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/sched.h>
  21 #include <linux/writeback.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/blkdev.h>
  24 #include "ctree.h"
  25 #include "disk-io.h"
  26 #include "transaction.h"
  27 #include "locking.h"
  28 #include "tree-log.h"
  29
  30 #define BTRFS_ROOT_TRANS_TAG 0
  31
  32 static noinline void put_transaction(struct btrfs_transaction *transaction)
  33 {
  34         WARN_ON(transaction->use_count == 0);
  35         transaction->use_count--;
  36         if (transaction->use_count == 0) {
  37                 list_del_init(&transaction->list);
  38                 memset(transaction, 0, sizeof(*transaction));
  39                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  40         }
  41 }
  42
  43 static noinline void switch_commit_root(struct btrfs_root *root)
  44 {
  45         free_extent_buffer(root->commit_root);
  46         root->commit_root = btrfs_root_node(root);
  47 }
  48
  49 /*
  50  * either allocate a new transaction or hop into the existing one
  51  */
  52 static noinline int join_transaction(struct btrfs_root *root)
  53 {
  54         struct btrfs_transaction *cur_trans;
  55         cur_trans = root->fs_info->running_transaction;
  56         if (!cur_trans) {
  57                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  58                                              GFP_NOFS);
  59                 BUG_ON(!cur_trans);
  60                 root->fs_info->generation++;
  61                 cur_trans->num_writers = 1;
  62                 cur_trans->num_joined = 0;
  63                 cur_trans->transid = root->fs_info->generation;
  64                 init_waitqueue_head(&cur_trans->writer_wait);
  65                 init_waitqueue_head(&cur_trans->commit_wait);
  66                 cur_trans->in_commit = 0;
  67                 cur_trans->blocked = 0;
  68                 cur_trans->use_count = 1;
  69                 cur_trans->commit_done = 0;
  70                 cur_trans->start_time = get_seconds();
  71
  72                 cur_trans->delayed_refs.root.rb_node = NULL;
  73                 cur_trans->delayed_refs.num_entries = 0;
  74                 cur_trans->delayed_refs.num_heads_ready = 0;
  75                 cur_trans->delayed_refs.num_heads = 0;
  76                 cur_trans->delayed_refs.flushing = 0;
  77                 cur_trans->delayed_refs.run_delayed_start = 0;
  78                 spin_lock_init(&cur_trans->delayed_refs.lock);
  79
  80                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  81                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  82                 extent_io_tree_init(&cur_trans->dirty_pages,
  83                                      root->fs_info->btree_inode->i_mapping,
  84                                      GFP_NOFS);
  85                 spin_lock(&root->fs_info->new_trans_lock);
  86                 root->fs_info->running_transaction = cur_trans;
  87                 spin_unlock(&root->fs_info->new_trans_lock);
  88         } else {
  89                 cur_trans->num_writers++;
  90                 cur_trans->num_joined++;
  91         }
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * this does all the record keeping required to make sure that a reference
  98  * counted root is properly recorded in a given transaction.  This is required
  99  * to make sure the old root from before we joined the transaction is deleted
 100  * when the transaction commits
 101  */
 102 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 103                                          struct btrfs_root *root)
 104 {
 105         if (root->ref_cows && root->last_trans < trans->transid) {
 106                 WARN_ON(root == root->fs_info->extent_root);
 107                 WARN_ON(root->commit_root != root->node);
 108
 109                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 110                            (unsigned long)root->root_key.objectid,
 111                            BTRFS_ROOT_TRANS_TAG);
 112                 root->last_trans = trans->transid;
 113                 btrfs_init_reloc_root(trans, root);
 114         }
 115         return 0;
 116 }
 117
 118 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 119                                struct btrfs_root *root)
 120 {
 121         if (!root->ref_cows)
 122                 return 0;
 123
 124         mutex_lock(&root->fs_info->trans_mutex);
 125         if (root->last_trans == trans->transid) {
 126                 mutex_unlock(&root->fs_info->trans_mutex);
 127                 return 0;
 128         }
 129
 130         record_root_in_trans(trans, root);
 131         mutex_unlock(&root->fs_info->trans_mutex);
 132         return 0;
 133 }
 134
 135 /* wait for commit against the current transaction to become unblocked
 136  * when this is done, it is safe to start a new transaction, but the current
 137  * transaction might not be fully on disk.
