fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33
  34 #define BTRFS_ROOT_TRANS_TAG 0
  35
  36 void put_transaction(struct btrfs_transaction *transaction)
  37 {
  38         WARN_ON(atomic_read(&transaction->use_count) == 0);
  39         if (atomic_dec_and_test(&transaction->use_count)) {
  40                 BUG_ON(!list_empty(&transaction->list));
  41                 WARN_ON(transaction->delayed_refs.root.rb_node);
  42                 memset(transaction, 0, sizeof(*transaction));
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static noinline void switch_commit_root(struct btrfs_root *root)
  48 {
  49         free_extent_buffer(root->commit_root);
  50         root->commit_root = btrfs_root_node(root);
  51 }
  52
  53 /*
  54  * either allocate a new transaction or hop into the existing one
  55  */
  56 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  57 {
  58         struct btrfs_transaction *cur_trans;
  59         struct btrfs_fs_info *fs_info = root->fs_info;
  60
  61         spin_lock(&fs_info->trans_lock);
  62 loop:
  63         /* The file system has been taken offline. No new transactions. */
  64         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  65                 spin_unlock(&fs_info->trans_lock);
  66                 return -EROFS;
  67         }
  68
  69         if (fs_info->trans_no_join) {
  70                 if (!nofail) {
  71                         spin_unlock(&fs_info->trans_lock);
  72                         return -EBUSY;
  73                 }
  74         }
  75
  76         cur_trans = fs_info->running_transaction;
  77         if (cur_trans) {
  78                 if (cur_trans->aborted) {
  79                         spin_unlock(&fs_info->trans_lock);
  80                         return cur_trans->aborted;
  81                 }
  82                 atomic_inc(&cur_trans->use_count);
  83                 atomic_inc(&cur_trans->num_writers);
  84                 cur_trans->num_joined++;
  85                 spin_unlock(&fs_info->trans_lock);
  86                 return 0;
  87         }
  88         spin_unlock(&fs_info->trans_lock);
  89
  90         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  91         if (!cur_trans)
  92                 return -ENOMEM;
  93
  94         spin_lock(&fs_info->trans_lock);
  95         if (fs_info->running_transaction) {
  96                 /*
  97                  * someone started a transaction after we unlocked.  Make sure
  98                  * to redo the trans_no_join checks above
  99                  */
 100                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 101                 cur_trans = fs_info->running_transaction;
 102                 goto loop;
 103         } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 104                 spin_unlock(&fs_info->trans_lock);
 105                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 106                 return -EROFS;
 107         }
 108
 109         atomic_set(&cur_trans->num_writers, 1);
 110         cur_trans->num_joined = 0;
 111         init_waitqueue_head(&cur_trans->writer_wait);
 112         init_waitqueue_head(&cur_trans->commit_wait);
 113         cur_trans->in_commit = 0;
 114         cur_trans->blocked = 0;
 115         /*
 116          * One for this trans handle, one so it will live on until we
 117          * commit the transaction.
 118          */
 119         atomic_set(&cur_trans->use_count, 2);
 120         cur_trans->commit_done = 0;
 121         cur_trans->start_time = get_seconds();
 122
 123         cur_trans->delayed_refs.root = RB_ROOT;
 124         cur_trans->delayed_refs.num_entries = 0;
 125         cur_trans->delayed_refs.num_heads_ready = 0;
 126         cur_trans->delayed_refs.num_heads = 0;
 127         cur_trans->delayed_refs.flushing = 0;
 128         cur_trans->delayed_refs.run_delayed_start = 0;
 129
 130         /*
 131          * although the tree mod log is per file system and not per transaction,
 132          * the log must never go across transaction boundaries.
 133          */
 134         smp_mb();
 135         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 136                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 137                         "creating a fresh transaction\n");
 138                 WARN_ON(1);
 139         }
 140         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 141                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 142                         "creating a fresh transaction\n");
 143                 WARN_ON(1);
 144         }
 145         atomic_set(&fs_info->tree_mod_seq, 0);
 146
 147         spin_lock_init(&cur_trans->commit_lock);
 148         spin_lock_init(&cur_trans->delayed_refs.lock);
 149
 150         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 151         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 152         extent_io_tree_init(&cur_trans->dirty_pages,
 153                              fs_info->btree_inode->i_mapping);
 154         fs_info->generation++;
 155         cur_trans->transid = fs_info->generation;
 156         fs_info->running_transaction = cur_trans;
 157         cur_trans->aborted = 0;
 158         spin_unlock(&fs_info->trans_lock);
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * this does all the record keeping required to make sure that a reference
 165  * counted root is properly recorded in a given transaction.  This is required
 166  * to make sure the old root from before we joined the transaction is deleted
 167  * when the transaction commits
 168  */
 169 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 170                                struct btrfs_root *root)
 171 {
 172         if (root->ref_cows && root->last_trans < trans->transid) {
 173                 WARN_ON(root == root->fs_info->extent_root);
 174                 WARN_ON(root->commit_root != root->node);
 175
 176                 /*
 177                  * see below for in_trans_setup usage rules
 178                  * we have the reloc mutex held now, so there
 179                  * is only one writer in this function
 180                  */
 181                 root->in_trans_setup = 1;
 182
 183                 /* make sure readers find in_trans_setup before
 184                  * they find our root->last_trans update
 185                  */
 186                 smp_wmb();
 187
 188                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 189                 if (root->last_trans == trans->transid) {
 190                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 191                         return 0;
 192                 }
 193                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 194                            (unsigned long)root->root_key.objectid,
 195                            BTRFS_ROOT_TRANS_TAG);
 196                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 197                 root->last_trans = trans->transid;
 198
 199                 /* this is pretty tricky.  We don't want to
 200                  * take the relocation lock in btrfs_record_root_in_trans
 201                  * unless we're really doing the first setup for this root in
 202                  * this transaction.
 203                  *
 204                  * Normally we'd use root->last_trans as a flag to decide
 205                  * if we want to take the expensive mutex.
 206                  *
 207                  * But, we have to set root->last_trans before we
 208                  * init the relocation root, otherwise, we trip over warnings
 209                  * in ctree.c.  The solution used here is to flag ourselves
 210                  * with root->in_trans_setup.  When this is 1, we're still
 211                  * fixing up the reloc trees and everyone must wait.
