fs/btrfs/extent-tree.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/sched.h>
  20 #include <linux/crc32c.h>
  21 #include "hash.h"
  22 #include "ctree.h"
  23 #include "disk-io.h"
  24 #include "print-tree.h"
  25 #include "transaction.h"
  26
  27 #define BLOCK_GROUP_DATA EXTENT_WRITEBACK
  28 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
  29 #define BLOCK_GROUP_DIRTY EXTENT_DIRTY
  30
  31 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
  32                                  btrfs_root *extent_root);
  33 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
  34                                btrfs_root *extent_root);
  35
  36 static int cache_block_group(struct btrfs_root *root,
  37                              struct btrfs_block_group_cache *block_group)
  38 {
  39         struct btrfs_path *path;
  40         int ret;
  41         struct btrfs_key key;
  42         struct extent_buffer *leaf;
  43         struct extent_map_tree *free_space_cache;
  44         int slot;
  45         u64 last = 0;
  46         u64 hole_size;
  47         u64 first_free;
  48         int found = 0;
  49
  50         if (!block_group)
  51                 return 0;
  52
  53         root = root->fs_info->extent_root;
  54         free_space_cache = &root->fs_info->free_space_cache;
  55
  56         if (block_group->cached)
  57                 return 0;
  58
  59         path = btrfs_alloc_path();
  60         if (!path)
  61                 return -ENOMEM;
  62
  63         path->reada = 2;
  64         first_free = block_group->key.objectid;
  65         key.objectid = block_group->key.objectid;
  66         key.offset = 0;
  67
  68         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
  69         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  70
  71         if (ret < 0)
  72                 return ret;
  73
  74         if (ret && path->slots[0] > 0)
  75                 path->slots[0]--;
  76
  77         while(1) {
  78                 leaf = path->nodes[0];
  79                 slot = path->slots[0];
  80                 if (slot >= btrfs_header_nritems(leaf)) {
  81                         ret = btrfs_next_leaf(root, path);
  82                         if (ret < 0)
  83                                 goto err;
  84                         if (ret == 0) {
  85                                 continue;
  86                         } else {
  87                                 break;
  88                         }
  89                 }
  90
  91                 btrfs_item_key_to_cpu(leaf, &key, slot);
  92                 if (key.objectid < block_group->key.objectid) {
  93                         if (btrfs_key_type(&key) != BTRFS_EXTENT_REF_KEY &&
  94                             key.objectid + key.offset > first_free)
  95                                 first_free = key.objectid + key.offset;
  96                         goto next;
  97                 }
  98
  99                 if (key.objectid >= block_group->key.objectid +
 100                     block_group->key.offset) {
 101                         break;
 102                 }
 103
 104                 if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
 105                         if (!found) {
 106                                 last = first_free;
 107                                 found = 1;
 108                         }
 109                         if (key.objectid > last) {
 110                                 hole_size = key.objectid - last;
 111                                 set_extent_dirty(free_space_cache, last,
 112                                                  last + hole_size - 1,
 113                                                  GFP_NOFS);
 114                         }
 115                         last = key.objectid + key.offset;
 116                 }
 117 next:
 118                 path->slots[0]++;
 119         }
 120
 121         if (!found)
 122                 last = first_free;
 123         if (block_group->key.objectid +
 124             block_group->key.offset > last) {
 125                 hole_size = block_group->key.objectid +
 126                         block_group->key.offset - last;
 127                 set_extent_dirty(free_space_cache, last,
 128                                  last + hole_size - 1, GFP_NOFS);
 129         }
 130         block_group->cached = 1;
 131 err:
 132         btrfs_free_path(path);
 133         return 0;
 134 }
 135
 136 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 137                                                          btrfs_fs_info *info,
 138                                                          u64 bytenr)
 139 {
 140         struct extent_map_tree *block_group_cache;
 141         struct btrfs_block_group_cache *block_group = NULL;
 142         u64 ptr;
 143         u64 start;
 144         u64 end;
 145         int ret;
 146
 147         block_group_cache = &info->block_group_cache;
 148         ret = find_first_extent_bit(block_group_cache,
 149                                     bytenr, &start, &end,
 150                                     BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA);
 151         if (ret) {
 152                 return NULL;
 153         }
 154         ret = get_state_private(block_group_cache, start, &ptr);
 155         if (ret)
 156                 return NULL;
 157
 158         block_group = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 159         if (block_group->key.objectid <= bytenr && bytenr <
 160             block_group->key.objectid + block_group->key.offset)
 161                 return block_group;
 162         return NULL;
 163 }
 164 static u64 find_search_start(struct btrfs_root *root,
 165                              struct btrfs_block_group_cache **cache_ret,
 166                              u64 search_start, int num,
 167                              int data, int full_scan)
 168 {
 169         int ret;
 170         struct btrfs_block_group_cache *cache = *cache_ret;
 171         u64 last;
 172         u64 start = 0;
 173         u64 end = 0;
 174         u64 cache_miss = 0;
 175         int wrapped = 0;
 176
 177         if (!cache) {
 178                 goto out;
 179         }
 180 again:
 181         ret = cache_block_group(root, cache);
 182         if (ret)
 183                 goto out;
 184
 185         last = max(search_start, cache->key.objectid);
 186
 187         while(1) {
 188                 ret = find_first_extent_bit(&root->fs_info->free_space_cache,
 189                                             last, &start, &end, EXTENT_DIRTY);
 190                 if (ret) {
 191                         if (!cache_miss)
 192                                 cache_miss = last;
 193                         goto new_group;
 194                 }
 195
 196                 start = max(last, start);
 197                 last = end + 1;
 198                 if (last - start < num) {
 199                         if (last == cache->key.objectid + cache->key.offset)
 200                                 cache_miss = start;
 201                         continue;
 202                 }
 203                 if (data != BTRFS_BLOCK_GROUP_MIXED &&
 204                     start + num > cache->key.objectid + cache->key.offset)
 205                         goto new_group;
 206                 return start;
 207         }
 208 out:
 209         cache = btrfs_lookup_block_group(root->fs_info, search_start);
 210         if (!cache) {
 211                 printk("Unable to find block group for %Lu\n",
 212                        search_start);
 213                 WARN_ON(1);
 214                 return search_start;
 215         }
 216         return search_start;
 217
 218 new_group:
 219         last = cache->key.objectid + cache->key.offset;
 220 wrapped:
 221         cache = btrfs_lookup_block_group(root->fs_info, last);
 222         if (!cache) {
 223 no_cache:
 224                 if (!wrapped) {
 225                         wrapped = 1;
 226                         last = search_start;
 227                         data = BTRFS_BLOCK_GROUP_MIXED;
 228                         goto wrapped;
 229                 }
 230                 goto out;
 231         }
 232         if (cache_miss && !cache->cached) {
 233                 cache_block_group(root, cache);
 234                 last = cache_miss;
 235                 cache = btrfs_lookup_block_group(root->fs_info, last);
 236         }
 237         cache = btrfs_find_block_group(root, cache, last, data, 0);
 238         if (!cache)
 239                 goto no_cache;
 240         *cache_ret = cache;
 241         cache_miss = 0;
 242         goto again;
 243 }
 244
 245 static u64 div_factor(u64 num, int factor)
 246 {
 247         if (factor == 10)
 248                 return num;
 249         num *= factor;
 250         do_div(num, 10);
 251         return num;
 252 }
 253
 254 struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 255                                                  struct btrfs_block_group_cache
 256                                                  *hint, u64 search_start,
 257                                                  int data, int owner)
 258 {
 259         struct btrfs_block_group_cache *cache;
 260         struct extent_map_tree *block_group_cache;
 261         struct btrfs_block_group_cache *found_group = NULL;
 262         struct btrfs_fs_info *info = root->fs_info;
 263         u64 used;
 264         u64 last = 0;
 265         u64 hint_last;
 266         u64 start;
 267         u64 end;
 268         u64 free_check;
 269         u64 ptr;
 270         int bit;
 271         int ret;
 272         int full_search = 0;
 273         int factor = 8;
 274         int data_swap = 0;
 275
 276         block_group_cache = &info->block_group_cache;
 277
 278         if (!owner)
 279                 factor = 8;
 280
 281         if (data == BTRFS_BLOCK_GROUP_MIXED) {
 282                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 283                 factor = 10;
 284         } else if (data)
 285                 bit = BLOCK_GROUP_DATA;
 286         else
 287                 bit = BLOCK_GROUP_METADATA;
 288
 289         if (search_start) {
 290                 struct btrfs_block_group_cache *shint;
 291                 shint = btrfs_lookup_block_group(info, search_start);
 292                 if (shint && (shint->data == data ||
 293                               shint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 294                         used = btrfs_block_group_used(&shint->item);
