git.oblomov.eu Git - linux-2.6/blob - 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 "ref-cache.h"
  29 #include "tree-log.h"
  30
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32
  33 static noinline void put_transaction(struct btrfs_transaction *transaction)
  34 {
  35         WARN_ON(transaction->use_count == 0);
  36         transaction->use_count--;
  37         if (transaction->use_count == 0) {
  38                 list_del_init(&transaction->list);
  39                 memset(transaction, 0, sizeof(*transaction));
  40                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  41         }
  42 }
  43
  44 /*
  45  * either allocate a new transaction or hop into the existing one
  46  */
  47 static noinline int join_transaction(struct btrfs_root *root)
  48 {
  49         struct btrfs_transaction *cur_trans;
  50         cur_trans = root->fs_info->running_transaction;
  51         if (!cur_trans) {
  52                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  53                                              GFP_NOFS);
  54                 BUG_ON(!cur_trans);
  55                 root->fs_info->generation++;
  56                 cur_trans->num_writers = 1;
  57                 cur_trans->num_joined = 0;
  58                 cur_trans->transid = root->fs_info->generation;
  59                 init_waitqueue_head(&cur_trans->writer_wait);
  60                 init_waitqueue_head(&cur_trans->commit_wait);
  61                 cur_trans->in_commit = 0;
  62                 cur_trans->blocked = 0;
  63                 cur_trans->use_count = 1;
  64                 cur_trans->commit_done = 0;
  65                 cur_trans->start_time = get_seconds();
  66
  67                 cur_trans->delayed_refs.root.rb_node = NULL;
  68                 cur_trans->delayed_refs.num_entries = 0;
  69                 cur_trans->delayed_refs.num_heads_ready = 0;
  70                 cur_trans->delayed_refs.num_heads = 0;
  71                 cur_trans->delayed_refs.flushing = 0;
  72                 cur_trans->delayed_refs.run_delayed_start = 0;
  73                 spin_lock_init(&cur_trans->delayed_refs.lock);
  74
  75                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  76                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  77                 extent_io_tree_init(&cur_trans->dirty_pages,
  78                                      root->fs_info->btree_inode->i_mapping,
  79                                      GFP_NOFS);
  80                 spin_lock(&root->fs_info->new_trans_lock);
  81                 root->fs_info->running_transaction = cur_trans;
  82                 spin_unlock(&root->fs_info->new_trans_lock);
  83         } else {
  84                 cur_trans->num_writers++;
  85                 cur_trans->num_joined++;
  86         }
  87
  88         return 0;
  89 }
  90
  91 /*
  92  * this does all the record keeping required to make sure that a reference
  93  * counted root is properly recorded in a given transaction.  This is required
  94  * to make sure the old root from before we joined the transaction is deleted
  95  * when the transaction commits
  96  */
  97 noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
  98 {
  99         struct btrfs_dirty_root *dirty;
 100         u64 running_trans_id = root->fs_info->running_transaction->transid;
 101         if (root->ref_cows && root->last_trans < running_trans_id) {
 102                 WARN_ON(root == root->fs_info->extent_root);
 103                 if (root->root_item.refs != 0) {
 104                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 105                                    (unsigned long)root->root_key.objectid,
 106                                    BTRFS_ROOT_TRANS_TAG);
 107
 108                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 109                         BUG_ON(!dirty);
 110                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 111                         BUG_ON(!dirty->root);
 112                         dirty->latest_root = root;
 113                         INIT_LIST_HEAD(&dirty->list);
 114
 115                         root->commit_root = btrfs_root_node(root);
 116
 117                         memcpy(dirty->root, root, sizeof(*root));
 118                         spin_lock_init(&dirty->root->node_lock);
 119                         spin_lock_init(&dirty->root->list_lock);
 120                         mutex_init(&dirty->root->objectid_mutex);
 121                         mutex_init(&dirty->root->log_mutex);
 122                         INIT_LIST_HEAD(&dirty->root->dead_list);
 123                         dirty->root->node = root->commit_root;
 124                         dirty->root->commit_root = NULL;
 125
 126                         spin_lock(&root->list_lock);
 127                         list_add(&dirty->root->dead_list, &root->dead_list);
 128                         spin_unlock(&root->list_lock);
 129
 130                         root->dirty_root = dirty;
 131                 } else {
 132                         WARN_ON(1);
 133                 }
 134                 root->last_trans = running_trans_id;
 135         }
 136         return 0;
 137 }
 138
 139 /* wait for commit against the current transaction to become unblocked
 140  * when this is done, it is safe to start a new transaction, but the current
 141  * transaction might not be fully on disk.
