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, 0);
 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         trans->block_rsv = NULL;
 457         while (count < 4) {
 458                 unsigned long cur = trans->delayed_ref_updates;
 459                 trans->delayed_ref_updates = 0;
 460                 if (cur &&
 461                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 462                         trans->delayed_ref_updates = 0;
 463
 464                         /*
 465                          * do a full flush if the transaction is trying
 466                          * to close
 467                          */
 468                         if (trans->transaction->delayed_refs.flushing)
 469                                 cur = 0;
 470                         btrfs_run_delayed_refs(trans, root, cur);
 471                 } else {
 472                         break;
 473                 }
 474                 count++;
 475         }
 476
 477         btrfs_trans_release_metadata(trans, root);
 478
 479         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 480             should_end_transaction(trans, root)) {
 481                 trans->transaction->blocked = 1;
 482                 smp_wmb();
 483         }
 484
 485         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 486                 if (throttle) {
 487                         /*
 488                          * We may race with somebody else here so end up having
 489                          * to call end_transaction on ourselves again, so inc
 490                          * our use_count.
 491                          */
 492                         trans->use_count++;
 493                         return btrfs_commit_transaction(trans, root);
 494                 } else {
 495                         wake_up_process(info->transaction_kthread);
 496                 }
 497         }
 498
 499         WARN_ON(cur_trans != info->running_transaction);
 500         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 501         atomic_dec(&cur_trans->num_writers);
 502
 503         smp_mb();
 504         if (waitqueue_active(&cur_trans->writer_wait))
 505                 wake_up(&cur_trans->writer_wait);
 506         put_transaction(cur_trans);
 507
 508         if (current->journal_info == trans)
 509                 current->journal_info = NULL;
 510         memset(trans, 0, sizeof(*trans));
 511         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 512
 513         if (throttle)
 514                 btrfs_run_delayed_iputs(root);
 515
 516         return 0;
 517 }
 518
 519 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 520                           struct btrfs_root *root)
 521 {
 522         int ret;
 523
 524         ret = __btrfs_end_transaction(trans, root, 0, 1);
 525         if (ret)
 526                 return ret;
 527         return 0;
 528 }
 529
 530 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 531                                    struct btrfs_root *root)
 532 {
 533         int ret;
 534
 535         ret = __btrfs_end_transaction(trans, root, 1, 1);
 536         if (ret)
 537                 return ret;
 538         return 0;
 539 }
 540
 541 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 542                                  struct btrfs_root *root)
 543 {
 544         int ret;
 545
 546         ret = __btrfs_end_transaction(trans, root, 0, 0);
 547         if (ret)
 548                 return ret;
 549         return 0;
 550 }
 551
 552 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 553                                 struct btrfs_root *root)
 554 {
 555         return __btrfs_end_transaction(trans, root, 1, 1);
 556 }
 557
 558 /*
 559  * when btree blocks are allocated, they have some corresponding bits set for
 560  * them in one of two extent_io trees.  This is used to make sure all of
 561  * those extents are sent to disk but does not wait on them
 562  */
 563 int btrfs_write_marked_extents(struct btrfs_root *root,
 564                                struct extent_io_tree *dirty_pages, int mark)
 565 {
 566         int ret;
 567         int err = 0;
 568         int werr = 0;
 569         struct page *page;
 570         struct inode *btree_inode = root->fs_info->btree_inode;
 571         u64 start = 0;
 572         u64 end;
 573         unsigned long index;
 574
 575         while (1) {
 576                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 577                                             mark);
 578                 if (ret)
 579                         break;
 580                 while (start <= end) {
 581                         cond_resched();
 582
 583                         index = start >> PAGE_CACHE_SHIFT;
 584                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 585                         page = find_get_page(btree_inode->i_mapping, index);
