988                         pending->error = ret;
 989                         goto fail;
 990                 }
 991         }
 992
 993         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
 994                                    objectid, pending->inherit);
 995         kfree(pending->inherit);
 996         if (ret) {
 997                 pending->error = ret;
 998                 goto fail;
 999         }
1000
1001         key.objectid = objectid;
1002         key.offset = (u64)-1;
1003         key.type = BTRFS_ROOT_ITEM_KEY;
1004
1005         trans->block_rsv = &pending->block_rsv;
1006
1007         dentry = pending->dentry;
1008         parent = dget_parent(dentry);
1009         parent_inode = parent->d_inode;
1010         parent_root = BTRFS_I(parent_inode)->root;
1011         record_root_in_trans(trans, parent_root);
1012
1013         /*
1014          * insert the directory item
1015          */
1016         ret = btrfs_set_inode_index(parent_inode, &index);
1017         BUG_ON(ret); /* -ENOMEM */
1018         ret = btrfs_insert_dir_item(trans, parent_root,
1019                                 dentry->d_name.name, dentry->d_name.len,
1020                                 parent_inode, &key,
1021                                 BTRFS_FT_DIR, index);
1022         if (ret == -EEXIST) {
1023                 pending->error = -EEXIST;
1024                 dput(parent);
1025                 goto fail;
1026         } else if (ret) {
1027                 goto abort_trans_dput;
1028         }
1029
1030         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1031                                          dentry->d_name.len * 2);
1032         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1033         if (ret)
1034                 goto abort_trans_dput;
1035
1036         /*
1037          * pull in the delayed directory update
1038          * and the delayed inode item
1039          * otherwise we corrupt the FS during
1040          * snapshot
1041          */
1042         ret = btrfs_run_delayed_items(trans, root);
1043         if (ret) { /* Transaction aborted */
1044                 dput(parent);
1045                 goto fail;
1046         }
1047
1048         record_root_in_trans(trans, root);
1049         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1050         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1051         btrfs_check_and_init_root_item(new_root_item);
1052
1053         root_flags = btrfs_root_flags(new_root_item);
1054         if (pending->readonly)
1055                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1056         else
1057                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1058         btrfs_set_root_flags(new_root_item, root_flags);
1059
1060         old = btrfs_lock_root_node(root);
1061         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1062         if (ret) {
1063                 btrfs_tree_unlock(old);
1064                 free_extent_buffer(old);
1065                 goto abort_trans_dput;
1066         }
1067
1068         btrfs_set_lock_blocking(old);
1069
1070         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1071         /* clean up in any case */
1072         btrfs_tree_unlock(old);
1073         free_extent_buffer(old);
1074         if (ret)
1075                 goto abort_trans_dput;
1076
1077         /* see comments in should_cow_block() */
1078         root->force_cow = 1;
1079         smp_wmb();
1080
1081         btrfs_set_root_node(new_root_item, tmp);
1082         /* record when the snapshot was created in key.offset */
1083         key.offset = trans->transid;
1084         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1085         btrfs_tree_unlock(tmp);
1086         free_extent_buffer(tmp);
1087         if (ret)
1088                 goto abort_trans_dput;
1089
1090         /*
1091          * insert root back/forward references
1092          */
1093         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1094                                  parent_root->root_key.objectid,
1095                                  btrfs_ino(parent_inode), index,
1096                                  dentry->d_name.name, dentry->d_name.len);
1097         dput(parent);
1098         if (ret)
1099                 goto fail;
1100
1101         key.offset = (u64)-1;
1102         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1103         if (IS_ERR(pending->snap)) {
1104                 ret = PTR_ERR(pending->snap);
1105                 goto abort_trans;
1106         }
1107
1108         ret = btrfs_reloc_post_snapshot(trans, pending);
1109         if (ret)
1110                 goto abort_trans;
1111         ret = 0;
1112 fail:
1113         kfree(new_root_item);
1114         trans->block_rsv = rsv;
1115         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1116         return ret;
1117
1118 abort_trans_dput:
1119         dput(parent);
1120 abort_trans:
1121         btrfs_abort_transaction(trans, root, ret);
1122         goto fail;
1123 }
1124
1125 /*