 142  */
 143 static void wait_current_trans(struct btrfs_root *root)
 144 {
 145         struct btrfs_transaction *cur_trans;
 146
 147         cur_trans = root->fs_info->running_transaction;
 148         if (cur_trans && cur_trans->blocked) {
 149                 DEFINE_WAIT(wait);
 150                 cur_trans->use_count++;
 151                 while (1) {
 152                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 153                                         TASK_UNINTERRUPTIBLE);
 154                         if (cur_trans->blocked) {
 155                                 mutex_unlock(&root->fs_info->trans_mutex);
 156                                 schedule();
 157                                 mutex_lock(&root->fs_info->trans_mutex);
 158                                 finish_wait(&root->fs_info->transaction_wait,
 159                                             &wait);
 160                         } else {
 161                                 finish_wait(&root->fs_info->transaction_wait,
 162                                             &wait);
 163                                 break;
 164                         }
 165                 }
 166                 put_transaction(cur_trans);
 167         }
 168 }
 169
 170 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 171                                              int num_blocks, int wait)
 172 {
 173         struct btrfs_trans_handle *h =
 174                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 175         int ret;
 176
 177         mutex_lock(&root->fs_info->trans_mutex);
 178         if (!root->fs_info->log_root_recovering &&
 179             ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2))
 180                 wait_current_trans(root);
 181         ret = join_transaction(root);
 182         BUG_ON(ret);
 183
 184         btrfs_record_root_in_trans(root);
 185         h->transid = root->fs_info->running_transaction->transid;
 186         h->transaction = root->fs_info->running_transaction;
 187         h->blocks_reserved = num_blocks;
 188         h->blocks_used = 0;
 189         h->block_group = 0;
 190         h->alloc_exclude_nr = 0;
 191         h->alloc_exclude_start = 0;
 192         h->delayed_ref_updates = 0;
 193
 194         root->fs_info->running_transaction->use_count++;
 195         mutex_unlock(&root->fs_info->trans_mutex);
 196         return h;
 197 }
 198
 199 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 200                                                    int num_blocks)
 201 {
 202         return start_transaction(root, num_blocks, 1);
 203 }
 204 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 205                                                    int num_blocks)
 206 {
 207         return start_transaction(root, num_blocks, 0);
 208 }
 209
 210 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 211                                                          int num_blocks)
 212 {
 213         return start_transaction(r, num_blocks, 2);
 214 }
 215
 216 /* wait for a transaction commit to be fully complete */
 217 static noinline int wait_for_commit(struct btrfs_root *root,
 218                                     struct btrfs_transaction *commit)
 219 {
 220         DEFINE_WAIT(wait);
 221         mutex_lock(&root->fs_info->trans_mutex);
 222         while (!commit->commit_done) {
 223                 prepare_to_wait(&commit->commit_wait, &wait,
 224                                 TASK_UNINTERRUPTIBLE);
 225                 if (commit->commit_done)
 226                         break;
 227                 mutex_unlock(&root->fs_info->trans_mutex);
 228                 schedule();
 229                 mutex_lock(&root->fs_info->trans_mutex);
 230         }
 231         mutex_unlock(&root->fs_info->trans_mutex);
 232         finish_wait(&commit->commit_wait, &wait);
 233         return 0;
 234 }
 235
 236 /*
 237  * rate limit against the drop_snapshot code.  This helps to slow down new
 238  * operations if the drop_snapshot code isn't able to keep up.
 239  */
 240 static void throttle_on_drops(struct btrfs_root *root)
 241 {
 242         struct btrfs_fs_info *info = root->fs_info;
 243         int harder_count = 0;
 244
 245 harder:
 246         if (atomic_read(&info->throttles)) {
 247                 DEFINE_WAIT(wait);
 248                 int thr;
 249                 thr = atomic_read(&info->throttle_gen);
 250
 251                 do {
 252                         prepare_to_wait(&info->transaction_throttle,
 253                                         &wait, TASK_UNINTERRUPTIBLE);
 254                         if (!atomic_read(&info->throttles)) {
 255                                 finish_wait(&info->transaction_throttle, &wait);
 256                                 break;
 257                         }
 258                         schedule();
 259                         finish_wait(&info->transaction_throttle, &wait);
 260                 } while (thr == atomic_read(&info->throttle_gen));
 261                 harder_count++;
 262
 263                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 264                     harder_count < 2)
 265                         goto harder;
 266
 267                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 268                     harder_count < 10)
 269                         goto harder;
 270
 271                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 272                     harder_count < 20)
 273                         goto harder;
 274         }
 275 }
 276
 277 void btrfs_throttle(struct btrfs_root *root)
 278 {
 279         mutex_lock(&root->fs_info->trans_mutex);
 280         if (!root->fs_info->open_ioctl_trans)
 281                 wait_current_trans(root);
 282         mutex_unlock(&root->fs_info->trans_mutex);
 283         throttle_on_drops(root);
 284 }
 285
 286 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 287                           struct btrfs_root *root, int throttle)
 288 {
 289         struct btrfs_transaction *cur_trans;
 290         struct btrfs_fs_info *info = root->fs_info;
 291         int count = 0;
 292
 293         while (count < 4) {
 294                 unsigned long cur = trans->delayed_ref_updates;
 295                 trans->delayed_ref_updates = 0;
 296                 if (cur &&