 138  */
 139 static void wait_current_trans(struct btrfs_root *root)
 140 {
 141         struct btrfs_transaction *cur_trans;
 142
 143         cur_trans = root->fs_info->running_transaction;
 144         if (cur_trans && cur_trans->blocked) {
 145                 DEFINE_WAIT(wait);
 146                 cur_trans->use_count++;
 147                 while (1) {
 148                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 149                                         TASK_UNINTERRUPTIBLE);
 150                         if (cur_trans->blocked) {
 151                                 mutex_unlock(&root->fs_info->trans_mutex);
 152                                 schedule();
 153                                 mutex_lock(&root->fs_info->trans_mutex);
 154                                 finish_wait(&root->fs_info->transaction_wait,
 155                                             &wait);
 156                         } else {
 157                                 finish_wait(&root->fs_info->transaction_wait,
 158                                             &wait);
 159                                 break;
 160                         }
 161                 }
 162                 put_transaction(cur_trans);
 163         }
 164 }
 165
 166 enum btrfs_trans_type {
 167         TRANS_START,
 168         TRANS_JOIN,
 169         TRANS_USERSPACE,
 170 };
 171
 172 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 173                                              int num_blocks, int type)
 174 {
 175         struct btrfs_trans_handle *h =
 176                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 177         int ret;
 178
 179         mutex_lock(&root->fs_info->trans_mutex);
 180         if (!root->fs_info->log_root_recovering &&
 181             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 182              type == TRANS_USERSPACE))
 183                 wait_current_trans(root);
 184         ret = join_transaction(root);
 185         BUG_ON(ret);
 186
 187         h->transid = root->fs_info->running_transaction->transid;
 188         h->transaction = root->fs_info->running_transaction;
 189         h->blocks_reserved = num_blocks;
 190         h->blocks_used = 0;
 191         h->block_group = 0;
 192         h->alloc_exclude_nr = 0;
 193         h->alloc_exclude_start = 0;
 194         h->delayed_ref_updates = 0;
 195
 196         if (!current->journal_info && type != TRANS_USERSPACE)
 197                 current->journal_info = h;
 198
 199         root->fs_info->running_transaction->use_count++;
 200         record_root_in_trans(h, root);
 201         mutex_unlock(&root->fs_info->trans_mutex);
 202         return h;
 203 }
 204
 205 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 206                                                    int num_blocks)
 207 {
 208         return start_transaction(root, num_blocks, TRANS_START);
 209 }
 210 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 211                                                    int num_blocks)
 212 {
 213         return start_transaction(root, num_blocks, TRANS_JOIN);
 214 }
 215
 216 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 217                                                          int num_blocks)
 218 {
 219         return start_transaction(r, num_blocks, TRANS_USERSPACE);
 220 }
 221
 222 /* wait for a transaction commit to be fully complete */
 223 static noinline int wait_for_commit(struct btrfs_root *root,
 224                                     struct btrfs_transaction *commit)
 225 {
 226         DEFINE_WAIT(wait);
 227         mutex_lock(&root->fs_info->trans_mutex);
 228         while (!commit->commit_done) {
 229                 prepare_to_wait(&commit->commit_wait, &wait,
 230                                 TASK_UNINTERRUPTIBLE);
 231                 if (commit->commit_done)
 232                         break;
 233                 mutex_unlock(&root->fs_info->trans_mutex);
 234                 schedule();
 235                 mutex_lock(&root->fs_info->trans_mutex);
 236         }
 237         mutex_unlock(&root->fs_info->trans_mutex);
 238         finish_wait(&commit->commit_wait, &wait);
 239         return 0;
 240 }
 241
 242 #if 0
 243 /*
 244  * rate limit against the drop_snapshot code.  This helps to slow down new
 245  * operations if the drop_snapshot code isn't able to keep up.
