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 "ctree.h"
  24 #include "disk-io.h"
  25 #include "transaction.h"
  26 #include "locking.h"
  27 #include "ref-cache.h"
  28
  29 static int total_trans = 0;
  30 extern struct kmem_cache *btrfs_trans_handle_cachep;
  31 extern struct kmem_cache *btrfs_transaction_cachep;
  32
  33 #define BTRFS_ROOT_TRANS_TAG 0
  34
  35 static noinline void put_transaction(struct btrfs_transaction *transaction)
  36 {
  37         WARN_ON(transaction->use_count == 0);
  38         transaction->use_count--;
  39         if (transaction->use_count == 0) {
  40                 WARN_ON(total_trans == 0);
  41                 total_trans--;
  42                 list_del_init(&transaction->list);
  43                 memset(transaction, 0, sizeof(*transaction));
  44                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  45         }
  46 }
  47
  48 static noinline int join_transaction(struct btrfs_root *root)
  49 {
  50         struct btrfs_transaction *cur_trans;
  51         cur_trans = root->fs_info->running_transaction;
  52         if (!cur_trans) {
  53                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  54                                              GFP_NOFS);
  55                 total_trans++;
  56                 BUG_ON(!cur_trans);
  57                 root->fs_info->generation++;
  58                 root->fs_info->last_alloc = 0;
  59                 root->fs_info->last_data_alloc = 0;
  60                 cur_trans->num_writers = 1;
  61                 cur_trans->num_joined = 0;
  62                 cur_trans->transid = root->fs_info->generation;
  63                 init_waitqueue_head(&cur_trans->writer_wait);
  64                 init_waitqueue_head(&cur_trans->commit_wait);
  65                 cur_trans->in_commit = 0;
  66                 cur_trans->blocked = 0;
  67                 cur_trans->use_count = 1;
  68                 cur_trans->commit_done = 0;
  69                 cur_trans->start_time = get_seconds();
  70                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  71                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  72                 extent_io_tree_init(&cur_trans->dirty_pages,
  73                                      root->fs_info->btree_inode->i_mapping,
  74                                      GFP_NOFS);
  75                 spin_lock(&root->fs_info->new_trans_lock);
  76                 root->fs_info->running_transaction = cur_trans;
  77                 spin_unlock(&root->fs_info->new_trans_lock);
  78         } else {
  79                 cur_trans->num_writers++;
  80                 cur_trans->num_joined++;
  81         }
  82
  83         return 0;
  84 }
  85
  86 static noinline int record_root_in_trans(struct btrfs_root *root)
  87 {
  88         struct btrfs_dirty_root *dirty;
  89         u64 running_trans_id = root->fs_info->running_transaction->transid;
  90         if (root->ref_cows && root->last_trans < running_trans_id) {
  91                 WARN_ON(root == root->fs_info->extent_root);
  92                 if (root->root_item.refs != 0) {
  93                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  94                                    (unsigned long)root->root_key.objectid,
  95                                    BTRFS_ROOT_TRANS_TAG);
  96
  97                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
  98                         BUG_ON(!dirty);
  99                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 100                         BUG_ON(!dirty->root);
 101                         dirty->latest_root = root;
 102                         INIT_LIST_HEAD(&dirty->list);
 103
 104                         root->commit_root = btrfs_root_node(root);
 105
 106                         memcpy(dirty->root, root, sizeof(*root));
 107                         spin_lock_init(&dirty->root->node_lock);
 108                         spin_lock_init(&dirty->root->list_lock);
 109                         mutex_init(&dirty->root->objectid_mutex);
 110                         INIT_LIST_HEAD(&dirty->root->dead_list);
 111                         dirty->root->node = root->commit_root;
 112                         dirty->root->commit_root = NULL;
 113
 114                         spin_lock(&root->list_lock);
 115                         list_add(&dirty->root->dead_list, &root->dead_list);
 116                         spin_unlock(&root->list_lock);
 117
 118                         root->dirty_root = dirty;
 119                 } else {
 120                         WARN_ON(1);
 121                 }
 122                 root->last_trans = running_trans_id;
 123         }
 124         return 0;
 125 }
 126
 127 static void wait_current_trans(struct btrfs_root *root)
 128 {
 129         struct btrfs_transaction *cur_trans;
 130
 131         cur_trans = root->fs_info->running_transaction;
 132         if (cur_trans && cur_trans->blocked) {
 133                 DEFINE_WAIT(wait);
 134                 cur_trans->use_count++;
 135                 while(1) {