 297                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 298                         trans->delayed_ref_updates = 0;
 299
 300                         /*
 301                          * do a full flush if the transaction is trying
 302                          * to close
 303                          */
 304                         if (trans->transaction->delayed_refs.flushing)
 305                                 cur = 0;
 306                         btrfs_run_delayed_refs(trans, root, cur);
 307                 } else {
 308                         break;
 309                 }
 310                 count++;
 311         }
 312
 313         mutex_lock(&info->trans_mutex);
 314         cur_trans = info->running_transaction;
 315         WARN_ON(cur_trans != trans->transaction);
 316         WARN_ON(cur_trans->num_writers < 1);
 317         cur_trans->num_writers--;
 318
 319         if (waitqueue_active(&cur_trans->writer_wait))
 320                 wake_up(&cur_trans->writer_wait);
 321         put_transaction(cur_trans);
 322         mutex_unlock(&info->trans_mutex);
 323         memset(trans, 0, sizeof(*trans));
 324         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 325
 326         if (throttle)
 327                 throttle_on_drops(root);
 328
 329         return 0;
 330 }
 331
 332 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 333                           struct btrfs_root *root)
 334 {
 335         return __btrfs_end_transaction(trans, root, 0);
 336 }
 337
 338 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 339                                    struct btrfs_root *root)
 340 {
 341         return __btrfs_end_transaction(trans, root, 1);
 342 }
 343
 344 /*
 345  * when btree blocks are allocated, they have some corresponding bits set for
 346  * them in one of two extent_io trees.  This is used to make sure all of
 347  * those extents are on disk for transaction or log commit
 348  */
 349 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 350                                         struct extent_io_tree *dirty_pages)
 351 {
 352         int ret;
 353         int err = 0;
 354         int werr = 0;
 355         struct page *page;
 356         struct inode *btree_inode = root->fs_info->btree_inode;
 357         u64 start = 0;
 358         u64 end;
 359         unsigned long index;
 360
 361         while (1) {
 362                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 363                                             EXTENT_DIRTY);
 364                 if (ret)
 365                         break;
 366                 while (start <= end) {
 367                         cond_resched();
 368
 369                         index = start >> PAGE_CACHE_SHIFT;
 370                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 371                         page = find_get_page(btree_inode->i_mapping, index);
 372                         if (!page)
 373                                 continue;
 374
 375                         btree_lock_page_hook(page);
 376                         if (!page->mapping) {
 377                                 unlock_page(page);
 378                                 page_cache_release(page);
 379                                 continue;
 380                         }
 381
 382                         if (PageWriteback(page)) {
 383                                 if (PageDirty(page))
 384                                         wait_on_page_writeback(page);
 385                                 else {
 386                                         unlock_page(page);
 387                                         page_cache_release(page);
 388                                         continue;
 389                                 }
 390                         }
 391                         err = write_one_page(page, 0);
 392                         if (err)
 393                                 werr = err;
 394                         page_cache_release(page);
 395                 }
 396         }
 397         while (1) {
 398                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
 399                                             EXTENT_DIRTY);
 400                 if (ret)
 401                         break;
 402
 403                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
 404                 while (start <= end) {
 405                         index = start >> PAGE_CACHE_SHIFT;
 406                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 407                         page = find_get_page(btree_inode->i_mapping, index);
 408                         if (!page)
 409                                 continue;
 410                         if (PageDirty(page)) {
 411                                 btree_lock_page_hook(page);
 412                                 wait_on_page_writeback(page);
 413                                 err = write_one_page(page, 0);
 414                                 if (err)
 415                                         werr = err;
 416                         }
 417                         wait_on_page_writeback(page);
 418                         page_cache_release(page);
 419                         cond_resched();
 420                 }
 421         }
 422         if (err)
 423                 werr = err;
 424         return werr;
 425 }
 426
 427 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 428                                      struct btrfs_root *root)
 429 {
 430         if (!trans || !trans->transaction) {
 431                 struct inode *btree_inode;
 432                 btree_inode = root->fs_info->btree_inode;
 433                 return filemap_write_and_wait(btree_inode->i_mapping);
 434         }
 435         return btrfs_write_and_wait_marked_extents(root,
 436                                            &trans->transaction->dirty_pages);
 437 }
 438
 439 /*
 440  * this is used to update the root pointer in the tree of tree roots.
 441  *
 442  * But, in the case of the extent allocation tree, updating the root
 443  * pointer may allocate blocks which may change the root of the extent
 444  * allocation tree.
 445  *
 446  * So, this loops and repeats and makes sure the cowonly root didn't
 447  * change while the root pointer was being updated in the metadata.
