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