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