 246  */
 247 static void throttle_on_drops(struct btrfs_root *root)
 248 {
 249         struct btrfs_fs_info *info = root->fs_info;
 250         int harder_count = 0;
 251
 252 harder:
 253         if (atomic_read(&info->throttles)) {
 254                 DEFINE_WAIT(wait);
 255                 int thr;
 256                 thr = atomic_read(&info->throttle_gen);
 257
 258                 do {
 259                         prepare_to_wait(&info->transaction_throttle,
 260                                         &wait, TASK_UNINTERRUPTIBLE);
 261                         if (!atomic_read(&info->throttles)) {
 262                                 finish_wait(&info->transaction_throttle, &wait);
 263                                 break;
 264                         }
 265                         schedule();
 266                         finish_wait(&info->transaction_throttle, &wait);
 267                 } while (thr == atomic_read(&info->throttle_gen));
 268                 harder_count++;
 269
 270                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 271                     harder_count < 2)
 272                         goto harder;
 273
 274                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 275                     harder_count < 10)
 276                         goto harder;
 277
 278                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 279                     harder_count < 20)
 280                         goto harder;
 281         }
 282 }
 283 #endif
 284
 285 void btrfs_throttle(struct btrfs_root *root)
 286 {
 287         mutex_lock(&root->fs_info->trans_mutex);
 288         if (!root->fs_info->open_ioctl_trans)
 289                 wait_current_trans(root);
 290         mutex_unlock(&root->fs_info->trans_mutex);
 291 }
 292
 293 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 294                           struct btrfs_root *root, int throttle)
 295 {
 296         struct btrfs_transaction *cur_trans;
 297         struct btrfs_fs_info *info = root->fs_info;
 298         int count = 0;
 299
 300         while (count < 4) {
 301                 unsigned long cur = trans->delayed_ref_updates;
 302                 trans->delayed_ref_updates = 0;
 303                 if (cur &&
 304                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 305                         trans->delayed_ref_updates = 0;
 306
 307                         /*
 308                          * do a full flush if the transaction is trying
 309                          * to close
 310                          */
 311                         if (trans->transaction->delayed_refs.flushing)
 312                                 cur = 0;
 313                         btrfs_run_delayed_refs(trans, root, cur);
 314                 } else {
 315                         break;
 316                 }
 317                 count++;
 318         }
 319
 320         mutex_lock(&info->trans_mutex);
 321         cur_trans = info->running_transaction;
 322         WARN_ON(cur_trans != trans->transaction);
 323         WARN_ON(cur_trans->num_writers < 1);
 324         cur_trans->num_writers--;
 325
 326         if (waitqueue_active(&cur_trans->writer_wait))
 327                 wake_up(&cur_trans->writer_wait);
 328         put_transaction(cur_trans);
 329         mutex_unlock(&info->trans_mutex);
 330
 331         if (current->journal_info == trans)
 332                 current->journal_info = NULL;
 333         memset(trans, 0, sizeof(*trans));
 334         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 335
 336         return 0;
 337 }
 338
 339 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 340                           struct btrfs_root *root)
 341 {
 342         return __btrfs_end_transaction(trans, root, 0);
 343 }
 344
 345 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 346                                    struct btrfs_root *root)
 347 {
 348         return __btrfs_end_transaction(trans, root, 1);
 349 }
 350
 351 /*
 352  * when btree blocks are allocated, they have some corresponding bits set for
 353  * them in one of two extent_io trees.  This is used to make sure all of
 354  * those extents are sent to disk but does not wait on them
 355  */
 356 int btrfs_write_marked_extents(struct btrfs_root *root,
 357                                struct extent_io_tree *dirty_pages, int mark)
 358 {
 359         int ret;
 360         int err = 0;
 361         int werr = 0;
 362         struct page *page;
 363         struct inode *btree_inode = root->fs_info->btree_inode;
 364         u64 start = 0;
 365         u64 end;
 366         unsigned long index;
 367
 368         while (1) {
 369                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 370                                             mark);
 371                 if (ret)
 372                         break;
 373                 while (start <= end) {
 374                         cond_resched();
 375
 376                         index = start >> PAGE_CACHE_SHIFT;
 377                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 378                         page = find_get_page(btree_inode->i_mapping, index);
 379                         if (!page)
 380                                 continue;
 381
 382                         btree_lock_page_hook(page);
 383                         if (!page->mapping) {
 384                                 unlock_page(page);
 385                                 page_cache_release(page);
 386                                 continue;
 387                         }
 388
 389                         if (PageWriteback(page)) {
 390                                 if (PageDirty(page))
 391                                         wait_on_page_writeback(page);
 392                                 else {
 393                                         unlock_page(page);
 394                                         page_cache_release(page);
 395                                         continue;
 396                                 }
 397                         }
 398                         err = write_one_page(page, 0);
 399                         if (err)
 400                                 werr = err;
 401                         page_cache_release(page);
 402                 }
 403         }
 404         if (err)
 405                 werr = err;
 406         return werr;
 407 }
 408
 409 /*
 410  * when btree blocks are allocated, they have some corresponding bits set for
 411  * them in one of two extent_io trees.  This is used to make sure all of
 412  * those extents are on disk for transaction or log commit.  We wait
 413  * on all the pages and clear them from the dirty pages state tree
 414  */
 415 int btrfs_wait_marked_extents(struct btrfs_root *root,
 416                               struct extent_io_tree *dirty_pages, int mark)
 417 {
 418         int ret;
 419         int err = 0;
 420         int werr = 0;
 421         struct page *page;
 422         struct inode *btree_inode = root->fs_info->btree_inode;
 423         u64 start = 0;
 424         u64 end;
 425         unsigned long index;
 426
 427         while (1) {
 428                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 429                                             mark);
 430                 if (ret)
 431                         break;
 432
 433                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 434                 while (start <= end) {