 448  */
 449 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 450                                struct btrfs_root *root)
 451 {
 452         int ret;
 453         u64 old_root_bytenr;
 454         struct btrfs_root *tree_root = root->fs_info->tree_root;
 455
 456         btrfs_write_dirty_block_groups(trans, root);
 457
 458         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 459         BUG_ON(ret);
 460
 461         while (1) {
 462                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 463                 if (old_root_bytenr == root->node->start)
 464                         break;
 465                 btrfs_set_root_bytenr(&root->root_item,
 466                                        root->node->start);
 467                 btrfs_set_root_level(&root->root_item,
 468                                      btrfs_header_level(root->node));
 469                 btrfs_set_root_generation(&root->root_item, trans->transid);
 470
 471                 ret = btrfs_update_root(trans, tree_root,
 472                                         &root->root_key,
 473                                         &root->root_item);
 474                 BUG_ON(ret);
 475                 btrfs_write_dirty_block_groups(trans, root);
 476
 477                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 478                 BUG_ON(ret);
 479         }
 480         return 0;
 481 }
 482
 483 /*
 484  * update all the cowonly tree roots on disk
 485  */
 486 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 487                             struct btrfs_root *root)
 488 {
 489         struct btrfs_fs_info *fs_info = root->fs_info;
 490         struct list_head *next;
 491         struct extent_buffer *eb;
 492         int ret;
 493
 494         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 495         BUG_ON(ret);
 496
 497         eb = btrfs_lock_root_node(fs_info->tree_root);
 498         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 499         btrfs_tree_unlock(eb);
 500         free_extent_buffer(eb);
 501
 502         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 503         BUG_ON(ret);
 504
 505         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 506                 next = fs_info->dirty_cowonly_roots.next;
 507                 list_del_init(next);
 508                 root = list_entry(next, struct btrfs_root, dirty_list);
 509
 510                 update_cowonly_root(trans, root);
 511
 512                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 513                 BUG_ON(ret);
 514         }
 515         return 0;
 516 }
 517
 518 /*
 519  * dead roots are old snapshots that need to be deleted.  This allocates
 520  * a dirty root struct and adds it into the list of dead roots that need to
 521  * be deleted
 522  */
 523 int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
 524 {
 525         struct btrfs_dirty_root *dirty;
 526
 527         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 528         if (!dirty)
 529                 return -ENOMEM;
 530         dirty->root = root;
 531         dirty->latest_root = latest;
 532
 533         mutex_lock(&root->fs_info->trans_mutex);
 534         list_add(&dirty->list, &latest->fs_info->dead_roots);
 535         mutex_unlock(&root->fs_info->trans_mutex);
 536         return 0;
 537 }
 538
 539 /*
 540  * at transaction commit time we need to schedule the old roots for
 541  * deletion via btrfs_drop_snapshot.  This runs through all the
 542  * reference counted roots that were modified in the current
 543  * transaction and puts them into the drop list
 544  */
 545 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 546                                     struct radix_tree_root *radix,
 547                                     struct list_head *list)
 548 {
 549         struct btrfs_dirty_root *dirty;
 550         struct btrfs_root *gang[8];
 551         struct btrfs_root *root;
 552         int i;
 553         int ret;
 554         int err = 0;
 555         u32 refs;
 556
 557         while (1) {
 558                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 559                                                  ARRAY_SIZE(gang),
 560                                                  BTRFS_ROOT_TRANS_TAG);
 561                 if (ret == 0)
 562                         break;
 563                 for (i = 0; i < ret; i++) {
 564                         root = gang[i];
 565                         radix_tree_tag_clear(radix,
 566                                      (unsigned long)root->root_key.objectid,
 567                                      BTRFS_ROOT_TRANS_TAG);
 568
 569                         BUG_ON(!root->ref_tree);
 570                         dirty = root->dirty_root;
 571
 572                         btrfs_free_log(trans, root);
 573                         btrfs_free_reloc_root(trans, root);
 574
 575                         if (root->commit_root == root->node) {
 576                                 WARN_ON(root->node->start !=
 577                                         btrfs_root_bytenr(&root->root_item));
 578
 579                                 free_extent_buffer(root->commit_root);
 580                                 root->commit_root = NULL;
 581                                 root->dirty_root = NULL;
 582
 583                                 spin_lock(&root->list_lock);
 584                                 list_del_init(&dirty->root->dead_list);
 585                                 spin_unlock(&root->list_lock);
 586
 587                                 kfree(dirty->root);
 588                                 kfree(dirty);
 589
 590                                 /* make sure to update the root on disk
 591                                  * so we get any updates to the block used
 592                                  * counts
 593                                  */
 594                                 err = btrfs_update_root(trans,
 595                                                 root->fs_info->tree_root,
 596                                                 &root->root_key,
 597                                                 &root->root_item);
 598                                 continue;
 599                         }
 600
 601                         memset(&root->root_item.drop_progress, 0,
 602                                sizeof(struct btrfs_disk_key));
 603                         root->root_item.drop_level = 0;
 604                         root->commit_root = NULL;
 605                         root->dirty_root = NULL;
 606                         root->root_key.offset = root->fs_info->generation;
 607                         btrfs_set_root_bytenr(&root->root_item,
 608                                               root->node->start);
 609                         btrfs_set_root_level(&root->root_item,
 610                                              btrfs_header_level(root->node));
 611                         btrfs_set_root_generation(&root->root_item,
 612                                                   root->root_key.offset);
 613
 614                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 615                                                 &root->root_key,
 616                                                 &root->root_item);
 617                         if (err)
 618                                 break;
 619
 620                         refs = btrfs_root_refs(&dirty->root->root_item);
 621                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 622                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 623                                                 &dirty->root->root_key,
 624                                                 &dirty->root->root_item);
 625
 626                         BUG_ON(err);
 627                         if (refs == 1) {
 628                                 list_add(&dirty->list, list);
 629                         } else {
 630                                 WARN_ON(1);
 631                                 free_extent_buffer(dirty->root->node);
 632                                 kfree(dirty->root);
 633                                 kfree(dirty);
 634                         }
 635                 }
 636         }
 637         return err;
 638 }
 639
 640 /*
 641  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 642  * otherwise every leaf in the btree is read and defragged.