 212                  *
 213                  * When this is zero, they can trust root->last_trans and fly
 214                  * through btrfs_record_root_in_trans without having to take the
 215                  * lock.  smp_wmb() makes sure that all the writes above are
 216                  * done before we pop in the zero below
 217                  */
 218                 btrfs_init_reloc_root(trans, root);
 219                 smp_wmb();
 220                 root->in_trans_setup = 0;
 221         }
 222         return 0;
 223 }
 224
 225
 226 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 227                                struct btrfs_root *root)
 228 {
 229         if (!root->ref_cows)
 230                 return 0;
 231
 232         /*
 233          * see record_root_in_trans for comments about in_trans_setup usage
 234          * and barriers
 235          */
 236         smp_rmb();
 237         if (root->last_trans == trans->transid &&
 238             !root->in_trans_setup)
 239                 return 0;
 240
 241         mutex_lock(&root->fs_info->reloc_mutex);
 242         record_root_in_trans(trans, root);
 243         mutex_unlock(&root->fs_info->reloc_mutex);
 244
 245         return 0;
 246 }
 247
 248 /* wait for commit against the current transaction to become unblocked
 249  * when this is done, it is safe to start a new transaction, but the current
 250  * transaction might not be fully on disk.
 251  */
 252 static void wait_current_trans(struct btrfs_root *root)
 253 {
 254         struct btrfs_transaction *cur_trans;
 255
 256         spin_lock(&root->fs_info->trans_lock);
 257         cur_trans = root->fs_info->running_transaction;
 258         if (cur_trans && cur_trans->blocked) {
 259                 atomic_inc(&cur_trans->use_count);
 260                 spin_unlock(&root->fs_info->trans_lock);
 261
 262                 wait_event(root->fs_info->transaction_wait,
 263                            !cur_trans->blocked);
 264                 put_transaction(cur_trans);
 265         } else {
 266                 spin_unlock(&root->fs_info->trans_lock);
 267         }
 268 }
 269
 270 enum btrfs_trans_type {
 271         TRANS_START,
 272         TRANS_JOIN,
 273         TRANS_USERSPACE,
 274         TRANS_JOIN_NOLOCK,
 275         TRANS_JOIN_FREEZE,
 276 };
 277
 278 static int may_wait_transaction(struct btrfs_root *root, int type)
 279 {
 280         if (root->fs_info->log_root_recovering)
 281                 return 0;
 282
 283         if (type == TRANS_USERSPACE)
 284                 return 1;
 285
 286         if (type == TRANS_START &&
 287             !atomic_read(&root->fs_info->open_ioctl_trans))
 288                 return 1;
 289
 290         return 0;
 291 }
 292
 293 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 294                                                     u64 num_items, int type,
 295                                                     int noflush)
 296 {
 297         struct btrfs_trans_handle *h;
 298         struct btrfs_transaction *cur_trans;
 299         u64 num_bytes = 0;
 300         int ret;
 301         u64 qgroup_reserved = 0;
 302
 303         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 304                 return ERR_PTR(-EROFS);
 305
 306         if (current->journal_info) {
 307                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 308                 h = current->journal_info;
 309                 h->use_count++;
 310                 h->orig_rsv = h->block_rsv;
 311                 h->block_rsv = NULL;
 312                 goto got_it;
 313         }
 314
 315         /*
 316          * Do the reservation before we join the transaction so we can do all
 317          * the appropriate flushing if need be.
 318          */
 319         if (num_items > 0 && root != root->fs_info->chunk_root) {
 320                 if (root->fs_info->quota_enabled &&
 321                     is_fstree(root->root_key.objectid)) {
 322                         qgroup_reserved = num_items * root->leafsize;
 323                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 324                         if (ret)
 325                                 return ERR_PTR(ret);
 326                 }
 327
 328                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 329                 if (noflush)
 330                         ret = btrfs_block_rsv_add_noflush(root,
 331                                                 &root->fs_info->trans_block_rsv,
 332                                                 num_bytes);
 333                 else
 334                         ret = btrfs_block_rsv_add(root,
 335                                                 &root->fs_info->trans_block_rsv,
 336                                                 num_bytes);
 337                 if (ret)
 338                         return ERR_PTR(ret);
 339         }
 340 again:
 341         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 342         if (!h)
 343                 return ERR_PTR(-ENOMEM);
 344
 345         if (!__sb_start_write(root->fs_info->sb, SB_FREEZE_FS, false)) {
 346                 if (type == TRANS_JOIN_FREEZE)
 347                         return ERR_PTR(-EPERM);
 348                 sb_start_intwrite(root->fs_info->sb);
 349         }
 350
 351         if (may_wait_transaction(root, type))
 352                 wait_current_trans(root);
 353
 354         do {
 355                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 356                 if (ret == -EBUSY)
 357                         wait_current_trans(root);
 358         } while (ret == -EBUSY);
 359
 360         if (ret < 0) {
 361                 sb_end_intwrite(root->fs_info->sb);
 362                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 363                 return ERR_PTR(ret);
 364         }
 365
 366         cur_trans = root->fs_info->running_transaction;
 367
 368         h->transid = cur_trans->transid;
 369         h->transaction = cur_trans;
 370         h->blocks_used = 0;
 371         h->bytes_reserved = 0;
 372         h->root = root;
 373         h->delayed_ref_updates = 0;
 374         h->use_count = 1;
 375         h->adding_csums = 0;
 376         h->block_rsv = NULL;
 377         h->orig_rsv = NULL;
 378         h->aborted = 0;
 379         h->qgroup_reserved = qgroup_reserved;
 380         h->delayed_ref_elem.seq = 0;
 381         INIT_LIST_HEAD(&h->qgroup_ref_list);
 382         INIT_LIST_HEAD(&h->new_bgs);
 383
 384         smp_mb();
 385         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 386                 btrfs_commit_transaction(h, root);
 387                 goto again;
 388         }
 389
 390         if (num_bytes) {
 391                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 392                                               h->transid, num_bytes, 1);
 393                 h->block_rsv = &root->fs_info->trans_block_rsv;
 394                 h->bytes_reserved = num_bytes;
 395         }
 396
 397 got_it:
 398         btrfs_record_root_in_trans(h, root);
 399
 400         if (!current->journal_info && type != TRANS_USERSPACE)
 401                 current->journal_info = h;
 402         return h;
 403 }
 404
 405 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 406                                                    int num_items)
 407 {
 408         return start_transaction(root, num_items, TRANS_START, 0);
 409 }
 410
 411 struct btrfs_trans_handle *btrfs_start_transaction_noflush(
 412                                         struct btrfs_root *root, int num_items)
 413 {
 414         return start_transaction(root, num_items, TRANS_START, 1);
 415 }
 416
 417 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 418 {
 419         return start_transaction(root, 0, TRANS_JOIN, 0);
 420 }
 421
 422 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 423 {
 424         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 425 }
 426
 427 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 428 {
 429         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 430 }
 431
 432 struct btrfs_trans_handle *btrfs_join_transaction_freeze(struct btrfs_root *root)
 433 {
 434         return start_transaction(root, 0, TRANS_JOIN_FREEZE, 0);
 435 }
 436
 437 /* wait for a transaction commit to be fully complete */
 438 static noinline void wait_for_commit(struct btrfs_root *root,
 439                                     struct btrfs_transaction *commit)
 440 {
 441         wait_event(commit->commit_wait, commit->commit_done);
 442 }
 443
 444 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 445 {
 446         struct btrfs_transaction *cur_trans = NULL, *t;
 447         int ret;
 448
 449         ret = 0;
 450         if (transid) {
 451                 if (transid <= root->fs_info->last_trans_committed)
 452                         goto out;
 453
 454                 /* find specified transaction */
 455                 spin_lock(&root->fs_info->trans_lock);
 456                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 457                         if (t->transid == transid) {
 458                                 cur_trans = t;