1126  * create all the snapshots we've scheduled for creation
1127  */
1128 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1129                                              struct btrfs_fs_info *fs_info)
1130 {
1131         struct btrfs_pending_snapshot *pending;
1132         struct list_head *head = &trans->transaction->pending_snapshots;
1133
1134         list_for_each_entry(pending, head, list)
1135                 create_pending_snapshot(trans, fs_info, pending);
1136         return 0;
1137 }
1138
1139 static void update_super_roots(struct btrfs_root *root)
1140 {
1141         struct btrfs_root_item *root_item;
1142         struct btrfs_super_block *super;
1143
1144         super = root->fs_info->super_copy;
1145
1146         root_item = &root->fs_info->chunk_root->root_item;
1147         super->chunk_root = root_item->bytenr;
1148         super->chunk_root_generation = root_item->generation;
1149         super->chunk_root_level = root_item->level;
1150
1151         root_item = &root->fs_info->tree_root->root_item;
1152         super->root = root_item->bytenr;
1153         super->generation = root_item->generation;
1154         super->root_level = root_item->level;
1155         if (btrfs_test_opt(root, SPACE_CACHE))
1156                 super->cache_generation = root_item->generation;
1157 }
1158
1159 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1160 {
1161         int ret = 0;
1162         spin_lock(&info->trans_lock);
1163         if (info->running_transaction)
1164                 ret = info->running_transaction->in_commit;
1165         spin_unlock(&info->trans_lock);
1166         return ret;
1167 }
1168
1169 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1170 {
1171         int ret = 0;
1172         spin_lock(&info->trans_lock);
1173         if (info->running_transaction)
1174                 ret = info->running_transaction->blocked;
1175         spin_unlock(&info->trans_lock);
1176         return ret;
1177 }
1178
1179 /*
1180  * wait for the current transaction commit to start and block subsequent
1181  * transaction joins
1182  */
1183 static void wait_current_trans_commit_start(struct btrfs_root *root,
1184                                             struct btrfs_transaction *trans)
1185 {
1186         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1187 }
1188
1189 /*
1190  * wait for the current transaction to start and then become unblocked.
1191  * caller holds ref.
1192  */
1193 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1194                                          struct btrfs_transaction *trans)
1195 {
1196         wait_event(root->fs_info->transaction_wait,
1197                    trans->commit_done || (trans->in_commit && !trans->blocked));
1198 }
1199
1200 /*
1201  * commit transactions asynchronously. once btrfs_commit_transaction_async
1202  * returns, any subsequent transaction will not be allowed to join.
1203  */
1204 struct btrfs_async_commit {
1205         struct btrfs_trans_handle *newtrans;
1206         struct btrfs_root *root;
1207         struct delayed_work work;
1208 };
1209
1210 static void do_async_commit(struct work_struct *work)
1211 {
1212         struct btrfs_async_commit *ac =
1213                 container_of(work, struct btrfs_async_commit, work.work);
1214
1215         btrfs_commit_transaction(ac->newtrans, ac->root);
1216         kfree(ac);
1217 }
1218
1219 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1220                                    struct btrfs_root *root,
1221                                    int wait_for_unblock)
1222 {
1223         struct btrfs_async_commit *ac;
1224         struct btrfs_transaction *cur_trans;
1225
1226         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1227         if (!ac)
1228                 return -ENOMEM;
1229
1230         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1231         ac->root = root;
1232         ac->newtrans = btrfs_join_transaction(root);
1233         if (IS_ERR(ac->newtrans)) {
1234                 int err = PTR_ERR(ac->newtrans);
1235                 kfree(ac);
1236                 return err;
1237         }
1238
1239         /* take transaction reference */
1240         cur_trans = trans->transaction;
1241         atomic_inc(&cur_trans->use_count);
1242
1243         btrfs_end_transaction(trans, root);
1244         schedule_delayed_work(&ac->work, 0);
1245
1246         /* wait for transaction to start and unblock */
1247         if (wait_for_unblock)
1248                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1249         else
1250                 wait_current_trans_commit_start(root, cur_trans);
1251
1252         if (current->journal_info == trans)
1253                 current->journal_info = NULL;
1254
1255         put_transaction(cur_trans);
1256         return 0;
1257 }
1258
1259
1260 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1261                                 struct btrfs_root *root, int err)
1262 {
1263         struct btrfs_transaction *cur_trans = trans->transaction;
