fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30 #include "inode-map.h"
  31 #include "volumes.h"
  32
  33 #define BTRFS_ROOT_TRANS_TAG 0
  34
  35 void put_transaction(struct btrfs_transaction *transaction)
  36 {
  37         WARN_ON(atomic_read(&transaction->use_count) == 0);
  38         if (atomic_dec_and_test(&transaction->use_count)) {
  39                 BUG_ON(!list_empty(&transaction->list));
  40                 WARN_ON(transaction->delayed_refs.root.rb_node);
  41                 WARN_ON(!list_empty(&transaction->delayed_refs.seq_head));
  42                 memset(transaction, 0, sizeof(*transaction));
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static noinline void switch_commit_root(struct btrfs_root *root)
  48 {
  49         free_extent_buffer(root->commit_root);
  50         root->commit_root = btrfs_root_node(root);
  51 }
  52
  53 /*
  54  * either allocate a new transaction or hop into the existing one
  55  */
  56 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  57 {
  58         struct btrfs_transaction *cur_trans;
  59         struct btrfs_fs_info *fs_info = root->fs_info;
  60
  61         spin_lock(&fs_info->trans_lock);
  62 loop:
  63         /* The file system has been taken offline. No new transactions. */
  64         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  65                 spin_unlock(&fs_info->trans_lock);
  66                 return -EROFS;
  67         }
  68
  69         if (fs_info->trans_no_join) {
  70                 if (!nofail) {
  71                         spin_unlock(&fs_info->trans_lock);
  72                         return -EBUSY;
  73                 }
  74         }
  75
  76         cur_trans = fs_info->running_transaction;
  77         if (cur_trans) {
  78                 if (cur_trans->aborted) {
  79                         spin_unlock(&fs_info->trans_lock);
  80                         return cur_trans->aborted;
  81                 }
  82                 atomic_inc(&cur_trans->use_count);
  83                 atomic_inc(&cur_trans->num_writers);
  84                 cur_trans->num_joined++;
  85                 spin_unlock(&fs_info->trans_lock);
  86                 return 0;
  87         }
  88         spin_unlock(&fs_info->trans_lock);
  89
  90         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  91         if (!cur_trans)
  92                 return -ENOMEM;
  93
  94         spin_lock(&fs_info->trans_lock);
  95         if (fs_info->running_transaction) {
  96                 /*
  97                  * someone started a transaction after we unlocked.  Make sure
  98                  * to redo the trans_no_join checks above
  99                  */
 100                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 101                 cur_trans = fs_info->running_transaction;
 102                 goto loop;
 103         } else if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 104                 spin_unlock(&root->fs_info->trans_lock);
 105                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 106                 return -EROFS;
 107         }
 108
 109         atomic_set(&cur_trans->num_writers, 1);
 110         cur_trans->num_joined = 0;
 111         init_waitqueue_head(&cur_trans->writer_wait);
 112         init_waitqueue_head(&cur_trans->commit_wait);
 113         cur_trans->in_commit = 0;
 114         cur_trans->blocked = 0;
 115         /*
 116          * One for this trans handle, one so it will live on until we
 117          * commit the transaction.
 118          */
 119         atomic_set(&cur_trans->use_count, 2);
 120         cur_trans->commit_done = 0;
 121         cur_trans->start_time = get_seconds();
 122
 123         cur_trans->delayed_refs.root = RB_ROOT;
 124         cur_trans->delayed_refs.num_entries = 0;
 125         cur_trans->delayed_refs.num_heads_ready = 0;
 126         cur_trans->delayed_refs.num_heads = 0;
 127         cur_trans->delayed_refs.flushing = 0;
 128         cur_trans->delayed_refs.run_delayed_start = 0;
 129         cur_trans->delayed_refs.seq = 1;
 130
 131         /*
 132          * although the tree mod log is per file system and not per transaction,
 133          * the log must never go across transaction boundaries.
 134          */
 135         smp_mb();
 136         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 137                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 138                         "creating a fresh transaction\n");
 139                 WARN_ON(1);
 140         }
 141         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 142                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 143                         "creating a fresh transaction\n");
 144                 WARN_ON(1);
 145         }
 146         atomic_set(&fs_info->tree_mod_seq, 0);
 147
 148         init_waitqueue_head(&cur_trans->delayed_refs.seq_wait);
 149         spin_lock_init(&cur_trans->commit_lock);
 150         spin_lock_init(&cur_trans->delayed_refs.lock);
 151         INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head);
 152
 153         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 154         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 155         extent_io_tree_init(&cur_trans->dirty_pages,
 156                              fs_info->btree_inode->i_mapping);
 157         fs_info->generation++;
 158         cur_trans->transid = fs_info->generation;
 159         fs_info->running_transaction = cur_trans;
 160         cur_trans->aborted = 0;
 161         spin_unlock(&fs_info->trans_lock);
 162
 163         return 0;
 164 }
 165
 166 /*
 167  * this does all the record keeping required to make sure that a reference
 168  * counted root is properly recorded in a given transaction.  This is required
 169  * to make sure the old root from before we joined the transaction is deleted
 170  * when the transaction commits
 171  */
 172 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 173                                struct btrfs_root *root)
 174 {
 175         if (root->ref_cows && root->last_trans < trans->transid) {
 176                 WARN_ON(root == root->fs_info->extent_root);
 177                 WARN_ON(root->commit_root != root->node);
 178
 179                 /*
 180                  * see below for in_trans_setup usage rules
 181                  * we have the reloc mutex held now, so there
 182                  * is only one writer in this function
 183                  */
 184                 root->in_trans_setup = 1;
 185
 186                 /* make sure readers find in_trans_setup before
 187                  * they find our root->last_trans update
 188                  */
 189                 smp_wmb();
 190
 191                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 192                 if (root->last_trans == trans->transid) {
 193                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 194                         return 0;
 195                 }
 196                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 197                            (unsigned long)root->root_key.objectid,
 198                            BTRFS_ROOT_TRANS_TAG);
 199                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 200                 root->last_trans = trans->transid;
 201
 202                 /* this is pretty tricky.  We don't want to
 203                  * take the relocation lock in btrfs_record_root_in_trans
 204                  * unless we're really doing the first setup for this root in
 205                  * this transaction.