 459                                 atomic_inc(&cur_trans->use_count);
 460                                 break;
 461                         }
 462                         if (t->transid > transid)
 463                                 break;
 464                 }
 465                 spin_unlock(&root->fs_info->trans_lock);
 466                 ret = -EINVAL;
 467                 if (!cur_trans)
 468                         goto out;  /* bad transid */
 469         } else {
 470                 /* find newest transaction that is committing | committed */
 471                 spin_lock(&root->fs_info->trans_lock);
 472                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 473                                             list) {
 474                         if (t->in_commit) {
 475                                 if (t->commit_done)
 476                                         break;
 477                                 cur_trans = t;
 478                                 atomic_inc(&cur_trans->use_count);
 479                                 break;
 480                         }
 481                 }
 482                 spin_unlock(&root->fs_info->trans_lock);
 483                 if (!cur_trans)
 484                         goto out;  /* nothing committing|committed */
 485         }
 486
 487         wait_for_commit(root, cur_trans);
 488
 489         put_transaction(cur_trans);
 490         ret = 0;
 491 out:
 492         return ret;
 493 }
 494
 495 void btrfs_throttle(struct btrfs_root *root)
 496 {
 497         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 498                 wait_current_trans(root);
 499 }
 500
 501 static int should_end_transaction(struct btrfs_trans_handle *trans,
 502                                   struct btrfs_root *root)
 503 {
 504         int ret;
 505
 506         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 507         return ret ? 1 : 0;
 508 }
 509
 510 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 511                                  struct btrfs_root *root)
 512 {
 513         struct btrfs_transaction *cur_trans = trans->transaction;
 514         int updates;
 515         int err;
 516
 517         smp_mb();
 518         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 519                 return 1;
 520
 521         updates = trans->delayed_ref_updates;
 522         trans->delayed_ref_updates = 0;
 523         if (updates) {
 524                 err = btrfs_run_delayed_refs(trans, root, updates);
 525                 if (err) /* Error code will also eval true */
 526                         return err;
 527         }
 528
 529         return should_end_transaction(trans, root);
 530 }
 531
 532 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 533                           struct btrfs_root *root, int throttle, int lock)
 534 {
 535         struct btrfs_transaction *cur_trans = trans->transaction;
 536         struct btrfs_fs_info *info = root->fs_info;
 537         int count = 0;
 538         int err = 0;
 539
 540         if (--trans->use_count) {
 541                 trans->block_rsv = trans->orig_rsv;
 542                 return 0;
 543         }
 544
 545         /*
 546          * do the qgroup accounting as early as possible
 547          */
 548         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 549
 550         btrfs_trans_release_metadata(trans, root);
 551         trans->block_rsv = NULL;
 552         /*
 553          * the same root has to be passed to start_transaction and
 554          * end_transaction. Subvolume quota depends on this.
 555          */
 556         WARN_ON(trans->root != root);
 557
 558         if (trans->qgroup_reserved) {
 559                 btrfs_qgroup_free(root, trans->qgroup_reserved);
 560                 trans->qgroup_reserved = 0;
 561         }
 562
 563         if (!list_empty(&trans->new_bgs))
 564                 btrfs_create_pending_block_groups(trans, root);
 565
 566         while (count < 2) {
 567                 unsigned long cur = trans->delayed_ref_updates;
 568                 trans->delayed_ref_updates = 0;
 569                 if (cur &&
 570                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 571                         trans->delayed_ref_updates = 0;
 572                         btrfs_run_delayed_refs(trans, root, cur);
 573                 } else {
 574                         break;
 575                 }
 576                 count++;
 577         }
 578         btrfs_trans_release_metadata(trans, root);
 579         trans->block_rsv = NULL;
 580
 581         if (!list_empty(&trans->new_bgs))
 582                 btrfs_create_pending_block_groups(trans, root);
 583
 584         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 585             should_end_transaction(trans, root)) {
 586                 trans->transaction->blocked = 1;
 587                 smp_wmb();
 588         }
 589
 590         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 591                 if (throttle) {
 592                         /*
 593                          * We may race with somebody else here so end up having
 594                          * to call end_transaction on ourselves again, so inc
 595                          * our use_count.
 596                          */
 597                         trans->use_count++;
 598                         return btrfs_commit_transaction(trans, root);
 599                 } else {
 600                         wake_up_process(info->transaction_kthread);
 601                 }
 602         }
 603
 604         sb_end_intwrite(root->fs_info->sb);
 605
 606         WARN_ON(cur_trans != info->running_transaction);
 607         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 608         atomic_dec(&cur_trans->num_writers);
 609
 610         smp_mb();
 611         if (waitqueue_active(&cur_trans->writer_wait))
 612                 wake_up(&cur_trans->writer_wait);
 613         put_transaction(cur_trans);
 614
 615         if (current->journal_info == trans)
 616                 current->journal_info = NULL;
 617
 618         if (throttle)
 619                 btrfs_run_delayed_iputs(root);
 620
 621         if (trans->aborted ||
 622             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 623                 err = -EIO;
 624         }
 625         assert_qgroups_uptodate(trans);
 626
 627         memset(trans, 0, sizeof(*trans));
 628         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 629         return err;
 630 }
 631
 632 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 633                           struct btrfs_root *root)
 634 {
 635         int ret;
 636
 637         ret = __btrfs_end_transaction(trans, root, 0, 1);
 638         if (ret)
 639                 return ret;
 640         return 0;
 641 }
 642
 643 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 644                                    struct btrfs_root *root)
 645 {
 646         int ret;
 647
 648         ret = __btrfs_end_transaction(trans, root, 1, 1);
 649         if (ret)
 650                 return ret;
 651         return 0;
 652 }
 653
 654 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 655                                  struct btrfs_root *root)
 656 {
 657         int ret;
 658
 659         ret = __btrfs_end_transaction(trans, root, 0, 0);
 660         if (ret)
 661                 return ret;
 662         return 0;
 663 }
 664
 665 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 666                                 struct btrfs_root *root)
 667 {
 668         return __btrfs_end_transaction(trans, root, 1, 1);
 669 }
 670
 671 /*
 672  * when btree blocks are allocated, they have some corresponding bits set for
 673  * them in one of two extent_io trees.  This is used to make sure all of
 674  * those extents are sent to disk but does not wait on them
 675  */
 676 int btrfs_write_marked_extents(struct btrfs_root *root,
 677                                struct extent_io_tree *dirty_pages, int mark)
 678 {
 679         int err = 0;
 680         int werr = 0;
 681         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 682         u64 start = 0;
 683         u64 end;
 684
 685         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 686                                       mark)) {
 687                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 688                                    GFP_NOFS);
 689                 err = filemap_fdatawrite_range(mapping, start, end);
 690                 if (err)
 691                         werr = err;
 692                 cond_resched();
 693                 start = end + 1;
 694         }
 695         if (err)
 696                 werr = err;
 697         return werr;
 698 }
 699
 700 /*
 701  * when btree blocks are allocated, they have some corresponding bits set for
 702  * them in one of two extent_io trees.  This is used to make sure all of
 703  * those extents are on disk for transaction or log commit.  We wait
 704  * on all the pages and clear them from the dirty pages state tree
 705  */
 706 int btrfs_wait_marked_extents(struct btrfs_root *root,
 707                               struct extent_io_tree *dirty_pages, int mark)