 435                         index = start >> PAGE_CACHE_SHIFT;
 436                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 437                         page = find_get_page(btree_inode->i_mapping, index);
 438                         if (!page)
 439                                 continue;
 440                         if (PageDirty(page)) {
 441                                 btree_lock_page_hook(page);
 442                                 wait_on_page_writeback(page);
 443                                 err = write_one_page(page, 0);
 444                                 if (err)
 445                                         werr = err;
 446                         }
 447                         wait_on_page_writeback(page);
 448                         page_cache_release(page);
 449                         cond_resched();
 450                 }
 451         }
 452         if (err)
 453                 werr = err;
 454         return werr;
 455 }
 456
 457 /*
 458  * when btree blocks are allocated, they have some corresponding bits set for
 459  * them in one of two extent_io trees.  This is used to make sure all of
 460  * those extents are on disk for transaction or log commit
 461  */
 462 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 463                                 struct extent_io_tree *dirty_pages, int mark)
 464 {
 465         int ret;
 466         int ret2;
 467
 468         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 469         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 470         return ret || ret2;
 471 }
 472
 473 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 474                                      struct btrfs_root *root)
 475 {
 476         if (!trans || !trans->transaction) {
 477                 struct inode *btree_inode;
 478                 btree_inode = root->fs_info->btree_inode;
 479                 return filemap_write_and_wait(btree_inode->i_mapping);
 480         }
 481         return btrfs_write_and_wait_marked_extents(root,
 482                                            &trans->transaction->dirty_pages,
 483                                            EXTENT_DIRTY);
 484 }
 485
 486 /*
 487  * this is used to update the root pointer in the tree of tree roots.
 488  *
 489  * But, in the case of the extent allocation tree, updating the root
 490  * pointer may allocate blocks which may change the root of the extent
 491  * allocation tree.
 492  *
 493  * So, this loops and repeats and makes sure the cowonly root didn't
 494  * change while the root pointer was being updated in the metadata.
 495  */
 496 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 497                                struct btrfs_root *root)
 498 {
 499         int ret;
 500         u64 old_root_bytenr;
 501         struct btrfs_root *tree_root = root->fs_info->tree_root;
 502
 503         btrfs_write_dirty_block_groups(trans, root);
 504
 505         while (1) {
 506                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 507                 if (old_root_bytenr == root->node->start)
 508                         break;
 509
 510                 btrfs_set_root_node(&root->root_item, root->node);
 511                 ret = btrfs_update_root(trans, tree_root,
 512                                         &root->root_key,
 513                                         &root->root_item);
 514                 BUG_ON(ret);
 515
 516                 ret = btrfs_write_dirty_block_groups(trans, root);
 517                 BUG_ON(ret);
 518         }
 519
 520         if (root != root->fs_info->extent_root)
 521                 switch_commit_root(root);
 522
 523         return 0;
 524 }
 525
 526 /*
 527  * update all the cowonly tree roots on disk
 528  */
 529 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 530                                          struct btrfs_root *root)
 531 {
 532         struct btrfs_fs_info *fs_info = root->fs_info;
 533         struct list_head *next;
 534         struct extent_buffer *eb;
 535         int ret;
 536
 537         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 538         BUG_ON(ret);
 539
 540         eb = btrfs_lock_root_node(fs_info->tree_root);
 541         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 542         btrfs_tree_unlock(eb);
 543         free_extent_buffer(eb);
 544
 545         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 546         BUG_ON(ret);
 547
 548         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 549                 next = fs_info->dirty_cowonly_roots.next;
 550                 list_del_init(next);
 551                 root = list_entry(next, struct btrfs_root, dirty_list);
 552
 553                 update_cowonly_root(trans, root);
 554         }
 555
 556         down_write(&fs_info->extent_commit_sem);
 557         switch_commit_root(fs_info->extent_root);
 558         up_write(&fs_info->extent_commit_sem);
 559
 560         return 0;
 561 }
 562
 563 /*
 564  * dead roots are old snapshots that need to be deleted.  This allocates
 565  * a dirty root struct and adds it into the list of dead roots that need to
 566  * be deleted
 567  */
 568 int btrfs_add_dead_root(struct btrfs_root *root)
 569 {
 570         mutex_lock(&root->fs_info->trans_mutex);
 571         list_add(&root->root_list, &root->fs_info->dead_roots);
 572         mutex_unlock(&root->fs_info->trans_mutex);
 573         return 0;
 574 }
 575
 576 /*
 577  * update all the cowonly tree roots on disk
 578  */
 579 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 580                                     struct btrfs_root *root)
 581 {
 582         struct btrfs_root *gang[8];
 583         struct btrfs_fs_info *fs_info = root->fs_info;
 584         int i;
 585         int ret;
 586         int err = 0;
 587
 588         while (1) {
 589                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 590                                                  (void **)gang, 0,
 591                                                  ARRAY_SIZE(gang),
 592                                                  BTRFS_ROOT_TRANS_TAG);
 593                 if (ret == 0)
 594                         break;
 595                 for (i = 0; i < ret; i++) {
 596                         root = gang[i];
 597                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 598                                         (unsigned long)root->root_key.objectid,
 599                                         BTRFS_ROOT_TRANS_TAG);
 600
 601                         btrfs_free_log(trans, root);
 602                         btrfs_update_reloc_root(trans, root);
 603
 604                         if (root->commit_root != root->node) {
 605                                 switch_commit_root(root);
 606                                 btrfs_set_root_node(&root->root_item,
 607                                                     root->node);
 608                         }
 609
 610                         err = btrfs_update_root(trans, fs_info->tree_root,
 611                                                 &root->root_key,
 612                                                 &root->root_item);
 613                         if (err)
 614                                 break;
 615                 }
 616         }
 617         return err;
 618 }
 619
 620 /*
 621  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 622  * otherwise every leaf in the btree is read and defragged.
