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 <linux/pagemap.h>
  22 #include "hash.h"
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "print-tree.h"
  26 #include "transaction.h"
  27
  28 #define BLOCK_GROUP_DATA EXTENT_WRITEBACK
  29 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
  30 #define BLOCK_GROUP_DIRTY EXTENT_DIRTY
  31
  32 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
  33                                  btrfs_root *extent_root);
  34 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
  35                                btrfs_root *extent_root);
  36 static int find_previous_extent(struct btrfs_root *root,
  37                                 struct btrfs_path *path)
  38 {
  39         struct btrfs_key found_key;
  40         struct extent_buffer *leaf;
  41         int ret;
  42
  43         while(1) {
  44                 if (path->slots[0] == 0) {
  45                         ret = btrfs_prev_leaf(root, path);
  46                         if (ret != 0)
  47                                 return ret;
  48                 } else {
  49                         path->slots[0]--;
  50                 }
  51                 leaf = path->nodes[0];
  52                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
  53                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY)
  54                         return 0;
  55         }
  56         return 1;
  57 }
  58
  59 static int cache_block_group(struct btrfs_root *root,
  60                              struct btrfs_block_group_cache *block_group)
  61 {
  62         struct btrfs_path *path;
  63         int ret;
  64         struct btrfs_key key;
  65         struct extent_buffer *leaf;
  66         struct extent_map_tree *free_space_cache;
  67         int slot;
  68         u64 last = 0;
  69         u64 hole_size;
  70         u64 first_free;
  71         int found = 0;
  72
  73         if (!block_group)
  74                 return 0;
  75
  76         root = root->fs_info->extent_root;
  77         free_space_cache = &root->fs_info->free_space_cache;
  78
  79         if (block_group->cached)
  80                 return 0;
  81
  82         path = btrfs_alloc_path();
  83         if (!path)
  84                 return -ENOMEM;
  85
  86         path->reada = 2;
  87         first_free = block_group->key.objectid;
  88         key.objectid = block_group->key.objectid;
  89         key.offset = 0;
  90         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
  91         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  92         if (ret < 0)
  93                 return ret;
  94         ret = find_previous_extent(root, path);
  95         if (ret < 0)
  96                 return ret;
  97         if (ret == 0) {
  98                 leaf = path->nodes[0];
  99                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 100                 if (key.objectid + key.offset > first_free)
 101                         first_free = key.objectid + key.offset;
 102         }
 103         while(1) {
 104                 leaf = path->nodes[0];
 105                 slot = path->slots[0];
 106                 if (slot >= btrfs_header_nritems(leaf)) {
 107                         ret = btrfs_next_leaf(root, path);
 108                         if (ret < 0)
 109                                 goto err;
 110                         if (ret == 0) {
 111                                 continue;
 112                         } else {
 113                                 break;
 114                         }
 115                 }
 116                 btrfs_item_key_to_cpu(leaf, &key, slot);
 117                 if (key.objectid < block_group->key.objectid) {
 118                         goto next;
 119                 }
 120                 if (key.objectid >= block_group->key.objectid +
 121                     block_group->key.offset) {
 122                         break;
 123                 }
 124
 125                 if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
 126                         if (!found) {
 127                                 last = first_free;
 128                                 found = 1;
 129                         }
 130                         if (key.objectid > last) {
 131                                 hole_size = key.objectid - last;
 132                                 set_extent_dirty(free_space_cache, last,
 133                                                  last + hole_size - 1,
 134                                                  GFP_NOFS);
 135                         }
 136                         last = key.objectid + key.offset;
 137                 }
 138 next:
 139                 path->slots[0]++;
 140         }
 141
 142         if (!found)
 143                 last = first_free;
 144         if (block_group->key.objectid +
 145             block_group->key.offset > last) {
 146                 hole_size = block_group->key.objectid +
 147                         block_group->key.offset - last;
 148                 set_extent_dirty(free_space_cache, last,
 149                                  last + hole_size - 1, GFP_NOFS);
 150         }
 151         block_group->cached = 1;
 152 err:
 153         btrfs_free_path(path);
 154         return 0;
 155 }
 156
 157 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 158                                                          btrfs_fs_info *info,
 159                                                          u64 bytenr)
 160 {
 161         struct extent_map_tree *block_group_cache;
 162         struct btrfs_block_group_cache *block_group = NULL;
 163         u64 ptr;
 164         u64 start;
 165         u64 end;
 166         int ret;
 167
 168         block_group_cache = &info->block_group_cache;
 169         ret = find_first_extent_bit(block_group_cache,
 170                                     bytenr, &start, &end,
 171                                     BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA);
 172         if (ret) {
 173                 return NULL;
 174         }
 175         ret = get_state_private(block_group_cache, start, &ptr);
 176         if (ret)
 177                 return NULL;
 178
 179         block_group = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 180         if (block_group->key.objectid <= bytenr && bytenr <
 181             block_group->key.objectid + block_group->key.offset)
 182                 return block_group;
 183         return NULL;
 184 }
 185 static u64 noinline find_search_start(struct btrfs_root *root,
 186                               struct btrfs_block_group_cache **cache_ret,
 187                               u64 search_start, int num, int data)
 188 {
 189         int ret;
 190         struct btrfs_block_group_cache *cache = *cache_ret;
 191         u64 last;
 192         u64 start = 0;
 193         u64 end = 0;
 194         u64 cache_miss = 0;
 195         int wrapped = 0;
 196
 197         if (!cache) {
 198                 goto out;
 199         }
 200 again:
 201         ret = cache_block_group(root, cache);
 202         if (ret)
 203                 goto out;
 204
 205         last = max(search_start, cache->key.objectid);
 206
 207         while(1) {
 208                 ret = find_first_extent_bit(&root->fs_info->free_space_cache,
 209                                             last, &start, &end, EXTENT_DIRTY);
 210                 if (ret) {
 211                         if (!cache_miss)
 212                                 cache_miss = last;
 213                         goto new_group;
 214                 }
 215
 216                 start = max(last, start);
 217                 last = end + 1;
 218                 if (last - start < num) {
 219                         if (last == cache->key.objectid + cache->key.offset)
 220                                 cache_miss = start;
 221                         continue;
 222                 }
 223                 if (data != BTRFS_BLOCK_GROUP_MIXED &&
 224                     start + num > cache->key.objectid + cache->key.offset)
 225                         goto new_group;
 226                 return start;
 227         }
 228 out:
 229         cache = btrfs_lookup_block_group(root->fs_info, search_start);
 230         if (!cache) {
 231                 printk("Unable to find block group for %Lu\n",
 232                        search_start);
 233                 WARN_ON(1);
 234                 return search_start;
 235         }
 236         return search_start;
 237
 238 new_group:
 239         last = cache->key.objectid + cache->key.offset;
 240 wrapped:
 241         cache = btrfs_lookup_block_group(root->fs_info, last);
 242         if (!cache) {
 243 no_cache:
 244                 if (!wrapped) {
 245                         wrapped = 1;
 246                         last = search_start;
 247                         data = BTRFS_BLOCK_GROUP_MIXED;
 248                         goto wrapped;
 249                 }
 250                 goto out;
 251         }
 252         if (cache_miss && !cache->cached) {
 253                 cache_block_group(root, cache);
 254                 last = cache_miss;
 255                 cache = btrfs_lookup_block_group(root->fs_info, last);
 256         }
 257         cache = btrfs_find_block_group(root, cache, last, data, 0);
 258         if (!cache)
 259                 goto no_cache;
 260         *cache_ret = cache;
 261         cache_miss = 0;
 262         goto again;
 263 }
 264
 265 static u64 div_factor(u64 num, int factor)
 266 {
 267         if (factor == 10)
 268                 return num;
 269         num *= factor;
 270         do_div(num, 10);
 271         return num;
 272 }
 273
 274 struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 275                                                  struct btrfs_block_group_cache
 276                                                  *hint, u64 search_start,
 277                                                  int data, int owner)
 278 {
 279         struct btrfs_block_group_cache *cache;
 280         struct extent_map_tree *block_group_cache;
 281         struct btrfs_block_group_cache *found_group = NULL;
 282         struct btrfs_fs_info *info = root->fs_info;
 283         u64 used;
 284         u64 last = 0;
 285         u64 hint_last;
 286         u64 start;
 287         u64 end;
 288         u64 free_check;
 289         u64 ptr;
 290         int bit;
 291         int ret;
 292         int full_search = 0;
 293         int factor = 8;
 294         int data_swap = 0;
 295
 296         block_group_cache = &info->block_group_cache;
 297
 298         if (!owner)
 299                 factor = 8;
 300
 301         if (data == BTRFS_BLOCK_GROUP_MIXED) {
 302                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 303                 factor = 10;
 304         } else if (data)
 305                 bit = BLOCK_GROUP_DATA;
 306         else
 307                 bit = BLOCK_GROUP_METADATA;
 308
 309         if (search_start) {
 310                 struct btrfs_block_group_cache *shint;
 311                 shint = btrfs_lookup_block_group(info, search_start);
 312                 if (shint && (shint->data == data ||
 313                               shint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 314                         used = btrfs_block_group_used(&shint->item);
 315                         if (used + shint->pinned <
 316                             div_factor(shint->key.offset, factor)) {
 317                                 return shint;
 318                         }
 319                 }
 320         }
 321         if (hint && (hint->data == data ||
 322                      hint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 323                 used = btrfs_block_group_used(&hint->item);
 324                 if (used + hint->pinned <
 325                     div_factor(hint->key.offset, factor)) {
 326                         return hint;
 327                 }
 328                 last = hint->key.objectid + hint->key.offset;
 329                 hint_last = last;
 330         } else {
 331                 if (hint)
 332                         hint_last = max(hint->key.objectid, search_start);
 333                 else
 334                         hint_last = search_start;
 335
 336                 last = hint_last;
 337         }
 338 again:
 339         while(1) {
 340                 ret = find_first_extent_bit(block_group_cache, last,
 341                                             &start, &end, bit);
 342                 if (ret)
 343                         break;
 344
 345                 ret = get_state_private(block_group_cache, start, &ptr);
 346                 if (ret)
 347                         break;
 348
 349                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 350                 last = cache->key.objectid + cache->key.offset;
 351                 used = btrfs_block_group_used(&cache->item);
 352
 353                 if (full_search)
 354                         free_check = cache->key.offset;
 355                 else
 356                         free_check = div_factor(cache->key.offset, factor);
 357                 if (used + cache->pinned < free_check) {
 358                         found_group = cache;
 359                         goto found;
 360                 }
 361                 cond_resched();
 362         }
 363         if (!full_search) {
 364                 last = search_start;
 365                 full_search = 1;
 366                 goto again;
 367         }
 368         if (!data_swap) {
 369                 data_swap = 1;
 370                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 371                 last = search_start;
 372                 goto again;
 373         }
 374 found:
 375         return found_group;
 376 }
 377
 378 static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
 379                            u64 owner, u64 owner_offset)
 380 {
 381         u32 high_crc = ~(u32)0;
 382         u32 low_crc = ~(u32)0;
 383         __le64 lenum;
 384
 385         lenum = cpu_to_le64(root_objectid);