 206                  *
 207                  * Normally we'd use root->last_trans as a flag to decide
 208                  * if we want to take the expensive mutex.
 209                  *
 210                  * But, we have to set root->last_trans before we
 211                  * init the relocation root, otherwise, we trip over warnings
 212                  * in ctree.c.  The solution used here is to flag ourselves
 213                  * with root->in_trans_setup.  When this is 1, we're still
 214                  * fixing up the reloc trees and everyone must wait.
 215                  *
 216                  * When this is zero, they can trust root->last_trans and fly
 217                  * through btrfs_record_root_in_trans without having to take the
 218                  * lock.  smp_wmb() makes sure that all the writes above are
 219                  * done before we pop in the zero below
 220                  */
 221                 btrfs_init_reloc_root(trans, root);
 222                 smp_wmb();
 223                 root->in_trans_setup = 0;
 224         }
 225         return 0;
 226 }
 227
 228
 229 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 230                                struct btrfs_root *root)
 231 {
 232         if (!root->ref_cows)
 233                 return 0;
 234
 235         /*
 236          * see record_root_in_trans for comments about in_trans_setup usage
 237          * and barriers
 238          */
 239         smp_rmb();
 240         if (root->last_trans == trans->transid &&
 241             !root->in_trans_setup)
 242                 return 0;
 243
 244         mutex_lock(&root->fs_info->reloc_mutex);
 245         record_root_in_trans(trans, root);
 246         mutex_unlock(&root->fs_info->reloc_mutex);
 247
 248         return 0;
 249 }
 250
 251 /* wait for commit against the current transaction to become unblocked
 252  * when this is done, it is safe to start a new transaction, but the current
 253  * transaction might not be fully on disk.
 254  */
 255 static void wait_current_trans(struct btrfs_root *root)
 256 {
 257         struct btrfs_transaction *cur_trans;
 258
 259         spin_lock(&root->fs_info->trans_lock);
 260         cur_trans = root->fs_info->running_transaction;
 261         if (cur_trans && cur_trans->blocked) {
 262                 atomic_inc(&cur_trans->use_count);
 263                 spin_unlock(&root->fs_info->trans_lock);
 264
 265                 wait_event(root->fs_info->transaction_wait,
 266                            !cur_trans->blocked);
 267                 put_transaction(cur_trans);
 268         } else {
 269                 spin_unlock(&root->fs_info->trans_lock);
 270         }
 271 }
 272
 273 enum btrfs_trans_type {
 274         TRANS_START,
 275         TRANS_JOIN,
 276         TRANS_USERSPACE,
 277         TRANS_JOIN_NOLOCK,
 278 };
 279
 280 static int may_wait_transaction(struct btrfs_root *root, int type)
 281 {
 282         if (root->fs_info->log_root_recovering)
 283                 return 0;
 284
 285         if (type == TRANS_USERSPACE)
 286                 return 1;
 287
 288         if (type == TRANS_START &&
 289             !atomic_read(&root->fs_info->open_ioctl_trans))
 290                 return 1;
 291
 292         return 0;
 293 }
 294
 295 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 296                                                     u64 num_items, int type)
 297 {
 298         struct btrfs_trans_handle *h;
 299         struct btrfs_transaction *cur_trans;
 300         u64 num_bytes = 0;
 301         int ret;
 302
 303         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 304                 return ERR_PTR(-EROFS);
 305
 306         if (current->journal_info) {
 307                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 308                 h = current->journal_info;
 309                 h->use_count++;
 310                 h->orig_rsv = h->block_rsv;
 311                 h->block_rsv = NULL;
 312                 goto got_it;
 313         }
 314
 315         /*
 316          * Do the reservation before we join the transaction so we can do all
 317          * the appropriate flushing if need be.
 318          */
 319         if (num_items > 0 && root != root->fs_info->chunk_root) {
 320                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 321                 ret = btrfs_block_rsv_add(root,
 322                                           &root->fs_info->trans_block_rsv,
 323                                           num_bytes);
 324                 if (ret)
 325                         return ERR_PTR(ret);
 326         }
 327 again:
 328         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 329         if (!h)
 330                 return ERR_PTR(-ENOMEM);
 331
 332         sb_start_intwrite(root->fs_info->sb);
 333
 334         if (may_wait_transaction(root, type))
 335                 wait_current_trans(root);
 336
 337         do {
 338                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 339                 if (ret == -EBUSY)
 340                         wait_current_trans(root);
 341         } while (ret == -EBUSY);
 342
 343         if (ret < 0) {
 344                 sb_end_intwrite(root->fs_info->sb);
 345                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 346                 return ERR_PTR(ret);
 347         }
 348
 349         cur_trans = root->fs_info->running_transaction;
 350
 351         h->transid = cur_trans->transid;
 352         h->transaction = cur_trans;
 353         h->blocks_used = 0;
 354         h->bytes_reserved = 0;
 355         h->delayed_ref_updates = 0;
 356         h->use_count = 1;
 357         h->block_rsv = NULL;
 358         h->orig_rsv = NULL;
 359         h->aborted = 0;
 360
 361         smp_mb();
 362         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 363                 btrfs_commit_transaction(h, root);
 364                 goto again;
 365         }
 366
 367         if (num_bytes) {
 368                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 369                                               h->transid, num_bytes, 1);
 370                 h->block_rsv = &root->fs_info->trans_block_rsv;
 371                 h->bytes_reserved = num_bytes;
 372         }
 373
 374 got_it:
 375         btrfs_record_root_in_trans(h, root);
 376
 377         if (!current->journal_info && type != TRANS_USERSPACE)
 378                 current->journal_info = h;
 379         return h;
 380 }
 381
 382 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 383                                                    int num_items)
 384 {
 385         return start_transaction(root, num_items, TRANS_START);
 386 }
 387 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 388 {
 389         return start_transaction(root, 0, TRANS_JOIN);
 390 }
 391
 392 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 393 {