 586                         if (!page)
 587                                 continue;
 588
 589                         btree_lock_page_hook(page);
 590                         if (!page->mapping) {
 591                                 unlock_page(page);
 592                                 page_cache_release(page);
 593                                 continue;
 594                         }
 595
 596                         if (PageWriteback(page)) {
 597                                 if (PageDirty(page))
 598                                         wait_on_page_writeback(page);
 599                                 else {
 600                                         unlock_page(page);
 601                                         page_cache_release(page);
 602                                         continue;
 603                                 }
 604                         }
 605                         err = write_one_page(page, 0);
 606                         if (err)
 607                                 werr = err;
 608                         page_cache_release(page);
 609                 }
 610         }
 611         if (err)
 612                 werr = err;
 613         return werr;
 614 }
 615
 616 /*
 617  * when btree blocks are allocated, they have some corresponding bits set for
 618  * them in one of two extent_io trees.  This is used to make sure all of
 619  * those extents are on disk for transaction or log commit.  We wait
 620  * on all the pages and clear them from the dirty pages state tree
 621  */
 622 int btrfs_wait_marked_extents(struct btrfs_root *root,
 623                               struct extent_io_tree *dirty_pages, int mark)
 624 {
 625         int ret;
 626         int err = 0;
 627         int werr = 0;
 628         struct page *page;
 629         struct inode *btree_inode = root->fs_info->btree_inode;
 630         u64 start = 0;
 631         u64 end;
 632         unsigned long index;
 633
 634         while (1) {
 635                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 636                                             mark);
 637                 if (ret)
 638                         break;
 639
 640                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 641                 while (start <= end) {
 642                         index = start >> PAGE_CACHE_SHIFT;
 643                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 644                         page = find_get_page(btree_inode->i_mapping, index);
 645                         if (!page)
 646                                 continue;
 647                         if (PageDirty(page)) {
 648                                 btree_lock_page_hook(page);
 649                                 wait_on_page_writeback(page);
 650                                 err = write_one_page(page, 0);
 651                                 if (err)
 652                                         werr = err;
 653                         }
 654                         wait_on_page_writeback(page);
 655                         page_cache_release(page);
 656                         cond_resched();
 657                 }
 658         }
 659         if (err)
 660                 werr = err;
 661         return werr;
 662 }
 663
 664 /*
 665  * when btree blocks are allocated, they have some corresponding bits set for
 666  * them in one of two extent_io trees.  This is used to make sure all of
 667  * those extents are on disk for transaction or log commit
 668  */
 669 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 670                                 struct extent_io_tree *dirty_pages, int mark)
 671 {
 672         int ret;
 673         int ret2;
 674
 675         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 676         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 677         return ret || ret2;
 678 }
 679
 680 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 681                                      struct btrfs_root *root)
 682 {
 683         if (!trans || !trans->transaction) {
 684                 struct inode *btree_inode;
 685                 btree_inode = root->fs_info->btree_inode;
 686                 return filemap_write_and_wait(btree_inode->i_mapping);
 687         }
 688         return btrfs_write_and_wait_marked_extents(root,
 689                                            &trans->transaction->dirty_pages,
 690                                            EXTENT_DIRTY);
 691 }
 692
 693 /*
 694  * this is used to update the root pointer in the tree of tree roots.
 695  *
 696  * But, in the case of the extent allocation tree, updating the root
 697  * pointer may allocate blocks which may change the root of the extent
 698  * allocation tree.
 699  *
 700  * So, this loops and repeats and makes sure the cowonly root didn't
 701  * change while the root pointer was being updated in the metadata.