 643  */
 644 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 645 {
 646         struct btrfs_fs_info *info = root->fs_info;
 647         int ret;
 648         struct btrfs_trans_handle *trans;
 649         unsigned long nr;
 650
 651         smp_mb();
 652         if (root->defrag_running)
 653                 return 0;
 654         trans = btrfs_start_transaction(root, 1);
 655         while (1) {
 656                 root->defrag_running = 1;
 657                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 658                 nr = trans->blocks_used;
 659                 btrfs_end_transaction(trans, root);
 660                 btrfs_btree_balance_dirty(info->tree_root, nr);
 661                 cond_resched();
 662
 663                 trans = btrfs_start_transaction(root, 1);
 664                 if (root->fs_info->closing || ret != -EAGAIN)
 665                         break;
 666         }
 667         root->defrag_running = 0;
 668         smp_mb();
 669         btrfs_end_transaction(trans, root);
 670         return 0;
 671 }
 672
 673 /*
 674  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 675  * sense not to join the transaction while it is trying to flush the current
 676  * queue of delayed refs out.
 677  *
 678  * This is used by the drop snapshot code only
 679  */
 680 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 681 {
 682         DEFINE_WAIT(wait);
 683
 684         mutex_lock(&info->trans_mutex);
 685         while (info->running_transaction &&
 686                info->running_transaction->delayed_refs.flushing) {
 687                 prepare_to_wait(&info->transaction_wait, &wait,
 688                                 TASK_UNINTERRUPTIBLE);
 689                 mutex_unlock(&info->trans_mutex);
 690                 schedule();
 691                 mutex_lock(&info->trans_mutex);
 692                 finish_wait(&info->transaction_wait, &wait);
 693         }
 694         mutex_unlock(&info->trans_mutex);
 695         return 0;
 696 }
 697
 698 /*
 699  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 700  * all of them
 701  */
 702 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
 703                                      struct list_head *list)
 704 {
 705         struct btrfs_dirty_root *dirty;
 706         struct btrfs_trans_handle *trans;
 707         unsigned long nr;
 708         u64 num_bytes;
 709         u64 bytes_used;
 710         u64 max_useless;
 711         int ret = 0;
 712         int err;
 713
 714         while (!list_empty(list)) {
 715                 struct btrfs_root *root;
 716
 717                 dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
 718                 list_del_init(&dirty->list);
 719
 720                 num_bytes = btrfs_root_used(&dirty->root->root_item);
 721                 root = dirty->latest_root;
 722                 atomic_inc(&root->fs_info->throttles);
 723
 724                 while (1) {
 725                         /*
 726                          * we don't want to jump in and create a bunch of
 727                          * delayed refs if the transaction is starting to close
 728                          */
 729                         wait_transaction_pre_flush(tree_root->fs_info);
 730                         trans = btrfs_start_transaction(tree_root, 1);
 731
 732                         /*
 733                          * we've joined a transaction, make sure it isn't
 734                          * closing right now
 735                          */
 736                         if (trans->transaction->delayed_refs.flushing) {
 737                                 btrfs_end_transaction(trans, tree_root);
 738                                 continue;
 739                         }
 740
 741                         mutex_lock(&root->fs_info->drop_mutex);
 742                         ret = btrfs_drop_snapshot(trans, dirty->root);
 743                         if (ret != -EAGAIN)
 744                                 break;
 745                         mutex_unlock(&root->fs_info->drop_mutex);
 746
 747                         err = btrfs_update_root(trans,
 748                                         tree_root,
 749                                         &dirty->root->root_key,
 750                                         &dirty->root->root_item);
 751                         if (err)
 752                                 ret = err;
 753                         nr = trans->blocks_used;
 754                         ret = btrfs_end_transaction(trans, tree_root);
 755                         BUG_ON(ret);
 756
 757                         btrfs_btree_balance_dirty(tree_root, nr);
 758                         cond_resched();
 759                 }
 760                 BUG_ON(ret);
 761                 atomic_dec(&root->fs_info->throttles);
 762                 wake_up(&root->fs_info->transaction_throttle);
 763
 764                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
 765                 bytes_used = btrfs_root_used(&root->root_item);
 766                 if (num_bytes) {
 767                         mutex_lock(&root->fs_info->trans_mutex);
 768                         btrfs_record_root_in_trans(root);
 769                         mutex_unlock(&root->fs_info->trans_mutex);
 770                         btrfs_set_root_used(&root->root_item,
 771                                             bytes_used - num_bytes);
 772                 }
 773
 774                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 775                 if (ret) {
 776                         BUG();
 777                         break;
 778                 }
 779                 mutex_unlock(&root->fs_info->drop_mutex);
 780
 781                 spin_lock(&root->list_lock);
 782                 list_del_init(&dirty->root->dead_list);
 783                 if (!list_empty(&root->dead_list)) {
 784                         struct btrfs_root *oldest;
 785                         oldest = list_entry(root->dead_list.prev,
 786                                             struct btrfs_root, dead_list);
 787                         max_useless = oldest->root_key.offset - 1;