 394         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 395 }
 396
 397 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 398 {
 399         return start_transaction(root, 0, TRANS_USERSPACE);
 400 }
 401
 402 /* wait for a transaction commit to be fully complete */
 403 static noinline void wait_for_commit(struct btrfs_root *root,
 404                                     struct btrfs_transaction *commit)
 405 {
 406         wait_event(commit->commit_wait, commit->commit_done);
 407 }
 408
 409 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 410 {
 411         struct btrfs_transaction *cur_trans = NULL, *t;
 412         int ret;
 413
 414         ret = 0;
 415         if (transid) {
 416                 if (transid <= root->fs_info->last_trans_committed)
 417                         goto out;
 418
 419                 /* find specified transaction */
 420                 spin_lock(&root->fs_info->trans_lock);
 421                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 422                         if (t->transid == transid) {
 423                                 cur_trans = t;
 424                                 atomic_inc(&cur_trans->use_count);
 425                                 break;
 426                         }
 427                         if (t->transid > transid)
 428                                 break;
 429                 }
 430                 spin_unlock(&root->fs_info->trans_lock);
 431                 ret = -EINVAL;
 432                 if (!cur_trans)
 433                         goto out;  /* bad transid */
 434         } else {
 435                 /* find newest transaction that is committing | committed */
 436                 spin_lock(&root->fs_info->trans_lock);
 437                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 438                                             list) {
 439                         if (t->in_commit) {
 440                                 if (t->commit_done)
 441                                         break;
 442                                 cur_trans = t;
 443                                 atomic_inc(&cur_trans->use_count);
 444                                 break;
 445                         }
 446                 }
 447                 spin_unlock(&root->fs_info->trans_lock);
 448                 if (!cur_trans)
 449                         goto out;  /* nothing committing|committed */
 450         }
 451
 452         wait_for_commit(root, cur_trans);
 453
 454         put_transaction(cur_trans);
 455         ret = 0;
 456 out:
 457         return ret;
 458 }
 459
 460 void btrfs_throttle(struct btrfs_root *root)
 461 {
 462         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 463                 wait_current_trans(root);
 464 }
 465
 466 static int should_end_transaction(struct btrfs_trans_handle *trans,
 467                                   struct btrfs_root *root)
 468 {
 469         int ret;
 470
 471         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 472         return ret ? 1 : 0;
 473 }
 474
 475 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 476                                  struct btrfs_root *root)
 477 {
 478         struct btrfs_transaction *cur_trans = trans->transaction;
 479         struct btrfs_block_rsv *rsv = trans->block_rsv;
 480         int updates;
 481         int err;
 482
 483         smp_mb();
 484         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 485                 return 1;
 486
 487         /*
 488          * We need to do this in case we're deleting csums so the global block
 489          * rsv get's used instead of the csum block rsv.
 490          */
 491         trans->block_rsv = NULL;
 492
 493         updates = trans->delayed_ref_updates;
 494         trans->delayed_ref_updates = 0;
 495         if (updates) {
 496                 err = btrfs_run_delayed_refs(trans, root, updates);
 497                 if (err) /* Error code will also eval true */
 498                         return err;
 499         }
 500
 501         trans->block_rsv = rsv;
 502
 503         return should_end_transaction(trans, root);
 504 }
 505
 506 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 507                           struct btrfs_root *root, int throttle, int lock)
 508 {
 509         struct btrfs_transaction *cur_trans = trans->transaction;
 510         struct btrfs_fs_info *info = root->fs_info;
 511         int count = 0;
 512         int err = 0;
 513
 514         if (--trans->use_count) {
 515                 trans->block_rsv = trans->orig_rsv;
 516                 return 0;
 517         }
 518
 519         btrfs_trans_release_metadata(trans, root);
 520         trans->block_rsv = NULL;
 521         while (count < 2) {
 522                 unsigned long cur = trans->delayed_ref_updates;
 523                 trans->delayed_ref_updates = 0;
 524                 if (cur &&
 525                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 526                         trans->delayed_ref_updates = 0;
 527                         btrfs_run_delayed_refs(trans, root, cur);
 528                 } else {
 529                         break;
 530                 }
 531                 count++;
 532         }
 533
 534         sb_end_intwrite(root->fs_info->sb);
 535
 536         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 537             should_end_transaction(trans, root)) {
 538                 trans->transaction->blocked = 1;
 539                 smp_wmb();
 540         }
 541
 542         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 543                 if (throttle) {
 544                         /*
 545                          * We may race with somebody else here so end up having
 546                          * to call end_transaction on ourselves again, so inc
 547                          * our use_count.
 548                          */
 549                         trans->use_count++;
 550                         return btrfs_commit_transaction(trans, root);
 551                 } else {
 552                         wake_up_process(info->transaction_kthread);
 553                 }
 554         }
 555
 556         WARN_ON(cur_trans != info->running_transaction);
 557         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 558         atomic_dec(&cur_trans->num_writers);
 559
 560         smp_mb();
 561         if (waitqueue_active(&cur_trans->writer_wait))
 562                 wake_up(&cur_trans->writer_wait);
 563         put_transaction(cur_trans);
 564
 565         if (current->journal_info == trans)
 566                 current->journal_info = NULL;
 567
 568         if (throttle)
 569                 btrfs_run_delayed_iputs(root);
 570
 571         if (trans->aborted ||
 572             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 573                 err = -EIO;
 574         }
 575
 576         memset(trans, 0, sizeof(*trans));