 295                         if (used + shint->pinned <
 296                             div_factor(shint->key.offset, factor)) {
 297                                 return shint;
 298                         }
 299                 }
 300         }
 301         if (hint && (hint->data == data ||
 302                      hint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 303                 used = btrfs_block_group_used(&hint->item);
 304                 if (used + hint->pinned <
 305                     div_factor(hint->key.offset, factor)) {
 306                         return hint;
 307                 }
 308                 last = hint->key.objectid + hint->key.offset;
 309                 hint_last = last;
 310         } else {
 311                 if (hint)
 312                         hint_last = max(hint->key.objectid, search_start);
 313                 else
 314                         hint_last = search_start;
 315
 316                 last = hint_last;
 317         }
 318 again:
 319         while(1) {
 320                 ret = find_first_extent_bit(block_group_cache, last,
 321                                             &start, &end, bit);
 322                 if (ret)
 323                         break;
 324
 325                 ret = get_state_private(block_group_cache, start, &ptr);
 326                 if (ret)
 327                         break;
 328
 329                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 330                 last = cache->key.objectid + cache->key.offset;
 331                 used = btrfs_block_group_used(&cache->item);
 332
 333                 if (full_search)
 334                         free_check = cache->key.offset;
 335                 else
 336                         free_check = div_factor(cache->key.offset, factor);
 337                 if (used + cache->pinned < free_check) {
 338                         found_group = cache;
 339                         goto found;
 340                 }
 341                 cond_resched();
 342         }
 343         if (!full_search) {
 344                 last = search_start;
 345                 full_search = 1;
 346                 goto again;
 347         }
 348         if (!data_swap) {
 349                 data_swap = 1;
 350                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 351                 last = search_start;
 352                 goto again;
 353         }
 354 found:
 355         return found_group;
 356 }
 357
 358 static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
 359                            u64 owner, u64 owner_offset)
 360 {
 361         u32 high_crc = ~(u32)0;
 362         u32 low_crc = ~(u32)0;
 363         __le64 lenum;
 364
 365         lenum = cpu_to_le64(root_objectid);
 366         high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
 367         lenum = cpu_to_le64(ref_generation);
 368         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 369
 370 #if 0
 371         lenum = cpu_to_le64(owner);
 372         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 373         lenum = cpu_to_le64(owner_offset);
 374         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 375 #endif
 376         return ((u64)high_crc << 32) | (u64)low_crc;
 377 }
 378
 379 static int match_extent_ref(struct extent_buffer *leaf,
 380                             struct btrfs_extent_ref *disk_ref,
 381                             struct btrfs_extent_ref *cpu_ref)
 382 {
 383         int ret;
 384         int len;
 385
 386         if (cpu_ref->objectid)
 387                 len = sizeof(*cpu_ref);
 388         else
 389                 len = 2 * sizeof(u64);
 390         ret = memcmp_extent_buffer(leaf, cpu_ref, (unsigned long)disk_ref,
 391                                    len);
 392         return ret == 0;
 393 }
 394
 395 static int lookup_extent_backref(struct btrfs_trans_handle *trans,
 396                                  struct btrfs_root *root,
 397                                  struct btrfs_path *path, u64 bytenr,
 398                                  u64 root_objectid, u64 ref_generation,
 399                                  u64 owner, u64 owner_offset, int del)
 400 {
 401         u64 hash;
 402         struct btrfs_key key;
 403         struct btrfs_key found_key;
 404         struct btrfs_extent_ref ref;
 405         struct extent_buffer *leaf;
 406         struct btrfs_extent_ref *disk_ref;
 407         int ret;
 408         int ret2;
 409
 410         btrfs_set_stack_ref_root(&ref, root_objectid);
 411         btrfs_set_stack_ref_generation(&ref, ref_generation);
 412         btrfs_set_stack_ref_objectid(&ref, owner);
 413         btrfs_set_stack_ref_offset(&ref, owner_offset);
 414
 415         hash = hash_extent_ref(root_objectid, ref_generation, owner,
 416                                owner_offset);
 417         key.offset = hash;
 418         key.objectid = bytenr;
 419         key.type = BTRFS_EXTENT_REF_KEY;
 420
 421         while (1) {
 422                 ret = btrfs_search_slot(trans, root, &key, path,
 423                                         del ? -1 : 0, del);
 424                 if (ret < 0)
 425                         goto out;
 426                 leaf = path->nodes[0];
 427                 if (ret != 0) {
 428                         u32 nritems = btrfs_header_nritems(leaf);
 429                         if (path->slots[0] >= nritems) {
 430                                 ret2 = btrfs_next_leaf(root, path);
 431                                 if (ret2)
 432                                         goto out;
 433                                 leaf = path->nodes[0];
 434                         }
 435                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 436                         if (found_key.objectid != bytenr ||
 437                             found_key.type != BTRFS_EXTENT_REF_KEY)
 438                                 goto out;
 439                         key.offset = found_key.offset;
 440                         if (del) {
 441                                 btrfs_release_path(root, path);
 442                                 continue;
 443                         }
 444                 }
 445                 disk_ref = btrfs_item_ptr(path->nodes[0],
 446                                           path->slots[0],
 447                                           struct btrfs_extent_ref);
 448                 if (match_extent_ref(path->nodes[0], disk_ref, &ref)) {
 449                         ret = 0;
 450                         goto out;
 451                 }
 452                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 453                 key.offset = found_key.offset + 1;
 454                 btrfs_release_path(root, path);
 455         }
 456 out:
 457         return ret;
 458 }
 459
 460 int btrfs_insert_extent_backref(struct btrfs_trans_handle *trans,
 461                                  struct btrfs_root *root,
 462                                  struct btrfs_path *path, u64 bytenr,
 463                                  u64 root_objectid, u64 ref_generation,
 464                                  u64 owner, u64 owner_offset)
 465 {
 466         u64 hash;
 467         struct btrfs_key key;
 468         struct btrfs_extent_ref ref;
 469         struct btrfs_extent_ref *disk_ref;
 470         int ret;
 471
 472         btrfs_set_stack_ref_root(&ref, root_objectid);
 473         btrfs_set_stack_ref_generation(&ref, ref_generation);
 474         btrfs_set_stack_ref_objectid(&ref, owner);
 475         btrfs_set_stack_ref_offset(&ref, owner_offset);
 476
 477         hash = hash_extent_ref(root_objectid, ref_generation, owner,
 478                                owner_offset);
 479         key.offset = hash;
 480         key.objectid = bytenr;
 481         key.type = BTRFS_EXTENT_REF_KEY;
 482
 483         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(ref));
 484         while (ret == -EEXIST) {
 485                 disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 486                                           struct btrfs_extent_ref);
 487                 if (match_extent_ref(path->nodes[0], disk_ref, &ref))
 488                         goto out;
 489                 key.offset++;
 490                 btrfs_release_path(root, path);
 491                 ret = btrfs_insert_empty_item(trans, root, path, &key,
 492                                               sizeof(ref));
 493         }
 494         if (ret)
 495                 goto out;
 496         disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 497                                   struct btrfs_extent_ref);
 498         write_extent_buffer(path->nodes[0], &ref, (unsigned long)disk_ref,
 499                             sizeof(ref));
 500         btrfs_mark_buffer_dirty(path->nodes[0]);
 501 out:
 502         btrfs_release_path(root, path);
 503         return ret;
 504 }
 505
 506 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 507                                 struct btrfs_root *root,
 508                                 u64 bytenr, u64 num_bytes,
 509                                 u64 root_objectid, u64 ref_generation,
 510                                 u64 owner, u64 owner_offset)
 511 {
 512         struct btrfs_path *path;
 513         int ret;
 514         struct btrfs_key key;
 515         struct extent_buffer *l;
 516         struct btrfs_extent_item *item;
 517         u32 refs;
 518
 519         WARN_ON(num_bytes < root->sectorsize);
 520         path = btrfs_alloc_path();
 521         if (!path)
 522                 return -ENOMEM;
 523
 524         key.objectid = bytenr;
 525         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 526         key.offset = num_bytes;
 527         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 528                                 0, 1);
 529         if (ret < 0)
 530                 return ret;
 531         if (ret != 0) {
 532                 BUG();
 533         }
 534         BUG_ON(ret != 0);
 535         l = path->nodes[0];
 536         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 537         refs = btrfs_extent_refs(l, item);
 538         btrfs_set_extent_refs(l, item, refs + 1);
 539         btrfs_mark_buffer_dirty(path->nodes[0]);
 540
 541         btrfs_release_path(root->fs_info->extent_root, path);
 542
 543         ret = btrfs_insert_extent_backref(trans, root->fs_info->extent_root,
 544                                           path, bytenr, root_objectid,
 545                                           ref_generation, owner, owner_offset);
 546         BUG_ON(ret);
