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