 577         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 578         return err;
 579 }
 580
 581 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 582                           struct btrfs_root *root)
 583 {
 584         int ret;
 585
 586         ret = __btrfs_end_transaction(trans, root, 0, 1);
 587         if (ret)
 588                 return ret;
 589         return 0;
 590 }
 591
 592 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 593                                    struct btrfs_root *root)
 594 {
 595         int ret;
 596
 597         ret = __btrfs_end_transaction(trans, root, 1, 1);
 598         if (ret)
 599                 return ret;
 600         return 0;
 601 }
 602
 603 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 604                                  struct btrfs_root *root)
 605 {
 606         int ret;
 607
 608         ret = __btrfs_end_transaction(trans, root, 0, 0);
 609         if (ret)
 610                 return ret;
 611         return 0;
 612 }
 613
 614 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 615                                 struct btrfs_root *root)
 616 {
 617         return __btrfs_end_transaction(trans, root, 1, 1);
 618 }
 619
 620 /*
 621  * when btree blocks are allocated, they have some corresponding bits set for
 622  * them in one of two extent_io trees.  This is used to make sure all of
 623  * those extents are sent to disk but does not wait on them
 624  */
 625 int btrfs_write_marked_extents(struct btrfs_root *root,
 626                                struct extent_io_tree *dirty_pages, int mark)
 627 {
 628         int err = 0;
 629         int werr = 0;
 630         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 631         u64 start = 0;
 632         u64 end;
 633
 634         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 635                                       mark)) {
 636                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 637                                    GFP_NOFS);
 638                 err = filemap_fdatawrite_range(mapping, start, end);
 639                 if (err)
 640                         werr = err;
 641                 cond_resched();
 642                 start = end + 1;
 643         }
 644         if (err)
 645                 werr = err;
 646         return werr;
 647 }
 648
 649 /*
 650  * when btree blocks are allocated, they have some corresponding bits set for
 651  * them in one of two extent_io trees.  This is used to make sure all of
 652  * those extents are on disk for transaction or log commit.  We wait
 653  * on all the pages and clear them from the dirty pages state tree
 654  */
 655 int btrfs_wait_marked_extents(struct btrfs_root *root,
 656                               struct extent_io_tree *dirty_pages, int mark)
 657 {
 658         int err = 0;
 659         int werr = 0;
 660         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 661         u64 start = 0;
 662         u64 end;
 663
 664         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 665                                       EXTENT_NEED_WAIT)) {
 666                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 667                 err = filemap_fdatawait_range(mapping, start, end);
 668                 if (err)
 669                         werr = err;
 670                 cond_resched();
 671                 start = end + 1;
 672         }
 673         if (err)
 674                 werr = err;
 675         return werr;
 676 }
 677
 678 /*
 679  * when btree blocks are allocated, they have some corresponding bits set for
 680  * them in one of two extent_io trees.  This is used to make sure all of
 681  * those extents are on disk for transaction or log commit
 682  */
 683 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 684                                 struct extent_io_tree *dirty_pages, int mark)
 685 {
 686         int ret;
 687         int ret2;
 688
 689         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 690         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 691
 692         if (ret)
 693                 return ret;
 694         if (ret2)
 695                 return ret2;
 696         return 0;
 697 }
 698
 699 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 700                                      struct btrfs_root *root)
 701 {
 702         if (!trans || !trans->transaction) {
 703                 struct inode *btree_inode;
 704                 btree_inode = root->fs_info->btree_inode;
 705                 return filemap_write_and_wait(btree_inode->i_mapping);
 706         }
 707         return btrfs_write_and_wait_marked_extents(root,
 708                                            &trans->transaction->dirty_pages,
 709                                            EXTENT_DIRTY);
 710 }
 711
 712 /*
 713  * this is used to update the root pointer in the tree of tree roots.
 714  *
 715  * But, in the case of the extent allocation tree, updating the root
 716  * pointer may allocate blocks which may change the root of the extent
 717  * allocation tree.
 718  *
 719  * So, this loops and repeats and makes sure the cowonly root didn't
 720  * change while the root pointer was being updated in the metadata.
 721  */
 722 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 723                                struct btrfs_root *root)
 724 {
 725         int ret;
 726         u64 old_root_bytenr;
 727         u64 old_root_used;
 728         struct btrfs_root *tree_root = root->fs_info->tree_root;
 729
 730         old_root_used = btrfs_root_used(&root->root_item);
 731         btrfs_write_dirty_block_groups(trans, root);
 732
 733         while (1) {
 734                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 735                 if (old_root_bytenr == root->node->start &&
 736                     old_root_used == btrfs_root_used(&root->root_item))
 737                         break;
 738
 739                 btrfs_set_root_node(&root->root_item, root->node);
 740                 ret = btrfs_update_root(trans, tree_root,
 741                                         &root->root_key,
 742                                         &root->root_item);
 743                 if (ret)
 744                         return ret;
 745
 746                 old_root_used = btrfs_root_used(&root->root_item);
 747                 ret = btrfs_write_dirty_block_groups(trans, root);
 748                 if (ret)
 749                         return ret;
 750         }
 751
 752         if (root != root->fs_info->extent_root)
 753                 switch_commit_root(root);
 754
 755         return 0;
 756 }
 757
 758 /*
 759  * update all the cowonly tree roots on disk
 760  *
 761  * The error handling in this function may not be obvious. Any of the
 762  * failures will cause the file system to go offline. We still need
 763  * to clean up the delayed refs.
