fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33
  34 #define BTRFS_ROOT_TRANS_TAG 0
  35
  36 void put_transaction(struct btrfs_transaction *transaction)
  37 {
  38         WARN_ON(atomic_read(&transaction->use_count) == 0);
  39         if (atomic_dec_and_test(&transaction->use_count)) {
  40                 BUG_ON(!list_empty(&transaction->list));
  41                 WARN_ON(transaction->delayed_refs.root.rb_node);
  42                 memset(transaction, 0, sizeof(*transaction));
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static noinline void switch_commit_root(struct btrfs_root *root)
  48 {
  49         free_extent_buffer(root->commit_root);
  50         root->commit_root = btrfs_root_node(root);
  51 }
  52
  53 /*
  54  * either allocate a new transaction or hop into the existing one
  55  */
  56 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  57 {
  58         struct btrfs_transaction *cur_trans;
  59         struct btrfs_fs_info *fs_info = root->fs_info;
  60
  61         spin_lock(&fs_info->trans_lock);
  62 loop:
  63         /* The file system has been taken offline. No new transactions. */
  64         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  65                 spin_unlock(&fs_info->trans_lock);
  66                 return -EROFS;
  67         }
  68
  69         if (fs_info->trans_no_join) {
  70                 if (!nofail) {
  71                         spin_unlock(&fs_info->trans_lock);
  72                         return -EBUSY;
  73                 }
  74         }
  75
  76         cur_trans = fs_info->running_transaction;
  77         if (cur_trans) {
  78                 if (cur_trans->aborted) {
  79                         spin_unlock(&fs_info->trans_lock);
  80                         return cur_trans->aborted;
  81                 }
  82                 atomic_inc(&cur_trans->use_count);
  83                 atomic_inc(&cur_trans->num_writers);
  84                 cur_trans->num_joined++;
  85                 spin_unlock(&fs_info->trans_lock);
  86                 return 0;
  87         }
  88         spin_unlock(&fs_info->trans_lock);
  89
  90         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  91         if (!cur_trans)
  92                 return -ENOMEM;
  93
  94         spin_lock(&fs_info->trans_lock);
  95         if (fs_info->running_transaction) {
  96                 /*
  97                  * someone started a transaction after we unlocked.  Make sure
  98                  * to redo the trans_no_join checks above
  99                  */
 100                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 101                 cur_trans = fs_info->running_transaction;
 102                 goto loop;
 103         } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 104                 spin_unlock(&fs_info->trans_lock);
 105                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 106                 return -EROFS;
 107         }
 108
 109         atomic_set(&cur_trans->num_writers, 1);
 110         cur_trans->num_joined = 0;
 111         init_waitqueue_head(&cur_trans->writer_wait);
 112         init_waitqueue_head(&cur_trans->commit_wait);
 113         cur_trans->in_commit = 0;
 114         cur_trans->blocked = 0;
 115         /*
 116          * One for this trans handle, one so it will live on until we
 117          * commit the transaction.
 118          */
 119         atomic_set(&cur_trans->use_count, 2);
 120         cur_trans->commit_done = 0;
 121         cur_trans->start_time = get_seconds();
 122
 123         cur_trans->delayed_refs.root = RB_ROOT;
 124         cur_trans->delayed_refs.num_entries = 0;
 125         cur_trans->delayed_refs.num_heads_ready = 0;
 126         cur_trans->delayed_refs.num_heads = 0;
 127         cur_trans->delayed_refs.flushing = 0;
 128         cur_trans->delayed_refs.run_delayed_start = 0;
 129
 130         /*
 131          * although the tree mod log is per file system and not per transaction,
 132          * the log must never go across transaction boundaries.
 133          */
 134         smp_mb();
 135         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 136                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 137                         "creating a fresh transaction\n");
 138                 WARN_ON(1);
 139         }
 140         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 141                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 142                         "creating a fresh transaction\n");
 143                 WARN_ON(1);
 144         }
 145         atomic_set(&fs_info->tree_mod_seq, 0);
 146
 147         spin_lock_init(&cur_trans->commit_lock);
 148         spin_lock_init(&cur_trans->delayed_refs.lock);
 149
 150         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 151         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 152         extent_io_tree_init(&cur_trans->dirty_pages,
 153                              fs_info->btree_inode->i_mapping);
 154         fs_info->generation++;
 155         cur_trans->transid = fs_info->generation;
 156         fs_info->running_transaction = cur_trans;
 157         cur_trans->aborted = 0;
 158         spin_unlock(&fs_info->trans_lock);
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * this does all the record keeping required to make sure that a reference
 165  * counted root is properly recorded in a given transaction.  This is required
 166  * to make sure the old root from before we joined the transaction is deleted
 167  * when the transaction commits
 168  */
 169 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 170                                struct btrfs_root *root)
 171 {
 172         if (root->ref_cows && root->last_trans < trans->transid) {
 173                 WARN_ON(root == root->fs_info->extent_root);
 174                 WARN_ON(root->commit_root != root->node);
 175
 176                 /*
 177                  * see below for in_trans_setup usage rules
 178                  * we have the reloc mutex held now, so there
 179                  * is only one writer in this function
 180                  */
 181                 root->in_trans_setup = 1;
 182
 183                 /* make sure readers find in_trans_setup before
 184                  * they find our root->last_trans update
 185                  */
 186                 smp_wmb();
 187
 188                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 189                 if (root->last_trans == trans->transid) {
 190                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 191                         return 0;
 192                 }
 193                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 194                            (unsigned long)root->root_key.objectid,
 195                            BTRFS_ROOT_TRANS_TAG);
 196                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 197                 root->last_trans = trans->transid;
 198
 199                 /* this is pretty tricky.  We don't want to
 200                  * take the relocation lock in btrfs_record_root_in_trans
 201                  * unless we're really doing the first setup for this root in
 202                  * this transaction.
 203                  *
 204                  * Normally we'd use root->last_trans as a flag to decide
 205                  * if we want to take the expensive mutex.
 206                  *
 207                  * But, we have to set root->last_trans before we
 208                  * init the relocation root, otherwise, we trip over warnings
 209                  * in ctree.c.  The solution used here is to flag ourselves
 210                  * with root->in_trans_setup.  When this is 1, we're still
 211                  * fixing up the reloc trees and everyone must wait.