 386         high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
 387         lenum = cpu_to_le64(ref_generation);
 388         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 389
 390 #if 0
 391         lenum = cpu_to_le64(owner);
 392         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 393         lenum = cpu_to_le64(owner_offset);
 394         low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
 395 #endif
 396         return ((u64)high_crc << 32) | (u64)low_crc;
 397 }
 398
 399 static int match_extent_ref(struct extent_buffer *leaf,
 400                             struct btrfs_extent_ref *disk_ref,
 401                             struct btrfs_extent_ref *cpu_ref)
 402 {
 403         int ret;
 404         int len;
 405
 406         if (cpu_ref->objectid)
 407                 len = sizeof(*cpu_ref);
 408         else
 409                 len = 2 * sizeof(u64);
 410         ret = memcmp_extent_buffer(leaf, cpu_ref, (unsigned long)disk_ref,
 411                                    len);
 412         return ret == 0;
 413 }
 414
 415 static int noinline lookup_extent_backref(struct btrfs_trans_handle *trans,
 416                                           struct btrfs_root *root,
 417                                           struct btrfs_path *path, u64 bytenr,
 418                                           u64 root_objectid,
 419                                           u64 ref_generation, u64 owner,
 420                                           u64 owner_offset, int del)
 421 {
 422         u64 hash;
 423         struct btrfs_key key;
 424         struct btrfs_key found_key;
 425         struct btrfs_extent_ref ref;
 426         struct extent_buffer *leaf;
 427         struct btrfs_extent_ref *disk_ref;
 428         int ret;
 429         int ret2;
 430
 431         btrfs_set_stack_ref_root(&ref, root_objectid);
 432         btrfs_set_stack_ref_generation(&ref, ref_generation);
 433         btrfs_set_stack_ref_objectid(&ref, owner);
 434         btrfs_set_stack_ref_offset(&ref, owner_offset);
 435
 436         hash = hash_extent_ref(root_objectid, ref_generation, owner,
 437                                owner_offset);
 438         key.offset = hash;
 439         key.objectid = bytenr;
 440         key.type = BTRFS_EXTENT_REF_KEY;
 441
 442         while (1) {
 443                 ret = btrfs_search_slot(trans, root, &key, path,
 444                                         del ? -1 : 0, del);
 445                 if (ret < 0)
 446                         goto out;
 447                 leaf = path->nodes[0];
 448                 if (ret != 0) {
 449                         u32 nritems = btrfs_header_nritems(leaf);
 450                         if (path->slots[0] >= nritems) {
 451                                 ret2 = btrfs_next_leaf(root, path);
 452                                 if (ret2)
 453                                         goto out;
 454                                 leaf = path->nodes[0];
 455                         }
 456                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 457                         if (found_key.objectid != bytenr ||
 458                             found_key.type != BTRFS_EXTENT_REF_KEY)
 459                                 goto out;
 460                         key.offset = found_key.offset;
 461                         if (del) {
 462                                 btrfs_release_path(root, path);
 463                                 continue;
 464                         }
 465                 }
 466                 disk_ref = btrfs_item_ptr(path->nodes[0],
 467                                           path->slots[0],
 468                                           struct btrfs_extent_ref);
 469                 if (match_extent_ref(path->nodes[0], disk_ref, &ref)) {
 470                         ret = 0;
 471                         goto out;
 472                 }
 473                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 474                 key.offset = found_key.offset + 1;
 475                 btrfs_release_path(root, path);
 476         }
 477 out:
 478         return ret;
 479 }
 480
 481 /*
 482  * Back reference rules.  Back refs have three main goals:
 483  *
 484  * 1) differentiate between all holders of references to an extent so that
 485  *    when a reference is dropped we can make sure it was a valid reference
 486  *    before freeing the extent.
 487  *
 488  * 2) Provide enough information to quickly find the holders of an extent
 489  *    if we notice a given block is corrupted or bad.
 490  *
 491  * 3) Make it easy to migrate blocks for FS shrinking or storage pool
 492  *    maintenance.  This is actually the same as #2, but with a slightly
 493  *    different use case.
 494  *
 495  * File extents can be referenced by:
 496  *
 497  * - multiple snapshots, subvolumes, or different generations in one subvol
 498  * - different files inside a single subvolume (in theory, not implemented yet)
 499  * - different offsets inside a file (bookend extents in file.c)
 500  *
 501  * The extent ref structure has fields for:
 502  *
 503  * - Objectid of the subvolume root
 504  * - Generation number of the tree holding the reference
 505  * - objectid of the file holding the reference
 506  * - offset in the file corresponding to the key holding the reference
 507  *
 508  * When a file extent is allocated the fields are filled in:
 509  *     (root_key.objectid, trans->transid, inode objectid, offset in file)
 510  *
 511  * When a leaf is cow'd new references are added for every file extent found
 512  * in the leaf.  It looks the same as the create case, but trans->transid
 513  * will be different when the block is cow'd.
 514  *
 515  *     (root_key.objectid, trans->transid, inode objectid, offset in file)
 516  *
 517  * When a file extent is removed either during snapshot deletion or file
 518  * truncation, the corresponding back reference is found
 519  * by searching for:
 520  *
 521  *     (btrfs_header_owner(leaf), btrfs_header_generation(leaf),
 522  *      inode objectid, offset in file)
 523  *
 524  * Btree extents can be referenced by:
 525  *
 526  * - Different subvolumes
 527  * - Different generations of the same subvolume
 528  *
 529  * Storing sufficient information for a full reverse mapping of a btree
 530  * block would require storing the lowest key of the block in the backref,
 531  * and it would require updating that lowest key either before write out or
 532  * every time it changed.  Instead, the objectid of the lowest key is stored
 533  * along with the level of the tree block.  This provides a hint
 534  * about where in the btree the block can be found.  Searches through the
 535  * btree only need to look for a pointer to that block, so they stop one
 536  * level higher than the level recorded in the backref.
 537  *
 538  * Some btrees do not do reference counting on their extents.  These
 539  * include the extent tree and the tree of tree roots.  Backrefs for these
 540  * trees always have a generation of zero.
 541  *
 542  * When a tree block is created, back references are inserted:
 543  *
 544  * (root->root_key.objectid, trans->transid or zero, level, lowest_key_objectid)
 545  *
 546  * When a tree block is cow'd in a reference counted root,
 547  * new back references are added for all the blocks it points to.
 548  * These are of the form (trans->transid will have increased since creation):
 549  *
 550  * (root->root_key.objectid, trans->transid, level, lowest_key_objectid)
 551  *
 552  * Because the lowest_key_objectid and the level are just hints
 553  * they are not used when backrefs are deleted.  When a backref is deleted:
 554  *
 555  * if backref was for a tree root:
 556  *     root_objectid = root->root_key.objectid
 557  * else
 558  *     root_objectid = btrfs_header_owner(parent)
 559  *
 560  * (root_objectid, btrfs_header_generation(parent) or zero, 0, 0)
 561  *
 562  * Back Reference Key hashing:
 563  *
 564  * Back references have four fields, each 64 bits long.  Unfortunately,
 565  * This is hashed into a single 64 bit number and placed into the key offset.
 566  * The key objectid corresponds to the first byte in the extent, and the
 567  * key type is set to BTRFS_EXTENT_REF_KEY
 568  */
 569 int btrfs_insert_extent_backref(struct btrfs_trans_handle *trans,
 570                                  struct btrfs_root *root,
 571                                  struct btrfs_path *path, u64 bytenr,
 572                                  u64 root_objectid, u64 ref_generation,
 573                                  u64 owner, u64 owner_offset)
 574 {
 575         u64 hash;
 576         struct btrfs_key key;
 577         struct btrfs_extent_ref ref;
 578         struct btrfs_extent_ref *disk_ref;
 579         int ret;
 580
 581         btrfs_set_stack_ref_root(&ref, root_objectid);
 582         btrfs_set_stack_ref_generation(&ref, ref_generation);
 583         btrfs_set_stack_ref_objectid(&ref, owner);
 584         btrfs_set_stack_ref_offset(&ref, owner_offset);
 585
 586         hash = hash_extent_ref(root_objectid, ref_generation, owner,
 587                                owner_offset);
 588         key.offset = hash;
 589         key.objectid = bytenr;
 590         key.type = BTRFS_EXTENT_REF_KEY;
 591
 592         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(ref));
 593         while (ret == -EEXIST) {
 594                 disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 595                                           struct btrfs_extent_ref);
 596                 if (match_extent_ref(path->nodes[0], disk_ref, &ref))
 597                         goto out;
 598                 key.offset++;
 599                 btrfs_release_path(root, path);
 600                 ret = btrfs_insert_empty_item(trans, root, path, &key,
 601                                               sizeof(ref));
 602         }
 603         if (ret)
 604                 goto out;
 605         disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
 606                                   struct btrfs_extent_ref);
 607         write_extent_buffer(path->nodes[0], &ref, (unsigned long)disk_ref,
 608                             sizeof(ref));
 609         btrfs_mark_buffer_dirty(path->nodes[0]);
 610 out:
 611         btrfs_release_path(root, path);
 612         return ret;
 613 }
 614
 615 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 616                                 struct btrfs_root *root,
 617                                 u64 bytenr, u64 num_bytes,
 618                                 u64 root_objectid, u64 ref_generation,
 619                                 u64 owner, u64 owner_offset)
 620 {
 621         struct btrfs_path *path;
 622         int ret;
 623         struct btrfs_key key;
 624         struct extent_buffer *l;
 625         struct btrfs_extent_item *item;
 626         u32 refs;
 627
 628         WARN_ON(num_bytes < root->sectorsize);
 629         path = btrfs_alloc_path();
 630         if (!path)
 631                 return -ENOMEM;
 632
 633         path->reada = 0;
 634         key.objectid = bytenr;
 635         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 636         key.offset = num_bytes;
 637         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 638                                 0, 1);
 639         if (ret < 0)
 640                 return ret;
 641         if (ret != 0) {
 642                 BUG();
 643         }
 644         BUG_ON(ret != 0);
 645         l = path->nodes[0];
 646         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 647         refs = btrfs_extent_refs(l, item);
 648         btrfs_set_extent_refs(l, item, refs + 1);
 649         btrfs_mark_buffer_dirty(path->nodes[0]);
 650
 651         btrfs_release_path(root->fs_info->extent_root, path);
 652
 653         path->reada = 0;
 654         ret = btrfs_insert_extent_backref(trans, root->fs_info->extent_root,
 655                                           path, bytenr, root_objectid,
 656                                           ref_generation, owner, owner_offset);
 657         BUG_ON(ret);
 658         finish_current_insert(trans, root->fs_info->extent_root);
 659         del_pending_extents(trans, root->fs_info->extent_root);
 660
 661         btrfs_free_path(path);
 662         return 0;
 663 }
 664
 665 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 666                          struct btrfs_root *root)
 667 {
 668         finish_current_insert(trans, root->fs_info->extent_root);
 669         del_pending_extents(trans, root->fs_info->extent_root);
 670         return 0;
 671 }
 672
 673 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 674                              struct btrfs_root *root, u64 bytenr,
 675                              u64 num_bytes, u32 *refs)
 676 {
 677         struct btrfs_path *path;
 678         int ret;
 679         struct btrfs_key key;
 680         struct extent_buffer *l;
 681         struct btrfs_extent_item *item;
 682
 683         WARN_ON(num_bytes < root->sectorsize);
 684         path = btrfs_alloc_path();
 685         path->reada = 0;
 686         key.objectid = bytenr;
 687         key.offset = num_bytes;
 688         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 689         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 690                                 0, 0);
 691         if (ret < 0)
 692                 goto out;
 693         if (ret != 0) {
 694                 btrfs_print_leaf(root, path->nodes[0]);
 695                 printk("failed to find block number %Lu\n", bytenr);
 696                 BUG();
 697         }
 698         l = path->nodes[0];
 699         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 700         *refs = btrfs_extent_refs(l, item);
 701 out:
 702         btrfs_free_path(path);
 703         return 0;
 704 }
 705
 706 u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
 707                                   struct btrfs_path *count_path,
 708                                   u64 first_extent)
 709 {
 710         struct btrfs_root *extent_root = root->fs_info->extent_root;