 708 {
 709         int err = 0;
 710         int werr = 0;
 711         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 712         u64 start = 0;
 713         u64 end;
 714
 715         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 716                                       EXTENT_NEED_WAIT)) {
 717                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 718                 err = filemap_fdatawait_range(mapping, start, end);
 719                 if (err)
 720                         werr = err;
 721                 cond_resched();
 722                 start = end + 1;
 723         }
 724         if (err)
 725                 werr = err;
 726         return werr;
 727 }
 728
 729 /*
 730  * when btree blocks are allocated, they have some corresponding bits set for
 731  * them in one of two extent_io trees.  This is used to make sure all of
 732  * those extents are on disk for transaction or log commit
 733  */
 734 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 735                                 struct extent_io_tree *dirty_pages, int mark)
 736 {
 737         int ret;
 738         int ret2;
 739
 740         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 741         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 742
 743         if (ret)
 744                 return ret;
 745         if (ret2)
 746                 return ret2;
 747         return 0;
 748 }
 749
 750 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 751                                      struct btrfs_root *root)
 752 {
 753         if (!trans || !trans->transaction) {
 754                 struct inode *btree_inode;
 755                 btree_inode = root->fs_info->btree_inode;
 756                 return filemap_write_and_wait(btree_inode->i_mapping);
 757         }
 758         return btrfs_write_and_wait_marked_extents(root,
 759                                            &trans->transaction->dirty_pages,
 760                                            EXTENT_DIRTY);
 761 }
 762
 763 /*
 764  * this is used to update the root pointer in the tree of tree roots.
 765  *
 766  * But, in the case of the extent allocation tree, updating the root
 767  * pointer may allocate blocks which may change the root of the extent
 768  * allocation tree.
 769  *
 770  * So, this loops and repeats and makes sure the cowonly root didn't
 771  * change while the root pointer was being updated in the metadata.
 772  */
 773 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 774                                struct btrfs_root *root)
 775 {
 776         int ret;
 777         u64 old_root_bytenr;
 778         u64 old_root_used;
 779         struct btrfs_root *tree_root = root->fs_info->tree_root;
 780
 781         old_root_used = btrfs_root_used(&root->root_item);
 782         btrfs_write_dirty_block_groups(trans, root);
 783
 784         while (1) {
 785                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 786                 if (old_root_bytenr == root->node->start &&
 787                     old_root_used == btrfs_root_used(&root->root_item))
 788                         break;
 789
 790                 btrfs_set_root_node(&root->root_item, root->node);
 791                 ret = btrfs_update_root(trans, tree_root,
 792                                         &root->root_key,
 793                                         &root->root_item);
 794                 if (ret)
 795                         return ret;
 796
 797                 old_root_used = btrfs_root_used(&root->root_item);
 798                 ret = btrfs_write_dirty_block_groups(trans, root);
 799                 if (ret)
 800                         return ret;
 801         }
 802
 803         if (root != root->fs_info->extent_root)
 804                 switch_commit_root(root);
 805
 806         return 0;
 807 }
 808
 809 /*
 810  * update all the cowonly tree roots on disk
 811  *
 812  * The error handling in this function may not be obvious. Any of the
 813  * failures will cause the file system to go offline. We still need
 814  * to clean up the delayed refs.
 815  */
 816 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 817                                          struct btrfs_root *root)
 818 {
 819         struct btrfs_fs_info *fs_info = root->fs_info;
 820         struct list_head *next;
 821         struct extent_buffer *eb;
 822         int ret;
 823
 824         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 825         if (ret)
 826                 return ret;
 827
 828         eb = btrfs_lock_root_node(fs_info->tree_root);
 829         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 830                               0, &eb);
 831         btrfs_tree_unlock(eb);
 832         free_extent_buffer(eb);
 833
 834         if (ret)
 835                 return ret;
 836
 837         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 838         if (ret)
 839                 return ret;
 840
 841         ret = btrfs_run_dev_stats(trans, root->fs_info);
 842         BUG_ON(ret);
 843
 844         ret = btrfs_run_qgroups(trans, root->fs_info);
 845         BUG_ON(ret);
 846
 847         /* run_qgroups might have added some more refs */
 848         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 849         BUG_ON(ret);
 850
 851         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 852                 next = fs_info->dirty_cowonly_roots.next;
 853                 list_del_init(next);
 854                 root = list_entry(next, struct btrfs_root, dirty_list);
 855
 856                 ret = update_cowonly_root(trans, root);
 857                 if (ret)
 858                         return ret;
 859         }
 860
 861         down_write(&fs_info->extent_commit_sem);
 862         switch_commit_root(fs_info->extent_root);
 863         up_write(&fs_info->extent_commit_sem);
 864
 865         return 0;
 866 }
 867
 868 /*
 869  * dead roots are old snapshots that need to be deleted.  This allocates
 870  * a dirty root struct and adds it into the list of dead roots that need to
 871  * be deleted
 872  */
 873 int btrfs_add_dead_root(struct btrfs_root *root)
 874 {
 875         spin_lock(&root->fs_info->trans_lock);
 876         list_add(&root->root_list, &root->fs_info->dead_roots);
 877         spin_unlock(&root->fs_info->trans_lock);
 878         return 0;
 879 }
 880
 881 /*
 882  * update all the cowonly tree roots on disk
 883  */
 884 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 885                                     struct btrfs_root *root)
 886 {
 887         struct btrfs_root *gang[8];
 888         struct btrfs_fs_info *fs_info = root->fs_info;
 889         int i;
 890         int ret;
 891         int err = 0;
 892
 893         spin_lock(&fs_info->fs_roots_radix_lock);
 894         while (1) {
 895                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 896                                                  (void **)gang, 0,
 897                                                  ARRAY_SIZE(gang),
 898                                                  BTRFS_ROOT_TRANS_TAG);
 899                 if (ret == 0)
 900                         break;
 901                 for (i = 0; i < ret; i++) {
 902                         root = gang[i];
 903                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 904                                         (unsigned long)root->root_key.objectid,
 905                                         BTRFS_ROOT_TRANS_TAG);
 906                         spin_unlock(&fs_info->fs_roots_radix_lock);
 907
 908                         btrfs_free_log(trans, root);
 909                         btrfs_update_reloc_root(trans, root);
 910                         btrfs_orphan_commit_root(trans, root);
 911
 912                         btrfs_save_ino_cache(root, trans);
 913
 914                         /* see comments in should_cow_block() */
 915                         root->force_cow = 0;
 916                         smp_wmb();
 917
 918                         if (root->commit_root != root->node) {
 919                                 mutex_lock(&root->fs_commit_mutex);
 920                                 switch_commit_root(root);
 921                                 btrfs_unpin_free_ino(root);
 922                                 mutex_unlock(&root->fs_commit_mutex);
 923
 924                                 btrfs_set_root_node(&root->root_item,
 925                                                     root->node);
 926                         }
 927
 928                         err = btrfs_update_root(trans, fs_info->tree_root,
 929                                                 &root->root_key,
 930                                                 &root->root_item);
 931                         spin_lock(&fs_info->fs_roots_radix_lock);
 932                         if (err)
 933                                 break;
 934                 }
 935         }
 936         spin_unlock(&fs_info->fs_roots_radix_lock);
 937         return err;
 938 }
 939
 940 /*
 941  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 942  * otherwise every leaf in the btree is read and defragged.