 788                 } else {
 789                         max_useless = root->root_key.offset - 1;
 790                 }
 791                 spin_unlock(&root->list_lock);
 792
 793                 nr = trans->blocks_used;
 794                 ret = btrfs_end_transaction(trans, tree_root);
 795                 BUG_ON(ret);
 796
 797                 ret = btrfs_remove_leaf_refs(root, max_useless, 0);
 798                 BUG_ON(ret);
 799
 800                 free_extent_buffer(dirty->root->node);
 801                 kfree(dirty->root);
 802                 kfree(dirty);
 803
 804                 btrfs_btree_balance_dirty(tree_root, nr);
 805                 cond_resched();
 806         }
 807         return ret;
 808 }
 809
 810 /*
 811  * new snapshots need to be created at a very specific time in the
 812  * transaction commit.  This does the actual creation
 813  */
 814 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 815                                    struct btrfs_fs_info *fs_info,
 816                                    struct btrfs_pending_snapshot *pending)
 817 {
 818         struct btrfs_key key;
 819         struct btrfs_root_item *new_root_item;
 820         struct btrfs_root *tree_root = fs_info->tree_root;
 821         struct btrfs_root *root = pending->root;
 822         struct extent_buffer *tmp;
 823         struct extent_buffer *old;
 824         int ret;
 825         u64 objectid;
 826
 827         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 828         if (!new_root_item) {
 829                 ret = -ENOMEM;
 830                 goto fail;
 831         }
 832         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 833         if (ret)
 834                 goto fail;
 835
 836         btrfs_record_root_in_trans(root);
 837         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 838         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 839
 840         key.objectid = objectid;
 841         key.offset = trans->transid;
 842         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 843
 844         old = btrfs_lock_root_node(root);
 845         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 846
 847         btrfs_copy_root(trans, root, old, &tmp, objectid);
 848         btrfs_tree_unlock(old);
 849         free_extent_buffer(old);
 850
 851         btrfs_set_root_bytenr(new_root_item, tmp->start);
 852         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
 853         btrfs_set_root_generation(new_root_item, trans->transid);
 854         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 855                                 new_root_item);
 856         btrfs_tree_unlock(tmp);
 857         free_extent_buffer(tmp);
 858         if (ret)
 859                 goto fail;
 860
 861         key.offset = (u64)-1;
 862         memcpy(&pending->root_key, &key, sizeof(key));
 863 fail:
 864         kfree(new_root_item);
 865         return ret;
 866 }
 867
 868 static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
 869                                    struct btrfs_pending_snapshot *pending)
 870 {
 871         int ret;
 872         int namelen;
 873         u64 index = 0;
 874         struct btrfs_trans_handle *trans;
 875         struct inode *parent_inode;
 876         struct inode *inode;
 877         struct btrfs_root *parent_root;
 878
 879         parent_inode = pending->dentry->d_parent->d_inode;
 880         parent_root = BTRFS_I(parent_inode)->root;
 881         trans = btrfs_join_transaction(parent_root, 1);
 882
 883         /*
 884          * insert the directory item
 885          */
 886         namelen = strlen(pending->name);
 887         ret = btrfs_set_inode_index(parent_inode, &index);
 888         ret = btrfs_insert_dir_item(trans, parent_root,
 889                             pending->name, namelen,
 890                             parent_inode->i_ino,
 891                             &pending->root_key, BTRFS_FT_DIR, index);
 892
 893         if (ret)
 894                 goto fail;
 895
 896         btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
 897         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 898         BUG_ON(ret);
 899
 900         /* add the backref first */
 901         ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
 902                                  pending->root_key.objectid,
 903                                  BTRFS_ROOT_BACKREF_KEY,
 904                                  parent_root->root_key.objectid,
 905                                  parent_inode->i_ino, index, pending->name,
 906                                  namelen);
 907
 908         BUG_ON(ret);
 909
 910         /* now add the forward ref */
 911         ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
 912                                  parent_root->root_key.objectid,
 913                                  BTRFS_ROOT_REF_KEY,
 914                                  pending->root_key.objectid,
 915                                  parent_inode->i_ino, index, pending->name,
 916                                  namelen);
 917
 918         inode = btrfs_lookup_dentry(parent_inode, pending->dentry);
 919         d_instantiate(pending->dentry, inode);
 920 fail:
 921         btrfs_end_transaction(trans, fs_info->fs_root);
 922         return ret;
 923 }
 924
 925 /*
 926  * create all the snapshots we've scheduled for creation
 927  */
 928 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 929                                              struct btrfs_fs_info *fs_info)
 930 {
 931         struct btrfs_pending_snapshot *pending;
 932         struct list_head *head = &trans->transaction->pending_snapshots;
 933         int ret;
 934
 935         list_for_each_entry(pending, head, list) {
 936                 ret = create_pending_snapshot(trans, fs_info, pending);
 937                 BUG_ON(ret);
 938         }
 939         return 0;
 940 }
 941
 942 static noinline int finish_pending_snapshots(struct btrfs_trans_handle *trans,
 943                                              struct btrfs_fs_info *fs_info)
 944 {
 945         struct btrfs_pending_snapshot *pending;