 212                  *
 213                  * When this is zero, they can trust root->last_trans and fly
 214                  * through btrfs_record_root_in_trans without having to take the
 215                  * lock.  smp_wmb() makes sure that all the writes above are
 216                  * done before we pop in the zero below
 217                  */
 218                 btrfs_init_reloc_root(trans, root);
 219                 smp_wmb();
 220                 root->in_trans_setup = 0;
 221         }
 222         return 0;
 223 }
 224
 225
 226 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 227                                struct btrfs_root *root)
 228 {
 229         if (!root->ref_cows)
 230                 return 0;
 231
 232         /*
 233          * see record_root_in_trans for comments about in_trans_setup usage
 234          * and barriers
 235          */
 236         smp_rmb();
 237         if (root->last_trans == trans->transid &&
 238             !root->in_trans_setup)
 239                 return 0;
 240
 241         mutex_lock(&root->fs_info->reloc_mutex);
 242         record_root_in_trans(trans, root);
 243         mutex_unlock(&root->fs_info->reloc_mutex);
 244
 245         return 0;
 246 }
 247
 248 /* wait for commit against the current transaction to become unblocked
 249  * when this is done, it is safe to start a new transaction, but the current
 250  * transaction might not be fully on disk.
 251  */
 252 static void wait_current_trans(struct btrfs_root *root)
 253 {
 254         struct btrfs_transaction *cur_trans;
 255
 256         spin_lock(&root->fs_info->trans_lock);
 257         cur_trans = root->fs_info->running_transaction;
 258         if (cur_trans && cur_trans->blocked) {
 259                 atomic_inc(&cur_trans->use_count);
 260                 spin_unlock(&root->fs_info->trans_lock);
 261
 262                 wait_event(root->fs_info->transaction_wait,
 263                            !cur_trans->blocked);
 264                 put_transaction(cur_trans);
 265         } else {
 266                 spin_unlock(&root->fs_info->trans_lock);
 267         }
 268 }
 269
 270 enum btrfs_trans_type {
 271         TRANS_START,
 272         TRANS_JOIN,
 273         TRANS_USERSPACE,
 274         TRANS_JOIN_NOLOCK,
 275 };
 276
 277 static int may_wait_transaction(struct btrfs_root *root, int type)
 278 {
 279         if (root->fs_info->log_root_recovering)
 280                 return 0;
 281
 282         if (type == TRANS_USERSPACE)
 283                 return 1;
 284
 285         if (type == TRANS_START &&
 286             !atomic_read(&root->fs_info->open_ioctl_trans))
 287                 return 1;
 288
 289         return 0;
 290 }
 291
 292 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 293                                                     u64 num_items, int type,
 294                                                     int noflush)
 295 {
 296         struct btrfs_trans_handle *h;
 297         struct btrfs_transaction *cur_trans;
 298         u64 num_bytes = 0;
 299         int ret;
 300         u64 qgroup_reserved = 0;
 301
 302         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 303                 return ERR_PTR(-EROFS);
 304
 305         if (current->journal_info) {
 306                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 307                 h = current->journal_info;
 308                 h->use_count++;
 309                 h->orig_rsv = h->block_rsv;
 310                 h->block_rsv = NULL;
 311                 goto got_it;
 312         }
 313
 314         /*
 315          * Do the reservation before we join the transaction so we can do all
 316          * the appropriate flushing if need be.
 317          */
 318         if (num_items > 0 && root != root->fs_info->chunk_root) {
 319                 if (root->fs_info->quota_enabled &&
 320                     is_fstree(root->root_key.objectid)) {
 321                         qgroup_reserved = num_items * root->leafsize;
 322                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 323                         if (ret)
 324                                 return ERR_PTR(ret);
 325                 }
 326
 327                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 328                 if (noflush)
 329                         ret = btrfs_block_rsv_add_noflush(root,
 330                                                 &root->fs_info->trans_block_rsv,
 331                                                 num_bytes);
 332                 else
 333                         ret = btrfs_block_rsv_add(root,
 334                                                 &root->fs_info->trans_block_rsv,
 335                                                 num_bytes);
 336                 if (ret)
 337                         return ERR_PTR(ret);
 338         }
 339 again:
 340         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 341         if (!h)
 342                 return ERR_PTR(-ENOMEM);
 343
 344         sb_start_intwrite(root->fs_info->sb);
 345
 346         if (may_wait_transaction(root, type))
 347                 wait_current_trans(root);
 348
 349         do {
 350                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 351                 if (ret == -EBUSY)
 352                         wait_current_trans(root);
 353         } while (ret == -EBUSY);
 354
 355         if (ret < 0) {
 356                 sb_end_intwrite(root->fs_info->sb);
 357                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 358                 return ERR_PTR(ret);
 359         }
 360
 361         cur_trans = root->fs_info->running_transaction;
 362
 363         h->transid = cur_trans->transid;
 364         h->transaction = cur_trans;
 365         h->blocks_used = 0;
 366         h->bytes_reserved = 0;
 367         h->root = root;
 368         h->delayed_ref_updates = 0;
 369         h->use_count = 1;
 370         h->adding_csums = 0;
 371         h->block_rsv = NULL;
 372         h->orig_rsv = NULL;
 373         h->aborted = 0;
 374         h->qgroup_reserved = qgroup_reserved;
 375         h->delayed_ref_elem.seq = 0;
 376         INIT_LIST_HEAD(&h->qgroup_ref_list);
 377
 378         smp_mb();
 379         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 380                 btrfs_commit_transaction(h, root);
 381                 goto again;
 382         }
 383
 384         if (num_bytes) {
 385                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 386                                               h->transid, num_bytes, 1);
 387                 h->block_rsv = &root->fs_info->trans_block_rsv;
 388                 h->bytes_reserved = num_bytes;
 389         }
 390
 391 got_it:
 392         btrfs_record_root_in_trans(h, root);
 393
 394         if (!current->journal_info && type != TRANS_USERSPACE)
 395                 current->journal_info = h;
 396         return h;
 397 }
 398
 399 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 400                                                    int num_items)
 401 {
 402         return start_transaction(root, num_items, TRANS_START, 0);
 403 }
 404
 405 struct btrfs_trans_handle *btrfs_start_transaction_noflush(
 406                                         struct btrfs_root *root, int num_items)
 407 {
 408         return start_transaction(root, num_items, TRANS_START, 1);
 409 }
 410
 411 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 412 {
 413         return start_transaction(root, 0, TRANS_JOIN, 0);
 414 }
 415
 416 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 417 {
 418         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 419 }
 420
 421 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 422 {
 423         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 424 }
 425
 426 /* wait for a transaction commit to be fully complete */
 427 static noinline void wait_for_commit(struct btrfs_root *root,
 428                                     struct btrfs_transaction *commit)
 429 {
 430         wait_event(commit->commit_wait, commit->commit_done);
 431 }
 432
 433 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 434 {
 435         struct btrfs_transaction *cur_trans = NULL, *t;
 436         int ret;
 437
 438         ret = 0;
 439         if (transid) {
 440                 if (transid <= root->fs_info->last_trans_committed)
 441                         goto out;
 442
 443                 /* find specified transaction */
 444                 spin_lock(&root->fs_info->trans_lock);
 445                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 446                         if (t->transid == transid) {
 447                                 cur_trans = t;
 448                                 atomic_inc(&cur_trans->use_count);
 449                                 break;
 450                         }
 451                         if (t->transid > transid)
 452                                 break;