 943  */
 944 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 945 {
 946         struct btrfs_fs_info *info = root->fs_info;
 947         struct btrfs_trans_handle *trans;
 948         int ret;
 949         unsigned long nr;
 950
 951         if (xchg(&root->defrag_running, 1))
 952                 return 0;
 953
 954         while (1) {
 955                 trans = btrfs_start_transaction(root, 0);
 956                 if (IS_ERR(trans))
 957                         return PTR_ERR(trans);
 958
 959                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 960
 961                 nr = trans->blocks_used;
 962                 btrfs_end_transaction(trans, root);
 963                 btrfs_btree_balance_dirty(info->tree_root, nr);
 964                 cond_resched();
 965
 966                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 967                         break;
 968         }
 969         root->defrag_running = 0;
 970         return ret;
 971 }
 972
 973 /*
 974  * new snapshots need to be created at a very specific time in the
 975  * transaction commit.  This does the actual creation
 976  */
 977 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 978                                    struct btrfs_fs_info *fs_info,
 979                                    struct btrfs_pending_snapshot *pending)
 980 {
 981         struct btrfs_key key;
 982         struct btrfs_root_item *new_root_item;
 983         struct btrfs_root *tree_root = fs_info->tree_root;
 984         struct btrfs_root *root = pending->root;
 985         struct btrfs_root *parent_root;
 986         struct btrfs_block_rsv *rsv;
 987         struct inode *parent_inode;
 988         struct btrfs_path *path;
 989         struct btrfs_dir_item *dir_item;
 990         struct dentry *parent;
 991         struct dentry *dentry;
 992         struct extent_buffer *tmp;
 993         struct extent_buffer *old;
 994         struct timespec cur_time = CURRENT_TIME;
 995         int ret;
 996         u64 to_reserve = 0;
 997         u64 index = 0;
 998         u64 objectid;
 999         u64 root_flags;
1000         uuid_le new_uuid;
1001
1002         path = btrfs_alloc_path();
1003         if (!path) {
1004                 ret = pending->error = -ENOMEM;
1005                 goto path_alloc_fail;
1006         }
1007
1008         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1009         if (!new_root_item) {
1010                 ret = pending->error = -ENOMEM;
1011                 goto root_item_alloc_fail;
1012         }
1013
1014         ret = btrfs_find_free_objectid(tree_root, &objectid);
1015         if (ret) {
1016                 pending->error = ret;
1017                 goto no_free_objectid;
1018         }
1019
1020         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1021
1022         if (to_reserve > 0) {
1023                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
1024                                                   to_reserve);
1025                 if (ret) {
1026                         pending->error = ret;
1027                         goto no_free_objectid;
1028                 }
1029         }
1030
1031         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
1032                                    objectid, pending->inherit);
1033         if (ret) {
1034                 pending->error = ret;
1035                 goto no_free_objectid;
1036         }
1037
1038         key.objectid = objectid;
1039         key.offset = (u64)-1;
1040         key.type = BTRFS_ROOT_ITEM_KEY;
1041
1042         rsv = trans->block_rsv;
1043         trans->block_rsv = &pending->block_rsv;
1044
1045         dentry = pending->dentry;
1046         parent = dget_parent(dentry);
1047         parent_inode = parent->d_inode;
1048         parent_root = BTRFS_I(parent_inode)->root;
1049         record_root_in_trans(trans, parent_root);
1050
1051         /*
1052          * insert the directory item
1053          */
1054         ret = btrfs_set_inode_index(parent_inode, &index);
1055         BUG_ON(ret); /* -ENOMEM */
1056
1057         /* check if there is a file/dir which has the same name. */
1058         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1059                                          btrfs_ino(parent_inode),
1060                                          dentry->d_name.name,
1061                                          dentry->d_name.len, 0);
1062         if (dir_item != NULL && !IS_ERR(dir_item)) {
1063                 pending->error = -EEXIST;
1064                 goto fail;
1065         } else if (IS_ERR(dir_item)) {
1066                 ret = PTR_ERR(dir_item);
1067                 goto abort_trans;
1068         }
1069         btrfs_release_path(path);
1070
1071         /*
1072          * pull in the delayed directory update
1073          * and the delayed inode item
1074          * otherwise we corrupt the FS during
1075          * snapshot
1076          */
1077         ret = btrfs_run_delayed_items(trans, root);
1078         if (ret)        /* Transaction aborted */
1079                 goto abort_trans;
1080
1081         record_root_in_trans(trans, root);
1082         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1083         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1084         btrfs_check_and_init_root_item(new_root_item);
1085
1086         root_flags = btrfs_root_flags(new_root_item);
1087         if (pending->readonly)
1088                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1089         else
1090                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1091         btrfs_set_root_flags(new_root_item, root_flags);
1092
1093         btrfs_set_root_generation_v2(new_root_item,
1094                         trans->transid);
1095         uuid_le_gen(&new_uuid);
1096         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1097         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1098                         BTRFS_UUID_SIZE);
1099         new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1100         new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1101         btrfs_set_root_otransid(new_root_item, trans->transid);
1102         memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1103         memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1104         btrfs_set_root_stransid(new_root_item, 0);
1105         btrfs_set_root_rtransid(new_root_item, 0);
1106
1107         old = btrfs_lock_root_node(root);
1108         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1109         if (ret) {
1110                 btrfs_tree_unlock(old);
1111                 free_extent_buffer(old);
1112                 goto abort_trans;
1113         }
1114
1115         btrfs_set_lock_blocking(old);
1116
1117         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1118         /* clean up in any case */
1119         btrfs_tree_unlock(old);
1120         free_extent_buffer(old);
1121         if (ret)
1122                 goto abort_trans;
1123
1124         /* see comments in should_cow_block() */
1125         root->force_cow = 1;
1126         smp_wmb();
1127
1128         btrfs_set_root_node(new_root_item, tmp);
1129         /* record when the snapshot was created in key.offset */
