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 <stdio.h>
  20 #include <stdlib.h>
  21 #include "kerncompat.h"
  22 #include "radix-tree.h"
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "print-tree.h"
  26 #include "transaction.h"
  27 #include "crc32c.h"
  28
  29 #define BLOCK_GROUP_DATA EXTENT_WRITEBACK
  30 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
  31 #define BLOCK_GROUP_DIRTY EXTENT_DIRTY
  32
  33 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
  34                                  btrfs_root *extent_root);
  35 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
  36                                btrfs_root *extent_root);
  37 static int find_previous_extent(struct btrfs_root *root,
  38                                 struct btrfs_path *path)
  39 {
  40         struct btrfs_key found_key;
  41         struct extent_buffer *leaf;
  42         int ret;
  43
  44         while(1) {
  45                 if (path->slots[0] == 0) {
  46                         ret = btrfs_prev_leaf(root, path);
  47                         if (ret != 0)
  48                                 return ret;
  49                 } else {
  50                         path->slots[0]--;
  51                 }
  52                 leaf = path->nodes[0];
  53                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
  54                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY)
  55                         return 0;
  56         }
  57         return 1;
  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         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         key.objectid = bytenr;
 634         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 635         key.offset = num_bytes;
 636         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 637                                 0, 1);
 638         if (ret < 0)
 639                 return ret;
 640         if (ret != 0) {
 641                 BUG();
 642         }
 643         BUG_ON(ret != 0);
 644         l = path->nodes[0];
 645         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 646         refs = btrfs_extent_refs(l, item);
 647         btrfs_set_extent_refs(l, item, refs + 1);
 648         btrfs_mark_buffer_dirty(path->nodes[0]);
 649
 650         btrfs_release_path(root->fs_info->extent_root, path);
 651
 652         ret = btrfs_insert_extent_backref(trans, root->fs_info->extent_root,
 653                                           path, bytenr, root_objectid,
 654                                           ref_generation, owner, owner_offset);
 655         BUG_ON(ret);
 656         finish_current_insert(trans, root->fs_info->extent_root);
 657         del_pending_extents(trans, root->fs_info->extent_root);
 658
 659         btrfs_free_path(path);
 660         return 0;
 661 }
 662
 663 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 664                          struct btrfs_root *root)
 665 {
 666         finish_current_insert(trans, root->fs_info->extent_root);
 667         del_pending_extents(trans, root->fs_info->extent_root);
 668         return 0;
 669 }
 670
 671 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 672                              struct btrfs_root *root, u64 bytenr,
 673                              u64 num_bytes, u32 *refs)
 674 {
 675         struct btrfs_path *path;
 676         int ret;
 677         struct btrfs_key key;
 678         struct extent_buffer *l;
 679         struct btrfs_extent_item *item;
 680
 681         WARN_ON(num_bytes < root->sectorsize);
 682         path = btrfs_alloc_path();
 683         key.objectid = bytenr;
 684         key.offset = num_bytes;
 685         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 686         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 687                                 0, 0);
 688         if (ret < 0)
 689                 goto out;
 690         if (ret != 0) {
 691                 btrfs_print_leaf(root, path->nodes[0]);
 692                 printk("failed to find block number %Lu\n", bytenr);
 693                 BUG();
 694         }
 695         l = path->nodes[0];
 696         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 697         *refs = btrfs_extent_refs(l, item);
 698 out:
 699         btrfs_free_path(path);
 700         return 0;
 701 }
 702
 703 u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
 704                                   struct btrfs_path *count_path,
 705                                   u64 first_extent)
 706 {
 707         struct btrfs_root *extent_root = root->fs_info->extent_root;
 708         struct btrfs_path *path;
 709         u64 bytenr;
 710         u64 found_objectid;
 711         u64 root_objectid = root->root_key.objectid;
 712         u32 total_count = 0;
 713         u32 cur_count;
 714         u32 refs;
 715         u32 nritems;
 716         int ret;
 717         struct btrfs_key key;
 718         struct btrfs_key found_key;
 719         struct extent_buffer *l;
 720         struct btrfs_extent_item *item;
 721         struct btrfs_extent_ref *ref_item;
 722         int level = -1;
 723
 724         path = btrfs_alloc_path();
 725 again:
 726         if (level == -1)
 727                 bytenr = first_extent;
 728         else
 729                 bytenr = count_path->nodes[level]->start;
 730
 731         cur_count = 0;
 732         key.objectid = bytenr;
 733         key.offset = 0;
 734
 735         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 736         ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
 737         if (ret < 0)
 738                 goto out;
 739         BUG_ON(ret == 0);
 740
 741         l = path->nodes[0];
 742         btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
 743
 744         if (found_key.objectid != bytenr ||
 745             found_key.type != BTRFS_EXTENT_ITEM_KEY) {
 746                 goto out;
 747         }
 748
 749         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 750         refs = btrfs_extent_refs(l, item);
 751         while (1) {
 752                 nritems = btrfs_header_nritems(l);
 753                 if (path->slots[0] >= nritems) {
 754                         ret = btrfs_next_leaf(extent_root, path);
 755                         if (ret == 0)