 702  */
 703 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 704                                struct btrfs_root *root)
 705 {
 706         int ret;
 707         u64 old_root_bytenr;
 708         u64 old_root_used;
 709         struct btrfs_root *tree_root = root->fs_info->tree_root;
 710
 711         old_root_used = btrfs_root_used(&root->root_item);
 712         btrfs_write_dirty_block_groups(trans, root);
 713
 714         while (1) {
 715                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 716                 if (old_root_bytenr == root->node->start &&
 717                     old_root_used == btrfs_root_used(&root->root_item))
 718                         break;
 719
 720                 btrfs_set_root_node(&root->root_item, root->node);
 721                 ret = btrfs_update_root(trans, tree_root,
 722                                         &root->root_key,
 723                                         &root->root_item);
 724                 BUG_ON(ret);
 725
 726                 old_root_used = btrfs_root_used(&root->root_item);
 727                 ret = btrfs_write_dirty_block_groups(trans, root);
 728                 BUG_ON(ret);
 729         }
 730
 731         if (root != root->fs_info->extent_root)
 732                 switch_commit_root(root);
 733
 734         return 0;
 735 }
 736
 737 /*
 738  * update all the cowonly tree roots on disk
 739  */
 740 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 741                                          struct btrfs_root *root)
 742 {
 743         struct btrfs_fs_info *fs_info = root->fs_info;
 744         struct list_head *next;
 745         struct extent_buffer *eb;
 746         int ret;
 747
 748         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 749         BUG_ON(ret);
 750
 751         eb = btrfs_lock_root_node(fs_info->tree_root);
 752         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 753         btrfs_tree_unlock(eb);
 754         free_extent_buffer(eb);
 755
 756         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 757         BUG_ON(ret);
 758
 759         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 760                 next = fs_info->dirty_cowonly_roots.next;
 761                 list_del_init(next);
 762                 root = list_entry(next, struct btrfs_root, dirty_list);
 763
 764                 update_cowonly_root(trans, root);
 765         }
 766
 767         down_write(&fs_info->extent_commit_sem);
 768         switch_commit_root(fs_info->extent_root);
 769         up_write(&fs_info->extent_commit_sem);
 770
 771         return 0;
 772 }
 773
 774 /*
 775  * dead roots are old snapshots that need to be deleted.  This allocates
 776  * a dirty root struct and adds it into the list of dead roots that need to
 777  * be deleted
 778  */
 779 int btrfs_add_dead_root(struct btrfs_root *root)
 780 {
 781         spin_lock(&root->fs_info->trans_lock);
 782         list_add(&root->root_list, &root->fs_info->dead_roots);
 783         spin_unlock(&root->fs_info->trans_lock);
 784         return 0;
 785 }
 786
 787 /*
 788  * update all the cowonly tree roots on disk
 789  */
 790 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 791                                     struct btrfs_root *root)
 792 {
 793         struct btrfs_root *gang[8];
 794         struct btrfs_fs_info *fs_info = root->fs_info;
 795         int i;
 796         int ret;
 797         int err = 0;
 798
 799         spin_lock(&fs_info->fs_roots_radix_lock);
 800         while (1) {
 801                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 802                                                  (void **)gang, 0,
 803                                                  ARRAY_SIZE(gang),
 804                                                  BTRFS_ROOT_TRANS_TAG);
 805                 if (ret == 0)
 806                         break;
 807                 for (i = 0; i < ret; i++) {
 808                         root = gang[i];
 809                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 810                                         (unsigned long)root->root_key.objectid,
 811                                         BTRFS_ROOT_TRANS_TAG);
 812                         spin_unlock(&fs_info->fs_roots_radix_lock);
 813
 814                         btrfs_free_log(trans, root);
 815                         btrfs_update_reloc_root(trans, root);
 816                         btrfs_orphan_commit_root(trans, root);
 817
 818                         btrfs_save_ino_cache(root, trans);
 819
 820                         if (root->commit_root != root->node) {
 821                                 mutex_lock(&root->fs_commit_mutex);
 822                                 switch_commit_root(root);
 823                                 btrfs_unpin_free_ino(root);
 824                                 mutex_unlock(&root->fs_commit_mutex);
 825
 826                                 btrfs_set_root_node(&root->root_item,
 827                                                     root->node);
 828                         }
 829
 830                         err = btrfs_update_root(trans, fs_info->tree_root,
 831                                                 &root->root_key,
 832                                                 &root->root_item);
 833                         spin_lock(&fs_info->fs_roots_radix_lock);
 834                         if (err)
 835                                 break;
 836                 }
 837         }
 838         spin_unlock(&fs_info->fs_roots_radix_lock);
 839         return err;
 840 }
 841
 842 /*
 843  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 844  * otherwise every leaf in the btree is read and defragged.