 711         struct btrfs_path *path;
 712         u64 bytenr;
 713         u64 found_objectid;
 714         u64 root_objectid = root->root_key.objectid;
 715         u32 total_count = 0;
 716         u32 cur_count;
 717         u32 nritems;
 718         int ret;
 719         struct btrfs_key key;
 720         struct btrfs_key found_key;
 721         struct extent_buffer *l;
 722         struct btrfs_extent_item *item;
 723         struct btrfs_extent_ref *ref_item;
 724         int level = -1;
 725
 726         path = btrfs_alloc_path();
 727 again:
 728         if (level == -1)
 729                 bytenr = first_extent;
 730         else
 731                 bytenr = count_path->nodes[level]->start;
 732
 733         cur_count = 0;
 734         key.objectid = bytenr;
 735         key.offset = 0;
 736
 737         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 738         ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
 739         if (ret < 0)
 740                 goto out;
 741         BUG_ON(ret == 0);
 742
 743         l = path->nodes[0];
 744         btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
 745
 746         if (found_key.objectid != bytenr ||
 747             found_key.type != BTRFS_EXTENT_ITEM_KEY) {
 748                 goto out;
 749         }
 750
 751         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 752         while (1) {
 753                 l = path->nodes[0];
 754                 nritems = btrfs_header_nritems(l);
 755                 if (path->slots[0] >= nritems) {
 756                         ret = btrfs_next_leaf(extent_root, path);
 757                         if (ret == 0)
 758                                 continue;
 759                         break;
 760                 }
 761                 btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
 762                 if (found_key.objectid != bytenr)
 763                         break;
 764
 765                 if (found_key.type != BTRFS_EXTENT_REF_KEY) {
 766                         path->slots[0]++;
 767                         continue;
 768                 }
 769
 770                 cur_count++;
 771                 ref_item = btrfs_item_ptr(l, path->slots[0],
 772                                           struct btrfs_extent_ref);
 773                 found_objectid = btrfs_ref_root(l, ref_item);
 774
 775                 if (found_objectid != root_objectid) {
 776                         total_count = 2;
 777                         goto out;
 778                 }
 779                 total_count = 1;
 780                 path->slots[0]++;
 781         }
 782         if (cur_count == 0) {
 783                 total_count = 0;
 784                 goto out;
 785         }
 786         if (level >= 0 && root->node == count_path->nodes[level])
 787                 goto out;
 788         level++;
 789         btrfs_release_path(root, path);
 790         goto again;
 791
 792 out:
 793         btrfs_free_path(path);
 794         return total_count;
 795 }
 796 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 797                        struct btrfs_root *root, u64 owner_objectid)
 798 {
 799         u64 generation;
 800         u64 key_objectid;
 801         u64 level;
 802         u32 nritems;
 803         struct btrfs_disk_key disk_key;
 804
 805         level = btrfs_header_level(root->node);
 806         generation = trans->transid;
 807         nritems = btrfs_header_nritems(root->node);
 808         if (nritems > 0) {
 809                 if (level == 0)
 810                         btrfs_item_key(root->node, &disk_key, 0);
 811                 else
 812                         btrfs_node_key(root->node, &disk_key, 0);
 813                 key_objectid = btrfs_disk_key_objectid(&disk_key);
 814         } else {
 815                 key_objectid = 0;
 816         }
 817         return btrfs_inc_extent_ref(trans, root, root->node->start,
 818                                     root->node->len, owner_objectid,
 819                                     generation, level, key_objectid);
 820 }
 821
 822 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 823                   struct extent_buffer *buf)
 824 {
 825         u64 bytenr;
 826         u32 nritems;
 827         struct btrfs_key key;
 828         struct btrfs_file_extent_item *fi;
 829         int i;
 830         int level;
 831         int ret;
 832         int faili;
 833
 834         if (!root->ref_cows)
 835                 return 0;
 836
 837         level = btrfs_header_level(buf);
 838         nritems = btrfs_header_nritems(buf);
 839         for (i = 0; i < nritems; i++) {
 840                 if (level == 0) {
 841                         u64 disk_bytenr;
 842                         btrfs_item_key_to_cpu(buf, &key, i);
 843                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 844                                 continue;
 845                         fi = btrfs_item_ptr(buf, i,
 846                                             struct btrfs_file_extent_item);
 847                         if (btrfs_file_extent_type(buf, fi) ==
 848                             BTRFS_FILE_EXTENT_INLINE)
 849                                 continue;
 850                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 851                         if (disk_bytenr == 0)
 852                                 continue;
 853                         ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
 854                                     btrfs_file_extent_disk_num_bytes(buf, fi),
 855                                     root->root_key.objectid, trans->transid,
 856                                     key.objectid, key.offset);
 857                         if (ret) {
 858                                 faili = i;
 859                                 goto fail;
 860                         }
 861                 } else {
 862                         bytenr = btrfs_node_blockptr(buf, i);
 863                         btrfs_node_key_to_cpu(buf, &key, i);
 864                         ret = btrfs_inc_extent_ref(trans, root, bytenr,
 865                                            btrfs_level_size(root, level - 1),
 866                                            root->root_key.objectid,
 867                                            trans->transid,
 868                                            level - 1, key.objectid);
 869                         if (ret) {
 870                                 faili = i;
 871                                 goto fail;
 872                         }
 873                 }
 874         }
 875         return 0;
 876 fail:
 877         WARN_ON(1);
 878 #if 0
 879         for (i =0; i < faili; i++) {
 880                 if (level == 0) {
 881                         u64 disk_bytenr;
 882                         btrfs_item_key_to_cpu(buf, &key, i);
 883                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 884                                 continue;
 885                         fi = btrfs_item_ptr(buf, i,
 886                                             struct btrfs_file_extent_item);
 887                         if (btrfs_file_extent_type(buf, fi) ==
 888                             BTRFS_FILE_EXTENT_INLINE)
 889                                 continue;
 890                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 891                         if (disk_bytenr == 0)
 892                                 continue;
 893                         err = btrfs_free_extent(trans, root, disk_bytenr,
 894                                     btrfs_file_extent_disk_num_bytes(buf,
 895                                                                       fi), 0);
 896                         BUG_ON(err);
 897                 } else {
 898                         bytenr = btrfs_node_blockptr(buf, i);
 899                         err = btrfs_free_extent(trans, root, bytenr,
 900                                         btrfs_level_size(root, level - 1), 0);
 901                         BUG_ON(err);
 902                 }
 903         }
 904 #endif
 905         return ret;
 906 }
 907
 908 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 909                                  struct btrfs_root *root,
 910                                  struct btrfs_path *path,
 911                                  struct btrfs_block_group_cache *cache)
 912 {
 913         int ret;
 914         int pending_ret;
 915         struct btrfs_root *extent_root = root->fs_info->extent_root;
 916         unsigned long bi;
 917         struct extent_buffer *leaf;
 918
 919         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 920         if (ret < 0)
 921                 goto fail;
 922         BUG_ON(ret);
 923
 924         leaf = path->nodes[0];
 925         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 926         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 927         btrfs_mark_buffer_dirty(leaf);
 928         btrfs_release_path(extent_root, path);
 929 fail:
 930         finish_current_insert(trans, extent_root);
 931         pending_ret = del_pending_extents(trans, extent_root);
 932         if (ret)
 933                 return ret;
 934         if (pending_ret)
 935                 return pending_ret;
 936         return 0;
 937
 938 }
 939
 940 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 941                                    struct btrfs_root *root)
 942 {
 943         struct extent_map_tree *block_group_cache;
 944         struct btrfs_block_group_cache *cache;
 945         int ret;
 946         int err = 0;
 947         int werr = 0;
 948         struct btrfs_path *path;
 949         u64 last = 0;
 950         u64 start;
 951         u64 end;
 952         u64 ptr;
 953
 954         block_group_cache = &root->fs_info->block_group_cache;
 955         path = btrfs_alloc_path();
 956         if (!path)
 957                 return -ENOMEM;
 958
 959         while(1) {
 960                 ret = find_first_extent_bit(block_group_cache, last,
 961                                             &start, &end, BLOCK_GROUP_DIRTY);
 962                 if (ret)
 963                         break;
 964
 965                 last = end + 1;
 966                 ret = get_state_private(block_group_cache, start, &ptr);
 967                 if (ret)
 968                         break;
 969
 970                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 971                 err = write_one_cache_group(trans, root,
 972                                             path, cache);
 973                 /*
 974                  * if we fail to write the cache group, we want
 975                  * to keep it marked dirty in hopes that a later
 976                  * write will work
 977                  */
 978                 if (err) {
 979                         werr = err;
 980                         continue;
 981                 }
 982                 clear_extent_bits(block_group_cache, start, end,
 983                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
 984         }
 985         btrfs_free_path(path);
 986         return werr;
 987 }
 988
 989 static int update_block_group(struct btrfs_trans_handle *trans,
 990                               struct btrfs_root *root,
 991                               u64 bytenr, u64 num_bytes, int alloc,
 992                               int mark_free, int data)
 993 {
 994         struct btrfs_block_group_cache *cache;
 995         struct btrfs_fs_info *info = root->fs_info;
 996         u64 total = num_bytes;
 997         u64 old_val;
 998         u64 byte_in_group;
 999         u64 start;
1000         u64 end;
1001
1002         while(total) {
1003                 cache = btrfs_lookup_block_group(info, bytenr);
1004                 if (!cache) {
1005                         return -1;
1006                 }
1007                 byte_in_group = bytenr - cache->key.objectid;
1008                 WARN_ON(byte_in_group > cache->key.offset);
1009                 start = cache->key.objectid;
1010                 end = start + cache->key.offset - 1;
1011                 set_extent_bits(&info->block_group_cache, start, end,
1012                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
1013
1014                 old_val = btrfs_block_group_used(&cache->item);
1015                 num_bytes = min(total, cache->key.offset - byte_in_group);
1016                 if (alloc) {
1017                         if (cache->data != data &&
1018                             old_val < (cache->key.offset >> 1)) {
1019                                 int bit_to_clear;
1020                                 int bit_to_set;
1021                                 cache->data = data;
1022                                 if (data) {
1023                                         bit_to_clear = BLOCK_GROUP_METADATA;
1024                                         bit_to_set = BLOCK_GROUP_DATA;
1025                                         cache->item.flags &=
1026                                                 ~BTRFS_BLOCK_GROUP_MIXED;
1027                                         cache->item.flags |=
1028                                                 BTRFS_BLOCK_GROUP_DATA;
1029                                 } else {
1030                                         bit_to_clear = BLOCK_GROUP_DATA;
1031                                         bit_to_set = BLOCK_GROUP_METADATA;
1032                                         cache->item.flags &=
1033                                                 ~BTRFS_BLOCK_GROUP_MIXED;
1034                                         cache->item.flags &=
1035                                                 ~BTRFS_BLOCK_GROUP_DATA;
1036                                 }
1037                                 clear_extent_bits(&info->block_group_cache,
1038                                                   start, end, bit_to_clear,
1039                                                   GFP_NOFS);
1040                                 set_extent_bits(&info->block_group_cache,
1041                                                 start, end, bit_to_set,