1264
1265         WARN_ON(trans->use_count > 1);
1266
1267         btrfs_abort_transaction(trans, root, err);
1268
1269         spin_lock(&root->fs_info->trans_lock);
1270         list_del_init(&cur_trans->list);
1271         if (cur_trans == root->fs_info->running_transaction) {
1272                 root->fs_info->running_transaction = NULL;
1273                 root->fs_info->trans_no_join = 0;
1274         }
1275         spin_unlock(&root->fs_info->trans_lock);
1276
1277         btrfs_cleanup_one_transaction(trans->transaction, root);
1278
1279         put_transaction(cur_trans);
1280         put_transaction(cur_trans);
1281
1282         trace_btrfs_transaction_commit(root);
1283
1284         btrfs_scrub_continue(root);
1285
1286         if (current->journal_info == trans)
1287                 current->journal_info = NULL;
1288
1289         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1290 }
1291
1292 /*
1293  * btrfs_transaction state sequence:
1294  *    in_commit = 0, blocked = 0  (initial)
1295  *    in_commit = 1, blocked = 1
1296  *    blocked = 0
1297  *    commit_done = 1
1298  */
1299 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1300                              struct btrfs_root *root)
1301 {
1302         unsigned long joined = 0;
1303         struct btrfs_transaction *cur_trans = trans->transaction;
1304         struct btrfs_transaction *prev_trans = NULL;
1305         DEFINE_WAIT(wait);
1306         int ret = -EIO;
1307         int should_grow = 0;
1308         unsigned long now = get_seconds();
1309         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1310
1311         btrfs_run_ordered_operations(root, 0);
1312
1313         btrfs_trans_release_metadata(trans, root);
1314         trans->block_rsv = NULL;
1315
1316         if (cur_trans->aborted)
1317                 goto cleanup_transaction;
1318
1319         /* make a pass through all the delayed refs we have so far
1320          * any runnings procs may add more while we are here
1321          */
1322         ret = btrfs_run_delayed_refs(trans, root, 0);
1323         if (ret)
1324                 goto cleanup_transaction;
1325
1326         cur_trans = trans->transaction;
1327
1328         /*
1329          * set the flushing flag so procs in this transaction have to
1330          * start sending their work down.
1331          */
1332         cur_trans->delayed_refs.flushing = 1;
1333
1334         ret = btrfs_run_delayed_refs(trans, root, 0);
1335         if (ret)
1336                 goto cleanup_transaction;
1337
1338         spin_lock(&cur_trans->commit_lock);
1339         if (cur_trans->in_commit) {
1340                 spin_unlock(&cur_trans->commit_lock);
1341                 atomic_inc(&cur_trans->use_count);
1342                 ret = btrfs_end_transaction(trans, root);
1343
1344                 wait_for_commit(root, cur_trans);
1345
1346                 put_transaction(cur_trans);
1347
1348                 return ret;
1349         }
1350
1351         trans->transaction->in_commit = 1;
1352         trans->transaction->blocked = 1;
1353         spin_unlock(&cur_trans->commit_lock);
1354         wake_up(&root->fs_info->transaction_blocked_wait);
1355
1356         spin_lock(&root->fs_info->trans_lock);
1357         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1358                 prev_trans = list_entry(cur_trans->list.prev,
1359                                         struct btrfs_transaction, list);
1360                 if (!prev_trans->commit_done) {
1361                         atomic_inc(&prev_trans->use_count);
1362                         spin_unlock(&root->fs_info->trans_lock);
1363
1364                         wait_for_commit(root, prev_trans);
1365
1366                         put_transaction(prev_trans);
1367                 } else {
1368                         spin_unlock(&root->fs_info->trans_lock);
1369                 }
1370         } else {
1371                 spin_unlock(&root->fs_info->trans_lock);
1372         }
1373
1374         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1375                 should_grow = 1;
1376
1377         do {
1378                 int snap_pending = 0;
1379
1380                 joined = cur_trans->num_joined;
1381                 if (!list_empty(&trans->transaction->pending_snapshots))
1382                         snap_pending = 1;
1383
1384                 WARN_ON(cur_trans != trans->transaction);
1385
1386                 if (flush_on_commit || snap_pending) {
1387                         btrfs_start_delalloc_inodes(root, 1);
1388                         btrfs_wait_ordered_extents(root, 0, 1);
1389                 }
1390
1391                 ret = btrfs_run_delayed_items(trans, root);
1392                 if (ret)
1393                         goto cleanup_transaction;
1394
1395                 /*
1396                  * running the delayed items may have added new refs. account
1397                  * them now so that they hinder processing of more delayed refs
1398                  * as little as possible.