 136                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 137                                         TASK_UNINTERRUPTIBLE);
 138                         if (cur_trans->blocked) {
 139                                 mutex_unlock(&root->fs_info->trans_mutex);
 140                                 schedule();
 141                                 mutex_lock(&root->fs_info->trans_mutex);
 142                                 finish_wait(&root->fs_info->transaction_wait,
 143                                             &wait);
 144                         } else {
 145                                 finish_wait(&root->fs_info->transaction_wait,
 146                                             &wait);
 147                                 break;
 148                         }
 149                 }
 150                 put_transaction(cur_trans);
 151         }
 152 }
 153
 154 struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 155                                              int num_blocks, int wait)
 156 {
 157         struct btrfs_trans_handle *h =
 158                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 159         int ret;
 160
 161         mutex_lock(&root->fs_info->trans_mutex);
 162         if ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2)
 163                 wait_current_trans(root);
 164         ret = join_transaction(root);
 165         BUG_ON(ret);
 166
 167         record_root_in_trans(root);
 168         h->transid = root->fs_info->running_transaction->transid;
 169         h->transaction = root->fs_info->running_transaction;
 170         h->blocks_reserved = num_blocks;
 171         h->blocks_used = 0;
 172         h->block_group = NULL;
 173         h->alloc_exclude_nr = 0;
 174         h->alloc_exclude_start = 0;
 175         root->fs_info->running_transaction->use_count++;
 176         mutex_unlock(&root->fs_info->trans_mutex);
 177         return h;
 178 }
 179
 180 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 181                                                    int num_blocks)
 182 {
 183         return start_transaction(root, num_blocks, 1);
 184 }
 185 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 186                                                    int num_blocks)
 187 {
 188         return start_transaction(root, num_blocks, 0);
 189 }
 190
 191 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 192                                                          int num_blocks)
 193 {
 194         return start_transaction(r, num_blocks, 2);
 195 }
 196
 197
 198 static noinline int wait_for_commit(struct btrfs_root *root,
 199                                     struct btrfs_transaction *commit)
 200 {
 201         DEFINE_WAIT(wait);
 202         mutex_lock(&root->fs_info->trans_mutex);
 203         while(!commit->commit_done) {
 204                 prepare_to_wait(&commit->commit_wait, &wait,
 205                                 TASK_UNINTERRUPTIBLE);
 206                 if (commit->commit_done)
 207                         break;
 208                 mutex_unlock(&root->fs_info->trans_mutex);
 209                 schedule();
 210                 mutex_lock(&root->fs_info->trans_mutex);
 211         }
 212         mutex_unlock(&root->fs_info->trans_mutex);
 213         finish_wait(&commit->commit_wait, &wait);
 214         return 0;
 215 }
 216
 217 static void throttle_on_drops(struct btrfs_root *root)
 218 {
 219         struct btrfs_fs_info *info = root->fs_info;
 220         int harder_count = 0;
 221
 222 harder:
 223         if (atomic_read(&info->throttles)) {
 224                 DEFINE_WAIT(wait);
 225                 int thr;
 226                 thr = atomic_read(&info->throttle_gen);
 227
 228                 do {
 229                         prepare_to_wait(&info->transaction_throttle,
 230                                         &wait, TASK_UNINTERRUPTIBLE);
 231                         if (!atomic_read(&info->throttles)) {
 232                                 finish_wait(&info->transaction_throttle, &wait);
 233                                 break;
 234                         }
 235                         schedule();
 236                         finish_wait(&info->transaction_throttle, &wait);
 237                 } while (thr == atomic_read(&info->throttle_gen));
 238                 harder_count++;
 239
 240                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 241                     harder_count < 2)
 242                         goto harder;
 243
 244                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 245                     harder_count < 10)
 246                         goto harder;
 247
 248                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 249                     harder_count < 20)
 250                         goto harder;
 251         }
 252 }
 253
 254 void btrfs_throttle(struct btrfs_root *root)
 255 {
 256         mutex_lock(&root->fs_info->trans_mutex);
 257         if (!root->fs_info->open_ioctl_trans)
 258                 wait_current_trans(root);
 259         mutex_unlock(&root->fs_info->trans_mutex);