1130         key.offset = trans->transid;
1131         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1132         btrfs_tree_unlock(tmp);
1133         free_extent_buffer(tmp);
1134         if (ret)
1135                 goto abort_trans;
1136
1137         /*
1138          * insert root back/forward references
1139          */
1140         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1141                                  parent_root->root_key.objectid,
1142                                  btrfs_ino(parent_inode), index,
1143                                  dentry->d_name.name, dentry->d_name.len);
1144         if (ret)
1145                 goto abort_trans;
1146
1147         key.offset = (u64)-1;
1148         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1149         if (IS_ERR(pending->snap)) {
1150                 ret = PTR_ERR(pending->snap);
1151                 goto abort_trans;
1152         }
1153
1154         ret = btrfs_reloc_post_snapshot(trans, pending);
1155         if (ret)
1156                 goto abort_trans;
1157
1158         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1159         if (ret)
1160                 goto abort_trans;
1161
1162         ret = btrfs_insert_dir_item(trans, parent_root,
1163                                     dentry->d_name.name, dentry->d_name.len,
1164                                     parent_inode, &key,
1165                                     BTRFS_FT_DIR, index);
1166         /* We have check then name at the beginning, so it is impossible. */
1167         BUG_ON(ret == -EEXIST);
1168         if (ret)
1169                 goto abort_trans;
1170
1171         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1172                                          dentry->d_name.len * 2);
1173         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1174         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1175         if (ret)
1176                 goto abort_trans;
1177 fail:
1178         dput(parent);
1179         trans->block_rsv = rsv;
1180 no_free_objectid:
1181         kfree(new_root_item);
1182 root_item_alloc_fail:
1183         btrfs_free_path(path);
1184 path_alloc_fail:
1185         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1186         return ret;
1187
1188 abort_trans:
1189         btrfs_abort_transaction(trans, root, ret);
1190         goto fail;
1191 }
1192
1193 /*
1194  * create all the snapshots we've scheduled for creation
1195  */
1196 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1197                                              struct btrfs_fs_info *fs_info)
1198 {
1199         struct btrfs_pending_snapshot *pending;
1200         struct list_head *head = &trans->transaction->pending_snapshots;
1201
1202         list_for_each_entry(pending, head, list)
1203                 create_pending_snapshot(trans, fs_info, pending);
1204         return 0;
1205 }
1206
1207 static void update_super_roots(struct btrfs_root *root)
1208 {
1209         struct btrfs_root_item *root_item;
1210         struct btrfs_super_block *super;
1211
1212         super = root->fs_info->super_copy;
1213
1214         root_item = &root->fs_info->chunk_root->root_item;
1215         super->chunk_root = root_item->bytenr;
1216         super->chunk_root_generation = root_item->generation;
1217         super->chunk_root_level = root_item->level;
1218
1219         root_item = &root->fs_info->tree_root->root_item;
1220         super->root = root_item->bytenr;
1221         super->generation = root_item->generation;
1222         super->root_level = root_item->level;
1223         if (btrfs_test_opt(root, SPACE_CACHE))
1224                 super->cache_generation = root_item->generation;
1225 }
1226
1227 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1228 {
1229         int ret = 0;
1230         spin_lock(&info->trans_lock);
1231         if (info->running_transaction)
1232                 ret = info->running_transaction->in_commit;
1233         spin_unlock(&info->trans_lock);
1234         return ret;
1235 }
1236
1237 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1238 {
1239         int ret = 0;
1240         spin_lock(&info->trans_lock);
1241         if (info->running_transaction)
1242                 ret = info->running_transaction->blocked;
1243         spin_unlock(&info->trans_lock);
1244         return ret;
1245 }
1246
1247 /*
1248  * wait for the current transaction commit to start and block subsequent
1249  * transaction joins
1250  */
1251 static void wait_current_trans_commit_start(struct btrfs_root *root,
1252                                             struct btrfs_transaction *trans)
1253 {
1254         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1255 }
1256
1257 /*
1258  * wait for the current transaction to start and then become unblocked.
1259  * caller holds ref.
1260  */
1261 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1262                                          struct btrfs_transaction *trans)
1263 {
1264         wait_event(root->fs_info->transaction_wait,
1265                    trans->commit_done || (trans->in_commit && !trans->blocked));
1266 }
1267
1268 /*
1269  * commit transactions asynchronously. once btrfs_commit_transaction_async
1270  * returns, any subsequent transaction will not be allowed to join.
1271  */
1272 struct btrfs_async_commit {
1273         struct btrfs_trans_handle *newtrans;
1274         struct btrfs_root *root;
1275         struct delayed_work work;
1276 };
1277
1278 static void do_async_commit(struct work_struct *work)
1279 {
1280         struct btrfs_async_commit *ac =
1281                 container_of(work, struct btrfs_async_commit, work.work);
1282
1283         /*
1284          * We've got freeze protection passed with the transaction.
1285          * Tell lockdep about it.
1286          */
1287         rwsem_acquire_read(
1288                 &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1289                 0, 1, _THIS_IP_);
1290
1291         current->journal_info = ac->newtrans;
1292
1293         btrfs_commit_transaction(ac->newtrans, ac->root);
1294         kfree(ac);
1295 }
1296
1297 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1298                                    struct btrfs_root *root,
1299                                    int wait_for_unblock)
1300 {
1301         struct btrfs_async_commit *ac;
1302         struct btrfs_transaction *cur_trans;
1303
1304         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1305         if (!ac)
1306                 return -ENOMEM;
1307
1308         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1309         ac->root = root;
1310         ac->newtrans = btrfs_join_transaction(root);
1311         if (IS_ERR(ac->newtrans)) {
1312                 int err = PTR_ERR(ac->newtrans);
1313                 kfree(ac);
1314                 return err;
1315         }
1316
1317         /* take transaction reference */
1318         cur_trans = trans->transaction;
1319         atomic_inc(&cur_trans->use_count);
1320
1321         btrfs_end_transaction(trans, root);
1322
1323         /*
1324          * Tell lockdep we've released the freeze rwsem, since the
1325          * async commit thread will be the one to unlock it.