1042                                                 GFP_NOFS);
1043                         } else if (cache->data != data &&
1044                                    cache->data != BTRFS_BLOCK_GROUP_MIXED) {
1045                                 cache->data = BTRFS_BLOCK_GROUP_MIXED;
1046                                 set_extent_bits(&info->block_group_cache,
1047                                                 start, end,
1048                                                 BLOCK_GROUP_DATA |
1049                                                 BLOCK_GROUP_METADATA,
1050                                                 GFP_NOFS);
1051                         }
1052                         old_val += num_bytes;
1053                 } else {
1054                         old_val -= num_bytes;
1055                         if (mark_free) {
1056                                 set_extent_dirty(&info->free_space_cache,
1057                                                  bytenr, bytenr + num_bytes - 1,
1058                                                  GFP_NOFS);
1059                         }
1060                 }
1061                 btrfs_set_block_group_used(&cache->item, old_val);
1062                 total -= num_bytes;
1063                 bytenr += num_bytes;
1064         }
1065         return 0;
1066 }
1067 static int update_pinned_extents(struct btrfs_root *root,
1068                                 u64 bytenr, u64 num, int pin)
1069 {
1070         u64 len;
1071         struct btrfs_block_group_cache *cache;
1072         struct btrfs_fs_info *fs_info = root->fs_info;
1073
1074         if (pin) {
1075                 set_extent_dirty(&fs_info->pinned_extents,
1076                                 bytenr, bytenr + num - 1, GFP_NOFS);
1077         } else {
1078                 clear_extent_dirty(&fs_info->pinned_extents,
1079                                 bytenr, bytenr + num - 1, GFP_NOFS);
1080         }
1081         while (num > 0) {
1082                 cache = btrfs_lookup_block_group(fs_info, bytenr);
1083                 WARN_ON(!cache);
1084                 len = min(num, cache->key.offset -
1085                           (bytenr - cache->key.objectid));
1086                 if (pin) {
1087                         cache->pinned += len;
1088                         fs_info->total_pinned += len;
1089                 } else {
1090                         cache->pinned -= len;
1091                         fs_info->total_pinned -= len;
1092                 }
1093                 bytenr += len;
1094                 num -= len;
1095         }
1096         return 0;
1097 }
1098
1099 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
1100 {
1101         u64 last = 0;
1102         u64 start;
1103         u64 end;
1104         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
1105         int ret;
1106
1107         while(1) {
1108                 ret = find_first_extent_bit(pinned_extents, last,
1109                                             &start, &end, EXTENT_DIRTY);
1110                 if (ret)
1111                         break;
1112                 set_extent_dirty(copy, start, end, GFP_NOFS);
1113                 last = end + 1;
1114         }
1115         return 0;
1116 }
1117
1118 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
1119                                struct btrfs_root *root,
1120                                struct extent_map_tree *unpin)
1121 {
1122         u64 start;
1123         u64 end;
1124         int ret;
1125         struct extent_map_tree *free_space_cache;
1126         free_space_cache = &root->fs_info->free_space_cache;
1127
1128         while(1) {
1129                 ret = find_first_extent_bit(unpin, 0, &start, &end,
1130                                             EXTENT_DIRTY);
1131                 if (ret)
1132                         break;
1133                 update_pinned_extents(root, start, end + 1 - start, 0);
1134                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
1135                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
1136         }
1137         return 0;
1138 }
1139
1140 static int finish_current_insert(struct btrfs_trans_handle *trans,
1141                                  struct btrfs_root *extent_root)
1142 {
1143         u64 start;
1144         u64 end;
1145         struct btrfs_fs_info *info = extent_root->fs_info;
1146         struct extent_buffer *eb;
1147         struct btrfs_path *path;
1148         struct btrfs_key ins;
1149         struct btrfs_disk_key first;
1150         struct btrfs_extent_item extent_item;
1151         int ret;
1152         int level;
1153         int err = 0;
1154
1155         btrfs_set_stack_extent_refs(&extent_item, 1);
1156         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
1157         path = btrfs_alloc_path();
1158
1159         while(1) {
1160                 ret = find_first_extent_bit(&info->extent_ins, 0, &start,
1161                                             &end, EXTENT_LOCKED);
1162                 if (ret)
1163                         break;
1164
1165                 ins.objectid = start;
1166                 ins.offset = end + 1 - start;
1167                 err = btrfs_insert_item(trans, extent_root, &ins,
1168                                         &extent_item, sizeof(extent_item));
1169                 clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
1170                                   GFP_NOFS);
1171                 eb = read_tree_block(extent_root, ins.objectid, ins.offset);
1172                 level = btrfs_header_level(eb);
1173                 if (level == 0) {
1174                         btrfs_item_key(eb, &first, 0);
1175                 } else {
1176                         btrfs_node_key(eb, &first, 0);
1177                 }
1178                 err = btrfs_insert_extent_backref(trans, extent_root, path,
1179                                           start, extent_root->root_key.objectid,
1180                                           0, level,
1181                                           btrfs_disk_key_objectid(&first));
1182                 BUG_ON(err);
1183                 free_extent_buffer(eb);
1184         }
1185         btrfs_free_path(path);
1186         return 0;
1187 }
1188
1189 static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
1190                           int pending)
1191 {
1192         int err = 0;
1193         struct extent_buffer *buf;
1194
1195         if (!pending) {
1196                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
1197                 if (buf) {
1198                         if (btrfs_buffer_uptodate(buf)) {
1199                                 u64 transid =
1200                                     root->fs_info->running_transaction->transid;
1201                                 u64 header_transid =
1202                                         btrfs_header_generation(buf);
1203                                 if (header_transid == transid) {
1204                                         free_extent_buffer(buf);
1205                                         return 1;
1206                                 }
1207                         }
1208                         free_extent_buffer(buf);
1209                 }
1210                 update_pinned_extents(root, bytenr, num_bytes, 1);
1211         } else {
1212                 set_extent_bits(&root->fs_info->pending_del,
1213                                 bytenr, bytenr + num_bytes - 1,
1214                                 EXTENT_LOCKED, GFP_NOFS);
1215         }
1216         BUG_ON(err < 0);
1217         return 0;
1218 }
1219
1220 /*
1221  * remove an extent from the root, returns 0 on success
1222  */
1223 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1224                          *root, u64 bytenr, u64 num_bytes,
1225                          u64 root_objectid, u64 ref_generation,
1226                          u64 owner_objectid, u64 owner_offset, int pin,
1227                          int mark_free)
1228 {
1229         struct btrfs_path *path;
1230         struct btrfs_key key;
1231         struct btrfs_fs_info *info = root->fs_info;
1232         struct btrfs_root *extent_root = info->extent_root;
1233         struct extent_buffer *leaf;
1234         int ret;
1235         struct btrfs_extent_item *ei;
1236         u32 refs;
1237
1238         key.objectid = bytenr;
1239         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
1240         key.offset = num_bytes;
1241
1242         path = btrfs_alloc_path();
1243         if (!path)
1244                 return -ENOMEM;
1245
1246         path->reada = 0;
1247         ret = lookup_extent_backref(trans, extent_root, path,
1248                                     bytenr, root_objectid,
1249                                     ref_generation,
1250                                     owner_objectid, owner_offset, 1);
1251         if (ret == 0) {
1252                 ret = btrfs_del_item(trans, extent_root, path);
1253         } else {
1254                 btrfs_print_leaf(extent_root, path->nodes[0]);
1255                 WARN_ON(1);
1256                 printk("Unable to find ref byte nr %Lu root %Lu "
1257                        " gen %Lu owner %Lu offset %Lu\n", bytenr,
1258                        root_objectid, ref_generation, owner_objectid,
1259                        owner_offset);
1260         }
1261         btrfs_release_path(extent_root, path);
1262         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
1263         if (ret < 0)
1264                 return ret;
1265         BUG_ON(ret);
1266
1267         leaf = path->nodes[0];
1268         ei = btrfs_item_ptr(leaf, path->slots[0],
1269                             struct btrfs_extent_item);
1270         refs = btrfs_extent_refs(leaf, ei);
1271         BUG_ON(refs == 0);
1272         refs -= 1;
1273         btrfs_set_extent_refs(leaf, ei, refs);
1274         btrfs_mark_buffer_dirty(leaf);
1275
1276         if (refs == 0) {
1277                 u64 super_used;
1278                 u64 root_used;
1279
1280                 if (pin) {
1281                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
1282                         if (ret > 0)
1283                                 mark_free = 1;
1284                         BUG_ON(ret < 0);
1285                 }
1286
1287                 /* block accounting for super block */
1288                 super_used = btrfs_super_bytes_used(&info->super_copy);
1289                 btrfs_set_super_bytes_used(&info->super_copy,
1290                                            super_used - num_bytes);
1291
1292                 /* block accounting for root item */
1293                 root_used = btrfs_root_used(&root->root_item);
1294                 btrfs_set_root_used(&root->root_item,
1295                                            root_used - num_bytes);
1296
1297                 ret = btrfs_del_item(trans, extent_root, path);
1298                 if (ret) {
1299                         return ret;
1300                 }
1301                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
1302                                          mark_free, 0);
1303                 BUG_ON(ret);
1304         }
1305         btrfs_free_path(path);
1306         finish_current_insert(trans, extent_root);
1307         return ret;
1308 }
1309
1310 /*
1311  * find all the blocks marked as pending in the radix tree and remove
1312  * them from the extent map
1313  */
1314 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
1315                                btrfs_root *extent_root)
1316 {
1317         int ret;
1318         int err = 0;
1319         u64 start;
1320         u64 end;
1321         struct extent_map_tree *pending_del;
1322         struct extent_map_tree *pinned_extents;
1323
1324         pending_del = &extent_root->fs_info->pending_del;
1325         pinned_extents = &extent_root->fs_info->pinned_extents;
1326
1327         while(1) {
1328                 ret = find_first_extent_bit(pending_del, 0, &start, &end,
1329                                             EXTENT_LOCKED);
1330                 if (ret)
1331                         break;
1332                 update_pinned_extents(extent_root, start, end + 1 - start, 1);
1333                 clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
1334                                   GFP_NOFS);
1335                 ret = __free_extent(trans, extent_root,
1336                                      start, end + 1 - start,
1337                                      extent_root->root_key.objectid,
1338                                      0, 0, 0, 0, 0);
1339                 if (ret)
1340                         err = ret;
1341         }
1342         return err;
1343 }
1344
1345 /*
1346  * remove an extent from the root, returns 0 on success
1347  */
1348 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1349                       *root, u64 bytenr, u64 num_bytes,
1350                       u64 root_objectid, u64 ref_generation,
1351                       u64 owner_objectid, u64 owner_offset, int pin)
1352 {
1353         struct btrfs_root *extent_root = root->fs_info->extent_root;
1354         int pending_ret;
1355         int ret;
1356
1357         WARN_ON(num_bytes < root->sectorsize);
1358         if (!root->ref_cows)
1359                 ref_generation = 0;
1360
1361         if (root == extent_root) {
1362                 pin_down_bytes(root, bytenr, num_bytes, 1);
1363                 return 0;
1364         }
1365         ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
1366                             ref_generation, owner_objectid, owner_offset,
1367                             pin, pin == 0);
1368         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
1369         return ret ? ret : pending_ret;
1370 }
1371
1372 static u64 stripe_align(struct btrfs_root *root, u64 val)
1373 {
1374         u64 mask = ((u64)root->stripesize - 1);
1375         u64 ret = (val + mask) & ~mask;
1376         return ret;
1377 }
1378
1379 /*
1380  * walks the btree of allocated extents and find a hole of a given size.