 260
 261         throttle_on_drops(root);
 262 }
 263
 264 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 265                           struct btrfs_root *root, int throttle)
 266 {
 267         struct btrfs_transaction *cur_trans;
 268         struct btrfs_fs_info *info = root->fs_info;
 269
 270         mutex_lock(&info->trans_mutex);
 271         cur_trans = info->running_transaction;
 272         WARN_ON(cur_trans != trans->transaction);
 273         WARN_ON(cur_trans->num_writers < 1);
 274         cur_trans->num_writers--;
 275
 276         if (waitqueue_active(&cur_trans->writer_wait))
 277                 wake_up(&cur_trans->writer_wait);
 278         put_transaction(cur_trans);
 279         mutex_unlock(&info->trans_mutex);
 280         memset(trans, 0, sizeof(*trans));
 281         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 282
 283         if (throttle)
 284                 throttle_on_drops(root);
 285
 286         return 0;
 287 }
 288
 289 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 290                           struct btrfs_root *root)
 291 {
 292         return __btrfs_end_transaction(trans, root, 0);
 293 }
 294
 295 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 296                                    struct btrfs_root *root)
 297 {
 298         return __btrfs_end_transaction(trans, root, 1);
 299 }
 300
 301
 302 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 303                                      struct btrfs_root *root)
 304 {
 305         int ret;
 306         int err;
 307         int werr = 0;
 308         struct extent_io_tree *dirty_pages;
 309         struct page *page;
 310         struct inode *btree_inode = root->fs_info->btree_inode;
 311         u64 start;
 312         u64 end;
 313         unsigned long index;
 314
 315         if (!trans || !trans->transaction) {
 316                 return filemap_write_and_wait(btree_inode->i_mapping);
 317         }
 318         dirty_pages = &trans->transaction->dirty_pages;
 319         while(1) {
 320                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
 321                                             EXTENT_DIRTY);
 322                 if (ret)
 323                         break;
 324                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
 325                 while(start <= end) {
 326                         index = start >> PAGE_CACHE_SHIFT;
 327                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 328                         page = find_lock_page(btree_inode->i_mapping, index);
 329                         if (!page)
 330                                 continue;
 331                         if (PageWriteback(page)) {
 332                                 if (PageDirty(page))
 333                                         wait_on_page_writeback(page);
 334                                 else {
 335                                         unlock_page(page);
 336                                         page_cache_release(page);
 337                                         continue;
 338                                 }
 339                         }
 340                         err = write_one_page(page, 0);
 341                         if (err)
 342                                 werr = err;
 343                         page_cache_release(page);
 344                 }
 345         }
 346         err = filemap_fdatawait(btree_inode->i_mapping);
 347         if (err)
 348                 werr = err;
 349         return werr;
 350 }
 351
 352 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 353                                struct btrfs_root *root)
 354 {
 355         int ret;
 356         u64 old_root_bytenr;
 357         struct btrfs_root *tree_root = root->fs_info->tree_root;
 358
 359         btrfs_write_dirty_block_groups(trans, root);
 360         while(1) {
 361                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 362                 if (old_root_bytenr == root->node->start)
 363                         break;
 364                 btrfs_set_root_bytenr(&root->root_item,
 365                                        root->node->start);
 366                 btrfs_set_root_level(&root->root_item,
 367                                      btrfs_header_level(root->node));
 368                 ret = btrfs_update_root(trans, tree_root,
 369                                         &root->root_key,
 370                                         &root->root_item);
 371                 BUG_ON(ret);
 372                 btrfs_write_dirty_block_groups(trans, root);
 373         }
 374         return 0;
 375 }
 376
 377 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 378                             struct btrfs_root *root)
 379 {
 380         struct btrfs_fs_info *fs_info = root->fs_info;
 381         struct list_head *next;
 382
 383         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 384                 next = fs_info->dirty_cowonly_roots.next;
 385                 list_del_init(next);
 386                 root = list_entry(next, struct btrfs_root, dirty_list);