 845  */
 846 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 847 {
 848         struct btrfs_fs_info *info = root->fs_info;
 849         struct btrfs_trans_handle *trans;
 850         int ret;
 851         unsigned long nr;
 852
 853         if (xchg(&root->defrag_running, 1))
 854                 return 0;
 855
 856         while (1) {
 857                 trans = btrfs_start_transaction(root, 0);
 858                 if (IS_ERR(trans))
 859                         return PTR_ERR(trans);
 860
 861                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 862
 863                 nr = trans->blocks_used;
 864                 btrfs_end_transaction(trans, root);
 865                 btrfs_btree_balance_dirty(info->tree_root, nr);
 866                 cond_resched();
 867
 868                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 869                         break;
 870         }
 871         root->defrag_running = 0;
 872         return ret;
 873 }
 874
 875 /*
 876  * new snapshots need to be created at a very specific time in the
 877  * transaction commit.  This does the actual creation
 878  */
 879 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 880                                    struct btrfs_fs_info *fs_info,
 881                                    struct btrfs_pending_snapshot *pending)
 882 {
 883         struct btrfs_key key;
 884         struct btrfs_root_item *new_root_item;
 885         struct btrfs_root *tree_root = fs_info->tree_root;
 886         struct btrfs_root *root = pending->root;
 887         struct btrfs_root *parent_root;
 888         struct btrfs_block_rsv *rsv;
 889         struct inode *parent_inode;
 890         struct dentry *parent;
 891         struct dentry *dentry;
 892         struct extent_buffer *tmp;
 893         struct extent_buffer *old;
 894         int ret;
 895         u64 to_reserve = 0;
 896         u64 index = 0;
 897         u64 objectid;
 898         u64 root_flags;
 899
 900         rsv = trans->block_rsv;
 901
 902         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 903         if (!new_root_item) {
 904                 pending->error = -ENOMEM;
 905                 goto fail;
 906         }
 907
 908         ret = btrfs_find_free_objectid(tree_root, &objectid);
 909         if (ret) {
 910                 pending->error = ret;
 911                 goto fail;
 912         }
 913
 914         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 915
 916         if (to_reserve > 0) {
 917                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 918                                           to_reserve);
 919                 if (ret) {
 920                         pending->error = ret;
 921                         goto fail;
 922                 }
 923         }
 924
 925         key.objectid = objectid;
 926         key.offset = (u64)-1;
 927         key.type = BTRFS_ROOT_ITEM_KEY;
 928
 929         trans->block_rsv = &pending->block_rsv;
 930
 931         dentry = pending->dentry;
 932         parent = dget_parent(dentry);
 933         parent_inode = parent->d_inode;
 934         parent_root = BTRFS_I(parent_inode)->root;
 935         record_root_in_trans(trans, parent_root);
 936
 937         /*
 938          * insert the directory item
 939          */
 940         ret = btrfs_set_inode_index(parent_inode, &index);
 941         BUG_ON(ret);
 942         ret = btrfs_insert_dir_item(trans, parent_root,
 943                                 dentry->d_name.name, dentry->d_name.len,
 944                                 parent_inode, &key,
 945                                 BTRFS_FT_DIR, index);
 946         BUG_ON(ret);
 947
 948         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 949                                          dentry->d_name.len * 2);
 950         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 951         BUG_ON(ret);
 952
 953         /*
 954          * pull in the delayed directory update
 955          * and the delayed inode item
 956          * otherwise we corrupt the FS during
 957          * snapshot
 958          */
 959         ret = btrfs_run_delayed_items(trans, root);
 960         BUG_ON(ret);
 961
 962         record_root_in_trans(trans, root);
 963         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 964         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 965         btrfs_check_and_init_root_item(new_root_item);