1381  * The key ins is changed to record the hole:
1382  * ins->objectid == block start
1383  * ins->flags = BTRFS_EXTENT_ITEM_KEY
1384  * ins->offset == number of blocks
1385  * Any available blocks before search_start are skipped.
1386  */
1387 static int noinline find_free_extent(struct btrfs_trans_handle *trans,
1388                                      struct btrfs_root *orig_root,
1389                                      u64 num_bytes, u64 empty_size,
1390                                      u64 search_start, u64 search_end,
1391                                      u64 hint_byte, struct btrfs_key *ins,
1392                                      u64 exclude_start, u64 exclude_nr,
1393                                      int data)
1394 {
1395         struct btrfs_path *path;
1396         struct btrfs_key key;
1397         u64 hole_size = 0;
1398         u64 aligned;
1399         int ret;
1400         int slot = 0;
1401         u64 last_byte = 0;
1402         u64 orig_search_start = search_start;
1403         int start_found;
1404         struct extent_buffer *l;
1405         struct btrfs_root * root = orig_root->fs_info->extent_root;
1406         struct btrfs_fs_info *info = root->fs_info;
1407         u64 total_needed = num_bytes;
1408         int level;
1409         struct btrfs_block_group_cache *block_group;
1410         int full_scan = 0;
1411         int wrapped = 0;
1412         u64 cached_start;
1413
1414         WARN_ON(num_bytes < root->sectorsize);
1415         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
1416
1417         level = btrfs_header_level(root->node);
1418
1419         if (num_bytes >= 32 * 1024 * 1024 && hint_byte) {
1420                 data = BTRFS_BLOCK_GROUP_MIXED;
1421         }
1422
1423         if (search_end == (u64)-1)
1424                 search_end = btrfs_super_total_bytes(&info->super_copy);
1425         if (hint_byte) {
1426                 block_group = btrfs_lookup_block_group(info, hint_byte);
1427                 if (!block_group)
1428                         hint_byte = search_start;
1429                 block_group = btrfs_find_block_group(root, block_group,
1430                                                      hint_byte, data, 1);
1431         } else {
1432                 block_group = btrfs_find_block_group(root,
1433                                                      trans->block_group,
1434                                                      search_start, data, 1);
1435         }
1436
1437         total_needed += empty_size;
1438         path = btrfs_alloc_path();
1439 check_failed:
1440         if (!block_group) {
1441                 block_group = btrfs_lookup_block_group(info, search_start);
1442                 if (!block_group)
1443                         block_group = btrfs_lookup_block_group(info,
1444                                                        orig_search_start);
1445         }
1446         search_start = find_search_start(root, &block_group, search_start,
1447                                          total_needed, data);
1448         search_start = stripe_align(root, search_start);
1449         cached_start = search_start;
1450         btrfs_init_path(path);
1451         ins->objectid = search_start;
1452         ins->offset = 0;
1453         start_found = 0;
1454         path->reada = 2;
1455
1456         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1457         if (ret < 0)
1458                 goto error;
1459         ret = find_previous_extent(root, path);
1460         if (ret < 0)
1461                 goto error;
1462         l = path->nodes[0];
1463         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
1464         while (1) {
1465                 l = path->nodes[0];
1466                 slot = path->slots[0];
1467                 if (slot >= btrfs_header_nritems(l)) {
1468                         ret = btrfs_next_leaf(root, path);
1469                         if (ret == 0)
1470                                 continue;
1471                         if (ret < 0)
1472                                 goto error;
1473
1474                         search_start = max(search_start,
1475                                            block_group->key.objectid);
1476                         if (!start_found) {
1477                                 aligned = stripe_align(root, search_start);
1478                                 ins->objectid = aligned;
1479                                 if (aligned >= search_end) {
1480                                         ret = -ENOSPC;
1481                                         goto error;
1482                                 }
1483                                 ins->offset = search_end - aligned;
1484                                 start_found = 1;
1485                                 goto check_pending;
1486                         }
1487                         ins->objectid = stripe_align(root,
1488                                                      last_byte > search_start ?
1489                                                      last_byte : search_start);
1490                         if (search_end <= ins->objectid) {
1491                                 ret = -ENOSPC;
1492                                 goto error;
1493                         }
1494                         ins->offset = search_end - ins->objectid;
1495                         BUG_ON(ins->objectid >= search_end);
1496                         goto check_pending;
1497                 }
1498                 btrfs_item_key_to_cpu(l, &key, slot);
1499
1500                 if (key.objectid >= search_start && key.objectid > last_byte &&
1501                     start_found) {
1502                         if (last_byte < search_start)
1503                                 last_byte = search_start;
1504                         aligned = stripe_align(root, last_byte);
1505                         hole_size = key.objectid - aligned;
1506                         if (key.objectid > aligned && hole_size >= num_bytes) {
1507                                 ins->objectid = aligned;
1508                                 ins->offset = hole_size;
1509                                 goto check_pending;
1510                         }
1511                 }
1512                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
1513                         if (!start_found && btrfs_key_type(&key) ==
1514                             BTRFS_BLOCK_GROUP_ITEM_KEY) {
1515                                 last_byte = key.objectid;
1516                                 start_found = 1;
1517                         }
1518                         goto next;
1519                 }
1520
1521
1522                 start_found = 1;
1523                 last_byte = key.objectid + key.offset;
1524
1525                 if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1526                     last_byte >= block_group->key.objectid +
1527                     block_group->key.offset) {
1528                         btrfs_release_path(root, path);
1529                         search_start = block_group->key.objectid +
1530                                 block_group->key.offset;
1531                         goto new_group;
1532                 }
1533 next:
1534                 path->slots[0]++;
1535                 cond_resched();
1536         }
1537 check_pending:
1538         /* we have to make sure we didn't find an extent that has already
1539          * been allocated by the map tree or the original allocation
1540          */
1541         btrfs_release_path(root, path);
1542         BUG_ON(ins->objectid < search_start);
1543
1544         if (ins->objectid + num_bytes >= search_end)
1545                 goto enospc;
1546         if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1547             ins->objectid + num_bytes > block_group->
1548             key.objectid + block_group->key.offset) {
1549                 search_start = block_group->key.objectid +
1550                         block_group->key.offset;
1551                 goto new_group;
1552         }
1553         if (test_range_bit(&info->extent_ins, ins->objectid,
1554                            ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
1555                 search_start = ins->objectid + num_bytes;
1556                 goto new_group;
1557         }
1558         if (test_range_bit(&info->pinned_extents, ins->objectid,
1559                            ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
1560                 search_start = ins->objectid + num_bytes;
1561                 goto new_group;
1562         }
1563         if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
1564             ins->objectid < exclude_start + exclude_nr)) {
1565                 search_start = exclude_start + exclude_nr;
1566                 goto new_group;
1567         }
1568         if (!data) {
1569                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1570                 if (block_group)
1571                         trans->block_group = block_group;
1572         }
1573         ins->offset = num_bytes;
1574         btrfs_free_path(path);
1575         return 0;
1576
1577 new_group:
1578         if (search_start + num_bytes >= search_end) {
1579 enospc:
1580                 search_start = orig_search_start;
1581                 if (full_scan) {
1582                         ret = -ENOSPC;
1583                         goto error;
1584                 }
1585                 if (wrapped) {
1586                         if (!full_scan)
1587                                 total_needed -= empty_size;
1588                         full_scan = 1;
1589                         data = BTRFS_BLOCK_GROUP_MIXED;
1590                 } else
1591                         wrapped = 1;
1592         }
1593         block_group = btrfs_lookup_block_group(info, search_start);
1594         cond_resched();
1595         block_group = btrfs_find_block_group(root, block_group,
1596                                              search_start, data, 0);
1597         goto check_failed;
1598
1599 error:
1600         btrfs_release_path(root, path);
1601         btrfs_free_path(path);
1602         return ret;
1603 }
1604 /*
1605  * finds a free extent and does all the dirty work required for allocation
1606  * returns the key for the extent through ins, and a tree buffer for
1607  * the first block of the extent through buf.
1608  *
1609  * returns 0 if everything worked, non-zero otherwise.
1610  */
1611 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1612                        struct btrfs_root *root,
1613                        u64 num_bytes, u64 root_objectid, u64 ref_generation,
1614                        u64 owner, u64 owner_offset,
1615                        u64 empty_size, u64 hint_byte,
1616                        u64 search_end, struct btrfs_key *ins, int data)
1617 {
1618         int ret;
1619         int pending_ret;
1620         u64 super_used, root_used;
1621         u64 search_start = 0;
1622         u64 new_hint;
1623         struct btrfs_fs_info *info = root->fs_info;
1624         struct btrfs_root *extent_root = info->extent_root;
1625         struct btrfs_extent_item extent_item;
1626         struct btrfs_path *path;
1627
1628         btrfs_set_stack_extent_refs(&extent_item, 1);
1629
1630         new_hint = max(hint_byte, root->fs_info->alloc_start);
1631         if (new_hint < btrfs_super_total_bytes(&info->super_copy))
1632                 hint_byte = new_hint;
1633
1634         WARN_ON(num_bytes < root->sectorsize);
1635         ret = find_free_extent(trans, root, num_bytes, empty_size,
1636                                search_start, search_end, hint_byte, ins,
1637                                trans->alloc_exclude_start,
1638                                trans->alloc_exclude_nr, data);
1639         BUG_ON(ret);
1640         if (ret)
1641                 return ret;
1642
1643         /* block accounting for super block */
1644         super_used = btrfs_super_bytes_used(&info->super_copy);
1645         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
1646
1647         /* block accounting for root item */
1648         root_used = btrfs_root_used(&root->root_item);
1649         btrfs_set_root_used(&root->root_item, root_used + num_bytes);
1650
1651         clear_extent_dirty(&root->fs_info->free_space_cache,
1652                            ins->objectid, ins->objectid + ins->offset - 1,
1653                            GFP_NOFS);
1654
1655         if (root == extent_root) {
1656                 set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
1657                                 ins->objectid + ins->offset - 1,
1658                                 EXTENT_LOCKED, GFP_NOFS);
1659                 WARN_ON(data == 1);
1660                 goto update_block;
1661         }
1662
1663         WARN_ON(trans->alloc_exclude_nr);
1664         trans->alloc_exclude_start = ins->objectid;
1665         trans->alloc_exclude_nr = ins->offset;
1666         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1667                                 sizeof(extent_item));
1668
1669         trans->alloc_exclude_start = 0;
1670         trans->alloc_exclude_nr = 0;
1671         BUG_ON(ret);
1672
1673         path = btrfs_alloc_path();
1674         BUG_ON(!path);
1675         ret = btrfs_insert_extent_backref(trans, extent_root, path,
1676                                           ins->objectid, root_objectid,
1677                                           ref_generation, owner, owner_offset);
1678
1679         BUG_ON(ret);
1680         btrfs_free_path(path);
1681         finish_current_insert(trans, extent_root);
1682         pending_ret = del_pending_extents(trans, extent_root);
1683
1684         if (ret) {
1685                 return ret;
1686         }
1687         if (pending_ret) {
1688                 return pending_ret;
1689         }
1690
1691 update_block:
1692         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1693                                  data);
1694         BUG_ON(ret);
1695         return 0;
1696 }
1697
1698 /*
1699  * helper function to allocate a block for a given tree
1700  * returns the tree buffer or NULL.