 387                 update_cowonly_root(trans, root);
 388         }
 389         return 0;
 390 }
 391
 392 int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
 393 {
 394         struct btrfs_dirty_root *dirty;
 395
 396         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 397         if (!dirty)
 398                 return -ENOMEM;
 399         dirty->root = root;
 400         dirty->latest_root = latest;
 401
 402         mutex_lock(&root->fs_info->trans_mutex);
 403         list_add(&dirty->list, &latest->fs_info->dead_roots);
 404         mutex_unlock(&root->fs_info->trans_mutex);
 405         return 0;
 406 }
 407
 408 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 409                                     struct radix_tree_root *radix,
 410                                     struct list_head *list)
 411 {
 412         struct btrfs_dirty_root *dirty;
 413         struct btrfs_root *gang[8];
 414         struct btrfs_root *root;
 415         int i;
 416         int ret;
 417         int err = 0;
 418         u32 refs;
 419
 420         while(1) {
 421                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 422                                                  ARRAY_SIZE(gang),
 423                                                  BTRFS_ROOT_TRANS_TAG);
 424                 if (ret == 0)
 425                         break;
 426                 for (i = 0; i < ret; i++) {
 427                         root = gang[i];
 428                         radix_tree_tag_clear(radix,
 429                                      (unsigned long)root->root_key.objectid,
 430                                      BTRFS_ROOT_TRANS_TAG);
 431
 432                         BUG_ON(!root->ref_tree);
 433                         dirty = root->dirty_root;
 434
 435                         if (root->commit_root == root->node) {
 436                                 WARN_ON(root->node->start !=
 437                                         btrfs_root_bytenr(&root->root_item));
 438
 439                                 free_extent_buffer(root->commit_root);
 440                                 root->commit_root = NULL;
 441                                 root->dirty_root = NULL;
 442
 443                                 spin_lock(&root->list_lock);
 444                                 list_del_init(&dirty->root->dead_list);
 445                                 spin_unlock(&root->list_lock);
 446
 447                                 kfree(dirty->root);
 448                                 kfree(dirty);
 449
 450                                 /* make sure to update the root on disk
 451                                  * so we get any updates to the block used
 452                                  * counts
 453                                  */
 454                                 err = btrfs_update_root(trans,
 455                                                 root->fs_info->tree_root,
 456                                                 &root->root_key,
 457                                                 &root->root_item);
 458                                 continue;
 459                         }
 460
 461                         memset(&root->root_item.drop_progress, 0,
 462                                sizeof(struct btrfs_disk_key));
 463                         root->root_item.drop_level = 0;
 464                         root->commit_root = NULL;
 465                         root->dirty_root = NULL;
 466                         root->root_key.offset = root->fs_info->generation;
 467                         btrfs_set_root_bytenr(&root->root_item,
 468                                               root->node->start);
 469                         btrfs_set_root_level(&root->root_item,
 470                                              btrfs_header_level(root->node));
 471                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 472                                                 &root->root_key,
 473                                                 &root->root_item);
 474                         if (err)
 475                                 break;
 476
 477                         refs = btrfs_root_refs(&dirty->root->root_item);
 478                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 479                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 480                                                 &dirty->root->root_key,
 481                                                 &dirty->root->root_item);
 482
 483                         BUG_ON(err);
 484                         if (refs == 1) {
 485                                 list_add(&dirty->list, list);
 486                         } else {
 487                                 WARN_ON(1);
 488                                 free_extent_buffer(dirty->root->node);
 489                                 kfree(dirty->root);
 490                                 kfree(dirty);
 491                         }
 492                 }
 493         }
 494         return err;
 495 }
 496
 497 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 498 {