 453                 }
 454                 spin_unlock(&root->fs_info->trans_lock);
 455                 ret = -EINVAL;
 456                 if (!cur_trans)
 457                         goto out;  /* bad transid */
 458         } else {
 459                 /* find newest transaction that is committing | committed */
 460                 spin_lock(&root->fs_info->trans_lock);
 461                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 462                                             list) {
 463                         if (t->in_commit) {
 464                                 if (t->commit_done)
 465                                         break;
 466                                 cur_trans = t;
 467                                 atomic_inc(&cur_trans->use_count);
 468                                 break;
 469                         }
 470                 }
 471                 spin_unlock(&root->fs_info->trans_lock);
 472                 if (!cur_trans)
 473                         goto out;  /* nothing committing|committed */
 474         }
 475
 476         wait_for_commit(root, cur_trans);
 477
 478         put_transaction(cur_trans);
 479         ret = 0;
 480 out:
 481         return ret;
 482 }
 483
 484 void btrfs_throttle(struct btrfs_root *root)
 485 {
 486         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 487                 wait_current_trans(root);
 488 }
 489
 490 static int should_end_transaction(struct btrfs_trans_handle *trans,
 491                                   struct btrfs_root *root)
 492 {
 493         int ret;
 494
 495         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 496         return ret ? 1 : 0;
 497 }
 498
 499 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 500                                  struct btrfs_root *root)
 501 {
 502         struct btrfs_transaction *cur_trans = trans->transaction;
 503         int updates;
 504         int err;
 505
 506         smp_mb();
 507         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 508                 return 1;
 509
 510         updates = trans->delayed_ref_updates;
 511         trans->delayed_ref_updates = 0;
 512         if (updates) {
 513                 err = btrfs_run_delayed_refs(trans, root, updates);
 514                 if (err) /* Error code will also eval true */
 515                         return err;
 516         }
 517
 518         return should_end_transaction(trans, root);
 519 }
 520
 521 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 522                           struct btrfs_root *root, int throttle, int lock)
 523 {
 524         struct btrfs_transaction *cur_trans = trans->transaction;
 525         struct btrfs_fs_info *info = root->fs_info;
 526         int count = 0;
 527         int err = 0;
 528
 529         if (--trans->use_count) {
 530                 trans->block_rsv = trans->orig_rsv;
 531                 return 0;
 532         }
 533
 534         /*
 535          * do the qgroup accounting as early as possible
 536          */
 537         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 538
 539         btrfs_trans_release_metadata(trans, root);
 540         trans->block_rsv = NULL;
 541         /*
 542          * the same root has to be passed to start_transaction and
 543          * end_transaction. Subvolume quota depends on this.
 544          */
 545         WARN_ON(trans->root != root);
 546
 547         if (trans->qgroup_reserved) {
 548                 btrfs_qgroup_free(root, trans->qgroup_reserved);
 549                 trans->qgroup_reserved = 0;
 550         }
 551
 552         while (count < 2) {
 553                 unsigned long cur = trans->delayed_ref_updates;
 554                 trans->delayed_ref_updates = 0;
 555                 if (cur &&
 556                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 557                         trans->delayed_ref_updates = 0;
 558                         btrfs_run_delayed_refs(trans, root, cur);
 559                 } else {
 560                         break;
 561                 }
 562                 count++;
 563         }
 564         btrfs_trans_release_metadata(trans, root);
 565         trans->block_rsv = NULL;
 566
 567         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 568             should_end_transaction(trans, root)) {
 569                 trans->transaction->blocked = 1;
 570                 smp_wmb();
 571         }
 572
 573         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 574                 if (throttle) {
 575                         /*
 576                          * We may race with somebody else here so end up having
 577                          * to call end_transaction on ourselves again, so inc
 578                          * our use_count.
 579                          */
 580                         trans->use_count++;
 581                         return btrfs_commit_transaction(trans, root);
 582                 } else {
 583                         wake_up_process(info->transaction_kthread);
 584                 }
 585         }
 586
 587         sb_end_intwrite(root->fs_info->sb);
 588
 589         WARN_ON(cur_trans != info->running_transaction);
 590         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 591         atomic_dec(&cur_trans->num_writers);
 592
 593         smp_mb();
 594         if (waitqueue_active(&cur_trans->writer_wait))
 595                 wake_up(&cur_trans->writer_wait);
 596         put_transaction(cur_trans);
 597
 598         if (current->journal_info == trans)
 599                 current->journal_info = NULL;
 600
 601         if (throttle)
 602                 btrfs_run_delayed_iputs(root);
 603
 604         if (trans->aborted ||
 605             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 606                 err = -EIO;
 607         }
 608         assert_qgroups_uptodate(trans);
 609
 610         memset(trans, 0, sizeof(*trans));
 611         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 612         return err;
 613 }
 614
 615 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 616                           struct btrfs_root *root)
 617 {
 618         int ret;
 619
 620         ret = __btrfs_end_transaction(trans, root, 0, 1);
 621         if (ret)
 622                 return ret;
 623         return 0;
 624 }
 625
 626 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 627                                    struct btrfs_root *root)
 628 {
 629         int ret;
 630
 631         ret = __btrfs_end_transaction(trans, root, 1, 1);
 632         if (ret)
 633                 return ret;
 634         return 0;
 635 }
 636
 637 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 638                                  struct btrfs_root *root)
 639 {
 640         int ret;
 641
 642         ret = __btrfs_end_transaction(trans, root, 0, 0);
 643         if (ret)
 644                 return ret;
 645         return 0;
 646 }
 647
 648 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 649                                 struct btrfs_root *root)
 650 {
 651         return __btrfs_end_transaction(trans, root, 1, 1);
 652 }
 653
 654 /*
 655  * when btree blocks are allocated, they have some corresponding bits set for
 656  * them in one of two extent_io trees.  This is used to make sure all of
 657  * those extents are sent to disk but does not wait on them
 658  */
 659 int btrfs_write_marked_extents(struct btrfs_root *root,
 660                                struct extent_io_tree *dirty_pages, int mark)
 661 {
 662         int err = 0;
 663         int werr = 0;
 664         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 665         u64 start = 0;
 666         u64 end;
 667
 668         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 669                                       mark)) {
 670                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 671                                    GFP_NOFS);
 672                 err = filemap_fdatawrite_range(mapping, start, end);
 673                 if (err)
 674                         werr = err;
 675                 cond_resched();
 676                 start = end + 1;
 677         }
 678         if (err)
 679                 werr = err;
 680         return werr;
 681 }
 682
 683 /*
 684  * when btree blocks are allocated, they have some corresponding bits set for
 685  * them in one of two extent_io trees.  This is used to make sure all of
 686  * those extents are on disk for transaction or log commit.  We wait
 687  * on all the pages and clear them from the dirty pages state tree
 688  */
 689 int btrfs_wait_marked_extents(struct btrfs_root *root,
 690                               struct extent_io_tree *dirty_pages, int mark)
 691 {
 692         int err = 0;
 693         int werr = 0;
 694         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 695         u64 start = 0;
 696         u64 end;
 697