 946         struct list_head *head = &trans->transaction->pending_snapshots;
 947         int ret;
 948
 949         while (!list_empty(head)) {
 950                 pending = list_entry(head->next,
 951                                      struct btrfs_pending_snapshot, list);
 952                 ret = finish_pending_snapshot(fs_info, pending);
 953                 BUG_ON(ret);
 954                 list_del(&pending->list);
 955                 kfree(pending->name);
 956                 kfree(pending);
 957         }
 958         return 0;
 959 }
 960
 961 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 962                              struct btrfs_root *root)
 963 {
 964         unsigned long joined = 0;
 965         unsigned long timeout = 1;
 966         struct btrfs_transaction *cur_trans;
 967         struct btrfs_transaction *prev_trans = NULL;
 968         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 969         struct list_head dirty_fs_roots;
 970         struct extent_io_tree *pinned_copy;
 971         DEFINE_WAIT(wait);
 972         int ret;
 973         int should_grow = 0;
 974         unsigned long now = get_seconds();
 975         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
 976
 977         btrfs_run_ordered_operations(root, 0);
 978
 979         /* make a pass through all the delayed refs we have so far
 980          * any runnings procs may add more while we are here
 981          */
 982         ret = btrfs_run_delayed_refs(trans, root, 0);
 983         BUG_ON(ret);
 984
 985         cur_trans = trans->transaction;
 986         /*
 987          * set the flushing flag so procs in this transaction have to
 988          * start sending their work down.
 989          */
 990         cur_trans->delayed_refs.flushing = 1;
 991
 992         ret = btrfs_run_delayed_refs(trans, root, 0);
 993         BUG_ON(ret);
 994
 995         mutex_lock(&root->fs_info->trans_mutex);
 996         INIT_LIST_HEAD(&dirty_fs_roots);
 997         if (cur_trans->in_commit) {
 998                 cur_trans->use_count++;
 999                 mutex_unlock(&root->fs_info->trans_mutex);
1000                 btrfs_end_transaction(trans, root);
1001
1002                 ret = wait_for_commit(root, cur_trans);
1003                 BUG_ON(ret);
1004
1005                 mutex_lock(&root->fs_info->trans_mutex);
1006                 put_transaction(cur_trans);
1007                 mutex_unlock(&root->fs_info->trans_mutex);
1008
1009                 return 0;
1010         }
1011
1012         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
1013         if (!pinned_copy)
1014                 return -ENOMEM;
1015
1016         extent_io_tree_init(pinned_copy,
1017                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
1018
1019         trans->transaction->in_commit = 1;
1020         trans->transaction->blocked = 1;
1021         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1022                 prev_trans = list_entry(cur_trans->list.prev,
1023                                         struct btrfs_transaction, list);
1024                 if (!prev_trans->commit_done) {
1025                         prev_trans->use_count++;
1026                         mutex_unlock(&root->fs_info->trans_mutex);
1027
1028                         wait_for_commit(root, prev_trans);
1029
1030                         mutex_lock(&root->fs_info->trans_mutex);
1031                         put_transaction(prev_trans);
1032                 }
1033         }
1034
1035         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1036                 should_grow = 1;
1037
1038         do {
1039                 int snap_pending = 0;
1040                 joined = cur_trans->num_joined;
1041                 if (!list_empty(&trans->transaction->pending_snapshots))
1042                         snap_pending = 1;
1043
1044                 WARN_ON(cur_trans != trans->transaction);
1045                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1046                                 TASK_UNINTERRUPTIBLE);
1047
1048                 if (cur_trans->num_writers > 1)
1049                         timeout = MAX_SCHEDULE_TIMEOUT;
1050                 else if (should_grow)
1051                         timeout = 1;
1052
1053                 mutex_unlock(&root->fs_info->trans_mutex);
1054
1055                 if (flush_on_commit || snap_pending) {
1056                         if (flush_on_commit)
1057                                 btrfs_start_delalloc_inodes(root);
1058                         ret = btrfs_wait_ordered_extents(root, 1);
1059                         BUG_ON(ret);
1060                 }
1061
1062                 /*
1063                  * rename don't use btrfs_join_transaction, so, once we
1064                  * set the transaction to blocked above, we aren't going
1065                  * to get any new ordered operations.  We can safely run
1066                  * it here and no for sure that nothing new will be added
1067                  * to the list
1068                  */
1069                 btrfs_run_ordered_operations(root, 1);
1070
1071                 smp_mb();
1072                 if (cur_trans->num_writers > 1 || should_grow)
1073                         schedule_timeout(timeout);
1074
1075                 mutex_lock(&root->fs_info->trans_mutex);
1076                 finish_wait(&cur_trans->writer_wait, &wait);
1077         } while (cur_trans->num_writers > 1 ||
1078                  (should_grow && cur_trans->num_joined != joined));
1079
1080         ret = create_pending_snapshots(trans, root->fs_info);
1081         BUG_ON(ret);
1082
1083         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1084         BUG_ON(ret);
1085
1086         WARN_ON(cur_trans != trans->transaction);
1087
1088         /* btrfs_commit_tree_roots is responsible for getting the
1089          * various roots consistent with each other.  Every pointer
1090          * in the tree of tree roots has to point to the most up to date
1091          * root for every subvolume and other tree.  So, we have to keep
1092          * the tree logging code from jumping in and changing any
1093          * of the trees.