 499         struct btrfs_fs_info *info = root->fs_info;
 500         int ret;
 501         struct btrfs_trans_handle *trans;
 502         unsigned long nr;
 503
 504         smp_mb();
 505         if (root->defrag_running)
 506                 return 0;
 507         trans = btrfs_start_transaction(root, 1);
 508         while (1) {
 509                 root->defrag_running = 1;
 510                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 511                 nr = trans->blocks_used;
 512                 btrfs_end_transaction(trans, root);
 513                 btrfs_btree_balance_dirty(info->tree_root, nr);
 514                 cond_resched();
 515
 516                 trans = btrfs_start_transaction(root, 1);
 517                 if (root->fs_info->closing || ret != -EAGAIN)
 518                         break;
 519         }
 520         root->defrag_running = 0;
 521         smp_mb();
 522         btrfs_end_transaction(trans, root);
 523         return 0;
 524 }
 525
 526 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
 527                                      struct list_head *list)
 528 {
 529         struct btrfs_dirty_root *dirty;
 530         struct btrfs_trans_handle *trans;
 531         unsigned long nr;
 532         u64 num_bytes;
 533         u64 bytes_used;
 534         u64 max_useless;
 535         int ret = 0;
 536         int err;
 537
 538         while(!list_empty(list)) {
 539                 struct btrfs_root *root;
 540
 541                 dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
 542                 list_del_init(&dirty->list);
 543
 544                 num_bytes = btrfs_root_used(&dirty->root->root_item);
 545                 root = dirty->latest_root;
 546                 atomic_inc(&root->fs_info->throttles);
 547
 548                 mutex_lock(&root->fs_info->drop_mutex);
 549                 while(1) {
 550                         trans = btrfs_start_transaction(tree_root, 1);
 551                         ret = btrfs_drop_snapshot(trans, dirty->root);
 552                         if (ret != -EAGAIN) {
 553                                 break;
 554                         }
 555
 556                         err = btrfs_update_root(trans,
 557                                         tree_root,
 558                                         &dirty->root->root_key,
 559                                         &dirty->root->root_item);
 560                         if (err)
 561                                 ret = err;
 562                         nr = trans->blocks_used;
 563                         ret = btrfs_end_transaction(trans, tree_root);
 564                         BUG_ON(ret);
 565
 566                         mutex_unlock(&root->fs_info->drop_mutex);
 567                         btrfs_btree_balance_dirty(tree_root, nr);
 568                         cond_resched();
 569                         mutex_lock(&root->fs_info->drop_mutex);
 570                 }
 571                 BUG_ON(ret);
 572                 atomic_dec(&root->fs_info->throttles);
 573                 wake_up(&root->fs_info->transaction_throttle);
 574
 575                 mutex_lock(&root->fs_info->alloc_mutex);
 576                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
 577                 bytes_used = btrfs_root_used(&root->root_item);
 578                 if (num_bytes) {
 579                         record_root_in_trans(root);
 580                         btrfs_set_root_used(&root->root_item,
 581                                             bytes_used - num_bytes);
 582                 }
 583                 mutex_unlock(&root->fs_info->alloc_mutex);
 584
 585                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 586                 if (ret) {
 587                         BUG();
 588                         break;
 589                 }
 590                 mutex_unlock(&root->fs_info->drop_mutex);
 591
 592                 spin_lock(&root->list_lock);
 593                 list_del_init(&dirty->root->dead_list);
 594                 if (!list_empty(&root->dead_list)) {
 595                         struct btrfs_root *oldest;
 596                         oldest = list_entry(root->dead_list.prev,
 597                                             struct btrfs_root, dead_list);
 598                         max_useless = oldest->root_key.offset - 1;
 599                 } else {
 600                         max_useless = root->root_key.offset - 1;
 601                 }
 602                 spin_unlock(&root->list_lock);
 603
 604                 nr = trans->blocks_used;
 605                 ret = btrfs_end_transaction(trans, tree_root);
 606                 BUG_ON(ret);
 607
 608                 ret = btrfs_remove_leaf_refs(root, max_useless);
 609                 BUG_ON(ret);
 610
 611                 free_extent_buffer(dirty->root->node);
 612                 kfree(dirty->root);
 613                 kfree(dirty);
 614
 615                 btrfs_btree_balance_dirty(tree_root, nr);
 616                 cond_resched();
 617         }
 618         return ret;