1326          */
1327         rwsem_release(&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1328                       1, _THIS_IP_);
1329
1330         schedule_delayed_work(&ac->work, 0);
1331
1332         /* wait for transaction to start and unblock */
1333         if (wait_for_unblock)
1334                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1335         else
1336                 wait_current_trans_commit_start(root, cur_trans);
1337
1338         if (current->journal_info == trans)
1339                 current->journal_info = NULL;
1340
1341         put_transaction(cur_trans);
1342         return 0;
1343 }
1344
1345
1346 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1347                                 struct btrfs_root *root, int err)
1348 {
1349         struct btrfs_transaction *cur_trans = trans->transaction;
1350
1351         WARN_ON(trans->use_count > 1);
1352
1353         btrfs_abort_transaction(trans, root, err);
1354
1355         spin_lock(&root->fs_info->trans_lock);
1356         list_del_init(&cur_trans->list);
1357         if (cur_trans == root->fs_info->running_transaction) {
1358                 root->fs_info->running_transaction = NULL;
1359                 root->fs_info->trans_no_join = 0;
1360         }
1361         spin_unlock(&root->fs_info->trans_lock);
1362
1363         btrfs_cleanup_one_transaction(trans->transaction, root);
1364
1365         put_transaction(cur_trans);
1366         put_transaction(cur_trans);
1367
1368         trace_btrfs_transaction_commit(root);
1369
1370         btrfs_scrub_continue(root);
1371
1372         if (current->journal_info == trans)
1373                 current->journal_info = NULL;
1374
1375         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1376 }
1377
1378 /*
1379  * btrfs_transaction state sequence:
1380  *    in_commit = 0, blocked = 0  (initial)
1381  *    in_commit = 1, blocked = 1
1382  *    blocked = 0
1383  *    commit_done = 1
1384  */
1385 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1386                              struct btrfs_root *root)
1387 {
1388         unsigned long joined = 0;
1389         struct btrfs_transaction *cur_trans = trans->transaction;
1390         struct btrfs_transaction *prev_trans = NULL;
1391         DEFINE_WAIT(wait);
1392         int ret = -EIO;
1393         int should_grow = 0;
1394         unsigned long now = get_seconds();
1395         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1396
1397         btrfs_run_ordered_operations(root, 0);
1398
1399         if (cur_trans->aborted)
1400                 goto cleanup_transaction;
1401
1402         /* make a pass through all the delayed refs we have so far
1403          * any runnings procs may add more while we are here
1404          */
1405         ret = btrfs_run_delayed_refs(trans, root, 0);
1406         if (ret)
1407                 goto cleanup_transaction;
1408
1409         btrfs_trans_release_metadata(trans, root);
1410         trans->block_rsv = NULL;
1411
1412         cur_trans = trans->transaction;
1413
1414         /*
1415          * set the flushing flag so procs in this transaction have to
1416          * start sending their work down.
1417          */
1418         cur_trans->delayed_refs.flushing = 1;
1419
1420         if (!list_empty(&trans->new_bgs))
1421                 btrfs_create_pending_block_groups(trans, root);
1422
1423         ret = btrfs_run_delayed_refs(trans, root, 0);
1424         if (ret)
1425                 goto cleanup_transaction;
1426
1427         spin_lock(&cur_trans->commit_lock);
1428         if (cur_trans->in_commit) {
1429                 spin_unlock(&cur_trans->commit_lock);
1430                 atomic_inc(&cur_trans->use_count);
1431                 ret = btrfs_end_transaction(trans, root);
1432
1433                 wait_for_commit(root, cur_trans);
1434
1435                 put_transaction(cur_trans);
1436
1437                 return ret;
1438         }
1439
1440         trans->transaction->in_commit = 1;
1441         trans->transaction->blocked = 1;
1442         spin_unlock(&cur_trans->commit_lock);
1443         wake_up(&root->fs_info->transaction_blocked_wait);
1444
1445         spin_lock(&root->fs_info->trans_lock);
1446         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1447                 prev_trans = list_entry(cur_trans->list.prev,
1448                                         struct btrfs_transaction, list);
1449                 if (!prev_trans->commit_done) {
1450                         atomic_inc(&prev_trans->use_count);
1451                         spin_unlock(&root->fs_info->trans_lock);
1452
1453                         wait_for_commit(root, prev_trans);
1454
1455                         put_transaction(prev_trans);
1456                 } else {
1457                         spin_unlock(&root->fs_info->trans_lock);
1458                 }
1459         } else {
1460                 spin_unlock(&root->fs_info->trans_lock);
1461         }
1462
1463         if (!btrfs_test_opt(root, SSD) &&
1464             (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1465                 should_grow = 1;
1466
1467         do {
1468                 int snap_pending = 0;
1469
1470                 joined = cur_trans->num_joined;
1471                 if (!list_empty(&trans->transaction->pending_snapshots))
1472                         snap_pending = 1;
1473
1474                 WARN_ON(cur_trans != trans->transaction);
1475
1476                 if (flush_on_commit || snap_pending) {
1477                         btrfs_start_delalloc_inodes(root, 1);
1478                         btrfs_wait_ordered_extents(root, 0, 1);
1479                 }
1480
1481                 ret = btrfs_run_delayed_items(trans, root);
1482                 if (ret)
1483                         goto cleanup_transaction;
1484
1485                 /*
1486                  * running the delayed items may have added new refs. account
1487                  * them now so that they hinder processing of more delayed refs
1488                  * as little as possible.
1489                  */
1490                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1491
1492                 /*
1493                  * rename don't use btrfs_join_transaction, so, once we
1494                  * set the transaction to blocked above, we aren't going
1495                  * to get any new ordered operations.  We can safely run
1496                  * it here and no for sure that nothing new will be added
1497                  * to the list
1498                  */
1499                 btrfs_run_ordered_operations(root, 1);
1500
1501                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1502                                 TASK_UNINTERRUPTIBLE);
1503
1504                 if (atomic_read(&cur_trans->num_writers) > 1)
1505                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1506                 else if (should_grow)
1507                         schedule_timeout(1);
1508
1509                 finish_wait(&cur_trans->writer_wait, &wait);
1510         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1511                  (should_grow && cur_trans->num_joined != joined));
1512
1513         /*
1514          * Ok now we need to make sure to block out any other joins while we
1515          * commit the transaction.  We could have started a join before setting
1516          * no_join so make sure to wait for num_writers to == 1 again.
1517          */
1518         spin_lock(&root->fs_info->trans_lock);
1519         root->fs_info->trans_no_join = 1;
1520         spin_unlock(&root->fs_info->trans_lock);
1521         wait_event(cur_trans->writer_wait,
1522                    atomic_read(&cur_trans->num_writers) == 1);
1523
1524         /*
1525          * the reloc mutex makes sure that we stop
1526          * the balancing code from coming in and moving
1527          * extents around in the middle of the commit
1528          */
1529         mutex_lock(&root->fs_info->reloc_mutex);
1530
1531         /*
1532          * We needn't worry about the delayed items because we will
1533          * deal with them in create_pending_snapshot(), which is the
1534          * core function of the snapshot creation.