 547         finish_current_insert(trans, root->fs_info->extent_root);
 548         del_pending_extents(trans, root->fs_info->extent_root);
 549
 550         btrfs_free_path(path);
 551         return 0;
 552 }
 553
 554 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 555                          struct btrfs_root *root)
 556 {
 557         finish_current_insert(trans, root->fs_info->extent_root);
 558         del_pending_extents(trans, root->fs_info->extent_root);
 559         return 0;
 560 }
 561
 562 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 563                              struct btrfs_root *root, u64 bytenr,
 564                              u64 num_bytes, u32 *refs)
 565 {
 566         struct btrfs_path *path;
 567         int ret;
 568         struct btrfs_key key;
 569         struct extent_buffer *l;
 570         struct btrfs_extent_item *item;
 571
 572         WARN_ON(num_bytes < root->sectorsize);
 573         path = btrfs_alloc_path();
 574         key.objectid = bytenr;
 575         key.offset = num_bytes;
 576         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 577         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 578                                 0, 0);
 579         if (ret < 0)
 580                 goto out;
 581         if (ret != 0) {
 582                 btrfs_print_leaf(root, path->nodes[0]);
 583                 printk("failed to find block number %Lu\n", bytenr);
 584                 BUG();
 585         }
 586         l = path->nodes[0];
 587         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 588         *refs = btrfs_extent_refs(l, item);
 589 out:
 590         btrfs_free_path(path);
 591         return 0;
 592 }
 593
 594 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 595                        struct btrfs_root *root, u64 owner_objectid)
 596 {
 597         u64 generation;
 598         u64 key_objectid;
 599         u64 level;
 600         u32 nritems;
 601         struct btrfs_disk_key disk_key;
 602
 603         level = btrfs_header_level(root->node);
 604         generation = trans->transid;
 605         nritems = btrfs_header_nritems(root->node);
 606         if (nritems > 0) {
 607                 if (level == 0)
 608                         btrfs_item_key(root->node, &disk_key, 0);
 609                 else
 610                         btrfs_node_key(root->node, &disk_key, 0);
 611                 key_objectid = btrfs_disk_key_objectid(&disk_key);
 612         } else {
 613                 key_objectid = 0;
 614         }
 615         return btrfs_inc_extent_ref(trans, root, root->node->start,
 616                                     root->node->len, owner_objectid,
 617                                     generation, 0, 0);
 618 }
 619
 620 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 621                   struct extent_buffer *buf)
 622 {
 623         u64 bytenr;
 624         u32 nritems;
 625         struct btrfs_key key;
 626         struct btrfs_file_extent_item *fi;
 627         int i;
 628         int level;
 629         int ret;
 630         int faili;
 631
 632         if (!root->ref_cows)
 633                 return 0;
 634
 635         level = btrfs_header_level(buf);
 636         nritems = btrfs_header_nritems(buf);
 637         for (i = 0; i < nritems; i++) {
 638                 if (level == 0) {
 639                         u64 disk_bytenr;
 640                         btrfs_item_key_to_cpu(buf, &key, i);
 641                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 642                                 continue;
 643                         fi = btrfs_item_ptr(buf, i,
 644                                             struct btrfs_file_extent_item);
 645                         if (btrfs_file_extent_type(buf, fi) ==
 646                             BTRFS_FILE_EXTENT_INLINE)
 647                                 continue;
 648                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 649                         if (disk_bytenr == 0)
 650                                 continue;
 651                         ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
 652                                     btrfs_file_extent_disk_num_bytes(buf, fi),
 653                                     root->root_key.objectid, trans->transid,
 654                                     key.objectid, key.offset);
 655                         if (ret) {
 656                                 faili = i;
 657                                 goto fail;
 658                         }
 659                 } else {
 660                         bytenr = btrfs_node_blockptr(buf, i);
 661                         ret = btrfs_inc_extent_ref(trans, root, bytenr,
 662                                            btrfs_level_size(root, level - 1),
 663                                            root->root_key.objectid,
 664                                            trans->transid, 0, 0);
 665                         if (ret) {
 666                                 faili = i;
 667                                 goto fail;
 668                         }
 669                 }
 670         }
 671         return 0;
 672 fail:
 673         WARN_ON(1);
 674 #if 0
 675         for (i =0; i < faili; i++) {
 676                 if (level == 0) {
 677                         u64 disk_bytenr;
 678                         btrfs_item_key_to_cpu(buf, &key, i);
 679                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 680                                 continue;
 681                         fi = btrfs_item_ptr(buf, i,
 682                                             struct btrfs_file_extent_item);
 683                         if (btrfs_file_extent_type(buf, fi) ==
 684                             BTRFS_FILE_EXTENT_INLINE)
 685                                 continue;
 686                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 687                         if (disk_bytenr == 0)
 688                                 continue;
 689                         err = btrfs_free_extent(trans, root, disk_bytenr,
 690                                     btrfs_file_extent_disk_num_bytes(buf,
 691                                                                       fi), 0);
 692                         BUG_ON(err);
 693                 } else {
 694                         bytenr = btrfs_node_blockptr(buf, i);
 695                         err = btrfs_free_extent(trans, root, bytenr,
 696                                         btrfs_level_size(root, level - 1), 0);
 697                         BUG_ON(err);
 698                 }
 699         }
 700 #endif
 701         return ret;
 702 }
 703
 704 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 705                                  struct btrfs_root *root,
 706                                  struct btrfs_path *path,
 707                                  struct btrfs_block_group_cache *cache)
 708 {
 709         int ret;
 710         int pending_ret;
 711         struct btrfs_root *extent_root = root->fs_info->extent_root;
 712         unsigned long bi;
 713         struct extent_buffer *leaf;
 714
 715         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 716         if (ret < 0)
 717                 goto fail;
 718         BUG_ON(ret);
 719
 720         leaf = path->nodes[0];
 721         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 722         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 723         btrfs_mark_buffer_dirty(leaf);
 724         btrfs_release_path(extent_root, path);
 725 fail:
 726         finish_current_insert(trans, extent_root);
 727         pending_ret = del_pending_extents(trans, extent_root);
 728         if (ret)
 729                 return ret;
 730         if (pending_ret)
 731                 return pending_ret;
 732         return 0;
 733
 734 }
 735
 736 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 737                                    struct btrfs_root *root)
 738 {
 739         struct extent_map_tree *block_group_cache;
 740         struct btrfs_block_group_cache *cache;
 741         int ret;
 742         int err = 0;
 743         int werr = 0;
 744         struct btrfs_path *path;
 745         u64 last = 0;
 746         u64 start;
 747         u64 end;
 748         u64 ptr;
 749
 750         block_group_cache = &root->fs_info->block_group_cache;
 751         path = btrfs_alloc_path();
 752         if (!path)
 753                 return -ENOMEM;
 754
 755         while(1) {
 756                 ret = find_first_extent_bit(block_group_cache, last,
 757                                             &start, &end, BLOCK_GROUP_DIRTY);
 758                 if (ret)
 759                         break;
 760
 761                 last = end + 1;
 762                 ret = get_state_private(block_group_cache, start, &ptr);
 763                 if (ret)
 764                         break;
 765
 766                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 767                 err = write_one_cache_group(trans, root,
 768                                             path, cache);
 769                 /*
 770                  * if we fail to write the cache group, we want
 771                  * to keep it marked dirty in hopes that a later
 772                  * write will work
 773                  */
 774                 if (err) {
 775                         werr = err;
 776                         continue;
 777                 }
 778                 clear_extent_bits(block_group_cache, start, end,
 779                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
 780         }
 781         btrfs_free_path(path);
 782         return werr;
 783 }
 784
 785 static int update_block_group(struct btrfs_trans_handle *trans,
 786                               struct btrfs_root *root,
 787                               u64 bytenr, u64 num_bytes, int alloc,
 788                               int mark_free, int data)
 789 {
 790         struct btrfs_block_group_cache *cache;
 791         struct btrfs_fs_info *info = root->fs_info;
 792         u64 total = num_bytes;
 793         u64 old_val;
 794         u64 byte_in_group;
 795         u64 start;
 796         u64 end;
 797
 798         while(total) {
 799                 cache = btrfs_lookup_block_group(info, bytenr);
 800                 if (!cache) {
 801                         return -1;
 802                 }
 803                 byte_in_group = bytenr - cache->key.objectid;
 804                 WARN_ON(byte_in_group > cache->key.offset);
 805                 start = cache->key.objectid;