 623  */
 624 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 625 {
 626         struct btrfs_fs_info *info = root->fs_info;
 627         int ret;
 628         struct btrfs_trans_handle *trans;
 629         unsigned long nr;
 630
 631         smp_mb();
 632         if (root->defrag_running)
 633                 return 0;
 634         trans = btrfs_start_transaction(root, 1);
 635         while (1) {
 636                 root->defrag_running = 1;
 637                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 638                 nr = trans->blocks_used;
 639                 btrfs_end_transaction(trans, root);
 640                 btrfs_btree_balance_dirty(info->tree_root, nr);
 641                 cond_resched();
 642
 643                 trans = btrfs_start_transaction(root, 1);
 644                 if (root->fs_info->closing || ret != -EAGAIN)
 645                         break;
 646         }
 647         root->defrag_running = 0;
 648         smp_mb();
 649         btrfs_end_transaction(trans, root);
 650         return 0;
 651 }
 652
 653 #if 0
 654 /*
 655  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 656  * sense not to join the transaction while it is trying to flush the current
 657  * queue of delayed refs out.
 658  *
 659  * This is used by the drop snapshot code only
 660  */
 661 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 662 {
 663         DEFINE_WAIT(wait);
 664
 665         mutex_lock(&info->trans_mutex);
 666         while (info->running_transaction &&
 667                info->running_transaction->delayed_refs.flushing) {
 668                 prepare_to_wait(&info->transaction_wait, &wait,
 669                                 TASK_UNINTERRUPTIBLE);
 670                 mutex_unlock(&info->trans_mutex);
 671
 672                 schedule();
 673
 674                 mutex_lock(&info->trans_mutex);
 675                 finish_wait(&info->transaction_wait, &wait);
 676         }
 677         mutex_unlock(&info->trans_mutex);
 678         return 0;
 679 }
 680
 681 /*
 682  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 683  * all of them
 684  */
 685 int btrfs_drop_dead_root(struct btrfs_root *root)
 686 {
 687         struct btrfs_trans_handle *trans;
 688         struct btrfs_root *tree_root = root->fs_info->tree_root;
 689         unsigned long nr;
 690         int ret;
 691
 692         while (1) {
 693                 /*
 694                  * we don't want to jump in and create a bunch of
 695                  * delayed refs if the transaction is starting to close
 696                  */
 697                 wait_transaction_pre_flush(tree_root->fs_info);
 698                 trans = btrfs_start_transaction(tree_root, 1);
 699
 700                 /*
 701                  * we've joined a transaction, make sure it isn't
 702                  * closing right now
 703                  */
 704                 if (trans->transaction->delayed_refs.flushing) {
 705                         btrfs_end_transaction(trans, tree_root);
 706                         continue;
 707                 }
 708
 709                 ret = btrfs_drop_snapshot(trans, root);
 710                 if (ret != -EAGAIN)
 711                         break;
 712
 713                 ret = btrfs_update_root(trans, tree_root,
 714                                         &root->root_key,
 715                                         &root->root_item);
 716                 if (ret)
 717                         break;
 718
 719                 nr = trans->blocks_used;
 720                 ret = btrfs_end_transaction(trans, tree_root);
 721                 BUG_ON(ret);
 722
 723                 btrfs_btree_balance_dirty(tree_root, nr);
 724                 cond_resched();
 725         }
 726         BUG_ON(ret);
 727
 728         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 729         BUG_ON(ret);
 730
 731         nr = trans->blocks_used;
 732         ret = btrfs_end_transaction(trans, tree_root);
 733         BUG_ON(ret);
 734
 735         free_extent_buffer(root->node);
 736         free_extent_buffer(root->commit_root);
 737         kfree(root);
 738
 739         btrfs_btree_balance_dirty(tree_root, nr);
 740         return ret;
 741 }
 742 #endif
 743
 744 /*
 745  * new snapshots need to be created at a very specific time in the
 746  * transaction commit.  This does the actual creation
 747  */
 748 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 749                                    struct btrfs_fs_info *fs_info,
 750                                    struct btrfs_pending_snapshot *pending)
 751 {
 752         struct btrfs_key key;
 753         struct btrfs_root_item *new_root_item;
 754         struct btrfs_root *tree_root = fs_info->tree_root;
 755         struct btrfs_root *root = pending->root;
 756         struct extent_buffer *tmp;
 757         struct extent_buffer *old;
 758         int ret;
 759         u64 objectid;
 760
 761         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 762         if (!new_root_item) {
 763                 ret = -ENOMEM;
 764                 goto fail;
 765         }
 766         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 767         if (ret)
 768                 goto fail;
 769