 966
 967         root_flags = btrfs_root_flags(new_root_item);
 968         if (pending->readonly)
 969                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
 970         else
 971                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
 972         btrfs_set_root_flags(new_root_item, root_flags);
 973
 974         old = btrfs_lock_root_node(root);
 975         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 976         btrfs_set_lock_blocking(old);
 977
 978         btrfs_copy_root(trans, root, old, &tmp, objectid);
 979         btrfs_tree_unlock(old);
 980         free_extent_buffer(old);
 981
 982         btrfs_set_root_node(new_root_item, tmp);
 983         /* record when the snapshot was created in key.offset */
 984         key.offset = trans->transid;
 985         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
 986         btrfs_tree_unlock(tmp);
 987         free_extent_buffer(tmp);
 988         BUG_ON(ret);
 989
 990         /*
 991          * insert root back/forward references
 992          */
 993         ret = btrfs_add_root_ref(trans, tree_root, objectid,
 994                                  parent_root->root_key.objectid,
 995                                  btrfs_ino(parent_inode), index,
 996                                  dentry->d_name.name, dentry->d_name.len);
 997         BUG_ON(ret);
 998         dput(parent);
 999
1000         key.offset = (u64)-1;
1001         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1002         BUG_ON(IS_ERR(pending->snap));
1003
1004         btrfs_reloc_post_snapshot(trans, pending);
1005 fail:
1006         kfree(new_root_item);
1007         trans->block_rsv = rsv;
1008         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1009         return 0;
1010 }
1011
1012 /*
1013  * create all the snapshots we've scheduled for creation
1014  */
1015 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1016                                              struct btrfs_fs_info *fs_info)
1017 {
1018         struct btrfs_pending_snapshot *pending;
1019         struct list_head *head = &trans->transaction->pending_snapshots;
1020         int ret;
1021
1022         list_for_each_entry(pending, head, list) {
1023                 ret = create_pending_snapshot(trans, fs_info, pending);
1024                 BUG_ON(ret);
1025         }
1026         return 0;
1027 }
1028
1029 static void update_super_roots(struct btrfs_root *root)
1030 {
1031         struct btrfs_root_item *root_item;
1032         struct btrfs_super_block *super;
1033
1034         super = &root->fs_info->super_copy;
1035
1036         root_item = &root->fs_info->chunk_root->root_item;
1037         super->chunk_root = root_item->bytenr;
1038         super->chunk_root_generation = root_item->generation;
1039         super->chunk_root_level = root_item->level;
1040
1041         root_item = &root->fs_info->tree_root->root_item;
1042         super->root = root_item->bytenr;
1043         super->generation = root_item->generation;
1044         super->root_level = root_item->level;
1045         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
1046                 super->cache_generation = root_item->generation;
1047 }
1048
1049 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1050 {
1051         int ret = 0;
1052         spin_lock(&info->trans_lock);
1053         if (info->running_transaction)
1054                 ret = info->running_transaction->in_commit;
1055         spin_unlock(&info->trans_lock);
1056         return ret;
1057 }
1058
1059 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1060 {
1061         int ret = 0;
1062         spin_lock(&info->trans_lock);
1063         if (info->running_transaction)
1064                 ret = info->running_transaction->blocked;
1065         spin_unlock(&info->trans_lock);
1066         return ret;
1067 }
1068
1069 /*
1070  * wait for the current transaction commit to start and block subsequent
1071  * transaction joins
1072  */
1073 static void wait_current_trans_commit_start(struct btrfs_root *root,
1074                                             struct btrfs_transaction *trans)
1075 {
1076         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1077 }
1078
1079 /*
1080  * wait for the current transaction to start and then become unblocked.
1081  * caller holds ref.