 806                 end = start + cache->key.offset - 1;
 807                 set_extent_bits(&info->block_group_cache, start, end,
 808                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
 809
 810                 old_val = btrfs_block_group_used(&cache->item);
 811                 num_bytes = min(total, cache->key.offset - byte_in_group);
 812                 if (alloc) {
 813                         if (cache->data != data &&
 814                             old_val < (cache->key.offset >> 1)) {
 815                                 int bit_to_clear;
 816                                 int bit_to_set;
 817                                 cache->data = data;
 818                                 if (data) {
 819                                         bit_to_clear = BLOCK_GROUP_METADATA;
 820                                         bit_to_set = BLOCK_GROUP_DATA;
 821                                         cache->item.flags &=
 822                                                 ~BTRFS_BLOCK_GROUP_MIXED;
 823                                         cache->item.flags |=
 824                                                 BTRFS_BLOCK_GROUP_DATA;
 825                                 } else {
 826                                         bit_to_clear = BLOCK_GROUP_DATA;
 827                                         bit_to_set = BLOCK_GROUP_METADATA;
 828                                         cache->item.flags &=
 829                                                 ~BTRFS_BLOCK_GROUP_MIXED;
 830                                         cache->item.flags &=
 831                                                 ~BTRFS_BLOCK_GROUP_DATA;
 832                                 }
 833                                 clear_extent_bits(&info->block_group_cache,
 834                                                   start, end, bit_to_clear,
 835                                                   GFP_NOFS);
 836                                 set_extent_bits(&info->block_group_cache,
 837                                                 start, end, bit_to_set,
 838                                                 GFP_NOFS);
 839                         } else if (cache->data != data &&
 840                                    cache->data != BTRFS_BLOCK_GROUP_MIXED) {
 841                                 cache->data = BTRFS_BLOCK_GROUP_MIXED;
 842                                 set_extent_bits(&info->block_group_cache,
 843                                                 start, end,
 844                                                 BLOCK_GROUP_DATA |
 845                                                 BLOCK_GROUP_METADATA,
 846                                                 GFP_NOFS);
 847                         }
 848                         old_val += num_bytes;
 849                 } else {
 850                         old_val -= num_bytes;
 851                         if (mark_free) {
 852                                 set_extent_dirty(&info->free_space_cache,
 853                                                  bytenr, bytenr + num_bytes - 1,
 854                                                  GFP_NOFS);
 855                         }
 856                 }
 857                 btrfs_set_block_group_used(&cache->item, old_val);
 858                 total -= num_bytes;
 859                 bytenr += num_bytes;
 860         }
 861         return 0;
 862 }
 863 static int update_pinned_extents(struct btrfs_root *root,
 864                                 u64 bytenr, u64 num, int pin)
 865 {
 866         u64 len;
 867         struct btrfs_block_group_cache *cache;
 868         struct btrfs_fs_info *fs_info = root->fs_info;
 869
 870         if (pin) {
 871                 set_extent_dirty(&fs_info->pinned_extents,
 872                                 bytenr, bytenr + num - 1, GFP_NOFS);
 873         } else {
 874                 clear_extent_dirty(&fs_info->pinned_extents,
 875                                 bytenr, bytenr + num - 1, GFP_NOFS);
 876         }
 877         while (num > 0) {
 878                 cache = btrfs_lookup_block_group(fs_info, bytenr);
 879                 WARN_ON(!cache);
 880                 len = min(num, cache->key.offset -
 881                           (bytenr - cache->key.objectid));
 882                 if (pin) {
 883                         cache->pinned += len;
 884                         fs_info->total_pinned += len;
 885                 } else {
 886                         cache->pinned -= len;
 887                         fs_info->total_pinned -= len;
 888                 }
 889                 bytenr += len;
 890                 num -= len;
 891         }
 892         return 0;
 893 }
 894
 895 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
 896 {
 897         u64 last = 0;
 898         u64 start;
 899         u64 end;
 900         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
 901         int ret;
 902
 903         while(1) {
 904                 ret = find_first_extent_bit(pinned_extents, last,
 905                                             &start, &end, EXTENT_DIRTY);
 906                 if (ret)
 907                         break;
 908                 set_extent_dirty(copy, start, end, GFP_NOFS);
 909                 last = end + 1;
 910         }
 911         return 0;
 912 }
 913
 914 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 915                                struct btrfs_root *root,
 916                                struct extent_map_tree *unpin)
 917 {
 918         u64 start;
 919         u64 end;
 920         int ret;
 921         struct extent_map_tree *free_space_cache;
 922         free_space_cache = &root->fs_info->free_space_cache;
 923
 924         while(1) {
 925                 ret = find_first_extent_bit(unpin, 0, &start, &end,
 926                                             EXTENT_DIRTY);
 927                 if (ret)
 928                         break;
 929                 update_pinned_extents(root, start, end + 1 - start, 0);
 930                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
 931                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
 932         }
 933         return 0;
 934 }
 935
 936 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 937                                  btrfs_root *extent_root)
 938 {
 939         u64 start;
 940         u64 end;
 941         struct btrfs_fs_info *info = extent_root->fs_info;
 942         struct btrfs_path *path;
 943         struct btrfs_key ins;
 944         struct btrfs_extent_item extent_item;
 945         int ret;
 946         int err = 0;
 947
 948         btrfs_set_stack_extent_refs(&extent_item, 1);
 949         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
 950         path = btrfs_alloc_path();
 951
 952         while(1) {
 953                 ret = find_first_extent_bit(&info->extent_ins, 0, &start,
 954                                             &end, EXTENT_LOCKED);
 955                 if (ret)
 956                         break;
 957
 958                 ins.objectid = start;
 959                 ins.offset = end + 1 - start;
 960                 err = btrfs_insert_item(trans, extent_root, &ins,
 961                                         &extent_item, sizeof(extent_item));
 962                 clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
 963                                   GFP_NOFS);
 964                 err = btrfs_insert_extent_backref(trans, extent_root, path,
 965                                           start, extent_root->root_key.objectid,
 966                                           0, 0, 0);
 967                 BUG_ON(err);
 968         }
 969         btrfs_free_path(path);
 970         return 0;
 971 }
 972
 973 static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
 974                           int pending)
 975 {
 976         int err = 0;
 977         struct extent_buffer *buf;
 978
 979         if (!pending) {
 980                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
 981                 if (buf) {
 982                         if (btrfs_buffer_uptodate(buf)) {
 983                                 u64 transid =
 984                                     root->fs_info->running_transaction->transid;
 985                                 if (btrfs_header_generation(buf) == transid) {
 986                                         free_extent_buffer(buf);
 987                                         return 1;
 988                                 }
 989                         }
 990                         free_extent_buffer(buf);
 991                 }
 992                 update_pinned_extents(root, bytenr, num_bytes, 1);
 993         } else {
 994                 set_extent_bits(&root->fs_info->pending_del,
 995                                 bytenr, bytenr + num_bytes - 1,
 996                                 EXTENT_LOCKED, GFP_NOFS);
 997         }
 998         BUG_ON(err < 0);
 999         return 0;
1000 }
1001
1002 /*
1003  * remove an extent from the root, returns 0 on success
1004  */
1005 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1006                          *root, u64 bytenr, u64 num_bytes,
1007                          u64 root_objectid, u64 ref_generation,
1008                          u64 owner_objectid, u64 owner_offset, int pin,
1009                          int mark_free)
1010 {
1011         struct btrfs_path *path;
1012         struct btrfs_key key;
1013         struct btrfs_fs_info *info = root->fs_info;
1014         struct btrfs_root *extent_root = info->extent_root;
1015         struct extent_buffer *leaf;
1016         int ret;
1017         struct btrfs_extent_item *ei;
1018         u32 refs;
1019
1020         key.objectid = bytenr;
1021         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
1022         key.offset = num_bytes;
1023
1024         path = btrfs_alloc_path();
1025         if (!path)
1026                 return -ENOMEM;
1027
1028         if (ref_generation && owner_objectid == 0 && root_objectid == 3) {
1029 //printk("drop backref root %Lu gen %Lu byte %Lu\n", root_objectid, ref_generation, bytenr );
1030         }
1031         ret = lookup_extent_backref(trans, extent_root, path,
1032                                     bytenr, root_objectid,
1033                                     ref_generation,
1034                                     owner_objectid, owner_offset, 1);
1035         if (ret == 0) {
1036                 ret = btrfs_del_item(trans, extent_root, path);
1037         } else {
1038                 btrfs_print_leaf(extent_root, path->nodes[0]);