 764  */
 765 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 766                                          struct btrfs_root *root)
 767 {
 768         struct btrfs_fs_info *fs_info = root->fs_info;
 769         struct list_head *next;
 770         struct extent_buffer *eb;
 771         int ret;
 772
 773         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 774         if (ret)
 775                 return ret;
 776
 777         eb = btrfs_lock_root_node(fs_info->tree_root);
 778         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 779                               0, &eb);
 780         btrfs_tree_unlock(eb);
 781         free_extent_buffer(eb);
 782
 783         if (ret)
 784                 return ret;
 785
 786         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 787         if (ret)
 788                 return ret;
 789
 790         ret = btrfs_run_dev_stats(trans, root->fs_info);
 791         BUG_ON(ret);
 792
 793         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 794                 next = fs_info->dirty_cowonly_roots.next;
 795                 list_del_init(next);
 796                 root = list_entry(next, struct btrfs_root, dirty_list);
 797
 798                 ret = update_cowonly_root(trans, root);
 799                 if (ret)
 800                         return ret;
 801         }
 802
 803         down_write(&fs_info->extent_commit_sem);
 804         switch_commit_root(fs_info->extent_root);
 805         up_write(&fs_info->extent_commit_sem);
 806
 807         return 0;
 808 }
 809
 810 /*
 811  * dead roots are old snapshots that need to be deleted.  This allocates
 812  * a dirty root struct and adds it into the list of dead roots that need to
 813  * be deleted
 814  */
 815 int btrfs_add_dead_root(struct btrfs_root *root)
 816 {
 817         spin_lock(&root->fs_info->trans_lock);
 818         list_add(&root->root_list, &root->fs_info->dead_roots);
 819         spin_unlock(&root->fs_info->trans_lock);
 820         return 0;
 821 }
 822
 823 /*
 824  * update all the cowonly tree roots on disk
 825  */
 826 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 827                                     struct btrfs_root *root)
 828 {
 829         struct btrfs_root *gang[8];
 830         struct btrfs_fs_info *fs_info = root->fs_info;
 831         int i;
 832         int ret;
 833         int err = 0;
 834
 835         spin_lock(&fs_info->fs_roots_radix_lock);
 836         while (1) {
 837                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 838                                                  (void **)gang, 0,
 839                                                  ARRAY_SIZE(gang),
 840                                                  BTRFS_ROOT_TRANS_TAG);
 841                 if (ret == 0)
 842                         break;
 843                 for (i = 0; i < ret; i++) {
 844                         root = gang[i];
 845                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 846                                         (unsigned long)root->root_key.objectid,
 847                                         BTRFS_ROOT_TRANS_TAG);
 848                         spin_unlock(&fs_info->fs_roots_radix_lock);
 849
 850                         btrfs_free_log(trans, root);
 851                         btrfs_update_reloc_root(trans, root);
 852                         btrfs_orphan_commit_root(trans, root);
 853
 854                         btrfs_save_ino_cache(root, trans);
 855
 856                         /* see comments in should_cow_block() */
 857                         root->force_cow = 0;
 858                         smp_wmb();
 859
 860                         if (root->commit_root != root->node) {
 861                                 mutex_lock(&root->fs_commit_mutex);
 862                                 switch_commit_root(root);
 863                                 btrfs_unpin_free_ino(root);
 864                                 mutex_unlock(&root->fs_commit_mutex);
 865
 866                                 btrfs_set_root_node(&root->root_item,
 867                                                     root->node);
 868                         }
 869
 870                         err = btrfs_update_root(trans, fs_info->tree_root,
 871                                                 &root->root_key,
 872                                                 &root->root_item);
 873                         spin_lock(&fs_info->fs_roots_radix_lock);
 874                         if (err)
 875                                 break;
 876                 }
 877         }
 878         spin_unlock(&fs_info->fs_roots_radix_lock);
 879         return err;
 880 }
 881
 882 /*
 883  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 884  * otherwise every leaf in the btree is read and defragged.
 885  */
 886 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 887 {
 888         struct btrfs_fs_info *info = root->fs_info;
 889         struct btrfs_trans_handle *trans;
 890         int ret;
 891         unsigned long nr;
 892
 893         if (xchg(&root->defrag_running, 1))
 894                 return 0;
 895
 896         while (1) {
 897                 trans = btrfs_start_transaction(root, 0);
 898                 if (IS_ERR(trans))
 899                         return PTR_ERR(trans);
 900
 901                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 902
 903                 nr = trans->blocks_used;
 904                 btrfs_end_transaction(trans, root);
 905                 btrfs_btree_balance_dirty(info->tree_root, nr);
 906                 cond_resched();
 907
 908                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 909                         break;
 910         }
 911         root->defrag_running = 0;
 912         return ret;
 913 }
 914
 915 /*
 916  * new snapshots need to be created at a very specific time in the
 917  * transaction commit.  This does the actual creation
 918  */
 919 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 920                                    struct btrfs_fs_info *fs_info,
 921                                    struct btrfs_pending_snapshot *pending)
 922 {
 923         struct btrfs_key key;
 924         struct btrfs_root_item *new_root_item;
 925         struct btrfs_root *tree_root = fs_info->tree_root;
 926         struct btrfs_root *root = pending->root;
 927         struct btrfs_root *parent_root;
 928         struct btrfs_block_rsv *rsv;
 929         struct inode *parent_inode;
 930         struct dentry *parent;
 931         struct dentry *dentry;
 932         struct extent_buffer *tmp;
 933         struct extent_buffer *old;
 934         int ret;
 935         u64 to_reserve = 0;
 936         u64 index = 0;
 937         u64 objectid;
 938         u64 root_flags;
 939
 940         rsv = trans->block_rsv;
 941
 942         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 943         if (!new_root_item) {
 944                 ret = pending->error = -ENOMEM;
 945                 goto fail;
 946         }
 947
 948         ret = btrfs_find_free_objectid(tree_root, &objectid);
 949         if (ret) {
 950                 pending->error = ret;
 951                 goto fail;
 952         }
 953
 954         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 955
 956         if (to_reserve > 0) {
 957                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
 958                                                   to_reserve);
 959                 if (ret) {
 960                         pending->error = ret;