 756                                 continue;
 757                         break;
 758                 }
 759                 btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
 760                 if (found_key.objectid != bytenr)
 761                         break;
 762                 if (found_key.type != BTRFS_EXTENT_REF_KEY) {
 763                         path->slots[0]++;
 764                         continue;
 765                 }
 766
 767                 cur_count++;
 768                 ref_item = btrfs_item_ptr(l, path->slots[0],
 769                                           struct btrfs_extent_ref);
 770                 found_objectid = btrfs_ref_root(l, ref_item);
 771
 772                 if (found_objectid != root_objectid) {
 773                         total_count = 2;
 774                         goto out;
 775                 }
 776                 total_count = 1;
 777                 path->slots[0]++;
 778         }
 779         if (cur_count == 0) {
 780                 total_count = 0;
 781                 goto out;
 782         }
 783         if (level >= 0 && root->node == count_path->nodes[level])
 784                 goto out;
 785         level++;
 786         btrfs_release_path(root, path);
 787         goto again;
 788
 789 out:
 790         btrfs_free_path(path);
 791         return total_count;
 792 }
 793 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 794                        struct btrfs_root *root, u64 owner_objectid)
 795 {
 796         u64 generation;
 797         u64 key_objectid;
 798         u64 level;
 799         u32 nritems;
 800         struct btrfs_disk_key disk_key;
 801
 802         level = btrfs_header_level(root->node);
 803         generation = trans->transid;
 804         nritems = btrfs_header_nritems(root->node);
 805         if (nritems > 0) {
 806                 if (level == 0)
 807                         btrfs_item_key(root->node, &disk_key, 0);
 808                 else
 809                         btrfs_node_key(root->node, &disk_key, 0);
 810                 key_objectid = btrfs_disk_key_objectid(&disk_key);
 811         } else {
 812                 key_objectid = 0;
 813         }
 814         return btrfs_inc_extent_ref(trans, root, root->node->start,
 815                                     root->node->len, owner_objectid,
 816                                     generation, level, key_objectid);
 817 }
 818
 819 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 820                   struct extent_buffer *buf)
 821 {
 822         u64 bytenr;
 823         u32 nritems;
 824         struct btrfs_key key;
 825         struct btrfs_file_extent_item *fi;
 826         int i;
 827         int level;
 828         int ret;
 829         int faili;
 830
 831         if (!root->ref_cows)
 832                 return 0;
 833
 834         level = btrfs_header_level(buf);
 835         nritems = btrfs_header_nritems(buf);
 836         for (i = 0; i < nritems; i++) {
 837                 if (level == 0) {
 838                         u64 disk_bytenr;
 839                         btrfs_item_key_to_cpu(buf, &key, i);
 840                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 841                                 continue;
 842                         fi = btrfs_item_ptr(buf, i,
 843                                             struct btrfs_file_extent_item);
 844                         if (btrfs_file_extent_type(buf, fi) ==
 845                             BTRFS_FILE_EXTENT_INLINE)
 846                                 continue;
 847                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 848                         if (disk_bytenr == 0)
 849                                 continue;
 850                         ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
 851                                     btrfs_file_extent_disk_num_bytes(buf, fi),
 852                                     root->root_key.objectid, trans->transid,
 853                                     key.objectid, key.offset);
 854                         if (ret) {
 855                                 faili = i;
 856                                 goto fail;
 857                         }
 858                 } else {
 859                         bytenr = btrfs_node_blockptr(buf, i);
 860                         btrfs_node_key_to_cpu(buf, &key, i);
 861                         ret = btrfs_inc_extent_ref(trans, root, bytenr,
 862                                            btrfs_level_size(root, level - 1),
 863                                            root->root_key.objectid,
 864                                            trans->transid,
 865                                            level - 1, key.objectid);
 866                         if (ret) {
 867                                 faili = i;
 868                                 goto fail;
 869                         }
 870                 }
 871         }
 872         return 0;
 873 fail:
 874         WARN_ON(1);
 875 #if 0
 876         for (i =0; i < faili; i++) {
 877                 if (level == 0) {
 878                         u64 disk_bytenr;
 879                         btrfs_item_key_to_cpu(buf, &key, i);
 880                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 881                                 continue;
 882                         fi = btrfs_item_ptr(buf, i,
 883                                             struct btrfs_file_extent_item);
 884                         if (btrfs_file_extent_type(buf, fi) ==
 885                             BTRFS_FILE_EXTENT_INLINE)
 886                                 continue;
 887                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 888                         if (disk_bytenr == 0)
 889                                 continue;
 890                         err = btrfs_free_extent(trans, root, disk_bytenr,
 891                                     btrfs_file_extent_disk_num_bytes(buf,
 892                                                                       fi), 0);
 893                         BUG_ON(err);
 894                 } else {
 895                         bytenr = btrfs_node_blockptr(buf, i);
 896                         err = btrfs_free_extent(trans, root, bytenr,