 770         record_root_in_trans(trans, root);
 771         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 772         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 773
 774         key.objectid = objectid;
 775         /* record when the snapshot was created in key.offset */
 776         key.offset = trans->transid;
 777         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 778
 779         old = btrfs_lock_root_node(root);
 780         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 781         btrfs_set_lock_blocking(old);
 782
 783         btrfs_copy_root(trans, root, old, &tmp, objectid);
 784         btrfs_tree_unlock(old);
 785         free_extent_buffer(old);
 786
 787         btrfs_set_root_node(new_root_item, tmp);
 788         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 789                                 new_root_item);
 790         btrfs_tree_unlock(tmp);
 791         free_extent_buffer(tmp);
 792         if (ret)
 793                 goto fail;
 794
 795         key.offset = (u64)-1;
 796         memcpy(&pending->root_key, &key, sizeof(key));
 797 fail:
 798         kfree(new_root_item);
 799         return ret;
 800 }
 801
 802 static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
 803                                    struct btrfs_pending_snapshot *pending)
 804 {
 805         int ret;
 806         int namelen;
 807         u64 index = 0;
 808         struct btrfs_trans_handle *trans;
 809         struct inode *parent_inode;
 810         struct btrfs_root *parent_root;
 811
 812         parent_inode = pending->dentry->d_parent->d_inode;
 813         parent_root = BTRFS_I(parent_inode)->root;
 814         trans = btrfs_join_transaction(parent_root, 1);
 815
 816         /*
 817          * insert the directory item
 818          */
 819         namelen = strlen(pending->name);
 820         ret = btrfs_set_inode_index(parent_inode, &index);
 821         ret = btrfs_insert_dir_item(trans, parent_root,
 822                             pending->name, namelen,
 823                             parent_inode->i_ino,
 824                             &pending->root_key, BTRFS_FT_DIR, index);
 825
 826         if (ret)
 827                 goto fail;
 828
 829         btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
 830         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 831         BUG_ON(ret);
 832
 833         ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
 834                                  pending->root_key.objectid,
 835                                  parent_root->root_key.objectid,
 836                                  parent_inode->i_ino, index, pending->name,
 837                                  namelen);
 838
 839         BUG_ON(ret);
 840
 841 fail:
 842         btrfs_end_transaction(trans, fs_info->fs_root);
 843         return ret;
 844 }
 845
 846 /*
 847  * create all the snapshots we've scheduled for creation
 848  */
 849 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 850                                              struct btrfs_fs_info *fs_info)
 851 {
 852         struct btrfs_pending_snapshot *pending;
 853         struct list_head *head = &trans->transaction->pending_snapshots;
 854         int ret;
 855
 856         list_for_each_entry(pending, head, list) {
 857                 ret = create_pending_snapshot(trans, fs_info, pending);
 858                 BUG_ON(ret);
 859         }
 860         return 0;
 861 }
 862
 863 static noinline int finish_pending_snapshots(struct btrfs_trans_handle *trans,
 864                                              struct btrfs_fs_info *fs_info)
 865 {
 866         struct btrfs_pending_snapshot *pending;
 867         struct list_head *head = &trans->transaction->pending_snapshots;
 868         int ret;
 869
 870         while (!list_empty(head)) {
 871                 pending = list_entry(head->next,
 872                                      struct btrfs_pending_snapshot, list);
 873                 ret = finish_pending_snapshot(fs_info, pending);
 874                 BUG_ON(ret);
 875                 list_del(&pending->list);
 876                 kfree(pending->name);
 877                 kfree(pending);
 878         }
 879         return 0;
 880 }
 881
 882 static void update_super_roots(struct btrfs_root *root)
 883 {
 884         struct btrfs_root_item *root_item;
 885         struct btrfs_super_block *super;
 886
 887         super = &root->fs_info->super_copy;
 888
 889         root_item = &root->fs_info->chunk_root->root_item;
 890         super->chunk_root = root_item->bytenr;
 891         super->chunk_root_generation = root_item->generation;
 892         super->chunk_root_level = root_item->level;
 893
 894         root_item = &root->fs_info->tree_root->root_item;
 895         super->root = root_item->bytenr;
 896         super->generation = root_item->generation;
 897         super->root_level = root_item->level;
 898 }
 899
 900 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
 901 {
 902         int ret = 0;
 903         spin_lock(&info->new_trans_lock);
 904         if (info->running_transaction)
 905                 ret = info->running_transaction->in_commit;
 906         spin_unlock(&info->new_trans_lock);
 907         return ret;