1701  */
1702 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1703                                              struct btrfs_root *root,
1704                                              u32 blocksize,
1705                                              u64 root_objectid, u64 hint,
1706                                              u64 empty_size)
1707 {
1708         u64 ref_generation;
1709
1710         if (root->ref_cows)
1711                 ref_generation = trans->transid;
1712         else
1713                 ref_generation = 0;
1714
1715
1716         return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
1717                                         ref_generation, 0, 0, hint, empty_size);
1718 }
1719
1720 /*
1721  * helper function to allocate a block for a given tree
1722  * returns the tree buffer or NULL.
1723  */
1724 struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1725                                              struct btrfs_root *root,
1726                                              u32 blocksize,
1727                                              u64 root_objectid,
1728                                              u64 ref_generation,
1729                                              u64 first_objectid,
1730                                              int level,
1731                                              u64 hint,
1732                                              u64 empty_size)
1733 {
1734         struct btrfs_key ins;
1735         int ret;
1736         struct extent_buffer *buf;
1737
1738         ret = btrfs_alloc_extent(trans, root, blocksize,
1739                                  root_objectid, ref_generation,
1740                                  level, first_objectid, empty_size, hint,
1741                                  (u64)-1, &ins, 0);
1742         if (ret) {
1743                 BUG_ON(ret > 0);
1744                 return ERR_PTR(ret);
1745         }
1746         buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
1747         if (!buf) {
1748                 btrfs_free_extent(trans, root, ins.objectid, blocksize,
1749                                   root->root_key.objectid, ref_generation,
1750                                   0, 0, 0);
1751                 return ERR_PTR(-ENOMEM);
1752         }
1753         btrfs_set_buffer_uptodate(buf);
1754         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1755                          buf->start + buf->len - 1, GFP_NOFS);
1756         set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
1757                         buf->start, buf->start + buf->len - 1,
1758                         EXTENT_CSUM, GFP_NOFS);
1759         buf->flags |= EXTENT_CSUM;
1760         btrfs_set_buffer_defrag(buf);
1761         trans->blocks_used++;
1762         return buf;
1763 }
1764
1765 static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
1766                                   struct btrfs_root *root,
1767                                   struct extent_buffer *leaf)
1768 {
1769         u64 leaf_owner;
1770         u64 leaf_generation;
1771         struct btrfs_key key;
1772         struct btrfs_file_extent_item *fi;
1773         int i;
1774         int nritems;
1775         int ret;
1776
1777         BUG_ON(!btrfs_is_leaf(leaf));
1778         nritems = btrfs_header_nritems(leaf);
1779         leaf_owner = btrfs_header_owner(leaf);
1780         leaf_generation = btrfs_header_generation(leaf);
1781
1782         for (i = 0; i < nritems; i++) {
1783                 u64 disk_bytenr;
1784
1785                 btrfs_item_key_to_cpu(leaf, &key, i);
1786                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1787                         continue;
1788                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1789                 if (btrfs_file_extent_type(leaf, fi) ==
1790                     BTRFS_FILE_EXTENT_INLINE)
1791                         continue;
1792                 /*
1793                  * FIXME make sure to insert a trans record that
1794                  * repeats the snapshot del on crash
1795                  */
1796                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1797                 if (disk_bytenr == 0)
1798                         continue;
1799                 ret = btrfs_free_extent(trans, root, disk_bytenr,
1800                                 btrfs_file_extent_disk_num_bytes(leaf, fi),
1801                                 leaf_owner, leaf_generation,
1802                                 key.objectid, key.offset, 0);
1803                 BUG_ON(ret);
1804         }
1805         return 0;
1806 }
1807
1808 static void noinline reada_walk_down(struct btrfs_root *root,
1809                                      struct extent_buffer *node)
1810 {
1811         int i;
1812         u32 nritems;
1813         u64 bytenr;
1814         int ret;
1815         u32 refs;
1816         int level;
1817         u32 blocksize;
1818
1819         nritems = btrfs_header_nritems(node);
1820         level = btrfs_header_level(node);
1821         for (i = 0; i < nritems; i++) {
1822                 bytenr = btrfs_node_blockptr(node, i);
1823                 blocksize = btrfs_level_size(root, level - 1);
1824                 ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
1825                 BUG_ON(ret);
1826                 if (refs != 1)
1827                         continue;
1828                 mutex_unlock(&root->fs_info->fs_mutex);
1829                 ret = readahead_tree_block(root, bytenr, blocksize);
1830                 cond_resched();
1831                 mutex_lock(&root->fs_info->fs_mutex);
1832                 if (ret)
1833                         break;
1834         }
1835 }
1836
1837 /*
1838  * helper function for drop_snapshot, this walks down the tree dropping ref
1839  * counts as it goes.
1840  */
1841 static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
1842                                    struct btrfs_root *root,
1843                                    struct btrfs_path *path, int *level)
1844 {
1845         u64 root_owner;
1846         u64 root_gen;
1847         u64 bytenr;
1848         struct extent_buffer *next;
1849         struct extent_buffer *cur;
1850         struct extent_buffer *parent;
1851         u32 blocksize;
1852         int ret;
1853         u32 refs;
1854
1855         WARN_ON(*level < 0);
1856         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1857         ret = lookup_extent_ref(trans, root,
1858                                 path->nodes[*level]->start,
1859                                 path->nodes[*level]->len, &refs);
1860         BUG_ON(ret);
1861         if (refs > 1)
1862                 goto out;
1863
1864         /*
1865          * walk down to the last node level and free all the leaves
1866          */
1867         while(*level >= 0) {
1868                 WARN_ON(*level < 0);
1869                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1870                 cur = path->nodes[*level];
1871
1872                 if (*level > 0 && path->slots[*level] == 0)
1873                         reada_walk_down(root, cur);
1874
1875                 if (btrfs_header_level(cur) != *level)
1876                         WARN_ON(1);
1877
1878                 if (path->slots[*level] >=
1879                     btrfs_header_nritems(cur))
1880                         break;
1881                 if (*level == 0) {
1882                         ret = drop_leaf_ref(trans, root, cur);
1883                         BUG_ON(ret);
1884                         break;
1885                 }
1886                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
1887                 blocksize = btrfs_level_size(root, *level - 1);
1888                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
1889                 BUG_ON(ret);
1890                 if (refs != 1) {
1891                         parent = path->nodes[*level];
1892                         root_owner = btrfs_header_owner(parent);
1893                         root_gen = btrfs_header_generation(parent);
1894                         path->slots[*level]++;
1895                         ret = btrfs_free_extent(trans, root, bytenr,
1896                                                 blocksize, root_owner,
1897                                                 root_gen, 0, 0, 1);
1898                         BUG_ON(ret);
1899                         continue;
1900                 }
1901                 next = btrfs_find_tree_block(root, bytenr, blocksize);
1902                 if (!next || !btrfs_buffer_uptodate(next)) {
1903                         free_extent_buffer(next);
1904                         mutex_unlock(&root->fs_info->fs_mutex);
1905                         next = read_tree_block(root, bytenr, blocksize);
1906                         mutex_lock(&root->fs_info->fs_mutex);
1907
1908                         /* we dropped the lock, check one more time */
1909                         ret = lookup_extent_ref(trans, root, bytenr,
1910                                                 blocksize, &refs);
1911                         BUG_ON(ret);
1912                         if (refs != 1) {
1913                                 parent = path->nodes[*level];
1914                                 root_owner = btrfs_header_owner(parent);
1915                                 root_gen = btrfs_header_generation(parent);
1916
1917                                 path->slots[*level]++;
1918                                 free_extent_buffer(next);
1919                                 ret = btrfs_free_extent(trans, root, bytenr,
1920                                                         blocksize,
1921                                                         root_owner,
1922                                                         root_gen, 0, 0, 1);
1923                                 BUG_ON(ret);
1924                                 continue;
1925                         }
1926                 }
1927                 WARN_ON(*level <= 0);
1928                 if (path->nodes[*level-1])
1929                         free_extent_buffer(path->nodes[*level-1]);
1930                 path->nodes[*level-1] = next;
1931                 *level = btrfs_header_level(next);
1932                 path->slots[*level] = 0;
1933         }
1934 out:
1935         WARN_ON(*level < 0);
1936         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1937
1938         if (path->nodes[*level] == root->node) {
1939                 root_owner = root->root_key.objectid;
1940                 parent = path->nodes[*level];
1941         } else {
1942                 parent = path->nodes[*level + 1];
1943                 root_owner = btrfs_header_owner(parent);
1944         }
1945
1946         root_gen = btrfs_header_generation(parent);
1947         ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
1948                                 path->nodes[*level]->len,
1949                                 root_owner, root_gen, 0, 0, 1);
1950         free_extent_buffer(path->nodes[*level]);
1951         path->nodes[*level] = NULL;
1952         *level += 1;
1953         BUG_ON(ret);
1954         return 0;
1955 }
1956
1957 /*
1958  * helper for dropping snapshots.  This walks back up the tree in the path
1959  * to find the first node higher up where we haven't yet gone through
1960  * all the slots
1961  */
1962 static int noinline walk_up_tree(struct btrfs_trans_handle *trans,
1963                                  struct btrfs_root *root,
1964                                  struct btrfs_path *path, int *level)
1965 {
1966         u64 root_owner;
1967         u64 root_gen;
1968         struct btrfs_root_item *root_item = &root->root_item;
1969         int i;
1970         int slot;
1971         int ret;
1972
1973         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1974                 slot = path->slots[i];
1975                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1976                         struct extent_buffer *node;
1977                         struct btrfs_disk_key disk_key;
1978                         node = path->nodes[i];
1979                         path->slots[i]++;
1980                         *level = i;
1981                         WARN_ON(*level == 0);
1982                         btrfs_node_key(node, &disk_key, path->slots[i]);
1983                         memcpy(&root_item->drop_progress,
1984                                &disk_key, sizeof(disk_key));
1985                         root_item->drop_level = i;
1986                         return 0;
1987                 } else {
1988                         if (path->nodes[*level] == root->node) {
1989                                 root_owner = root->root_key.objectid;
1990                                 root_gen =
1991                                    btrfs_header_generation(path->nodes[*level]);
1992                         } else {
1993                                 struct extent_buffer *node;
1994                                 node = path->nodes[*level + 1];
1995                                 root_owner = btrfs_header_owner(node);
1996                                 root_gen = btrfs_header_generation(node);
1997                         }
1998                         ret = btrfs_free_extent(trans, root,
1999                                                 path->nodes[*level]->start,
2000                                                 path->nodes[*level]->len,
2001                                                 root_owner, root_gen, 0, 0, 1);
2002                         BUG_ON(ret);
2003                         free_extent_buffer(path->nodes[*level]);
2004                         path->nodes[*level] = NULL;
2005                         *level = i + 1;
2006                 }
2007         }
2008         return 1;
2009 }
2010
2011 /*
2012  * drop the reference count on the tree rooted at 'snap'.  This traverses
2013  * the tree freeing any blocks that have a ref count of zero after being
2014  * decremented.