 698         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 699                                       EXTENT_NEED_WAIT)) {
 700                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 701                 err = filemap_fdatawait_range(mapping, start, end);
 702                 if (err)
 703                         werr = err;
 704                 cond_resched();
 705                 start = end + 1;
 706         }
 707         if (err)
 708                 werr = err;
 709         return werr;
 710 }
 711
 712 /*
 713  * when btree blocks are allocated, they have some corresponding bits set for
 714  * them in one of two extent_io trees.  This is used to make sure all of
 715  * those extents are on disk for transaction or log commit
 716  */
 717 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 718                                 struct extent_io_tree *dirty_pages, int mark)
 719 {
 720         int ret;
 721         int ret2;
 722
 723         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 724         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 725
 726         if (ret)
 727                 return ret;
 728         if (ret2)
 729                 return ret2;
 730         return 0;
 731 }
 732
 733 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 734                                      struct btrfs_root *root)
 735 {
 736         if (!trans || !trans->transaction) {
 737                 struct inode *btree_inode;
 738                 btree_inode = root->fs_info->btree_inode;
 739                 return filemap_write_and_wait(btree_inode->i_mapping);
 740         }
 741         return btrfs_write_and_wait_marked_extents(root,
 742                                            &trans->transaction->dirty_pages,
 743                                            EXTENT_DIRTY);
 744 }
 745
 746 /*
 747  * this is used to update the root pointer in the tree of tree roots.
 748  *
 749  * But, in the case of the extent allocation tree, updating the root
 750  * pointer may allocate blocks which may change the root of the extent
 751  * allocation tree.
 752  *
 753  * So, this loops and repeats and makes sure the cowonly root didn't
 754  * change while the root pointer was being updated in the metadata.
 755  */
 756 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 757                                struct btrfs_root *root)
 758 {
 759         int ret;
 760         u64 old_root_bytenr;
 761         u64 old_root_used;
 762         struct btrfs_root *tree_root = root->fs_info->tree_root;
 763
 764         old_root_used = btrfs_root_used(&root->root_item);
 765         btrfs_write_dirty_block_groups(trans, root);
 766
 767         while (1) {
 768                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 769                 if (old_root_bytenr == root->node->start &&
 770                     old_root_used == btrfs_root_used(&root->root_item))
 771                         break;
 772
 773                 btrfs_set_root_node(&root->root_item, root->node);
 774                 ret = btrfs_update_root(trans, tree_root,
 775                                         &root->root_key,
 776                                         &root->root_item);
 777                 if (ret)
 778                         return ret;
 779
 780                 old_root_used = btrfs_root_used(&root->root_item);
 781                 ret = btrfs_write_dirty_block_groups(trans, root);
 782                 if (ret)
 783                         return ret;
 784         }
 785
 786         if (root != root->fs_info->extent_root)
 787                 switch_commit_root(root);
 788
 789         return 0;
 790 }
 791
 792 /*
 793  * update all the cowonly tree roots on disk
 794  *
 795  * The error handling in this function may not be obvious. Any of the
 796  * failures will cause the file system to go offline. We still need
 797  * to clean up the delayed refs.
 798  */
 799 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 800                                          struct btrfs_root *root)
 801 {
 802         struct btrfs_fs_info *fs_info = root->fs_info;
 803         struct list_head *next;
 804         struct extent_buffer *eb;
 805         int ret;
 806
 807         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 808         if (ret)
 809                 return ret;
 810
 811         eb = btrfs_lock_root_node(fs_info->tree_root);
 812         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 813                               0, &eb);
 814         btrfs_tree_unlock(eb);
 815         free_extent_buffer(eb);
 816
 817         if (ret)
 818                 return ret;
 819
 820         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 821         if (ret)
 822                 return ret;
 823
 824         ret = btrfs_run_dev_stats(trans, root->fs_info);
 825         BUG_ON(ret);
 826
 827         ret = btrfs_run_qgroups(trans, root->fs_info);
 828         BUG_ON(ret);
 829
 830         /* run_qgroups might have added some more refs */
 831         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 832         BUG_ON(ret);
 833
 834         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 835                 next = fs_info->dirty_cowonly_roots.next;
 836                 list_del_init(next);
 837                 root = list_entry(next, struct btrfs_root, dirty_list);
 838
 839                 ret = update_cowonly_root(trans, root);
 840                 if (ret)
 841                         return ret;
 842         }
 843
 844         down_write(&fs_info->extent_commit_sem);
 845         switch_commit_root(fs_info->extent_root);
 846         up_write(&fs_info->extent_commit_sem);
 847
 848         return 0;
 849 }
 850
 851 /*
 852  * dead roots are old snapshots that need to be deleted.  This allocates
 853  * a dirty root struct and adds it into the list of dead roots that need to
 854  * be deleted
 855  */
 856 int btrfs_add_dead_root(struct btrfs_root *root)
 857 {
 858         spin_lock(&root->fs_info->trans_lock);
 859         list_add(&root->root_list, &root->fs_info->dead_roots);
 860         spin_unlock(&root->fs_info->trans_lock);
 861         return 0;
 862 }
 863
 864 /*
 865  * update all the cowonly tree roots on disk
 866  */
 867 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 868                                     struct btrfs_root *root)
 869 {
 870         struct btrfs_root *gang[8];
 871         struct btrfs_fs_info *fs_info = root->fs_info;
 872         int i;
 873         int ret;
 874         int err = 0;
 875
 876         spin_lock(&fs_info->fs_roots_radix_lock);
 877         while (1) {
 878                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 879                                                  (void **)gang, 0,
 880                                                  ARRAY_SIZE(gang),
 881                                                  BTRFS_ROOT_TRANS_TAG);
 882                 if (ret == 0)
 883                         break;
 884                 for (i = 0; i < ret; i++) {
 885                         root = gang[i];
 886                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 887                                         (unsigned long)root->root_key.objectid,
 888                                         BTRFS_ROOT_TRANS_TAG);
 889                         spin_unlock(&fs_info->fs_roots_radix_lock);
 890
 891                         btrfs_free_log(trans, root);
 892                         btrfs_update_reloc_root(trans, root);
 893                         btrfs_orphan_commit_root(trans, root);
 894
 895                         btrfs_save_ino_cache(root, trans);
 896
 897                         /* see comments in should_cow_block() */
 898                         root->force_cow = 0;
 899                         smp_wmb();
 900
 901                         if (root->commit_root != root->node) {
 902                                 mutex_lock(&root->fs_commit_mutex);
 903                                 switch_commit_root(root);
 904                                 btrfs_unpin_free_ino(root);
 905                                 mutex_unlock(&root->fs_commit_mutex);
 906
 907                                 btrfs_set_root_node(&root->root_item,
 908                                                     root->node);
 909                         }
 910
 911                         err = btrfs_update_root(trans, fs_info->tree_root,
 912                                                 &root->root_key,
 913                                                 &root->root_item);
 914                         spin_lock(&fs_info->fs_roots_radix_lock);
 915                         if (err)
 916                                 break;
 917                 }
 918         }
 919         spin_unlock(&fs_info->fs_roots_radix_lock);
 920         return err;
 921 }
 922
 923 /*
 924  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 925  * otherwise every leaf in the btree is read and defragged.
