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