2015  */
2016 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
2017                         *root)
2018 {
2019         int ret = 0;
2020         int wret;
2021         int level;
2022         struct btrfs_path *path;
2023         int i;
2024         int orig_level;
2025         struct btrfs_root_item *root_item = &root->root_item;
2026
2027         path = btrfs_alloc_path();
2028         BUG_ON(!path);
2029
2030         level = btrfs_header_level(root->node);
2031         orig_level = level;
2032         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2033                 path->nodes[level] = root->node;
2034                 extent_buffer_get(root->node);
2035                 path->slots[level] = 0;
2036         } else {
2037                 struct btrfs_key key;
2038                 struct btrfs_disk_key found_key;
2039                 struct extent_buffer *node;
2040
2041                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2042                 level = root_item->drop_level;
2043                 path->lowest_level = level;
2044                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2045                 if (wret < 0) {
2046                         ret = wret;
2047                         goto out;
2048                 }
2049                 node = path->nodes[level];
2050                 btrfs_node_key(node, &found_key, path->slots[level]);
2051                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
2052                                sizeof(found_key)));
2053         }
2054         while(1) {
2055                 wret = walk_down_tree(trans, root, path, &level);
2056                 if (wret > 0)
2057                         break;
2058                 if (wret < 0)
2059                         ret = wret;
2060
2061                 wret = walk_up_tree(trans, root, path, &level);
2062                 if (wret > 0)
2063                         break;
2064                 if (wret < 0)
2065                         ret = wret;
2066                 ret = -EAGAIN;
2067                 break;
2068         }
2069         for (i = 0; i <= orig_level; i++) {
2070                 if (path->nodes[i]) {
2071                         free_extent_buffer(path->nodes[i]);
2072                         path->nodes[i] = NULL;
2073                 }
2074         }
2075 out:
2076         btrfs_free_path(path);
2077         return ret;
2078 }
2079
2080 int btrfs_free_block_groups(struct btrfs_fs_info *info)
2081 {
2082         u64 start;
2083         u64 end;
2084         u64 ptr;
2085         int ret;
2086         while(1) {
2087                 ret = find_first_extent_bit(&info->block_group_cache, 0,
2088                                             &start, &end, (unsigned int)-1);
2089                 if (ret)
2090                         break;
2091                 ret = get_state_private(&info->block_group_cache, start, &ptr);
2092                 if (!ret)
2093                         kfree((void *)(unsigned long)ptr);
2094                 clear_extent_bits(&info->block_group_cache, start,
2095                                   end, (unsigned int)-1, GFP_NOFS);
2096         }
2097         while(1) {
2098                 ret = find_first_extent_bit(&info->free_space_cache, 0,
2099                                             &start, &end, EXTENT_DIRTY);
2100                 if (ret)
2101                         break;
2102                 clear_extent_dirty(&info->free_space_cache, start,
2103                                    end, GFP_NOFS);
2104         }
2105         return 0;
2106 }
2107
2108 static int noinline relocate_inode_pages(struct inode *inode, u64 start,
2109                                          u64 len)
2110 {
2111         u64 page_start;
2112         u64 page_end;
2113         u64 delalloc_start;
2114         u64 existing_delalloc;
2115         unsigned long last_index;
2116         unsigned long i;
2117         struct page *page;
2118         struct btrfs_root *root = BTRFS_I(inode)->root;
2119         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2120         struct file_ra_state *ra;
2121
2122         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2123
2124         mutex_lock(&inode->i_mutex);
2125         i = start >> PAGE_CACHE_SHIFT;
2126         last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
2127
2128         file_ra_state_init(ra, inode->i_mapping);
2129         btrfs_force_ra(inode->i_mapping, ra, NULL, i, last_index);
2130         kfree(ra);
2131
2132         for (; i <= last_index; i++) {
2133                 page = grab_cache_page(inode->i_mapping, i);
2134                 if (!page)
2135                         goto out_unlock;
2136                 if (!PageUptodate(page)) {
2137                         btrfs_readpage(NULL, page);
2138                         lock_page(page);
2139                         if (!PageUptodate(page)) {
2140                                 unlock_page(page);
2141                                 page_cache_release(page);
2142                                 goto out_unlock;
2143                         }
2144                 }
2145                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2146                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2147
2148                 lock_extent(em_tree, page_start, page_end, GFP_NOFS);
2149
2150                 delalloc_start = page_start;
2151                 existing_delalloc =
2152                         count_range_bits(&BTRFS_I(inode)->extent_tree,
2153                                          &delalloc_start, page_end,
2154                                          PAGE_CACHE_SIZE, EXTENT_DELALLOC);
2155
2156                 set_extent_delalloc(em_tree, page_start,
2157                                     page_end, GFP_NOFS);
2158
2159                 spin_lock(&root->fs_info->delalloc_lock);
2160                 root->fs_info->delalloc_bytes += PAGE_CACHE_SIZE -
2161                                                  existing_delalloc;
2162                 spin_unlock(&root->fs_info->delalloc_lock);
2163
2164                 unlock_extent(em_tree, page_start, page_end, GFP_NOFS);
2165                 set_page_dirty(page);
2166                 unlock_page(page);
2167                 page_cache_release(page);
2168         }
2169
2170 out_unlock:
2171         mutex_unlock(&inode->i_mutex);
2172         return 0;
2173 }
2174
2175 /*
2176  * note, this releases the path
2177  */
2178 static int noinline relocate_one_reference(struct btrfs_root *extent_root,
2179                                   struct btrfs_path *path,
2180                                   struct btrfs_key *extent_key)
2181 {
2182         struct inode *inode;
2183         struct btrfs_root *found_root;
2184         struct btrfs_key *root_location;
2185         struct btrfs_extent_ref *ref;
2186         u64 ref_root;
2187         u64 ref_gen;
2188         u64 ref_objectid;
2189         u64 ref_offset;
2190         int ret;
2191
2192         ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
2193                              struct btrfs_extent_ref);
2194         ref_root = btrfs_ref_root(path->nodes[0], ref);
2195         ref_gen = btrfs_ref_generation(path->nodes[0], ref);
2196         ref_objectid = btrfs_ref_objectid(path->nodes[0], ref);
2197         ref_offset = btrfs_ref_offset(path->nodes[0], ref);
2198         btrfs_release_path(extent_root, path);
2199
2200         root_location = kmalloc(sizeof(*root_location), GFP_NOFS);
2201         root_location->objectid = ref_root;
2202         if (ref_gen == 0)
2203                 root_location->offset = 0;
2204         else
2205                 root_location->offset = (u64)-1;
2206         root_location->type = BTRFS_ROOT_ITEM_KEY;
2207
2208         found_root = btrfs_read_fs_root_no_name(extent_root->fs_info,
2209                                                 root_location);
2210         BUG_ON(!found_root);
2211         kfree(root_location);
2212
2213         if (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
2214                 mutex_unlock(&extent_root->fs_info->fs_mutex);
2215                 inode = btrfs_iget_locked(extent_root->fs_info->sb,
2216                                           ref_objectid, found_root);
2217                 if (inode->i_state & I_NEW) {
2218                         /* the inode and parent dir are two different roots */
2219                         BTRFS_I(inode)->root = found_root;
2220                         BTRFS_I(inode)->location.objectid = ref_objectid;
2221                         BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
2222                         BTRFS_I(inode)->location.offset = 0;
2223                         btrfs_read_locked_inode(inode);
2224                         unlock_new_inode(inode);
2225
2226                 }
2227                 /* this can happen if the reference is not against
2228                  * the latest version of the tree root
2229                  */
2230                 if (is_bad_inode(inode)) {
2231                         mutex_lock(&extent_root->fs_info->fs_mutex);
2232                         goto out;
2233                 }
2234                 relocate_inode_pages(inode, ref_offset, extent_key->offset);
2235                 /* FIXME, data=ordered will help get rid of this */
2236                 filemap_fdatawrite(inode->i_mapping);
2237                 iput(inode);
2238                 mutex_lock(&extent_root->fs_info->fs_mutex);
2239         } else {
2240                 struct btrfs_trans_handle *trans;
2241                 struct btrfs_key found_key;
2242                 struct extent_buffer *eb;
2243                 int level;
2244                 int i;
2245
2246                 trans = btrfs_start_transaction(found_root, 1);
2247                 eb = read_tree_block(found_root, extent_key->objectid,
2248                                      extent_key->offset);
2249                 level = btrfs_header_level(eb);
2250
2251                 if (level == 0)
2252                         btrfs_item_key_to_cpu(eb, &found_key, 0);
2253                 else
2254                         btrfs_node_key_to_cpu(eb, &found_key, 0);
2255
2256                 free_extent_buffer(eb);
2257
2258                 path->lowest_level = level;
2259                 path->reada = 2;
2260                 ret = btrfs_search_slot(trans, found_root, &found_key, path,
2261                                         0, 1);
2262                 path->lowest_level = 0;
2263                 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2264                         if (!path->nodes[i])
2265                                 break;
2266                         free_extent_buffer(path->nodes[i]);
2267                         path->nodes[i] = NULL;
2268                 }
2269                 btrfs_release_path(found_root, path);
2270                 btrfs_end_transaction(trans, found_root);
2271         }
2272
2273 out:
2274         return 0;
2275 }
2276
2277 static int noinline relocate_one_extent(struct btrfs_root *extent_root,
2278                                         struct btrfs_path *path,
2279                                         struct btrfs_key *extent_key)
2280 {
2281         struct btrfs_key key;
2282         struct btrfs_key found_key;
2283         struct extent_buffer *leaf;
2284         u32 nritems;
2285         u32 item_size;
2286         int ret = 0;
2287
2288         key.objectid = extent_key->objectid;
2289         key.type = BTRFS_EXTENT_REF_KEY;
2290         key.offset = 0;
2291
2292         while(1) {
2293                 ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
2294
2295                 BUG_ON(ret == 0);
2296
2297                 if (ret < 0)
2298                         goto out;
2299
2300                 ret = 0;
2301                 leaf = path->nodes[0];
2302                 nritems = btrfs_header_nritems(leaf);
2303                 if (path->slots[0] == nritems)
2304                         goto out;
2305
2306                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2307                 if (found_key.objectid != extent_key->objectid)
2308                         break;
2309
2310                 if (found_key.type != BTRFS_EXTENT_REF_KEY)
2311                         break;
2312
2313                 key.offset = found_key.offset + 1;
2314                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
2315
2316                 ret = relocate_one_reference(extent_root, path, extent_key);
2317                 if (ret)
2318                         goto out;
2319         }
2320         ret = 0;
2321 out:
2322         btrfs_release_path(extent_root, path);
2323         return ret;
2324 }
2325
2326 int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
2327 {
2328         struct btrfs_trans_handle *trans;
2329         struct btrfs_root *tree_root = root->fs_info->tree_root;
2330         struct btrfs_path *path;
2331         u64 cur_byte;
2332         u64 total_found;
2333         struct btrfs_fs_info *info = root->fs_info;
2334         struct extent_map_tree *block_group_cache;
2335         struct btrfs_key key;
2336         struct btrfs_key found_key;
2337         struct extent_buffer *leaf;
2338         u32 nritems;
2339         int ret;
2340         int progress = 0;
2341
2342         btrfs_set_super_total_bytes(&info->super_copy, new_size);
2343         block_group_cache = &info->block_group_cache;