 926  */
 927 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 928 {
 929         struct btrfs_fs_info *info = root->fs_info;
 930         struct btrfs_trans_handle *trans;
 931         int ret;
 932         unsigned long nr;
 933
 934         if (xchg(&root->defrag_running, 1))
 935                 return 0;
 936
 937         while (1) {
 938                 trans = btrfs_start_transaction(root, 0);
 939                 if (IS_ERR(trans))
 940                         return PTR_ERR(trans);
 941
 942                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 943
 944                 nr = trans->blocks_used;
 945                 btrfs_end_transaction(trans, root);
 946                 btrfs_btree_balance_dirty(info->tree_root, nr);
 947                 cond_resched();
 948
 949                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 950                         break;
 951         }
 952         root->defrag_running = 0;
 953         return ret;
 954 }
 955
 956 /*
 957  * new snapshots need to be created at a very specific time in the
 958  * transaction commit.  This does the actual creation
 959  */
 960 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 961                                    struct btrfs_fs_info *fs_info,
 962                                    struct btrfs_pending_snapshot *pending)
 963 {
 964         struct btrfs_key key;
 965         struct btrfs_root_item *new_root_item;
 966         struct btrfs_root *tree_root = fs_info->tree_root;
 967         struct btrfs_root *root = pending->root;
 968         struct btrfs_root *parent_root;
 969         struct btrfs_block_rsv *rsv;
 970         struct inode *parent_inode;
 971         struct btrfs_path *path;
 972         struct btrfs_dir_item *dir_item;
 973         struct dentry *parent;
 974         struct dentry *dentry;
 975         struct extent_buffer *tmp;
 976         struct extent_buffer *old;
 977         struct timespec cur_time = CURRENT_TIME;
 978         int ret;
 979         u64 to_reserve = 0;
 980         u64 index = 0;
 981         u64 objectid;
 982         u64 root_flags;
 983         uuid_le new_uuid;
 984
 985         path = btrfs_alloc_path();
 986         if (!path) {
 987                 ret = pending->error = -ENOMEM;
 988                 goto path_alloc_fail;
 989         }
 990
 991         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 992         if (!new_root_item) {
 993                 ret = pending->error = -ENOMEM;
 994                 goto root_item_alloc_fail;
 995         }
 996
 997         ret = btrfs_find_free_objectid(tree_root, &objectid);
 998         if (ret) {
 999                 pending->error = ret;
1000                 goto no_free_objectid;
1001         }
1002
1003         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1004
1005         if (to_reserve > 0) {
1006                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
1007                                                   to_reserve);
1008                 if (ret) {
1009                         pending->error = ret;
1010                         goto no_free_objectid;
1011                 }
1012         }
1013
1014         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
1015                                    objectid, pending->inherit);
1016         if (ret) {
1017                 pending->error = ret;
1018                 goto no_free_objectid;
1019         }
1020
1021         key.objectid = objectid;
1022         key.offset = (u64)-1;
1023         key.type = BTRFS_ROOT_ITEM_KEY;
1024
1025         rsv = trans->block_rsv;
1026         trans->block_rsv = &pending->block_rsv;
1027
1028         dentry = pending->dentry;
1029         parent = dget_parent(dentry);
1030         parent_inode = parent->d_inode;
1031         parent_root = BTRFS_I(parent_inode)->root;
1032         record_root_in_trans(trans, parent_root);
1033
1034         /*
1035          * insert the directory item
1036          */
1037         ret = btrfs_set_inode_index(parent_inode, &index);
1038         BUG_ON(ret); /* -ENOMEM */
1039
1040         /* check if there is a file/dir which has the same name. */
1041         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1042                                          btrfs_ino(parent_inode),
1043                                          dentry->d_name.name,
1044                                          dentry->d_name.len, 0);
1045         if (dir_item != NULL && !IS_ERR(dir_item)) {
1046                 pending->error = -EEXIST;
1047                 goto fail;
1048         } else if (IS_ERR(dir_item)) {
1049                 ret = PTR_ERR(dir_item);
1050                 goto abort_trans;
1051         }
1052         btrfs_release_path(path);
1053
1054         /*
1055          * pull in the delayed directory update
1056          * and the delayed inode item
1057          * otherwise we corrupt the FS during
1058          * snapshot
1059          */
1060         ret = btrfs_run_delayed_items(trans, root);
1061         if (ret)        /* Transaction aborted */
1062                 goto abort_trans;
1063
1064         record_root_in_trans(trans, root);
1065         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1066         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1067         btrfs_check_and_init_root_item(new_root_item);
1068
1069         root_flags = btrfs_root_flags(new_root_item);
1070         if (pending->readonly)
1071                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1072         else
1073                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1074         btrfs_set_root_flags(new_root_item, root_flags);
1075
1076         btrfs_set_root_generation_v2(new_root_item,
1077                         trans->transid);
1078         uuid_le_gen(&new_uuid);
1079         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1080         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1081                         BTRFS_UUID_SIZE);
1082         new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1083         new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1084         btrfs_set_root_otransid(new_root_item, trans->transid);
1085         memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1086         memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1087         btrfs_set_root_stransid(new_root_item, 0);
1088         btrfs_set_root_rtransid(new_root_item, 0);
1089
1090         old = btrfs_lock_root_node(root);
1091         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1092         if (ret) {
1093                 btrfs_tree_unlock(old);
1094                 free_extent_buffer(old);
1095                 goto abort_trans;
1096         }
1097
1098         btrfs_set_lock_blocking(old);
1099
1100         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1101         /* clean up in any case */
1102         btrfs_tree_unlock(old);
1103         free_extent_buffer(old);
1104         if (ret)
1105                 goto abort_trans;
1106
1107         /* see comments in should_cow_block() */
1108         root->force_cow = 1;
1109         smp_wmb();
1110
1111         btrfs_set_root_node(new_root_item, tmp);
1112         /* record when the snapshot was created in key.offset */