 619 }
 620
 621 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 622                                    struct btrfs_fs_info *fs_info,
 623                                    struct btrfs_pending_snapshot *pending)
 624 {
 625         struct btrfs_key key;
 626         struct btrfs_root_item *new_root_item;
 627         struct btrfs_root *tree_root = fs_info->tree_root;
 628         struct btrfs_root *root = pending->root;
 629         struct extent_buffer *tmp;
 630         struct extent_buffer *old;
 631         int ret;
 632         int namelen;
 633         u64 objectid;
 634
 635         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 636         if (!new_root_item) {
 637                 ret = -ENOMEM;
 638                 goto fail;
 639         }
 640         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 641         if (ret)
 642                 goto fail;
 643
 644         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 645
 646         key.objectid = objectid;
 647         key.offset = 1;
 648         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 649
 650         old = btrfs_lock_root_node(root);
 651         btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
 652
 653         btrfs_copy_root(trans, root, old, &tmp, objectid);
 654         btrfs_tree_unlock(old);
 655         free_extent_buffer(old);
 656
 657         btrfs_set_root_bytenr(new_root_item, tmp->start);
 658         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
 659         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 660                                 new_root_item);
 661         btrfs_tree_unlock(tmp);
 662         free_extent_buffer(tmp);
 663         if (ret)
 664                 goto fail;
 665
 666         /*
 667          * insert the directory item
 668          */
 669         key.offset = (u64)-1;
 670         namelen = strlen(pending->name);
 671         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
 672                                     pending->name, namelen,
 673                                     root->fs_info->sb->s_root->d_inode->i_ino,
 674                                     &key, BTRFS_FT_DIR, 0);
 675
 676         if (ret)
 677                 goto fail;
 678
 679         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
 680                              pending->name, strlen(pending->name), objectid,
 681                              root->fs_info->sb->s_root->d_inode->i_ino, 0);
 682
 683         /* Invalidate existing dcache entry for new snapshot. */
 684         btrfs_invalidate_dcache_root(root, pending->name, namelen);
 685
 686 fail:
 687         kfree(new_root_item);
 688         return ret;
 689 }
 690
 691 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 692                                              struct btrfs_fs_info *fs_info)
 693 {
 694         struct btrfs_pending_snapshot *pending;
 695         struct list_head *head = &trans->transaction->pending_snapshots;
 696         int ret;
 697
 698         while(!list_empty(head)) {
 699                 pending = list_entry(head->next,
 700                                      struct btrfs_pending_snapshot, list);
 701                 ret = create_pending_snapshot(trans, fs_info, pending);
 702                 BUG_ON(ret);
 703                 list_del(&pending->list);
 704                 kfree(pending->name);
 705                 kfree(pending);
 706         }
 707         return 0;
 708 }
 709
 710 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 711                              struct btrfs_root *root)
 712 {
 713         unsigned long joined = 0;
 714         unsigned long timeout = 1;
 715         struct btrfs_transaction *cur_trans;
 716         struct btrfs_transaction *prev_trans = NULL;
 717         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 718         struct list_head dirty_fs_roots;
 719         struct extent_io_tree *pinned_copy;
 720         DEFINE_WAIT(wait);
 721         int ret;
 722
 723         INIT_LIST_HEAD(&dirty_fs_roots);
 724
 725         mutex_lock(&root->fs_info->trans_mutex);
 726         if (trans->transaction->in_commit) {
 727                 cur_trans = trans->transaction;
 728                 trans->transaction->use_count++;
 729                 mutex_unlock(&root->fs_info->trans_mutex);
 730                 btrfs_end_transaction(trans, root);
 731
 732                 ret = wait_for_commit(root, cur_trans);
 733                 BUG_ON(ret);
 734
 735                 mutex_lock(&root->fs_info->trans_mutex);
 736                 put_transaction(cur_trans);
 737                 mutex_unlock(&root->fs_info->trans_mutex);
 738
 739                 return 0;
 740         }
 741
 742         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
 743         if (!pinned_copy)
 744                 return -ENOMEM;
 745
 746         extent_io_tree_init(pinned_copy,
 747                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
 748
 749         trans->transaction->in_commit = 1;
 750         trans->transaction->blocked = 1;
 751         cur_trans = trans->transaction;