1039                 WARN_ON(1);
1040                 printk("Unable to find ref byte nr %Lu root %Lu "
1041                        " gen %Lu owner %Lu offset %Lu\n", bytenr,
1042                        root_objectid, ref_generation, owner_objectid,
1043                        owner_offset);
1044         }
1045         btrfs_release_path(extent_root, path);
1046         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
1047         if (ret < 0)
1048                 return ret;
1049         BUG_ON(ret);
1050
1051         leaf = path->nodes[0];
1052         ei = btrfs_item_ptr(leaf, path->slots[0],
1053                             struct btrfs_extent_item);
1054         refs = btrfs_extent_refs(leaf, ei);
1055         BUG_ON(refs == 0);
1056         refs -= 1;
1057         btrfs_set_extent_refs(leaf, ei, refs);
1058         btrfs_mark_buffer_dirty(leaf);
1059
1060         if (refs == 0) {
1061                 u64 super_used;
1062                 u64 root_used;
1063
1064                 if (pin) {
1065                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
1066                         if (ret > 0)
1067                                 mark_free = 1;
1068                         BUG_ON(ret < 0);
1069                 }
1070
1071                 /* block accounting for super block */
1072                 super_used = btrfs_super_bytes_used(&info->super_copy);
1073                 btrfs_set_super_bytes_used(&info->super_copy,
1074                                            super_used - num_bytes);
1075
1076                 /* block accounting for root item */
1077                 root_used = btrfs_root_used(&root->root_item);
1078                 btrfs_set_root_used(&root->root_item,
1079                                            root_used - num_bytes);
1080
1081                 ret = btrfs_del_item(trans, extent_root, path);
1082                 if (ret) {
1083                         return ret;
1084                 }
1085                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
1086                                          mark_free, 0);
1087                 BUG_ON(ret);
1088         }
1089         btrfs_free_path(path);
1090         finish_current_insert(trans, extent_root);
1091         return ret;
1092 }
1093
1094 /*
1095  * find all the blocks marked as pending in the radix tree and remove
1096  * them from the extent map
1097  */
1098 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
1099                                btrfs_root *extent_root)
1100 {
1101         int ret;
1102         int err = 0;
1103         u64 start;
1104         u64 end;
1105         struct extent_map_tree *pending_del;
1106         struct extent_map_tree *pinned_extents;
1107
1108         pending_del = &extent_root->fs_info->pending_del;
1109         pinned_extents = &extent_root->fs_info->pinned_extents;
1110
1111         while(1) {
1112                 ret = find_first_extent_bit(pending_del, 0, &start, &end,
1113                                             EXTENT_LOCKED);
1114                 if (ret)
1115                         break;
1116                 update_pinned_extents(extent_root, start, end + 1 - start, 1);
1117                 clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
1118                                   GFP_NOFS);
1119                 ret = __free_extent(trans, extent_root,
1120                                      start, end + 1 - start,
1121                                      extent_root->root_key.objectid,
1122                                      0, 0, 0, 0, 0);
1123                 if (ret)
1124                         err = ret;
1125         }
1126         return err;
1127 }
1128
1129 /*
1130  * remove an extent from the root, returns 0 on success
1131  */
1132 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1133                       *root, u64 bytenr, u64 num_bytes,
1134                       u64 root_objectid, u64 ref_generation,
1135                       u64 owner_objectid, u64 owner_offset, int pin)
1136 {
1137         struct btrfs_root *extent_root = root->fs_info->extent_root;
1138         int pending_ret;
1139         int ret;
1140
1141         WARN_ON(num_bytes < root->sectorsize);
1142         if (!root->ref_cows)
1143                 ref_generation = 0;
1144
1145         if (root == extent_root) {
1146                 pin_down_bytes(root, bytenr, num_bytes, 1);
1147                 return 0;
1148         }
1149         ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
1150                             ref_generation, owner_objectid, owner_offset,
1151                             pin, pin == 0);
1152         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
1153         return ret ? ret : pending_ret;
1154 }
1155
1156 static u64 stripe_align(struct btrfs_root *root, u64 val)
1157 {
1158         u64 mask = ((u64)root->stripesize - 1);
1159         u64 ret = (val + mask) & ~mask;
1160         return ret;
1161 }
1162
1163 /*
1164  * walks the btree of allocated extents and find a hole of a given size.
1165  * The key ins is changed to record the hole:
1166  * ins->objectid == block start
1167  * ins->flags = BTRFS_EXTENT_ITEM_KEY
1168  * ins->offset == number of blocks
1169  * Any available blocks before search_start are skipped.
1170  */
1171 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1172                             *orig_root, u64 num_bytes, u64 empty_size,
1173                             u64 search_start, u64 search_end, u64 hint_byte,
1174                             struct btrfs_key *ins, u64 exclude_start,
1175                             u64 exclude_nr, int data)
1176 {
1177         struct btrfs_path *path;
1178         struct btrfs_key key;
1179         u64 hole_size = 0;
1180         u64 aligned;
1181         int ret;
1182         int slot = 0;
1183         u64 last_byte = 0;
1184         u64 orig_search_start = search_start;
1185         int start_found;
1186         struct extent_buffer *l;
1187         struct btrfs_root * root = orig_root->fs_info->extent_root;
1188         struct btrfs_fs_info *info = root->fs_info;
1189         u64 total_needed = num_bytes;
1190         int level;
1191         struct btrfs_block_group_cache *block_group;
1192         int full_scan = 0;
1193         int wrapped = 0;
1194         u64 cached_start;
1195
1196         WARN_ON(num_bytes < root->sectorsize);
1197         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
1198
1199         level = btrfs_header_level(root->node);
1200
1201         if (num_bytes >= 32 * 1024 * 1024 && hint_byte) {
1202                 data = BTRFS_BLOCK_GROUP_MIXED;
1203         }
1204
1205         if (search_end == (u64)-1)
1206                 search_end = btrfs_super_total_bytes(&info->super_copy);
1207         if (hint_byte) {
1208                 block_group = btrfs_lookup_block_group(info, hint_byte);
1209                 if (!block_group)
1210                         hint_byte = search_start;
1211                 block_group = btrfs_find_block_group(root, block_group,
1212                                                      hint_byte, data, 1);
1213         } else {
1214                 block_group = btrfs_find_block_group(root,
1215                                                      trans->block_group,
1216                                                      search_start, data, 1);
1217         }
1218
1219         total_needed += empty_size;
1220         path = btrfs_alloc_path();
1221 check_failed:
1222         search_start = find_search_start(root, &block_group, search_start,
1223                                          total_needed, data, full_scan);
1224         search_start = stripe_align(root, search_start);
1225         cached_start = search_start;
1226         btrfs_init_path(path);
1227         ins->objectid = search_start;
1228         ins->offset = 0;
1229         start_found = 0;
1230         path->reada = 2;
1231
1232         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1233         if (ret < 0)
1234                 goto error;
1235
1236         if (path->slots[0] > 0) {
1237                 path->slots[0]--;
1238         }
1239
1240         l = path->nodes[0];
1241         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
1242
1243         /*
1244          * walk backwards to find the first extent item key
1245          */
1246         while(btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
1247                 if (path->slots[0] == 0) {
1248                         ret = btrfs_prev_leaf(root, path);
1249                         if (ret != 0) {
1250                                 ret = btrfs_search_slot(trans, root, ins,
1251                                                         path, 0, 0);
1252                                 if (ret < 0)
1253                                         goto error;
1254                                 if (path->slots[0] > 0)
1255                                         path->slots[0]--;
1256                                 break;
1257                         }
1258                 } else {
1259                         path->slots[0]--;
1260                 }
1261                 l = path->nodes[0];
1262                 btrfs_item_key_to_cpu(l, &key, path->slots[0]);
1263         }
1264         while (1) {
1265                 l = path->nodes[0];
1266                 slot = path->slots[0];
1267                 if (slot >= btrfs_header_nritems(l)) {
1268                         ret = btrfs_next_leaf(root, path);
1269                         if (ret == 0)
1270                                 continue;
1271                         if (ret < 0)
1272                                 goto error;
1273
1274                         search_start = max(search_start,
1275                                            block_group->key.objectid);
1276                         if (!start_found) {
1277                                 aligned = stripe_align(root, search_start);
1278                                 ins->objectid = aligned;
1279                                 if (aligned >= search_end) {
1280                                         ret = -ENOSPC;
1281                                         goto error;
1282                                 }
1283                                 ins->offset = search_end - aligned;
1284                                 start_found = 1;
1285                                 goto check_pending;
1286                         }
1287                         ins->objectid = stripe_align(root,
1288                                                      last_byte > search_start ?