 908 }
 909
 910 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 911                              struct btrfs_root *root)
 912 {
 913         unsigned long joined = 0;
 914         unsigned long timeout = 1;
 915         struct btrfs_transaction *cur_trans;
 916         struct btrfs_transaction *prev_trans = NULL;
 917         DEFINE_WAIT(wait);
 918         int ret;
 919         int should_grow = 0;
 920         unsigned long now = get_seconds();
 921         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
 922
 923         btrfs_run_ordered_operations(root, 0);
 924
 925         /* make a pass through all the delayed refs we have so far
 926          * any runnings procs may add more while we are here
 927          */
 928         ret = btrfs_run_delayed_refs(trans, root, 0);
 929         BUG_ON(ret);
 930
 931         cur_trans = trans->transaction;
 932         /*
 933          * set the flushing flag so procs in this transaction have to
 934          * start sending their work down.
 935          */
 936         cur_trans->delayed_refs.flushing = 1;
 937
 938         ret = btrfs_run_delayed_refs(trans, root, 0);
 939         BUG_ON(ret);
 940
 941         mutex_lock(&root->fs_info->trans_mutex);
 942         if (cur_trans->in_commit) {
 943                 cur_trans->use_count++;
 944                 mutex_unlock(&root->fs_info->trans_mutex);
 945                 btrfs_end_transaction(trans, root);
 946
 947                 ret = wait_for_commit(root, cur_trans);
 948                 BUG_ON(ret);
 949
 950                 mutex_lock(&root->fs_info->trans_mutex);
 951                 put_transaction(cur_trans);
 952                 mutex_unlock(&root->fs_info->trans_mutex);
 953
 954                 return 0;
 955         }
 956
 957         trans->transaction->in_commit = 1;
 958         trans->transaction->blocked = 1;
 959         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 960                 prev_trans = list_entry(cur_trans->list.prev,
 961                                         struct btrfs_transaction, list);
 962                 if (!prev_trans->commit_done) {
 963                         prev_trans->use_count++;
 964                         mutex_unlock(&root->fs_info->trans_mutex);
 965
 966                         wait_for_commit(root, prev_trans);
 967
 968                         mutex_lock(&root->fs_info->trans_mutex);
 969                         put_transaction(prev_trans);
 970                 }
 971         }
 972
 973         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
 974                 should_grow = 1;
 975
 976         do {
 977                 int snap_pending = 0;
 978                 joined = cur_trans->num_joined;
 979                 if (!list_empty(&trans->transaction->pending_snapshots))
 980                         snap_pending = 1;
 981
 982                 WARN_ON(cur_trans != trans->transaction);
 983                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 984                                 TASK_UNINTERRUPTIBLE);
 985
 986                 if (cur_trans->num_writers > 1)
 987                         timeout = MAX_SCHEDULE_TIMEOUT;
 988                 else if (should_grow)
 989                         timeout = 1;
 990
 991                 mutex_unlock(&root->fs_info->trans_mutex);
 992
 993                 if (flush_on_commit) {
 994                         btrfs_start_delalloc_inodes(root);
 995                         ret = btrfs_wait_ordered_extents(root, 0);
 996                         BUG_ON(ret);
 997                 } else if (snap_pending) {
 998                         ret = btrfs_wait_ordered_extents(root, 1);
 999                         BUG_ON(ret);
1000                 }
1001
1002                 /*
1003                  * rename don't use btrfs_join_transaction, so, once we
1004                  * set the transaction to blocked above, we aren't going
1005                  * to get any new ordered operations.  We can safely run
1006                  * it here and no for sure that nothing new will be added
1007                  * to the list
1008                  */
1009                 btrfs_run_ordered_operations(root, 1);
1010
1011                 smp_mb();
1012                 if (cur_trans->num_writers > 1 || should_grow)
1013                         schedule_timeout(timeout);
1014
1015                 mutex_lock(&root->fs_info->trans_mutex);
1016                 finish_wait(&cur_trans->writer_wait, &wait);
1017         } while (cur_trans->num_writers > 1 ||
1018                  (should_grow && cur_trans->num_joined != joined));
1019
1020         ret = create_pending_snapshots(trans, root->fs_info);
1021         BUG_ON(ret);
1022
1023         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1024         BUG_ON(ret);
1025
1026         WARN_ON(cur_trans != trans->transaction);
1027
1028         /* btrfs_commit_tree_roots is responsible for getting the
1029          * various roots consistent with each other.  Every pointer
1030          * in the tree of tree roots has to point to the most up to date
1031          * root for every subvolume and other tree.  So, we have to keep
1032          * the tree logging code from jumping in and changing any
1033          * of the trees.