1094          *
1095          * At this point in the commit, there can't be any tree-log
1096          * writers, but a little lower down we drop the trans mutex
1097          * and let new people in.  By holding the tree_log_mutex
1098          * from now until after the super is written, we avoid races
1099          * with the tree-log code.
1100          */
1101         mutex_lock(&root->fs_info->tree_log_mutex);
1102         /*
1103          * keep tree reloc code from adding new reloc trees
1104          */
1105         mutex_lock(&root->fs_info->tree_reloc_mutex);
1106
1107
1108         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
1109                               &dirty_fs_roots);
1110         BUG_ON(ret);
1111
1112         /* add_dirty_roots gets rid of all the tree log roots, it is now
1113          * safe to free the root of tree log roots
1114          */
1115         btrfs_free_log_root_tree(trans, root->fs_info);
1116
1117         ret = btrfs_commit_tree_roots(trans, root);
1118         BUG_ON(ret);
1119
1120         cur_trans = root->fs_info->running_transaction;
1121         spin_lock(&root->fs_info->new_trans_lock);
1122         root->fs_info->running_transaction = NULL;
1123         spin_unlock(&root->fs_info->new_trans_lock);
1124         btrfs_set_super_generation(&root->fs_info->super_copy,
1125                                    cur_trans->transid);
1126         btrfs_set_super_root(&root->fs_info->super_copy,
1127                              root->fs_info->tree_root->node->start);
1128         btrfs_set_super_root_level(&root->fs_info->super_copy,
1129                            btrfs_header_level(root->fs_info->tree_root->node));
1130
1131         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
1132                                    chunk_root->node->start);
1133         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
1134                                          btrfs_header_level(chunk_root->node));
1135         btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
1136                                 btrfs_header_generation(chunk_root->node));
1137
1138         if (!root->fs_info->log_root_recovering) {
1139                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1140                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1141         }
1142
1143         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1144                sizeof(root->fs_info->super_copy));
1145
1146         btrfs_copy_pinned(root, pinned_copy);
1147
1148         trans->transaction->blocked = 0;
1149
1150         wake_up(&root->fs_info->transaction_throttle);
1151         wake_up(&root->fs_info->transaction_wait);
1152
1153         mutex_unlock(&root->fs_info->trans_mutex);
1154         ret = btrfs_write_and_wait_transaction(trans, root);
1155         BUG_ON(ret);
1156         write_ctree_super(trans, root, 0);
1157
1158         /*
1159          * the super is written, we can safely allow the tree-loggers
1160          * to go about their business
1161          */
1162         mutex_unlock(&root->fs_info->tree_log_mutex);
1163
1164         btrfs_finish_extent_commit(trans, root, pinned_copy);
1165         kfree(pinned_copy);
1166
1167         btrfs_drop_dead_reloc_roots(root);
1168         mutex_unlock(&root->fs_info->tree_reloc_mutex);
1169
1170         /* do the directory inserts of any pending snapshot creations */
1171         finish_pending_snapshots(trans, root->fs_info);
1172
1173         mutex_lock(&root->fs_info->trans_mutex);
1174
1175         cur_trans->commit_done = 1;
1176
1177         root->fs_info->last_trans_committed = cur_trans->transid;
1178         wake_up(&cur_trans->commit_wait);
1179
1180         put_transaction(cur_trans);
1181         put_transaction(cur_trans);
1182
1183         list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
1184         if (root->fs_info->closing)
1185                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
1186
1187         mutex_unlock(&root->fs_info->trans_mutex);
1188
1189         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1190
1191         if (root->fs_info->closing)
1192                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
1193         return ret;
1194 }
1195
1196 /*
1197  * interface function to delete all the snapshots we have scheduled for deletion
1198  */
1199 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1200 {
1201         struct list_head dirty_roots;
1202         INIT_LIST_HEAD(&dirty_roots);
1203 again:
1204         mutex_lock(&root->fs_info->trans_mutex);
1205         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
1206         mutex_unlock(&root->fs_info->trans_mutex);
1207
1208         if (!list_empty(&dirty_roots)) {
1209                 drop_dirty_roots(root, &dirty_roots);
1210                 goto again;
1211         }
1212         return 0;
1213 }