 752         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 753                 prev_trans = list_entry(cur_trans->list.prev,
 754                                         struct btrfs_transaction, list);
 755                 if (!prev_trans->commit_done) {
 756                         prev_trans->use_count++;
 757                         mutex_unlock(&root->fs_info->trans_mutex);
 758
 759                         wait_for_commit(root, prev_trans);
 760
 761                         mutex_lock(&root->fs_info->trans_mutex);
 762                         put_transaction(prev_trans);
 763                 }
 764         }
 765
 766         do {
 767                 int snap_pending = 0;
 768                 joined = cur_trans->num_joined;
 769                 if (!list_empty(&trans->transaction->pending_snapshots))
 770                         snap_pending = 1;
 771
 772                 WARN_ON(cur_trans != trans->transaction);
 773                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 774                                 TASK_UNINTERRUPTIBLE);
 775
 776                 if (cur_trans->num_writers > 1)
 777                         timeout = MAX_SCHEDULE_TIMEOUT;
 778                 else
 779                         timeout = 1;
 780
 781                 mutex_unlock(&root->fs_info->trans_mutex);
 782
 783                 if (snap_pending) {
 784                         ret = btrfs_wait_ordered_extents(root, 1);
 785                         BUG_ON(ret);
 786                 }
 787
 788                 schedule_timeout(timeout);
 789
 790                 mutex_lock(&root->fs_info->trans_mutex);
 791                 finish_wait(&cur_trans->writer_wait, &wait);
 792         } while (cur_trans->num_writers > 1 ||
 793                  (cur_trans->num_joined != joined));
 794
 795         ret = create_pending_snapshots(trans, root->fs_info);
 796         BUG_ON(ret);
 797
 798         WARN_ON(cur_trans != trans->transaction);
 799
 800         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 801                               &dirty_fs_roots);
 802         BUG_ON(ret);
 803
 804         ret = btrfs_commit_tree_roots(trans, root);
 805         BUG_ON(ret);
 806
 807         cur_trans = root->fs_info->running_transaction;
 808         spin_lock(&root->fs_info->new_trans_lock);
 809         root->fs_info->running_transaction = NULL;
 810         spin_unlock(&root->fs_info->new_trans_lock);
 811         btrfs_set_super_generation(&root->fs_info->super_copy,
 812                                    cur_trans->transid);
 813         btrfs_set_super_root(&root->fs_info->super_copy,
 814                              root->fs_info->tree_root->node->start);
 815         btrfs_set_super_root_level(&root->fs_info->super_copy,
 816                            btrfs_header_level(root->fs_info->tree_root->node));
 817
 818         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
 819                                    chunk_root->node->start);
 820         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
 821                                          btrfs_header_level(chunk_root->node));
 822         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
 823                sizeof(root->fs_info->super_copy));
 824
 825         btrfs_copy_pinned(root, pinned_copy);
 826
 827         trans->transaction->blocked = 0;
 828         wake_up(&root->fs_info->transaction_throttle);
 829         wake_up(&root->fs_info->transaction_wait);
 830
 831         mutex_unlock(&root->fs_info->trans_mutex);
 832         ret = btrfs_write_and_wait_transaction(trans, root);
 833         BUG_ON(ret);
 834         write_ctree_super(trans, root);
 835
 836         btrfs_finish_extent_commit(trans, root, pinned_copy);
 837         mutex_lock(&root->fs_info->trans_mutex);
 838
 839         kfree(pinned_copy);
 840
 841         cur_trans->commit_done = 1;
 842         root->fs_info->last_trans_committed = cur_trans->transid;
 843         wake_up(&cur_trans->commit_wait);
 844         put_transaction(cur_trans);
 845         put_transaction(cur_trans);
 846
 847         list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 848         if (root->fs_info->closing)
 849                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 850
 851         mutex_unlock(&root->fs_info->trans_mutex);
 852         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 853
 854         if (root->fs_info->closing) {
 855                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 856         }
 857         return ret;
 858 }
 859
 860 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 861 {
 862         struct list_head dirty_roots;
 863         INIT_LIST_HEAD(&dirty_roots);
 864 again:
 865         mutex_lock(&root->fs_info->trans_mutex);
 866         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 867         mutex_unlock(&root->fs_info->trans_mutex);
 868
 869         if (!list_empty(&dirty_roots)) {
 870                 drop_dirty_roots(root, &dirty_roots);
 871                 goto again;
 872         }
 873         return 0;
 874 }