2344         path = btrfs_alloc_path();
2345         root = root->fs_info->extent_root;
2346         path->reada = 2;
2347
2348 again:
2349         total_found = 0;
2350         key.objectid = new_size;
2351         key.offset = 0;
2352         key.type = 0;
2353         cur_byte = key.objectid;
2354
2355         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2356         if (ret < 0)
2357                 goto out;
2358
2359         ret = find_previous_extent(root, path);
2360         if (ret < 0)
2361                 goto out;
2362         if (ret == 0) {
2363                 leaf = path->nodes[0];
2364                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2365                 if (found_key.objectid + found_key.offset > new_size) {
2366                         cur_byte = found_key.objectid;
2367                         key.objectid = cur_byte;
2368                 }
2369         }
2370         btrfs_release_path(root, path);
2371
2372         while(1) {
2373                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2374                 if (ret < 0)
2375                         goto out;
2376
2377                 leaf = path->nodes[0];
2378                 nritems = btrfs_header_nritems(leaf);
2379 next:
2380                 if (path->slots[0] >= nritems) {
2381                         ret = btrfs_next_leaf(root, path);
2382                         if (ret < 0)
2383                                 goto out;
2384                         if (ret == 1) {
2385                                 ret = 0;
2386                                 break;
2387                         }
2388                         leaf = path->nodes[0];
2389                         nritems = btrfs_header_nritems(leaf);
2390                 }
2391
2392                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2393
2394                 if (progress && need_resched()) {
2395                         memcpy(&key, &found_key, sizeof(key));
2396                         mutex_unlock(&root->fs_info->fs_mutex);
2397                         cond_resched();
2398                         mutex_lock(&root->fs_info->fs_mutex);
2399                         btrfs_release_path(root, path);
2400                         btrfs_search_slot(NULL, root, &key, path, 0, 0);
2401                         progress = 0;
2402                         goto next;
2403                 }
2404                 progress = 1;
2405
2406                 if (btrfs_key_type(&found_key) != BTRFS_EXTENT_ITEM_KEY ||
2407                     found_key.objectid + found_key.offset <= cur_byte) {
2408                         path->slots[0]++;
2409                         goto next;
2410                 }
2411
2412                 total_found++;
2413                 cur_byte = found_key.objectid + found_key.offset;
2414                 key.objectid = cur_byte;
2415                 btrfs_release_path(root, path);
2416                 ret = relocate_one_extent(root, path, &found_key);
2417         }
2418
2419         btrfs_release_path(root, path);
2420
2421         if (total_found > 0) {
2422                 trans = btrfs_start_transaction(tree_root, 1);
2423                 btrfs_commit_transaction(trans, tree_root);
2424
2425                 mutex_unlock(&root->fs_info->fs_mutex);
2426                 btrfs_clean_old_snapshots(tree_root);
2427                 mutex_lock(&root->fs_info->fs_mutex);
2428
2429                 trans = btrfs_start_transaction(tree_root, 1);
2430                 btrfs_commit_transaction(trans, tree_root);
2431                 goto again;
2432         }
2433
2434         trans = btrfs_start_transaction(root, 1);
2435         key.objectid = new_size;
2436         key.offset = 0;
2437         key.type = 0;
2438         while(1) {
2439                 u64 ptr;
2440
2441                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
2442                 if (ret < 0)
2443                         goto out;
2444
2445                 leaf = path->nodes[0];
2446                 nritems = btrfs_header_nritems(leaf);
2447 bg_next:
2448                 if (path->slots[0] >= nritems) {
2449                         ret = btrfs_next_leaf(root, path);
2450                         if (ret < 0)
2451                                 break;
2452                         if (ret == 1) {
2453                                 ret = 0;
2454                                 break;
2455                         }
2456                         leaf = path->nodes[0];
2457                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2458
2459                         /*
2460                          * btrfs_next_leaf doesn't cow buffers, we have to
2461                          * do the search again
2462                          */
2463                         memcpy(&key, &found_key, sizeof(key));
2464                         btrfs_release_path(root, path);
2465                         goto resched_check;
2466                 }
2467
2468                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2469                 if (btrfs_key_type(&found_key) != BTRFS_BLOCK_GROUP_ITEM_KEY) {
2470                         printk("shrinker found key %Lu %u %Lu\n",
2471                                 found_key.objectid, found_key.type,
2472                                 found_key.offset);
2473                         path->slots[0]++;
2474                         goto bg_next;
2475                 }
2476                 ret = get_state_private(&info->block_group_cache,
2477                                         found_key.objectid, &ptr);
2478                 if (!ret)
2479                         kfree((void *)(unsigned long)ptr);
2480
2481                 clear_extent_bits(&info->block_group_cache, found_key.objectid,
2482                                   found_key.objectid + found_key.offset - 1,
2483                                   (unsigned int)-1, GFP_NOFS);
2484
2485                 key.objectid = found_key.objectid + 1;
2486                 btrfs_del_item(trans, root, path);
2487                 btrfs_release_path(root, path);
2488 resched_check:
2489                 if (need_resched()) {
2490                         mutex_unlock(&root->fs_info->fs_mutex);
2491                         cond_resched();
2492                         mutex_lock(&root->fs_info->fs_mutex);
2493                 }
2494         }
2495         clear_extent_dirty(&info->free_space_cache, new_size, (u64)-1,
2496                            GFP_NOFS);
2497         btrfs_commit_transaction(trans, root);
2498 out:
2499         btrfs_free_path(path);
2500         return ret;
2501 }
2502
2503 int btrfs_grow_extent_tree(struct btrfs_trans_handle *trans,
2504                            struct btrfs_root *root, u64 new_size)
2505 {
2506         struct btrfs_path *path;
2507         u64 nr = 0;
2508         u64 cur_byte;
2509         u64 old_size;
2510         unsigned long rem;
2511         struct btrfs_block_group_cache *cache;
2512         struct btrfs_block_group_item *item;
2513         struct btrfs_fs_info *info = root->fs_info;
2514         struct extent_map_tree *block_group_cache;
2515         struct btrfs_key key;
2516         struct extent_buffer *leaf;
2517         int ret;
2518         int bit;
2519
2520         old_size = btrfs_super_total_bytes(&info->super_copy);
2521         block_group_cache = &info->block_group_cache;
2522
2523         root = info->extent_root;
2524
2525         cache = btrfs_lookup_block_group(root->fs_info, old_size - 1);
2526
2527         cur_byte = cache->key.objectid + cache->key.offset;
2528         if (cur_byte >= new_size)
2529                 goto set_size;
2530
2531         key.offset = BTRFS_BLOCK_GROUP_SIZE;
2532         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
2533
2534         path = btrfs_alloc_path();
2535         if (!path)
2536                 return -ENOMEM;
2537
2538         while(cur_byte < new_size) {
2539                 key.objectid = cur_byte;
2540                 ret = btrfs_insert_empty_item(trans, root, path, &key,
2541                                         sizeof(struct btrfs_block_group_item));
2542                 BUG_ON(ret);
2543                 leaf = path->nodes[0];
2544                 item = btrfs_item_ptr(leaf, path->slots[0],
2545                                       struct btrfs_block_group_item);
2546
2547                 btrfs_set_disk_block_group_used(leaf, item, 0);
2548                 div_long_long_rem(nr, 3, &rem);
2549                 if (rem) {
2550                         btrfs_set_disk_block_group_flags(leaf, item,
2551                                                  BTRFS_BLOCK_GROUP_DATA);
2552                 } else {
2553                         btrfs_set_disk_block_group_flags(leaf, item, 0);
2554                 }
2555                 nr++;
2556
2557                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
2558                 BUG_ON(!cache);
2559
2560                 read_extent_buffer(leaf, &cache->item, (unsigned long)item,
2561                                    sizeof(cache->item));
2562
2563                 memcpy(&cache->key, &key, sizeof(key));
2564                 cache->cached = 0;
2565                 cache->pinned = 0;
2566                 cur_byte = key.objectid + key.offset;
2567                 btrfs_release_path(root, path);
2568
2569                 if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
2570                         bit = BLOCK_GROUP_DATA;
2571                         cache->data = BTRFS_BLOCK_GROUP_DATA;
2572                 } else {
2573                         bit = BLOCK_GROUP_METADATA;
2574                         cache->data = 0;
2575                 }
2576
2577                 /* use EXTENT_LOCKED to prevent merging */
2578                 set_extent_bits(block_group_cache, key.objectid,
2579                                 key.objectid + key.offset - 1,
2580                                 bit | EXTENT_LOCKED, GFP_NOFS);
2581                 set_state_private(block_group_cache, key.objectid,
2582                                   (unsigned long)cache);
2583         }
2584         btrfs_free_path(path);
2585 set_size:
2586         btrfs_set_super_total_bytes(&info->super_copy, new_size);
2587         return 0;
2588 }
2589
2590 int btrfs_read_block_groups(struct btrfs_root *root)
2591 {
2592         struct btrfs_path *path;
2593         int ret;
2594         int err = 0;
2595         int bit;
2596         struct btrfs_block_group_cache *cache;
2597         struct btrfs_fs_info *info = root->fs_info;
2598         struct extent_map_tree *block_group_cache;
2599         struct btrfs_key key;
2600         struct btrfs_key found_key;
2601         struct extent_buffer *leaf;
2602
2603         block_group_cache = &info->block_group_cache;
2604
2605         root = info->extent_root;
2606         key.objectid = 0;
2607         key.offset = BTRFS_BLOCK_GROUP_SIZE;
2608         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
2609
2610         path = btrfs_alloc_path();
2611         if (!path)
2612                 return -ENOMEM;
2613
2614         while(1) {
2615                 ret = btrfs_search_slot(NULL, info->extent_root,
2616                                         &key, path, 0, 0);
2617                 if (ret != 0) {
2618                         err = ret;
2619                         break;
2620                 }
2621                 leaf = path->nodes[0];
2622                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2623                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
2624                 if (!cache) {
2625                         err = -1;
2626                         break;
2627                 }
2628
2629                 read_extent_buffer(leaf, &cache->item,
2630                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
2631                                    sizeof(cache->item));
2632                 memcpy(&cache->key, &found_key, sizeof(found_key));
2633                 cache->cached = 0;
2634                 cache->pinned = 0;
2635                 key.objectid = found_key.objectid + found_key.offset;
2636                 btrfs_release_path(root, path);
2637
2638                 if (cache->item.flags & BTRFS_BLOCK_GROUP_MIXED) {
2639                         bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
2640                         cache->data = BTRFS_BLOCK_GROUP_MIXED;
2641                 } else if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
2642                         bit = BLOCK_GROUP_DATA;
2643                         cache->data = BTRFS_BLOCK_GROUP_DATA;
2644                 } else {
2645                         bit = BLOCK_GROUP_METADATA;
2646                         cache->data = 0;
2647                 }
2648
2649                 /* use EXTENT_LOCKED to prevent merging */
2650                 set_extent_bits(block_group_cache, found_key.objectid,
2651                                 found_key.objectid + found_key.offset - 1,
2652                                 bit | EXTENT_LOCKED, GFP_NOFS);
2653                 set_state_private(block_group_cache, found_key.objectid,
2654                                   (unsigned long)cache);
2655
2656                 if (key.objectid >=
2657                     btrfs_super_total_bytes(&info->super_copy))
2658                         break;
2659         }
2660
2661         btrfs_free_path(path);
2662         return 0;
2663 }