 961                         goto fail;
 962                 }
 963         }
 964
 965         key.objectid = objectid;
 966         key.offset = (u64)-1;
 967         key.type = BTRFS_ROOT_ITEM_KEY;
 968
 969         trans->block_rsv = &pending->block_rsv;
 970
 971         dentry = pending->dentry;
 972         parent = dget_parent(dentry);
 973         parent_inode = parent->d_inode;
 974         parent_root = BTRFS_I(parent_inode)->root;
 975         record_root_in_trans(trans, parent_root);
 976
 977         /*
 978          * insert the directory item
 979          */
 980         ret = btrfs_set_inode_index(parent_inode, &index);
 981         BUG_ON(ret); /* -ENOMEM */
 982         ret = btrfs_insert_dir_item(trans, parent_root,
 983                                 dentry->d_name.name, dentry->d_name.len,
 984                                 parent_inode, &key,
 985                                 BTRFS_FT_DIR, index);
 986         if (ret == -EEXIST) {
 987                 pending->error = -EEXIST;
 988                 dput(parent);
 989                 goto fail;
 990         } else if (ret) {
 991                 goto abort_trans_dput;
 992         }
 993
 994         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 995                                          dentry->d_name.len * 2);
 996         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 997         if (ret)
 998                 goto abort_trans_dput;
 999
1000         /*
1001          * pull in the delayed directory update
1002          * and the delayed inode item
1003          * otherwise we corrupt the FS during
1004          * snapshot
1005          */
1006         ret = btrfs_run_delayed_items(trans, root);
1007         if (ret) { /* Transaction aborted */
1008                 dput(parent);
1009                 goto fail;
1010         }
1011
1012         record_root_in_trans(trans, root);
1013         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1014         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1015         btrfs_check_and_init_root_item(new_root_item);
1016
1017         root_flags = btrfs_root_flags(new_root_item);
1018         if (pending->readonly)
1019                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1020         else
1021                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1022         btrfs_set_root_flags(new_root_item, root_flags);
1023
1024         old = btrfs_lock_root_node(root);
1025         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1026         if (ret) {
1027                 btrfs_tree_unlock(old);
1028                 free_extent_buffer(old);
1029                 goto abort_trans_dput;
1030         }
1031
1032         btrfs_set_lock_blocking(old);
1033
1034         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1035         /* clean up in any case */
1036         btrfs_tree_unlock(old);
1037         free_extent_buffer(old);
1038         if (ret)
1039                 goto abort_trans_dput;
1040
1041         /* see comments in should_cow_block() */
1042         root->force_cow = 1;
1043         smp_wmb();
1044
1045         btrfs_set_root_node(new_root_item, tmp);
1046         /* record when the snapshot was created in key.offset */
1047         key.offset = trans->transid;
1048         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1049         btrfs_tree_unlock(tmp);
1050         free_extent_buffer(tmp);
1051         if (ret)
1052                 goto abort_trans_dput;
1053
1054         /*
1055          * insert root back/forward references
1056          */
1057         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1058                                  parent_root->root_key.objectid,
1059                                  btrfs_ino(parent_inode), index,
1060                                  dentry->d_name.name, dentry->d_name.len);
1061         dput(parent);
1062         if (ret)
1063                 goto fail;
1064
1065         key.offset = (u64)-1;
1066         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1067         if (IS_ERR(pending->snap)) {
1068                 ret = PTR_ERR(pending->snap);
1069                 goto abort_trans;
1070         }
1071
1072         ret = btrfs_reloc_post_snapshot(trans, pending);
1073         if (ret)
1074                 goto abort_trans;
1075         ret = 0;
1076 fail:
1077         kfree(new_root_item);
1078         trans->block_rsv = rsv;
1079         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1080         return ret;
1081
1082 abort_trans_dput:
1083         dput(parent);
1084 abort_trans:
1085         btrfs_abort_transaction(trans, root, ret);
1086         goto fail;
1087 }
1088
1089 /*
1090  * create all the snapshots we've scheduled for creation
1091  */
1092 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1093                                              struct btrfs_fs_info *fs_info)
1094 {
1095         struct btrfs_pending_snapshot *pending;
1096         struct list_head *head = &trans->transaction->pending_snapshots;
1097
1098         list_for_each_entry(pending, head, list)
1099                 create_pending_snapshot(trans, fs_info, pending);
1100         return 0;
1101 }
1102
1103 static void update_super_roots(struct btrfs_root *root)
1104 {
1105         struct btrfs_root_item *root_item;
1106         struct btrfs_super_block *super;
1107
1108         super = root->fs_info->super_copy;
1109
1110         root_item = &root->fs_info->chunk_root->root_item;
1111         super->chunk_root = root_item->bytenr;
1112         super->chunk_root_generation = root_item->generation;
1113         super->chunk_root_level = root_item->level;
1114
1115         root_item = &root->fs_info->tree_root->root_item;
1116         super->root = root_item->bytenr;
1117         super->generation = root_item->generation;
1118         super->root_level = root_item->level;
1119         if (btrfs_test_opt(root, SPACE_CACHE))
1120                 super->cache_generation = root_item->generation;
1121 }
1122
1123 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1124 {
1125         int ret = 0;
1126         spin_lock(&info->trans_lock);
1127         if (info->running_transaction)
1128                 ret = info->running_transaction->in_commit;
1129         spin_unlock(&info->trans_lock);
1130         return ret;
1131 }
1132
1133 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1134 {
1135         int ret = 0;
1136         spin_lock(&info->trans_lock);
1137         if (info->running_transaction)
1138                 ret = info->running_transaction->blocked;
1139         spin_unlock(&info->trans_lock);
1140         return ret;
1141 }
1142
1143 /*
1144  * wait for the current transaction commit to start and block subsequent
1145  * transaction joins
1146  */
1147 static void wait_current_trans_commit_start(struct btrfs_root *root,
1148                                             struct btrfs_transaction *trans)
1149 {
1150         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1151 }
1152
1153 /*
1154  * wait for the current transaction to start and then become unblocked.
1155  * caller holds ref.
1156  */
1157 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1158                                          struct btrfs_transaction *trans)
1159 {
1160         wait_event(root->fs_info->transaction_wait,
1161                    trans->commit_done || (trans->in_commit && !trans->blocked));
1162 }
1163
1164 /*
1165  * commit transactions asynchronously. once btrfs_commit_transaction_async
1166  * returns, any subsequent transaction will not be allowed to join.