1113         key.offset = trans->transid;
1114         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1115         btrfs_tree_unlock(tmp);
1116         free_extent_buffer(tmp);
1117         if (ret)
1118                 goto abort_trans;
1119
1120         /*
1121          * insert root back/forward references
1122          */
1123         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1124                                  parent_root->root_key.objectid,
1125                                  btrfs_ino(parent_inode), index,
1126                                  dentry->d_name.name, dentry->d_name.len);
1127         if (ret)
1128                 goto abort_trans;
1129
1130         key.offset = (u64)-1;
1131         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1132         if (IS_ERR(pending->snap)) {
1133                 ret = PTR_ERR(pending->snap);
1134                 goto abort_trans;
1135         }
1136
1137         ret = btrfs_reloc_post_snapshot(trans, pending);
1138         if (ret)
1139                 goto abort_trans;
1140
1141         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1142         if (ret)
1143                 goto abort_trans;
1144
1145         ret = btrfs_insert_dir_item(trans, parent_root,
1146                                     dentry->d_name.name, dentry->d_name.len,
1147                                     parent_inode, &key,
1148                                     BTRFS_FT_DIR, index);
1149         /* We have check then name at the beginning, so it is impossible. */
1150         BUG_ON(ret == -EEXIST);
1151         if (ret)
1152                 goto abort_trans;
1153
1154         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1155                                          dentry->d_name.len * 2);
1156         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1157         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1158         if (ret)
1159                 goto abort_trans;
1160 fail:
1161         dput(parent);
1162         trans->block_rsv = rsv;
1163 no_free_objectid:
1164         kfree(new_root_item);
1165 root_item_alloc_fail:
1166         btrfs_free_path(path);
1167 path_alloc_fail:
1168         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1169         return ret;
1170
1171 abort_trans:
1172         btrfs_abort_transaction(trans, root, ret);
1173         goto fail;
1174 }
1175
1176 /*
1177  * create all the snapshots we've scheduled for creation
1178  */
1179 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1180                                              struct btrfs_fs_info *fs_info)
1181 {
1182         struct btrfs_pending_snapshot *pending;
1183         struct list_head *head = &trans->transaction->pending_snapshots;
1184
1185         list_for_each_entry(pending, head, list)
1186                 create_pending_snapshot(trans, fs_info, pending);
1187         return 0;
1188 }
1189
1190 static void update_super_roots(struct btrfs_root *root)
1191 {
1192         struct btrfs_root_item *root_item;
1193         struct btrfs_super_block *super;
1194
1195         super = root->fs_info->super_copy;
1196
1197         root_item = &root->fs_info->chunk_root->root_item;
1198         super->chunk_root = root_item->bytenr;
1199         super->chunk_root_generation = root_item->generation;
1200         super->chunk_root_level = root_item->level;
1201
1202         root_item = &root->fs_info->tree_root->root_item;
1203         super->root = root_item->bytenr;
1204         super->generation = root_item->generation;
1205         super->root_level = root_item->level;
1206         if (btrfs_test_opt(root, SPACE_CACHE))
1207                 super->cache_generation = root_item->generation;
1208 }
1209
1210 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1211 {
1212         int ret = 0;
1213         spin_lock(&info->trans_lock);
1214         if (info->running_transaction)
1215                 ret = info->running_transaction->in_commit;
1216         spin_unlock(&info->trans_lock);
1217         return ret;
1218 }
1219
1220 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1221 {
1222         int ret = 0;
1223         spin_lock(&info->trans_lock);
1224         if (info->running_transaction)
1225                 ret = info->running_transaction->blocked;
1226         spin_unlock(&info->trans_lock);
1227         return ret;
1228 }
1229
1230 /*
1231  * wait for the current transaction commit to start and block subsequent
1232  * transaction joins
1233  */
1234 static void wait_current_trans_commit_start(struct btrfs_root *root,
1235                                             struct btrfs_transaction *trans)
1236 {
1237         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1238 }
1239
1240 /*
1241  * wait for the current transaction to start and then become unblocked.
1242  * caller holds ref.
1243  */
1244 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1245                                          struct btrfs_transaction *trans)
1246 {
1247         wait_event(root->fs_info->transaction_wait,
1248                    trans->commit_done || (trans->in_commit && !trans->blocked));
1249 }
1250
1251 /*
1252  * commit transactions asynchronously. once btrfs_commit_transaction_async
1253  * returns, any subsequent transaction will not be allowed to join.
1254  */
1255 struct btrfs_async_commit {
1256         struct btrfs_trans_handle *newtrans;
1257         struct btrfs_root *root;
1258         struct delayed_work work;
1259 };
1260
1261 static void do_async_commit(struct work_struct *work)
1262 {
1263         struct btrfs_async_commit *ac =
1264                 container_of(work, struct btrfs_async_commit, work.work);
1265
1266         /*
1267          * We've got freeze protection passed with the transaction.
1268          * Tell lockdep about it.
1269          */
1270         rwsem_acquire_read(
1271                 &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1272                 0, 1, _THIS_IP_);
1273
1274         current->journal_info = ac->newtrans;
1275
1276         btrfs_commit_transaction(ac->newtrans, ac->root);
1277         kfree(ac);
1278 }
1279
1280 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1281                                    struct btrfs_root *root,
1282                                    int wait_for_unblock)
1283 {
1284         struct btrfs_async_commit *ac;
1285         struct btrfs_transaction *cur_trans;
1286
1287         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1288         if (!ac)
1289                 return -ENOMEM;
1290
1291         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1292         ac->root = root;
1293         ac->newtrans = btrfs_join_transaction(root);
1294         if (IS_ERR(ac->newtrans)) {
1295                 int err = PTR_ERR(ac->newtrans);
1296                 kfree(ac);
1297                 return err;
1298         }
1299
1300         /* take transaction reference */
1301         cur_trans = trans->transaction;
1302         atomic_inc(&cur_trans->use_count);
1303
1304         btrfs_end_transaction(trans, root);
1305
1306         /*
1307          * Tell lockdep we've released the freeze rwsem, since the
1308          * async commit thread will be the one to unlock it.