1289                                                      last_byte : search_start);
1290                         if (search_end <= ins->objectid) {
1291                                 ret = -ENOSPC;
1292                                 goto error;
1293                         }
1294                         ins->offset = search_end - ins->objectid;
1295                         BUG_ON(ins->objectid >= search_end);
1296                         goto check_pending;
1297                 }
1298                 btrfs_item_key_to_cpu(l, &key, slot);
1299
1300                 if (key.objectid >= search_start && key.objectid > last_byte &&
1301                     start_found) {
1302                         if (last_byte < search_start)
1303                                 last_byte = search_start;
1304                         aligned = stripe_align(root, last_byte);
1305                         hole_size = key.objectid - aligned;
1306                         if (key.objectid > aligned && hole_size >= num_bytes) {
1307                                 ins->objectid = aligned;
1308                                 ins->offset = hole_size;
1309                                 goto check_pending;
1310                         }
1311                 }
1312                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
1313                         if (!start_found && btrfs_key_type(&key) ==
1314                             BTRFS_BLOCK_GROUP_ITEM_KEY) {
1315                                 last_byte = key.objectid;
1316                                 start_found = 1;
1317                         }
1318                         goto next;
1319                 }
1320
1321
1322                 start_found = 1;
1323                 last_byte = key.objectid + key.offset;
1324
1325                 if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1326                     last_byte >= block_group->key.objectid +
1327                     block_group->key.offset) {
1328                         btrfs_release_path(root, path);
1329                         search_start = block_group->key.objectid +
1330                                 block_group->key.offset;
1331                         goto new_group;
1332                 }
1333 next:
1334                 path->slots[0]++;
1335                 cond_resched();
1336         }
1337 check_pending:
1338         /* we have to make sure we didn't find an extent that has already
1339          * been allocated by the map tree or the original allocation
1340          */
1341         btrfs_release_path(root, path);
1342         BUG_ON(ins->objectid < search_start);
1343
1344         if (ins->objectid + num_bytes >= search_end)
1345                 goto enospc;
1346         if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1347             ins->objectid + num_bytes > block_group->
1348             key.objectid + block_group->key.offset) {
1349                 search_start = block_group->key.objectid +
1350                         block_group->key.offset;
1351                 goto new_group;
1352         }
1353         if (test_range_bit(&info->extent_ins, ins->objectid,
1354                            ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
1355                 search_start = ins->objectid + num_bytes;
1356                 goto new_group;
1357         }
1358         if (test_range_bit(&info->pinned_extents, ins->objectid,
1359                            ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
1360                 search_start = ins->objectid + num_bytes;
1361                 goto new_group;
1362         }
1363         if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
1364             ins->objectid < exclude_start + exclude_nr)) {
1365                 search_start = exclude_start + exclude_nr;
1366                 goto new_group;
1367         }
1368         if (!data) {
1369                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1370                 if (block_group)
1371                         trans->block_group = block_group;
1372         }
1373         ins->offset = num_bytes;
1374         btrfs_free_path(path);
1375         return 0;
1376
1377 new_group:
1378         if (search_start + num_bytes >= search_end) {
1379 enospc:
1380                 search_start = orig_search_start;
1381                 if (full_scan) {
1382                         ret = -ENOSPC;
1383                         goto error;
1384                 }
1385                 if (wrapped) {
1386                         if (!full_scan)
1387                                 total_needed -= empty_size;
1388                         full_scan = 1;
1389                         data = BTRFS_BLOCK_GROUP_MIXED;
1390                 } else
1391                         wrapped = 1;
1392         }
1393         block_group = btrfs_lookup_block_group(info, search_start);
1394         cond_resched();
1395         block_group = btrfs_find_block_group(root, block_group,
1396                                              search_start, data, 0);
1397         goto check_failed;
1398
1399 error:
1400         btrfs_release_path(root, path);
1401         btrfs_free_path(path);
1402         return ret;
1403 }
1404 /*
1405  * finds a free extent and does all the dirty work required for allocation
1406  * returns the key for the extent through ins, and a tree buffer for
1407  * the first block of the extent through buf.
1408  *
1409  * returns 0 if everything worked, non-zero otherwise.
1410  */
1411 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1412                        struct btrfs_root *root,
1413                        u64 num_bytes, u64 root_objectid, u64 ref_generation,
1414                        u64 owner, u64 owner_offset,
1415                        u64 empty_size, u64 hint_byte,
1416                        u64 search_end, struct btrfs_key *ins, int data)
1417 {
1418         int ret;
1419         int pending_ret;
1420         u64 super_used, root_used;
1421         u64 search_start = 0;
1422         struct btrfs_fs_info *info = root->fs_info;
1423         struct btrfs_root *extent_root = info->extent_root;
1424         struct btrfs_extent_item extent_item;
1425         struct btrfs_path *path;
1426
1427         btrfs_set_stack_extent_refs(&extent_item, 1);
1428
1429         WARN_ON(num_bytes < root->sectorsize);
1430         ret = find_free_extent(trans, root, num_bytes, empty_size,
1431                                search_start, search_end, hint_byte, ins,
1432                                trans->alloc_exclude_start,
1433                                trans->alloc_exclude_nr, data);
1434         BUG_ON(ret);
1435         if (ret)
1436                 return ret;
1437
1438         /* block accounting for super block */
1439         super_used = btrfs_super_bytes_used(&info->super_copy);
1440         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
1441
1442         /* block accounting for root item */
1443         root_used = btrfs_root_used(&root->root_item);
1444         btrfs_set_root_used(&root->root_item, root_used + num_bytes);
1445
1446         clear_extent_dirty(&root->fs_info->free_space_cache,
1447                            ins->objectid, ins->objectid + ins->offset - 1,
1448                            GFP_NOFS);
1449
1450         if (root == extent_root) {
1451                 set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
1452                                 ins->objectid + ins->offset - 1,
1453                                 EXTENT_LOCKED, GFP_NOFS);
1454                 WARN_ON(data == 1);
1455                 goto update_block;
1456         }
1457
1458         WARN_ON(trans->alloc_exclude_nr);
1459         trans->alloc_exclude_start = ins->objectid;
1460         trans->alloc_exclude_nr = ins->offset;
1461         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1462                                 sizeof(extent_item));
1463
1464         trans->alloc_exclude_start = 0;
1465         trans->alloc_exclude_nr = 0;
1466         BUG_ON(ret);
1467
1468         path = btrfs_alloc_path();
1469         BUG_ON(!path);
1470         ret = btrfs_insert_extent_backref(trans, extent_root, path,
1471                                           ins->objectid, root_objectid,
1472                                           ref_generation, owner, owner_offset);
1473
1474         BUG_ON(ret);
1475         btrfs_free_path(path);
1476         finish_current_insert(trans, extent_root);
1477         pending_ret = del_pending_extents(trans, extent_root);
1478
1479         if (ret) {
1480                 return ret;
1481         }
1482         if (pending_ret) {
1483                 return pending_ret;
1484         }
1485
1486 update_block:
1487         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1488                                  data);
1489         BUG_ON(ret);
1490         return 0;
1491 }
1492
1493 /*
1494  * helper function to allocate a block for a given tree
1495  * returns the tree buffer or NULL.