1167  */
1168 struct btrfs_async_commit {
1169         struct btrfs_trans_handle *newtrans;
1170         struct btrfs_root *root;
1171         struct delayed_work work;
1172 };
1173
1174 static void do_async_commit(struct work_struct *work)
1175 {
1176         struct btrfs_async_commit *ac =
1177                 container_of(work, struct btrfs_async_commit, work.work);
1178
1179         btrfs_commit_transaction(ac->newtrans, ac->root);
1180         kfree(ac);
1181 }
1182
1183 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1184                                    struct btrfs_root *root,
1185                                    int wait_for_unblock)
1186 {
1187         struct btrfs_async_commit *ac;
1188         struct btrfs_transaction *cur_trans;
1189
1190         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1191         if (!ac)
1192                 return -ENOMEM;
1193
1194         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1195         ac->root = root;
1196         ac->newtrans = btrfs_join_transaction(root);
1197         if (IS_ERR(ac->newtrans)) {
1198                 int err = PTR_ERR(ac->newtrans);
1199                 kfree(ac);
1200                 return err;
1201         }
1202
1203         /* take transaction reference */
1204         cur_trans = trans->transaction;
1205         atomic_inc(&cur_trans->use_count);
1206
1207         btrfs_end_transaction(trans, root);
1208         schedule_delayed_work(&ac->work, 0);
1209
1210         /* wait for transaction to start and unblock */
1211         if (wait_for_unblock)
1212                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1213         else
1214                 wait_current_trans_commit_start(root, cur_trans);
1215
1216         if (current->journal_info == trans)
1217                 current->journal_info = NULL;
1218
1219         put_transaction(cur_trans);
1220         return 0;
1221 }
1222
1223
1224 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1225                                 struct btrfs_root *root, int err)
1226 {
1227         struct btrfs_transaction *cur_trans = trans->transaction;
1228
1229         WARN_ON(trans->use_count > 1);
1230
1231         btrfs_abort_transaction(trans, root, err);
1232
1233         spin_lock(&root->fs_info->trans_lock);
1234         list_del_init(&cur_trans->list);
1235         if (cur_trans == root->fs_info->running_transaction) {
1236                 root->fs_info->running_transaction = NULL;
1237                 root->fs_info->trans_no_join = 0;
1238         }
1239         spin_unlock(&root->fs_info->trans_lock);
1240
1241         btrfs_cleanup_one_transaction(trans->transaction, root);
1242
1243         put_transaction(cur_trans);
1244         put_transaction(cur_trans);
1245
1246         trace_btrfs_transaction_commit(root);
1247
1248         btrfs_scrub_continue(root);
1249
1250         if (current->journal_info == trans)
1251                 current->journal_info = NULL;
1252
1253         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1254 }
1255
1256 /*
1257  * btrfs_transaction state sequence:
1258  *    in_commit = 0, blocked = 0  (initial)
1259  *    in_commit = 1, blocked = 1
1260  *    blocked = 0
1261  *    commit_done = 1
1262  */
1263 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1264                              struct btrfs_root *root)
1265 {
1266         unsigned long joined = 0;
1267         struct btrfs_transaction *cur_trans = trans->transaction;
1268         struct btrfs_transaction *prev_trans = NULL;
1269         DEFINE_WAIT(wait);
1270         int ret = -EIO;
1271         int should_grow = 0;
1272         unsigned long now = get_seconds();
1273         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1274
1275         btrfs_run_ordered_operations(root, 0);
1276
1277         btrfs_trans_release_metadata(trans, root);
1278         trans->block_rsv = NULL;
1279
1280         if (cur_trans->aborted)
1281                 goto cleanup_transaction;
1282
1283         /* make a pass through all the delayed refs we have so far
1284          * any runnings procs may add more while we are here
1285          */
1286         ret = btrfs_run_delayed_refs(trans, root, 0);
1287         if (ret)
1288                 goto cleanup_transaction;
1289
1290         cur_trans = trans->transaction;
1291
1292         /*
1293          * set the flushing flag so procs in this transaction have to
1294          * start sending their work down.
1295          */
1296         cur_trans->delayed_refs.flushing = 1;
1297
1298         ret = btrfs_run_delayed_refs(trans, root, 0);
1299         if (ret)
1300                 goto cleanup_transaction;
1301
1302         spin_lock(&cur_trans->commit_lock);
1303         if (cur_trans->in_commit) {
1304                 spin_unlock(&cur_trans->commit_lock);
1305                 atomic_inc(&cur_trans->use_count);
1306                 ret = btrfs_end_transaction(trans, root);
1307
1308                 wait_for_commit(root, cur_trans);
1309
1310                 put_transaction(cur_trans);
1311
1312                 return ret;
1313         }
1314
1315         trans->transaction->in_commit = 1;
1316         trans->transaction->blocked = 1;
1317         spin_unlock(&cur_trans->commit_lock);
1318         wake_up(&root->fs_info->transaction_blocked_wait);
1319
1320         spin_lock(&root->fs_info->trans_lock);
1321         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1322                 prev_trans = list_entry(cur_trans->list.prev,
1323                                         struct btrfs_transaction, list);
1324                 if (!prev_trans->commit_done) {
1325                         atomic_inc(&prev_trans->use_count);
1326                         spin_unlock(&root->fs_info->trans_lock);
1327
1328                         wait_for_commit(root, prev_trans);
1329
1330                         put_transaction(prev_trans);
1331                 } else {
1332                         spin_unlock(&root->fs_info->trans_lock);
1333                 }
1334         } else {
1335                 spin_unlock(&root->fs_info->trans_lock);
1336         }
1337
1338         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1339                 should_grow = 1;
1340
1341         do {
1342                 int snap_pending = 0;
1343
1344                 joined = cur_trans->num_joined;
1345                 if (!list_empty(&trans->transaction->pending_snapshots))
1346                         snap_pending = 1;
1347
1348                 WARN_ON(cur_trans != trans->transaction);
1349
1350                 if (flush_on_commit || snap_pending) {
1351                         btrfs_start_delalloc_inodes(root, 1);
1352                         btrfs_wait_ordered_extents(root, 0, 1);
1353                 }
1354
1355                 ret = btrfs_run_delayed_items(trans, root);
1356                 if (ret)
1357                         goto cleanup_transaction;
1358
1359                 /*
1360                  * rename don't use btrfs_join_transaction, so, once we
1361                  * set the transaction to blocked above, we aren't going
1362                  * to get any new ordered operations.  We can safely run
1363                  * it here and no for sure that nothing new will be added
1364                  * to the list
1365                  */
1366                 btrfs_run_ordered_operations(root, 1);
1367
1368                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1369                                 TASK_UNINTERRUPTIBLE);
1370
1371                 if (atomic_read(&cur_trans->num_writers) > 1)
1372                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1373                 else if (should_grow)
1374                         schedule_timeout(1);
1375
1376                 finish_wait(&cur_trans->writer_wait, &wait);
1377         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1378                  (should_grow && cur_trans->num_joined != joined));
1379
1380         /*
1381          * Ok now we need to make sure to block out any other joins while we
1382          * commit the transaction.  We could have started a join before setting
1383          * no_join so make sure to wait for num_writers to == 1 again.