1399                  */
1400                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1401
1402                 /*
1403                  * rename don't use btrfs_join_transaction, so, once we
1404                  * set the transaction to blocked above, we aren't going
1405                  * to get any new ordered operations.  We can safely run
1406                  * it here and no for sure that nothing new will be added
1407                  * to the list
1408                  */
1409                 btrfs_run_ordered_operations(root, 1);
1410
1411                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1412                                 TASK_UNINTERRUPTIBLE);
1413
1414                 if (atomic_read(&cur_trans->num_writers) > 1)
1415                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1416                 else if (should_grow)
1417                         schedule_timeout(1);
1418
1419                 finish_wait(&cur_trans->writer_wait, &wait);
1420         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1421                  (should_grow && cur_trans->num_joined != joined));
1422
1423         /*
1424          * Ok now we need to make sure to block out any other joins while we
1425          * commit the transaction.  We could have started a join before setting
1426          * no_join so make sure to wait for num_writers to == 1 again.
1427          */
1428         spin_lock(&root->fs_info->trans_lock);
1429         root->fs_info->trans_no_join = 1;
1430         spin_unlock(&root->fs_info->trans_lock);
1431         wait_event(cur_trans->writer_wait,
1432                    atomic_read(&cur_trans->num_writers) == 1);
1433
1434         /*
1435          * the reloc mutex makes sure that we stop
1436          * the balancing code from coming in and moving
1437          * extents around in the middle of the commit
1438          */
1439         mutex_lock(&root->fs_info->reloc_mutex);
1440
1441         ret = btrfs_run_delayed_items(trans, root);
1442         if (ret) {
1443                 mutex_unlock(&root->fs_info->reloc_mutex);
1444                 goto cleanup_transaction;
1445         }
1446
1447         ret = create_pending_snapshots(trans, root->fs_info);
1448         if (ret) {
1449                 mutex_unlock(&root->fs_info->reloc_mutex);
1450                 goto cleanup_transaction;
1451         }
1452
1453         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1454         if (ret) {
1455                 mutex_unlock(&root->fs_info->reloc_mutex);
1456                 goto cleanup_transaction;
1457         }
1458
1459         /*
1460          * make sure none of the code above managed to slip in a
1461          * delayed item
1462          */
1463         btrfs_assert_delayed_root_empty(root);
1464
1465         WARN_ON(cur_trans != trans->transaction);
1466
1467         btrfs_scrub_pause(root);
1468         /* btrfs_commit_tree_roots is responsible for getting the
1469          * various roots consistent with each other.  Every pointer
1470          * in the tree of tree roots has to point to the most up to date
1471          * root for every subvolume and other tree.  So, we have to keep
1472          * the tree logging code from jumping in and changing any
1473          * of the trees.
1474          *
1475          * At this point in the commit, there can't be any tree-log
1476          * writers, but a little lower down we drop the trans mutex
1477          * and let new people in.  By holding the tree_log_mutex
1478          * from now until after the super is written, we avoid races
1479          * with the tree-log code.