1082  */
1083 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1084                                          struct btrfs_transaction *trans)
1085 {
1086         wait_event(root->fs_info->transaction_wait,
1087                    trans->commit_done || (trans->in_commit && !trans->blocked));
1088 }
1089
1090 /*
1091  * commit transactions asynchronously. once btrfs_commit_transaction_async
1092  * returns, any subsequent transaction will not be allowed to join.
1093  */
1094 struct btrfs_async_commit {
1095         struct btrfs_trans_handle *newtrans;
1096         struct btrfs_root *root;
1097         struct delayed_work work;
1098 };
1099
1100 static void do_async_commit(struct work_struct *work)
1101 {
1102         struct btrfs_async_commit *ac =
1103                 container_of(work, struct btrfs_async_commit, work.work);
1104
1105         btrfs_commit_transaction(ac->newtrans, ac->root);
1106         kfree(ac);
1107 }
1108
1109 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1110                                    struct btrfs_root *root,
1111                                    int wait_for_unblock)
1112 {
1113         struct btrfs_async_commit *ac;
1114         struct btrfs_transaction *cur_trans;
1115
1116         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1117         if (!ac)
1118                 return -ENOMEM;
1119
1120         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1121         ac->root = root;
1122         ac->newtrans = btrfs_join_transaction(root);
1123         if (IS_ERR(ac->newtrans)) {
1124                 int err = PTR_ERR(ac->newtrans);
1125                 kfree(ac);
1126                 return err;
1127         }
1128
1129         /* take transaction reference */
1130         cur_trans = trans->transaction;
1131         atomic_inc(&cur_trans->use_count);
1132
1133         btrfs_end_transaction(trans, root);
1134         schedule_delayed_work(&ac->work, 0);
1135
1136         /* wait for transaction to start and unblock */
1137         if (wait_for_unblock)
1138                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1139         else
1140                 wait_current_trans_commit_start(root, cur_trans);
1141
1142         if (current->journal_info == trans)
1143                 current->journal_info = NULL;
1144
1145         put_transaction(cur_trans);
1146         return 0;
1147 }
1148
1149 /*
1150  * btrfs_transaction state sequence:
1151  *    in_commit = 0, blocked = 0  (initial)
1152  *    in_commit = 1, blocked = 1
1153  *    blocked = 0
1154  *    commit_done = 1
1155  */
1156 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1157                              struct btrfs_root *root)
1158 {
1159         unsigned long joined = 0;
1160         struct btrfs_transaction *cur_trans;
1161         struct btrfs_transaction *prev_trans = NULL;
1162         DEFINE_WAIT(wait);
1163         int ret;
1164         int should_grow = 0;
1165         unsigned long now = get_seconds();
1166         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1167
1168         btrfs_run_ordered_operations(root, 0);
1169
1170         /* make a pass through all the delayed refs we have so far
1171          * any runnings procs may add more while we are here
1172          */
1173         ret = btrfs_run_delayed_refs(trans, root, 0);
1174         BUG_ON(ret);
1175
1176         btrfs_trans_release_metadata(trans, root);
1177
1178         cur_trans = trans->transaction;
1179         /*
1180          * set the flushing flag so procs in this transaction have to
1181          * start sending their work down.