1496  */
1497 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1498                                              struct btrfs_root *root,
1499                                              u32 blocksize,
1500                                              u64 root_objectid, u64 hint,
1501                                              u64 empty_size)
1502 {
1503         u64 ref_generation;
1504
1505         if (root->ref_cows)
1506                 ref_generation = trans->transid;
1507         else
1508                 ref_generation = 0;
1509
1510
1511         return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
1512                                         ref_generation, 0, 0, hint, empty_size);
1513 }
1514
1515 /*
1516  * helper function to allocate a block for a given tree
1517  * returns the tree buffer or NULL.
1518  */
1519 struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1520                                              struct btrfs_root *root,
1521                                              u32 blocksize,
1522                                              u64 root_objectid,
1523                                              u64 ref_generation,
1524                                              u64 first_objectid,
1525                                              int level,
1526                                              u64 hint,
1527                                              u64 empty_size)
1528 {
1529         struct btrfs_key ins;
1530         int ret;
1531         struct extent_buffer *buf;
1532
1533         ret = btrfs_alloc_extent(trans, root, blocksize,
1534                                  root_objectid, ref_generation,
1535                                  first_objectid, level, empty_size, hint,
1536                                  (u64)-1, &ins, 0);
1537         if (ret) {
1538                 BUG_ON(ret > 0);
1539                 return ERR_PTR(ret);
1540         }
1541         buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
1542         if (!buf) {
1543                 btrfs_free_extent(trans, root, ins.objectid, blocksize,
1544                                   root->root_key.objectid, ref_generation,
1545                                   0, 0, 0);
1546                 return ERR_PTR(-ENOMEM);
1547         }
1548         btrfs_set_buffer_uptodate(buf);
1549         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1550                          buf->start + buf->len - 1, GFP_NOFS);
1551         set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
1552                         buf->start, buf->start + buf->len - 1,
1553                         EXTENT_CSUM, GFP_NOFS);
1554         buf->flags |= EXTENT_CSUM;
1555         btrfs_set_buffer_defrag(buf);
1556         trans->blocks_used++;
1557         return buf;
1558 }
1559
1560 static int drop_leaf_ref(struct btrfs_trans_handle *trans,
1561                          struct btrfs_root *root, struct extent_buffer *leaf)
1562 {
1563         u64 leaf_owner;
1564         u64 leaf_generation;
1565         struct btrfs_key key;
1566         struct btrfs_file_extent_item *fi;
1567         int i;
1568         int nritems;
1569         int ret;
1570
1571         BUG_ON(!btrfs_is_leaf(leaf));
1572         nritems = btrfs_header_nritems(leaf);
1573         leaf_owner = btrfs_header_owner(leaf);
1574         leaf_generation = btrfs_header_generation(leaf);
1575
1576         for (i = 0; i < nritems; i++) {
1577                 u64 disk_bytenr;
1578
1579                 btrfs_item_key_to_cpu(leaf, &key, i);
1580                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1581                         continue;
1582                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1583                 if (btrfs_file_extent_type(leaf, fi) ==
1584                     BTRFS_FILE_EXTENT_INLINE)
1585                         continue;
1586                 /*
1587                  * FIXME make sure to insert a trans record that
1588                  * repeats the snapshot del on crash
1589                  */
1590                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1591                 if (disk_bytenr == 0)
1592                         continue;
1593                 ret = btrfs_free_extent(trans, root, disk_bytenr,
1594                                 btrfs_file_extent_disk_num_bytes(leaf, fi),
1595                                 leaf_owner, leaf_generation,
1596                                 key.objectid, key.offset, 0);
1597                 BUG_ON(ret);
1598         }
1599         return 0;
1600 }
1601
1602 static void reada_walk_down(struct btrfs_root *root,
1603                             struct extent_buffer *node)
1604 {
1605         int i;
1606         u32 nritems;
1607         u64 bytenr;
1608         int ret;
1609         u32 refs;
1610         int level;
1611         u32 blocksize;
1612
1613         nritems = btrfs_header_nritems(node);
1614         level = btrfs_header_level(node);
1615         for (i = 0; i < nritems; i++) {
1616                 bytenr = btrfs_node_blockptr(node, i);
1617                 blocksize = btrfs_level_size(root, level - 1);
1618                 ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
1619                 BUG_ON(ret);
1620                 if (refs != 1)
1621                         continue;
1622                 mutex_unlock(&root->fs_info->fs_mutex);
1623                 ret = readahead_tree_block(root, bytenr, blocksize);
1624                 cond_resched();
1625                 mutex_lock(&root->fs_info->fs_mutex);
1626                 if (ret)
1627                         break;
1628         }
1629 }
1630
1631 /*
1632  * helper function for drop_snapshot, this walks down the tree dropping ref
1633  * counts as it goes.
1634  */
1635 static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1636                           *root, struct btrfs_path *path, int *level)
1637 {
1638         u64 root_owner;
1639         u64 root_gen;
1640         u64 bytenr;
1641         struct extent_buffer *next;
1642         struct extent_buffer *cur;
1643         struct extent_buffer *parent;
1644         u32 blocksize;
1645         int ret;
1646         u32 refs;
1647
1648         WARN_ON(*level < 0);
1649         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1650         ret = lookup_extent_ref(trans, root,
1651                                 path->nodes[*level]->start,
1652                                 path->nodes[*level]->len, &refs);
1653         BUG_ON(ret);
1654         if (refs > 1)
1655                 goto out;
1656
1657         /*
1658          * walk down to the last node level and free all the leaves
1659          */
1660         while(*level >= 0) {
1661                 WARN_ON(*level < 0);
1662                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1663                 cur = path->nodes[*level];
1664
1665                 if (*level > 0 && path->slots[*level] == 0)
1666                         reada_walk_down(root, cur);
1667
1668                 if (btrfs_header_level(cur) != *level)
1669                         WARN_ON(1);
1670
1671                 if (path->slots[*level] >=
1672                     btrfs_header_nritems(cur))
1673                         break;
1674                 if (*level == 0) {
1675                         ret = drop_leaf_ref(trans, root, cur);
1676                         BUG_ON(ret);
1677                         break;
1678                 }
1679                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
1680                 blocksize = btrfs_level_size(root, *level - 1);
1681                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
1682                 BUG_ON(ret);
1683                 if (refs != 1) {
1684                         parent = path->nodes[*level];
1685                         root_owner = btrfs_header_owner(parent);
1686                         root_gen = btrfs_header_generation(parent);
1687                         path->slots[*level]++;
1688                         ret = btrfs_free_extent(trans, root, bytenr,
1689                                                 blocksize, root_owner,
1690                                                 root_gen, 0, 0, 1);
1691                         BUG_ON(ret);
1692                         continue;
1693                 }
1694                 next = btrfs_find_tree_block(root, bytenr, blocksize);
1695                 if (!next || !btrfs_buffer_uptodate(next)) {
1696                         free_extent_buffer(next);
1697                         mutex_unlock(&root->fs_info->fs_mutex);
1698                         next = read_tree_block(root, bytenr, blocksize);
1699                         mutex_lock(&root->fs_info->fs_mutex);
1700
1701                         /* we dropped the lock, check one more time */
1702                         ret = lookup_extent_ref(trans, root, bytenr,
1703                                                 blocksize, &refs);
1704                         BUG_ON(ret);
1705                         if (refs != 1) {
1706                                 parent = path->nodes[*level];
1707                                 root_owner = btrfs_header_owner(parent);
1708                                 root_gen = btrfs_header_generation(parent);
1709
1710                                 path->slots[*level]++;
1711                                 free_extent_buffer(next);
1712                                 ret = btrfs_free_extent(trans, root, bytenr,
1713                                                         blocksize,
1714                                                         root_owner,
1715                                                         root_gen, 0, 0, 1);
1716                                 BUG_ON(ret);
1717                                 continue;
1718                         }
1719                 }
1720                 WARN_ON(*level <= 0);
1721                 if (path->nodes[*level-1])
1722                         free_extent_buffer(path->nodes[*level-1]);
1723                 path->nodes[*level-1] = next;
1724                 *level = btrfs_header_level(next);
1725                 path->slots[*level] = 0;
1726         }
1727 out:
1728         WARN_ON(*level < 0);
1729         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1730
