fs/btrfs/transaction.c

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