1182          */
1183         cur_trans->delayed_refs.flushing = 1;
1184
1185         ret = btrfs_run_delayed_refs(trans, root, 0);
1186         BUG_ON(ret);
1187
1188         spin_lock(&cur_trans->commit_lock);
1189         if (cur_trans->in_commit) {
1190                 spin_unlock(&cur_trans->commit_lock);
1191                 atomic_inc(&cur_trans->use_count);
1192                 btrfs_end_transaction(trans, root);
1193
1194                 wait_for_commit(root, cur_trans);
1195
1196                 put_transaction(cur_trans);
1197
1198                 return 0;
1199         }
1200
1201         trans->transaction->in_commit = 1;
1202         trans->transaction->blocked = 1;
1203         spin_unlock(&cur_trans->commit_lock);
1204         wake_up(&root->fs_info->transaction_blocked_wait);
1205
1206         spin_lock(&root->fs_info->trans_lock);
1207         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1208                 prev_trans = list_entry(cur_trans->list.prev,
1209                                         struct btrfs_transaction, list);
1210                 if (!prev_trans->commit_done) {
1211                         atomic_inc(&prev_trans->use_count);
1212                         spin_unlock(&root->fs_info->trans_lock);
1213
1214                         wait_for_commit(root, prev_trans);
1215
1216                         put_transaction(prev_trans);
1217                 } else {
1218                         spin_unlock(&root->fs_info->trans_lock);
1219                 }
1220         } else {
1221                 spin_unlock(&root->fs_info->trans_lock);
1222         }
1223
1224         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1225                 should_grow = 1;
1226
1227         do {
1228                 int snap_pending = 0;
1229
1230                 joined = cur_trans->num_joined;
1231                 if (!list_empty(&trans->transaction->pending_snapshots))
1232                         snap_pending = 1;
1233
1234                 WARN_ON(cur_trans != trans->transaction);
1235
1236                 if (flush_on_commit || snap_pending) {
1237                         btrfs_start_delalloc_inodes(root, 1);
1238                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1239                         BUG_ON(ret);
1240                 }
1241
1242                 ret = btrfs_run_delayed_items(trans, root);
1243                 BUG_ON(ret);
1244
1245                 /*
1246                  * rename don't use btrfs_join_transaction, so, once we
1247                  * set the transaction to blocked above, we aren't going
1248                  * to get any new ordered operations.  We can safely run
1249                  * it here and no for sure that nothing new will be added
1250                  * to the list
1251                  */
1252                 btrfs_run_ordered_operations(root, 1);
1253
1254                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1255                                 TASK_UNINTERRUPTIBLE);
1256
1257                 if (atomic_read(&cur_trans->num_writers) > 1)
1258                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1259                 else if (should_grow)
1260                         schedule_timeout(1);
1261
1262                 finish_wait(&cur_trans->writer_wait, &wait);
1263         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1264                  (should_grow && cur_trans->num_joined != joined));
1265
1266         /*
1267          * Ok now we need to make sure to block out any other joins while we
1268          * commit the transaction.  We could have started a join before setting
1269          * no_join so make sure to wait for num_writers to == 1 again.
1270          */
1271         spin_lock(&root->fs_info->trans_lock);
1272         root->fs_info->trans_no_join = 1;
1273         spin_unlock(&root->fs_info->trans_lock);
1274         wait_event(cur_trans->writer_wait,
1275                    atomic_read(&cur_trans->num_writers) == 1);
1276
1277         /*
1278          * the reloc mutex makes sure that we stop
1279          * the balancing code from coming in and moving
1280          * extents around in the middle of the commit
1281          */
1282         mutex_lock(&root->fs_info->reloc_mutex);
1283
1284         ret = btrfs_run_delayed_items(trans, root);
1285         BUG_ON(ret);
1286
1287         ret = create_pending_snapshots(trans, root->fs_info);
1288         BUG_ON(ret);
1289
1290         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1291         BUG_ON(ret);
1292
1293         /*
1294          * make sure none of the code above managed to slip in a
1295          * delayed item
1296          */
1297         btrfs_assert_delayed_root_empty(root);
1298
1299         WARN_ON(cur_trans != trans->transaction);
1300
1301         btrfs_scrub_pause(root);
1302         /* btrfs_commit_tree_roots is responsible for getting the
1303          * various roots consistent with each other.  Every pointer
1304          * in the tree of tree roots has to point to the most up to date
1305          * root for every subvolume and other tree.  So, we have to keep
1306          * the tree logging code from jumping in and changing any
1307          * of the trees.