1034          *
1035          * At this point in the commit, there can't be any tree-log
1036          * writers, but a little lower down we drop the trans mutex
1037          * and let new people in.  By holding the tree_log_mutex
1038          * from now until after the super is written, we avoid races
1039          * with the tree-log code.
1040          */
1041         mutex_lock(&root->fs_info->tree_log_mutex);
1042
1043         ret = commit_fs_roots(trans, root);
1044         BUG_ON(ret);
1045
1046         /* commit_fs_roots gets rid of all the tree log roots, it is now
1047          * safe to free the root of tree log roots
1048          */
1049         btrfs_free_log_root_tree(trans, root->fs_info);
1050
1051         ret = commit_cowonly_roots(trans, root);
1052         BUG_ON(ret);
1053
1054         btrfs_prepare_extent_commit(trans, root);
1055
1056         cur_trans = root->fs_info->running_transaction;
1057         spin_lock(&root->fs_info->new_trans_lock);
1058         root->fs_info->running_transaction = NULL;
1059         spin_unlock(&root->fs_info->new_trans_lock);
1060
1061         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1062                             root->fs_info->tree_root->node);
1063         switch_commit_root(root->fs_info->tree_root);
1064
1065         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1066                             root->fs_info->chunk_root->node);
1067         switch_commit_root(root->fs_info->chunk_root);
1068
1069         update_super_roots(root);
1070
1071         if (!root->fs_info->log_root_recovering) {
1072                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1073                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1074         }
1075
1076         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1077                sizeof(root->fs_info->super_copy));
1078
1079         trans->transaction->blocked = 0;
1080
1081         wake_up(&root->fs_info->transaction_wait);
1082
1083         mutex_unlock(&root->fs_info->trans_mutex);
1084         ret = btrfs_write_and_wait_transaction(trans, root);
1085         BUG_ON(ret);
1086         write_ctree_super(trans, root, 0);
1087
1088         /*
1089          * the super is written, we can safely allow the tree-loggers
1090          * to go about their business
1091          */
1092         mutex_unlock(&root->fs_info->tree_log_mutex);
1093
1094         btrfs_finish_extent_commit(trans, root);
1095
1096         /* do the directory inserts of any pending snapshot creations */
1097         finish_pending_snapshots(trans, root->fs_info);
1098
1099         mutex_lock(&root->fs_info->trans_mutex);
1100
1101         cur_trans->commit_done = 1;
1102
1103         root->fs_info->last_trans_committed = cur_trans->transid;
1104
1105         wake_up(&cur_trans->commit_wait);
1106
1107         put_transaction(cur_trans);
1108         put_transaction(cur_trans);
1109
1110         mutex_unlock(&root->fs_info->trans_mutex);
1111
1112         if (current->journal_info == trans)
1113                 current->journal_info = NULL;
1114
1115         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1116         return ret;
1117 }
1118
1119 /*
1120  * interface function to delete all the snapshots we have scheduled for deletion
1121  */
1122 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1123 {
1124         LIST_HEAD(list);
1125         struct btrfs_fs_info *fs_info = root->fs_info;
1126
1127         mutex_lock(&fs_info->trans_mutex);
1128         list_splice_init(&fs_info->dead_roots, &list);
1129         mutex_unlock(&fs_info->trans_mutex);
1130
1131         while (!list_empty(&list)) {
1132                 root = list_entry(list.next, struct btrfs_root, root_list);
1133                 list_del(&root->root_list);
1134
1135                 if (btrfs_header_backref_rev(root->node) <
1136                     BTRFS_MIXED_BACKREF_REV)
1137                         btrfs_drop_snapshot(root, 0);
1138                 else
1139                         btrfs_drop_snapshot(root, 1);
1140         }
1141         return 0;
1142 }