1309          */
1310         rwsem_release(&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1311                       1, _THIS_IP_);
1312
1313         schedule_delayed_work(&ac->work, 0);
1314
1315         /* wait for transaction to start and unblock */
1316         if (wait_for_unblock)
1317                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1318         else
1319                 wait_current_trans_commit_start(root, cur_trans);
1320
1321         if (current->journal_info == trans)
1322                 current->journal_info = NULL;
1323
1324         put_transaction(cur_trans);
1325         return 0;
1326 }
1327
1328
1329 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1330                                 struct btrfs_root *root, int err)
1331 {
1332         struct btrfs_transaction *cur_trans = trans->transaction;
1333
1334         WARN_ON(trans->use_count > 1);
1335
1336         btrfs_abort_transaction(trans, root, err);
1337
1338         spin_lock(&root->fs_info->trans_lock);
1339         list_del_init(&cur_trans->list);
1340         if (cur_trans == root->fs_info->running_transaction) {
1341                 root->fs_info->running_transaction = NULL;
1342                 root->fs_info->trans_no_join = 0;
1343         }
1344         spin_unlock(&root->fs_info->trans_lock);
1345
1346         btrfs_cleanup_one_transaction(trans->transaction, root);
1347
1348         put_transaction(cur_trans);
1349         put_transaction(cur_trans);
1350
1351         trace_btrfs_transaction_commit(root);
1352
1353         btrfs_scrub_continue(root);
1354
1355         if (current->journal_info == trans)
1356                 current->journal_info = NULL;
1357
1358         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1359 }
1360
1361 /*
1362  * btrfs_transaction state sequence:
1363  *    in_commit = 0, blocked = 0  (initial)
1364  *    in_commit = 1, blocked = 1
1365  *    blocked = 0
1366  *    commit_done = 1
1367  */
1368 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1369                              struct btrfs_root *root)
1370 {
1371         unsigned long joined = 0;
1372         struct btrfs_transaction *cur_trans = trans->transaction;
1373         struct btrfs_transaction *prev_trans = NULL;
1374         DEFINE_WAIT(wait);
1375         int ret = -EIO;
1376         int should_grow = 0;
1377         unsigned long now = get_seconds();
1378         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1379
1380         btrfs_run_ordered_operations(root, 0);
1381
1382         if (cur_trans->aborted)
1383                 goto cleanup_transaction;
1384
1385         /* make a pass through all the delayed refs we have so far
1386          * any runnings procs may add more while we are here
1387          */
1388         ret = btrfs_run_delayed_refs(trans, root, 0);
1389         if (ret)
1390                 goto cleanup_transaction;
1391
1392         btrfs_trans_release_metadata(trans, root);
1393         trans->block_rsv = NULL;
1394
1395         cur_trans = trans->transaction;
1396
1397         /*
1398          * set the flushing flag so procs in this transaction have to
1399          * start sending their work down.
1400          */
1401         cur_trans->delayed_refs.flushing = 1;
1402
1403         ret = btrfs_run_delayed_refs(trans, root, 0);
1404         if (ret)
1405                 goto cleanup_transaction;
1406
1407         spin_lock(&cur_trans->commit_lock);
1408         if (cur_trans->in_commit) {
1409                 spin_unlock(&cur_trans->commit_lock);
1410                 atomic_inc(&cur_trans->use_count);
1411                 ret = btrfs_end_transaction(trans, root);
1412
1413                 wait_for_commit(root, cur_trans);
1414
1415                 put_transaction(cur_trans);
1416
1417                 return ret;
1418         }
1419
1420         trans->transaction->in_commit = 1;
1421         trans->transaction->blocked = 1;
1422         spin_unlock(&cur_trans->commit_lock);
1423         wake_up(&root->fs_info->transaction_blocked_wait);
1424
1425         spin_lock(&root->fs_info->trans_lock);
1426         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1427                 prev_trans = list_entry(cur_trans->list.prev,
1428                                         struct btrfs_transaction, list);
1429                 if (!prev_trans->commit_done) {
1430                         atomic_inc(&prev_trans->use_count);
1431                         spin_unlock(&root->fs_info->trans_lock);
1432
1433                         wait_for_commit(root, prev_trans);
1434
1435                         put_transaction(prev_trans);
1436                 } else {
1437                         spin_unlock(&root->fs_info->trans_lock);
1438                 }
1439         } else {
1440                 spin_unlock(&root->fs_info->trans_lock);
1441         }
1442
1443         if (!btrfs_test_opt(root, SSD) &&
1444             (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1445                 should_grow = 1;
1446
1447         do {
1448                 int snap_pending = 0;
1449
1450                 joined = cur_trans->num_joined;
1451                 if (!list_empty(&trans->transaction->pending_snapshots))
1452                         snap_pending = 1;
1453
1454                 WARN_ON(cur_trans != trans->transaction);
1455
1456                 if (flush_on_commit || snap_pending) {
1457                         btrfs_start_delalloc_inodes(root, 1);
1458                         btrfs_wait_ordered_extents(root, 0, 1);
1459                 }
1460
1461                 ret = btrfs_run_delayed_items(trans, root);
1462                 if (ret)
1463                         goto cleanup_transaction;
1464
1465                 /*
1466                  * running the delayed items may have added new refs. account
1467                  * them now so that they hinder processing of more delayed refs
1468                  * as little as possible.
1469                  */
1470                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1471
1472                 /*
1473                  * rename don't use btrfs_join_transaction, so, once we
1474                  * set the transaction to blocked above, we aren't going
1475                  * to get any new ordered operations.  We can safely run
1476                  * it here and no for sure that nothing new will be added
1477                  * to the list
1478                  */
1479                 btrfs_run_ordered_operations(root, 1);
1480
1481                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1482                                 TASK_UNINTERRUPTIBLE);
1483
1484                 if (atomic_read(&cur_trans->num_writers) > 1)
1485                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1486                 else if (should_grow)
1487                         schedule_timeout(1);
1488
1489                 finish_wait(&cur_trans->writer_wait, &wait);
1490         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1491                  (should_grow && cur_trans->num_joined != joined));
1492
1493         /*
1494          * Ok now we need to make sure to block out any other joins while we
1495          * commit the transaction.  We could have started a join before setting
1496          * no_join so make sure to wait for num_writers to == 1 again.
1497          */
1498         spin_lock(&root->fs_info->trans_lock);
1499         root->fs_info->trans_no_join = 1;
1500         spin_unlock(&root->fs_info->trans_lock);
1501         wait_event(cur_trans->writer_wait,
1502                    atomic_read(&cur_trans->num_writers) == 1);
1503
1504         /*
1505          * the reloc mutex makes sure that we stop
1506          * the balancing code from coming in and moving
1507          * extents around in the middle of the commit
1508          */
1509         mutex_lock(&root->fs_info->reloc_mutex);
1510
1511         /*
1512          * We needn't worry about the delayed items because we will
1513          * deal with them in create_pending_snapshot(), which is the
1514          * core function of the snapshot creation.