1308          *
1309          * At this point in the commit, there can't be any tree-log
1310          * writers, but a little lower down we drop the trans mutex
1311          * and let new people in.  By holding the tree_log_mutex
1312          * from now until after the super is written, we avoid races
1313          * with the tree-log code.
1314          */
1315         mutex_lock(&root->fs_info->tree_log_mutex);
1316
1317         ret = commit_fs_roots(trans, root);
1318         BUG_ON(ret);
1319
1320         /* commit_fs_roots gets rid of all the tree log roots, it is now
1321          * safe to free the root of tree log roots
1322          */
1323         btrfs_free_log_root_tree(trans, root->fs_info);
1324
1325         ret = commit_cowonly_roots(trans, root);
1326         BUG_ON(ret);
1327
1328         btrfs_prepare_extent_commit(trans, root);
1329
1330         cur_trans = root->fs_info->running_transaction;
1331
1332         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1333                             root->fs_info->tree_root->node);
1334         switch_commit_root(root->fs_info->tree_root);
1335
1336         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1337                             root->fs_info->chunk_root->node);
1338         switch_commit_root(root->fs_info->chunk_root);
1339
1340         update_super_roots(root);
1341
1342         if (!root->fs_info->log_root_recovering) {
1343                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1344                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1345         }
1346
1347         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1348                sizeof(root->fs_info->super_copy));
1349
1350         trans->transaction->blocked = 0;
1351         spin_lock(&root->fs_info->trans_lock);
1352         root->fs_info->running_transaction = NULL;
1353         root->fs_info->trans_no_join = 0;
1354         spin_unlock(&root->fs_info->trans_lock);
1355         mutex_unlock(&root->fs_info->reloc_mutex);
1356
1357         wake_up(&root->fs_info->transaction_wait);
1358
1359         ret = btrfs_write_and_wait_transaction(trans, root);
1360         BUG_ON(ret);
1361         write_ctree_super(trans, root, 0);
1362
1363         /*
1364          * the super is written, we can safely allow the tree-loggers
1365          * to go about their business
1366          */
1367         mutex_unlock(&root->fs_info->tree_log_mutex);
1368
1369         btrfs_finish_extent_commit(trans, root);
1370
1371         cur_trans->commit_done = 1;
1372
1373         root->fs_info->last_trans_committed = cur_trans->transid;
1374
1375         wake_up(&cur_trans->commit_wait);
1376
1377         spin_lock(&root->fs_info->trans_lock);
1378         list_del_init(&cur_trans->list);
1379         spin_unlock(&root->fs_info->trans_lock);
1380
1381         put_transaction(cur_trans);
1382         put_transaction(cur_trans);
1383
1384         trace_btrfs_transaction_commit(root);
1385
1386         btrfs_scrub_continue(root);
1387
1388         if (current->journal_info == trans)
1389                 current->journal_info = NULL;
1390
1391         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1392
1393         if (current != root->fs_info->transaction_kthread)
1394                 btrfs_run_delayed_iputs(root);
1395
1396         return ret;
1397 }
1398
1399 /*
1400  * interface function to delete all the snapshots we have scheduled for deletion
1401  */
1402 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1403 {
1404         LIST_HEAD(list);
1405         struct btrfs_fs_info *fs_info = root->fs_info;
1406
1407         spin_lock(&fs_info->trans_lock);
1408         list_splice_init(&fs_info->dead_roots, &list);
1409         spin_unlock(&fs_info->trans_lock);
1410
1411         while (!list_empty(&list)) {
1412                 root = list_entry(list.next, struct btrfs_root, root_list);
1413                 list_del(&root->root_list);
1414
1415                 btrfs_kill_all_delayed_nodes(root);
1416
1417                 if (btrfs_header_backref_rev(root->node) <
1418                     BTRFS_MIXED_BACKREF_REV)
1419                         btrfs_drop_snapshot(root, NULL, 0);
1420                 else
1421                         btrfs_drop_snapshot(root, NULL, 1);
1422         }
1423         return 0;
1424 }