1384          */
1385         spin_lock(&root->fs_info->trans_lock);
1386         root->fs_info->trans_no_join = 1;
1387         spin_unlock(&root->fs_info->trans_lock);
1388         wait_event(cur_trans->writer_wait,
1389                    atomic_read(&cur_trans->num_writers) == 1);
1390
1391         /*
1392          * the reloc mutex makes sure that we stop
1393          * the balancing code from coming in and moving
1394          * extents around in the middle of the commit
1395          */
1396         mutex_lock(&root->fs_info->reloc_mutex);
1397
1398         ret = btrfs_run_delayed_items(trans, root);
1399         if (ret) {
1400                 mutex_unlock(&root->fs_info->reloc_mutex);
1401                 goto cleanup_transaction;
1402         }
1403
1404         ret = create_pending_snapshots(trans, root->fs_info);
1405         if (ret) {
1406                 mutex_unlock(&root->fs_info->reloc_mutex);
1407                 goto cleanup_transaction;
1408         }
1409
1410         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1411         if (ret) {
1412                 mutex_unlock(&root->fs_info->reloc_mutex);
1413                 goto cleanup_transaction;
1414         }
1415
1416         /*
1417          * make sure none of the code above managed to slip in a
1418          * delayed item
1419          */
1420         btrfs_assert_delayed_root_empty(root);
1421
1422         WARN_ON(cur_trans != trans->transaction);
1423
1424         btrfs_scrub_pause(root);
1425         /* btrfs_commit_tree_roots is responsible for getting the
1426          * various roots consistent with each other.  Every pointer
1427          * in the tree of tree roots has to point to the most up to date
1428          * root for every subvolume and other tree.  So, we have to keep
1429          * the tree logging code from jumping in and changing any
1430          * of the trees.
1431          *
1432          * At this point in the commit, there can't be any tree-log
1433          * writers, but a little lower down we drop the trans mutex
1434          * and let new people in.  By holding the tree_log_mutex
1435          * from now until after the super is written, we avoid races
1436          * with the tree-log code.
1437          */
1438         mutex_lock(&root->fs_info->tree_log_mutex);
1439
1440         ret = commit_fs_roots(trans, root);
1441         if (ret) {
1442                 mutex_unlock(&root->fs_info->tree_log_mutex);
1443                 mutex_unlock(&root->fs_info->reloc_mutex);
1444                 goto cleanup_transaction;
1445         }
1446
1447         /* commit_fs_roots gets rid of all the tree log roots, it is now
1448          * safe to free the root of tree log roots
1449          */
1450         btrfs_free_log_root_tree(trans, root->fs_info);
1451
1452         ret = commit_cowonly_roots(trans, root);
1453         if (ret) {
1454                 mutex_unlock(&root->fs_info->tree_log_mutex);
1455                 mutex_unlock(&root->fs_info->reloc_mutex);
1456                 goto cleanup_transaction;
1457         }
1458
1459         btrfs_prepare_extent_commit(trans, root);
1460
1461         cur_trans = root->fs_info->running_transaction;
1462
1463         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1464                             root->fs_info->tree_root->node);
1465         switch_commit_root(root->fs_info->tree_root);
1466
1467         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1468                             root->fs_info->chunk_root->node);
1469         switch_commit_root(root->fs_info->chunk_root);
1470
1471         update_super_roots(root);
1472
1473         if (!root->fs_info->log_root_recovering) {
1474                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1475                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1476         }
1477
1478         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1479                sizeof(*root->fs_info->super_copy));
1480
1481         trans->transaction->blocked = 0;
1482         spin_lock(&root->fs_info->trans_lock);
1483         root->fs_info->running_transaction = NULL;
1484         root->fs_info->trans_no_join = 0;
1485         spin_unlock(&root->fs_info->trans_lock);
1486         mutex_unlock(&root->fs_info->reloc_mutex);
1487
1488         wake_up(&root->fs_info->transaction_wait);
1489
1490         ret = btrfs_write_and_wait_transaction(trans, root);
1491         if (ret) {
1492                 btrfs_error(root->fs_info, ret,
1493                             "Error while writing out transaction.");
1494                 mutex_unlock(&root->fs_info->tree_log_mutex);
1495                 goto cleanup_transaction;
1496         }
1497
1498         ret = write_ctree_super(trans, root, 0);
1499         if (ret) {
1500                 mutex_unlock(&root->fs_info->tree_log_mutex);
1501                 goto cleanup_transaction;
1502         }
1503
1504         /*
1505          * the super is written, we can safely allow the tree-loggers
1506          * to go about their business
1507          */
1508         mutex_unlock(&root->fs_info->tree_log_mutex);
1509
1510         btrfs_finish_extent_commit(trans, root);
1511
1512         cur_trans->commit_done = 1;
1513
1514         root->fs_info->last_trans_committed = cur_trans->transid;
1515
1516         wake_up(&cur_trans->commit_wait);
1517
1518         spin_lock(&root->fs_info->trans_lock);
1519         list_del_init(&cur_trans->list);
1520         spin_unlock(&root->fs_info->trans_lock);
1521
1522         put_transaction(cur_trans);
1523         put_transaction(cur_trans);
1524
1525         sb_end_intwrite(root->fs_info->sb);
1526
1527         trace_btrfs_transaction_commit(root);
1528
1529         btrfs_scrub_continue(root);
1530
1531         if (current->journal_info == trans)
1532                 current->journal_info = NULL;
1533
1534         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1535
1536         if (current != root->fs_info->transaction_kthread)
1537                 btrfs_run_delayed_iputs(root);
1538
1539         return ret;
1540
1541 cleanup_transaction:
1542         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1543 //      WARN_ON(1);
1544         if (current->journal_info == trans)
1545                 current->journal_info = NULL;
1546         cleanup_transaction(trans, root, ret);
1547
1548         return ret;
1549 }
1550
1551 /*
1552  * interface function to delete all the snapshots we have scheduled for deletion
1553  */
1554 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1555 {
1556         LIST_HEAD(list);
1557         struct btrfs_fs_info *fs_info = root->fs_info;
1558
1559         spin_lock(&fs_info->trans_lock);
1560         list_splice_init(&fs_info->dead_roots, &list);
1561         spin_unlock(&fs_info->trans_lock);
1562
1563         while (!list_empty(&list)) {
1564                 int ret;
1565
1566                 root = list_entry(list.next, struct btrfs_root, root_list);
1567                 list_del(&root->root_list);
1568
1569                 btrfs_kill_all_delayed_nodes(root);
1570
1571                 if (btrfs_header_backref_rev(root->node) <
1572                     BTRFS_MIXED_BACKREF_REV)
1573                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1574                 else
1575                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1576                 BUG_ON(ret < 0);
1577         }
1578         return 0;
1579 }