1731         if (path->nodes[*level] == root->node) {
1732                 root_owner = root->root_key.objectid;
1733                 parent = path->nodes[*level];
1734         } else {
1735                 parent = path->nodes[*level + 1];
1736                 root_owner = btrfs_header_owner(parent);
1737         }
1738
1739         root_gen = btrfs_header_generation(parent);
1740         ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
1741                                 path->nodes[*level]->len,
1742                                 root_owner, root_gen, 0, 0, 1);
1743         free_extent_buffer(path->nodes[*level]);
1744         path->nodes[*level] = NULL;
1745         *level += 1;
1746         BUG_ON(ret);
1747         return 0;
1748 }
1749
1750 /*
1751  * helper for dropping snapshots.  This walks back up the tree in the path
1752  * to find the first node higher up where we haven't yet gone through
1753  * all the slots
1754  */
1755 static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1756                         *root, struct btrfs_path *path, int *level)
1757 {
1758         u64 root_owner;
1759         u64 root_gen;
1760         struct btrfs_root_item *root_item = &root->root_item;
1761         int i;
1762         int slot;
1763         int ret;
1764
1765         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1766                 slot = path->slots[i];
1767                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1768                         struct extent_buffer *node;
1769                         struct btrfs_disk_key disk_key;
1770                         node = path->nodes[i];
1771                         path->slots[i]++;
1772                         *level = i;
1773                         WARN_ON(*level == 0);
1774                         btrfs_node_key(node, &disk_key, path->slots[i]);
1775                         memcpy(&root_item->drop_progress,
1776                                &disk_key, sizeof(disk_key));
1777                         root_item->drop_level = i;
1778                         return 0;
1779                 } else {
1780                         if (path->nodes[*level] == root->node) {
1781                                 root_owner = root->root_key.objectid;
1782                                 root_gen =
1783                                    btrfs_header_generation(path->nodes[*level]);
1784                         } else {
1785                                 struct extent_buffer *node;
1786                                 node = path->nodes[*level + 1];
1787                                 root_owner = btrfs_header_owner(node);
1788                                 root_gen = btrfs_header_generation(node);
1789                         }
1790                         ret = btrfs_free_extent(trans, root,
1791                                                 path->nodes[*level]->start,
1792                                                 path->nodes[*level]->len,
1793                                                 root_owner, root_gen, 0, 0, 1);
1794                         BUG_ON(ret);
1795                         free_extent_buffer(path->nodes[*level]);
1796                         path->nodes[*level] = NULL;
1797                         *level = i + 1;
1798                 }
1799         }
1800         return 1;
1801 }
1802
1803 /*
1804  * drop the reference count on the tree rooted at 'snap'.  This traverses
1805  * the tree freeing any blocks that have a ref count of zero after being
1806  * decremented.
1807  */
1808 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
1809                         *root)
1810 {
1811         int ret = 0;
1812         int wret;
1813         int level;
1814         struct btrfs_path *path;
1815         int i;
1816         int orig_level;
1817         struct btrfs_root_item *root_item = &root->root_item;
1818
1819         path = btrfs_alloc_path();
1820         BUG_ON(!path);
1821
1822         level = btrfs_header_level(root->node);
1823         orig_level = level;
1824         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
1825                 path->nodes[level] = root->node;
1826                 extent_buffer_get(root->node);
1827                 path->slots[level] = 0;
1828         } else {
1829                 struct btrfs_key key;
1830                 struct btrfs_disk_key found_key;
1831                 struct extent_buffer *node;
1832
1833                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
1834                 level = root_item->drop_level;
1835                 path->lowest_level = level;
1836                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1837                 if (wret < 0) {
1838                         ret = wret;
1839                         goto out;
1840                 }
1841                 node = path->nodes[level];
1842                 btrfs_node_key(node, &found_key, path->slots[level]);
1843                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
1844                                sizeof(found_key)));
1845         }
1846         while(1) {
1847                 wret = walk_down_tree(trans, root, path, &level);
1848                 if (wret > 0)
1849                         break;
1850                 if (wret < 0)
1851                         ret = wret;
1852
1853                 wret = walk_up_tree(trans, root, path, &level);
1854                 if (wret > 0)
1855                         break;
1856                 if (wret < 0)
1857                         ret = wret;
1858                 ret = -EAGAIN;
1859                 break;
1860         }
1861         for (i = 0; i <= orig_level; i++) {
1862                 if (path->nodes[i]) {
1863                         free_extent_buffer(path->nodes[i]);
1864                         path->nodes[i] = NULL;
1865                 }
1866         }
1867 out:
1868         btrfs_free_path(path);
1869         return ret;
1870 }
1871
1872 int btrfs_free_block_groups(struct btrfs_fs_info *info)
1873 {
1874         u64 start;
1875         u64 end;
1876         u64 ptr;
1877         int ret;
1878         while(1) {
1879                 ret = find_first_extent_bit(&info->block_group_cache, 0,
1880                                             &start, &end, (unsigned int)-1);
1881                 if (ret)
1882                         break;
1883                 ret = get_state_private(&info->block_group_cache, start, &ptr);
1884                 if (!ret)
1885                         kfree((void *)(unsigned long)ptr);
1886                 clear_extent_bits(&info->block_group_cache, start,
1887                                   end, (unsigned int)-1, GFP_NOFS);
1888         }
1889         while(1) {
1890                 ret = find_first_extent_bit(&info->free_space_cache, 0,
1891                                             &start, &end, EXTENT_DIRTY);
1892                 if (ret)
1893                         break;
1894                 clear_extent_dirty(&info->free_space_cache, start,
1895                                    end, GFP_NOFS);
1896         }
1897         return 0;
1898 }
1899
1900 int btrfs_read_block_groups(struct btrfs_root *root)
1901 {
1902         struct btrfs_path *path;
1903         int ret;
1904         int err = 0;
1905         int bit;
1906         struct btrfs_block_group_cache *cache;
1907         struct btrfs_fs_info *info = root->fs_info;
1908         struct extent_map_tree *block_group_cache;
1909         struct btrfs_key key;
1910         struct btrfs_key found_key;
1911         struct extent_buffer *leaf;
1912
1913         block_group_cache = &info->block_group_cache;
1914
1915         root = info->extent_root;
1916         key.objectid = 0;
1917         key.offset = BTRFS_BLOCK_GROUP_SIZE;
1918         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
1919
1920         path = btrfs_alloc_path();
1921         if (!path)
1922                 return -ENOMEM;
1923
1924         while(1) {
1925                 ret = btrfs_search_slot(NULL, info->extent_root,
1926                                         &key, path, 0, 0);
1927                 if (ret != 0) {
1928                         err = ret;
1929                         break;
1930                 }
1931                 leaf = path->nodes[0];
1932                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1933                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
1934                 if (!cache) {
1935                         err = -1;
1936                         break;
1937                 }
1938
1939                 read_extent_buffer(leaf, &cache->item,
1940                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
1941                                    sizeof(cache->item));
1942                 memcpy(&cache->key, &found_key, sizeof(found_key));
1943                 cache->cached = 0;
1944                 cache->pinned = 0;
1945                 key.objectid = found_key.objectid + found_key.offset;
1946                 btrfs_release_path(root, path);
1947
1948                 if (cache->item.flags & BTRFS_BLOCK_GROUP_MIXED) {
1949                         bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
1950                         cache->data = BTRFS_BLOCK_GROUP_MIXED;
1951                 } else if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
1952                         bit = BLOCK_GROUP_DATA;
1953                         cache->data = BTRFS_BLOCK_GROUP_DATA;
1954                 } else {
1955                         bit = BLOCK_GROUP_METADATA;
1956                         cache->data = 0;
1957                 }
1958
1959                 /* use EXTENT_LOCKED to prevent merging */
1960                 set_extent_bits(block_group_cache, found_key.objectid,
1961                                 found_key.objectid + found_key.offset - 1,
1962                                 bit | EXTENT_LOCKED, GFP_NOFS);
1963                 set_state_private(block_group_cache, found_key.objectid,
1964                                   (unsigned long)cache);
1965
1966                 if (key.objectid >=
1967                     btrfs_super_total_bytes(&info->super_copy))
1968                         break;
1969         }
1970
1971         btrfs_free_path(path);
1972         return 0;
1973 }