1535          */
1536         ret = create_pending_snapshots(trans, root->fs_info);
1537         if (ret) {
1538                 mutex_unlock(&root->fs_info->reloc_mutex);
1539                 goto cleanup_transaction;
1540         }
1541
1542         /*
1543          * We insert the dir indexes of the snapshots and update the inode
1544          * of the snapshots' parents after the snapshot creation, so there
1545          * are some delayed items which are not dealt with. Now deal with
1546          * them.
1547          *
1548          * We needn't worry that this operation will corrupt the snapshots,
1549          * because all the tree which are snapshoted will be forced to COW
1550          * the nodes and leaves.
1551          */
1552         ret = btrfs_run_delayed_items(trans, root);
1553         if (ret) {
1554                 mutex_unlock(&root->fs_info->reloc_mutex);
1555                 goto cleanup_transaction;
1556         }
1557
1558         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1559         if (ret) {
1560                 mutex_unlock(&root->fs_info->reloc_mutex);
1561                 goto cleanup_transaction;
1562         }
1563
1564         /*
1565          * make sure none of the code above managed to slip in a
1566          * delayed item
1567          */
1568         btrfs_assert_delayed_root_empty(root);
1569
1570         WARN_ON(cur_trans != trans->transaction);
1571
1572         btrfs_scrub_pause(root);
1573         /* btrfs_commit_tree_roots is responsible for getting the
1574          * various roots consistent with each other.  Every pointer
1575          * in the tree of tree roots has to point to the most up to date
1576          * root for every subvolume and other tree.  So, we have to keep
1577          * the tree logging code from jumping in and changing any
1578          * of the trees.
1579          *
1580          * At this point in the commit, there can't be any tree-log
1581          * writers, but a little lower down we drop the trans mutex
1582          * and let new people in.  By holding the tree_log_mutex
1583          * from now until after the super is written, we avoid races
1584          * with the tree-log code.
1585          */
1586         mutex_lock(&root->fs_info->tree_log_mutex);
1587
1588         ret = commit_fs_roots(trans, root);
1589         if (ret) {
1590                 mutex_unlock(&root->fs_info->tree_log_mutex);
1591                 mutex_unlock(&root->fs_info->reloc_mutex);
1592                 goto cleanup_transaction;
1593         }
1594
1595         /* commit_fs_roots gets rid of all the tree log roots, it is now
1596          * safe to free the root of tree log roots
1597          */
1598         btrfs_free_log_root_tree(trans, root->fs_info);
1599
1600         ret = commit_cowonly_roots(trans, root);
1601         if (ret) {
1602                 mutex_unlock(&root->fs_info->tree_log_mutex);
1603                 mutex_unlock(&root->fs_info->reloc_mutex);
1604                 goto cleanup_transaction;
1605         }
1606
1607         btrfs_prepare_extent_commit(trans, root);
1608
1609         cur_trans = root->fs_info->running_transaction;
1610
1611         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1612                             root->fs_info->tree_root->node);
1613         switch_commit_root(root->fs_info->tree_root);
1614
1615         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1616                             root->fs_info->chunk_root->node);
1617         switch_commit_root(root->fs_info->chunk_root);
1618
1619         assert_qgroups_uptodate(trans);
1620         update_super_roots(root);
1621
1622         if (!root->fs_info->log_root_recovering) {
1623                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1624                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1625         }
1626
1627         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1628                sizeof(*root->fs_info->super_copy));
1629
1630         trans->transaction->blocked = 0;
1631         spin_lock(&root->fs_info->trans_lock);
1632         root->fs_info->running_transaction = NULL;
1633         root->fs_info->trans_no_join = 0;
1634         spin_unlock(&root->fs_info->trans_lock);
1635         mutex_unlock(&root->fs_info->reloc_mutex);
1636
1637         wake_up(&root->fs_info->transaction_wait);
1638
1639         ret = btrfs_write_and_wait_transaction(trans, root);
1640         if (ret) {
1641                 btrfs_error(root->fs_info, ret,
1642                             "Error while writing out transaction.");
1643                 mutex_unlock(&root->fs_info->tree_log_mutex);
1644                 goto cleanup_transaction;
1645         }
1646
1647         ret = write_ctree_super(trans, root, 0);
1648         if (ret) {
1649                 mutex_unlock(&root->fs_info->tree_log_mutex);
1650                 goto cleanup_transaction;
1651         }
1652
1653         /*
1654          * the super is written, we can safely allow the tree-loggers
1655          * to go about their business
1656          */
1657         mutex_unlock(&root->fs_info->tree_log_mutex);
1658
1659         btrfs_finish_extent_commit(trans, root);
1660
1661         cur_trans->commit_done = 1;
1662
1663         root->fs_info->last_trans_committed = cur_trans->transid;
1664
1665         wake_up(&cur_trans->commit_wait);
1666
1667         spin_lock(&root->fs_info->trans_lock);
1668         list_del_init(&cur_trans->list);
1669         spin_unlock(&root->fs_info->trans_lock);
1670
1671         put_transaction(cur_trans);
1672         put_transaction(cur_trans);
1673
1674         sb_end_intwrite(root->fs_info->sb);
1675
1676         trace_btrfs_transaction_commit(root);
1677
1678         btrfs_scrub_continue(root);
1679
1680         if (current->journal_info == trans)
1681                 current->journal_info = NULL;
1682
1683         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1684
1685         if (current != root->fs_info->transaction_kthread)
1686                 btrfs_run_delayed_iputs(root);
1687
1688         return ret;
1689
1690 cleanup_transaction:
1691         btrfs_trans_release_metadata(trans, root);
1692         trans->block_rsv = NULL;
1693         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1694 //      WARN_ON(1);
1695         if (current->journal_info == trans)
1696                 current->journal_info = NULL;
1697         cleanup_transaction(trans, root, ret);
1698
1699         return ret;
1700 }
1701
1702 /*
1703  * interface function to delete all the snapshots we have scheduled for deletion
1704  */
1705 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1706 {
1707         LIST_HEAD(list);
1708         struct btrfs_fs_info *fs_info = root->fs_info;
1709
1710         spin_lock(&fs_info->trans_lock);
1711         list_splice_init(&fs_info->dead_roots, &list);
1712         spin_unlock(&fs_info->trans_lock);
1713
1714         while (!list_empty(&list)) {
1715                 int ret;
1716
1717                 root = list_entry(list.next, struct btrfs_root, root_list);
1718                 list_del(&root->root_list);
1719
1720                 btrfs_kill_all_delayed_nodes(root);
1721
1722                 if (btrfs_header_backref_rev(root->node) <
1723                     BTRFS_MIXED_BACKREF_REV)
1724                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1725                 else
1726                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1727                 BUG_ON(ret < 0);
1728         }
1729         return 0;
1730 }