fs/btrfs/transaction.c

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