1515          */
1516         ret = create_pending_snapshots(trans, root->fs_info);
1517         if (ret) {
1518                 mutex_unlock(&root->fs_info->reloc_mutex);
1519                 goto cleanup_transaction;
1520         }
1521
1522         /*
1523          * We insert the dir indexes of the snapshots and update the inode
1524          * of the snapshots' parents after the snapshot creation, so there
1525          * are some delayed items which are not dealt with. Now deal with
1526          * them.
1527          *
1528          * We needn't worry that this operation will corrupt the snapshots,
1529          * because all the tree which are snapshoted will be forced to COW
1530          * the nodes and leaves.
1531          */
1532         ret = btrfs_run_delayed_items(trans, root);
1533         if (ret) {
1534                 mutex_unlock(&root->fs_info->reloc_mutex);
1535                 goto cleanup_transaction;
1536         }
1537
1538         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1539         if (ret) {
1540                 mutex_unlock(&root->fs_info->reloc_mutex);
1541                 goto cleanup_transaction;
1542         }
1543
1544         /*
1545          * make sure none of the code above managed to slip in a
1546          * delayed item
1547          */
1548         btrfs_assert_delayed_root_empty(root);
1549
1550         WARN_ON(cur_trans != trans->transaction);
1551
1552         btrfs_scrub_pause(root);
1553         /* btrfs_commit_tree_roots is responsible for getting the
1554          * various roots consistent with each other.  Every pointer
1555          * in the tree of tree roots has to point to the most up to date
1556          * root for every subvolume and other tree.  So, we have to keep
1557          * the tree logging code from jumping in and changing any
1558          * of the trees.
1559          *
1560          * At this point in the commit, there can't be any tree-log
1561          * writers, but a little lower down we drop the trans mutex
1562          * and let new people in.  By holding the tree_log_mutex
1563          * from now until after the super is written, we avoid races
1564          * with the tree-log code.
1565          */
1566         mutex_lock(&root->fs_info->tree_log_mutex);
1567
1568         ret = commit_fs_roots(trans, root);
1569         if (ret) {
1570                 mutex_unlock(&root->fs_info->tree_log_mutex);
1571                 mutex_unlock(&root->fs_info->reloc_mutex);
1572                 goto cleanup_transaction;
1573         }
1574
1575         /* commit_fs_roots gets rid of all the tree log roots, it is now
1576          * safe to free the root of tree log roots
1577          */
1578         btrfs_free_log_root_tree(trans, root->fs_info);
1579
1580         ret = commit_cowonly_roots(trans, root);
1581         if (ret) {
1582                 mutex_unlock(&root->fs_info->tree_log_mutex);
1583                 mutex_unlock(&root->fs_info->reloc_mutex);
1584                 goto cleanup_transaction;
1585         }
1586
1587         btrfs_prepare_extent_commit(trans, root);
1588
1589         cur_trans = root->fs_info->running_transaction;
1590
1591         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1592                             root->fs_info->tree_root->node);
1593         switch_commit_root(root->fs_info->tree_root);
1594
1595         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1596                             root->fs_info->chunk_root->node);
1597         switch_commit_root(root->fs_info->chunk_root);
1598
1599         assert_qgroups_uptodate(trans);
1600         update_super_roots(root);
1601
1602         if (!root->fs_info->log_root_recovering) {
1603                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1604                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1605         }
1606
1607         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1608                sizeof(*root->fs_info->super_copy));
1609
1610         trans->transaction->blocked = 0;
1611         spin_lock(&root->fs_info->trans_lock);
1612         root->fs_info->running_transaction = NULL;
1613         root->fs_info->trans_no_join = 0;
1614         spin_unlock(&root->fs_info->trans_lock);
1615         mutex_unlock(&root->fs_info->reloc_mutex);
1616
1617         wake_up(&root->fs_info->transaction_wait);
1618
1619         ret = btrfs_write_and_wait_transaction(trans, root);
1620         if (ret) {
1621                 btrfs_error(root->fs_info, ret,
1622                             "Error while writing out transaction.");
1623                 mutex_unlock(&root->fs_info->tree_log_mutex);
1624                 goto cleanup_transaction;
1625         }
1626
1627         ret = write_ctree_super(trans, root, 0);
1628         if (ret) {
1629                 mutex_unlock(&root->fs_info->tree_log_mutex);
1630                 goto cleanup_transaction;
1631         }
1632
1633         /*
1634          * the super is written, we can safely allow the tree-loggers
1635          * to go about their business
1636          */
1637         mutex_unlock(&root->fs_info->tree_log_mutex);
1638
1639         btrfs_finish_extent_commit(trans, root);
1640
1641         cur_trans->commit_done = 1;
1642
1643         root->fs_info->last_trans_committed = cur_trans->transid;
1644
1645         wake_up(&cur_trans->commit_wait);
1646
1647         spin_lock(&root->fs_info->trans_lock);
1648         list_del_init(&cur_trans->list);
1649         spin_unlock(&root->fs_info->trans_lock);
1650
1651         put_transaction(cur_trans);
1652         put_transaction(cur_trans);
1653
1654         sb_end_intwrite(root->fs_info->sb);
1655
1656         trace_btrfs_transaction_commit(root);
1657
1658         btrfs_scrub_continue(root);
1659
1660         if (current->journal_info == trans)
1661                 current->journal_info = NULL;
1662
1663         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1664
1665         if (current != root->fs_info->transaction_kthread)
1666                 btrfs_run_delayed_iputs(root);
1667
1668         return ret;
1669
1670 cleanup_transaction:
1671         btrfs_trans_release_metadata(trans, root);
1672         trans->block_rsv = NULL;
1673         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1674 //      WARN_ON(1);
1675         if (current->journal_info == trans)
1676                 current->journal_info = NULL;
1677         cleanup_transaction(trans, root, ret);
1678
1679         return ret;
1680 }
1681
1682 /*
1683  * interface function to delete all the snapshots we have scheduled for deletion
1684  */
1685 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1686 {
1687         LIST_HEAD(list);
1688         struct btrfs_fs_info *fs_info = root->fs_info;
1689
1690         spin_lock(&fs_info->trans_lock);
1691         list_splice_init(&fs_info->dead_roots, &list);
1692         spin_unlock(&fs_info->trans_lock);
1693
1694         while (!list_empty(&list)) {
1695                 int ret;
1696
1697                 root = list_entry(list.next, struct btrfs_root, root_list);
1698                 list_del(&root->root_list);
1699
1700                 btrfs_kill_all_delayed_nodes(root);
1701
1702                 if (btrfs_header_backref_rev(root->node) <
1703                     BTRFS_MIXED_BACKREF_REV)
1704                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1705                 else
1706                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1707                 BUG_ON(ret < 0);
1708         }
1709         return 0;
1710 }