1480          */
1481         mutex_lock(&root->fs_info->tree_log_mutex);
1482
1483         ret = commit_fs_roots(trans, root);
1484         if (ret) {
1485                 mutex_unlock(&root->fs_info->tree_log_mutex);
1486                 mutex_unlock(&root->fs_info->reloc_mutex);
1487                 goto cleanup_transaction;
1488         }
1489
1490         /* commit_fs_roots gets rid of all the tree log roots, it is now
1491          * safe to free the root of tree log roots
1492          */
1493         btrfs_free_log_root_tree(trans, root->fs_info);
1494
1495         ret = commit_cowonly_roots(trans, root);
1496         if (ret) {
1497                 mutex_unlock(&root->fs_info->tree_log_mutex);
1498                 mutex_unlock(&root->fs_info->reloc_mutex);
1499                 goto cleanup_transaction;
1500         }
1501
1502         btrfs_prepare_extent_commit(trans, root);
1503
1504         cur_trans = root->fs_info->running_transaction;
1505
1506         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1507                             root->fs_info->tree_root->node);
1508         switch_commit_root(root->fs_info->tree_root);
1509
1510         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1511                             root->fs_info->chunk_root->node);
1512         switch_commit_root(root->fs_info->chunk_root);
1513
1514         assert_qgroups_uptodate(trans);
1515         update_super_roots(root);
1516
1517         if (!root->fs_info->log_root_recovering) {
1518                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1519                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1520         }
1521
1522         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1523                sizeof(*root->fs_info->super_copy));
1524
1525         trans->transaction->blocked = 0;
1526         spin_lock(&root->fs_info->trans_lock);
1527         root->fs_info->running_transaction = NULL;
1528         root->fs_info->trans_no_join = 0;
1529         spin_unlock(&root->fs_info->trans_lock);
1530         mutex_unlock(&root->fs_info->reloc_mutex);
1531
1532         wake_up(&root->fs_info->transaction_wait);
1533
1534         ret = btrfs_write_and_wait_transaction(trans, root);
1535         if (ret) {
1536                 btrfs_error(root->fs_info, ret,
1537                             "Error while writing out transaction.");
1538                 mutex_unlock(&root->fs_info->tree_log_mutex);
1539                 goto cleanup_transaction;
1540         }
1541
1542         ret = write_ctree_super(trans, root, 0);
1543         if (ret) {
1544                 mutex_unlock(&root->fs_info->tree_log_mutex);
1545                 goto cleanup_transaction;
1546         }
1547
1548         /*
1549          * the super is written, we can safely allow the tree-loggers
1550          * to go about their business
1551          */
1552         mutex_unlock(&root->fs_info->tree_log_mutex);
1553
1554         btrfs_finish_extent_commit(trans, root);
1555
1556         cur_trans->commit_done = 1;
1557
1558         root->fs_info->last_trans_committed = cur_trans->transid;
1559
1560         wake_up(&cur_trans->commit_wait);
1561
1562         spin_lock(&root->fs_info->trans_lock);
1563         list_del_init(&cur_trans->list);
1564         spin_unlock(&root->fs_info->trans_lock);
1565
1566         put_transaction(cur_trans);
1567         put_transaction(cur_trans);
1568
1569         trace_btrfs_transaction_commit(root);
1570
1571         btrfs_scrub_continue(root);
1572
1573         if (current->journal_info == trans)
1574                 current->journal_info = NULL;
1575
1576         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1577
1578         if (current != root->fs_info->transaction_kthread)
1579                 btrfs_run_delayed_iputs(root);
1580
1581         return ret;
1582
1583 cleanup_transaction:
1584         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1585 //      WARN_ON(1);
1586         if (current->journal_info == trans)
1587                 current->journal_info = NULL;
1588         cleanup_transaction(trans, root, ret);
1589
1590         return ret;
1591 }
1592
1593 /*
1594  * interface function to delete all the snapshots we have scheduled for deletion
1595  */
1596 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1597 {
1598         LIST_HEAD(list);
1599         struct btrfs_fs_info *fs_info = root->fs_info;
1600
1601         spin_lock(&fs_info->trans_lock);
1602         list_splice_init(&fs_info->dead_roots, &list);
1603         spin_unlock(&fs_info->trans_lock);
1604
1605         while (!list_empty(&list)) {
1606                 int ret;
1607
1608                 root = list_entry(list.next, struct btrfs_root, root_list);
1609                 list_del(&root->root_list);
1610
1611                 btrfs_kill_all_delayed_nodes(root);
1612
1613                 if (btrfs_header_backref_rev(root->node) <
1614                     BTRFS_MIXED_BACKREF_REV)
1615                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1616                 else
1617                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1618                 BUG_ON(ret < 0);
1619         }
1620         return 0;
1621 }