 897                                         btrfs_level_size(root, level - 1), 0);
 898                         BUG_ON(err);
 899                 }
 900         }
 901 #endif
 902         return ret;
 903 }
 904
 905 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 906                                  struct btrfs_root *root,
 907                                  struct btrfs_path *path,
 908                                  struct btrfs_block_group_cache *cache)
 909 {
 910         int ret;
 911         int pending_ret;
 912         struct btrfs_root *extent_root = root->fs_info->extent_root;
 913         unsigned long bi;
 914         struct extent_buffer *leaf;
 915
 916         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 917         if (ret < 0)
 918                 goto fail;
 919         BUG_ON(ret);
 920
 921         leaf = path->nodes[0];
 922         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 923         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 924         btrfs_mark_buffer_dirty(leaf);
 925         btrfs_release_path(extent_root, path);
 926 fail:
 927         finish_current_insert(trans, extent_root);
 928         pending_ret = del_pending_extents(trans, extent_root);
 929         if (ret)
 930                 return ret;
 931         if (pending_ret)
 932                 return pending_ret;
 933         return 0;
 934
 935 }
 936
 937 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 938                                    struct btrfs_root *root)
 939 {
 940         struct extent_map_tree *block_group_cache;
 941         struct btrfs_block_group_cache *cache;
 942         int ret;
 943         int err = 0;
 944         int werr = 0;
 945         struct btrfs_path *path;
 946         u64 last = 0;
 947         u64 start;
 948         u64 end;
 949         u64 ptr;
 950
 951         block_group_cache = &root->fs_info->block_group_cache;
 952         path = btrfs_alloc_path();
 953         if (!path)
 954                 return -ENOMEM;
 955
 956         while(1) {
 957                 ret = find_first_extent_bit(block_group_cache, last,
 958                                             &start, &end, BLOCK_GROUP_DIRTY);
 959                 if (ret)
 960                         break;
 961
 962                 last = end + 1;
 963                 ret = get_state_private(block_group_cache, start, &ptr);
 964                 if (ret)
 965                         break;
 966
 967                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 968                 err = write_one_cache_group(trans, root,
 969                                             path, cache);
 970                 /*
 971                  * if we fail to write the cache group, we want
 972                  * to keep it marked dirty in hopes that a later
 973                  * write will work
 974                  */
 975                 if (err) {
 976                         werr = err;
 977                         continue;
 978                 }
 979                 clear_extent_bits(block_group_cache, start, end,
 980                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
 981         }
 982         btrfs_free_path(path);
 983         return werr;
 984 }
 985
 986 static int update_block_group(struct btrfs_trans_handle *trans,
 987                               struct btrfs_root *root,
 988                               u64 bytenr, u64 num_bytes, int alloc,
 989                               int mark_free, int data)
 990 {
 991         struct btrfs_block_group_cache *cache;
 992         struct btrfs_fs_info *info = root->fs_info;
 993         u64 total = num_bytes;
 994         u64 old_val;
 995         u64 byte_in_group;
 996         u64 start;
 997         u64 end;
 998
 999         while(total) {
1000                 cache = btrfs_lookup_block_group(info, bytenr);
1001                 if (!cache) {
1002                         return -1;
1003                 }
1004                 byte_in_group = bytenr - cache->key.objectid;
1005                 WARN_ON(byte_in_group > cache->key.offset);
1006                 start = cache->key.objectid;
1007                 end = start + cache->key.offset - 1;
1008                 set_extent_bits(&info->block_group_cache, start, end,
1009                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
1010
1011                 old_val = btrfs_block_group_used(&cache->item);
1012                 num_bytes = min(total, cache->key.offset - byte_in_group);
1013                 if (alloc) {
1014                         if (cache->data != data &&
1015                             old_val < (cache->key.offset >> 1)) {
1016                                 int bit_to_clear;
1017                                 int bit_to_set;
1018                                 cache->data = data;
1019                                 if (data) {
1020                                         bit_to_clear = BLOCK_GROUP_METADATA;
1021                                         bit_to_set = BLOCK_GROUP_DATA;
1022                                         cache->item.flags &=
1023                                                 ~BTRFS_BLOCK_GROUP_MIXED;
1024                                         cache->item.flags |=
1025                                                 BTRFS_BLOCK_GROUP_DATA;
1026                                 } else {
1027                                         bit_to_clear = BLOCK_GROUP_DATA;
1028                                         bit_to_set = BLOCK_GROUP_METADATA;
1029                                         cache->item.flags &=
1030                                                 ~BTRFS_BLOCK_GROUP_MIXED;
1031                                         cache->item.flags &=
1032                                                 ~BTRFS_BLOCK_GROUP_DATA;
1033                                 }
1034                                 clear_extent_bits(&info->block_group_cache,
1035                                                   start, end, bit_to_clear,
1036                                                   GFP_NOFS);
1037                                 set_extent_bits(&info->block_group_cache,
1038                                                 start, end, bit_to_set,
1039                                                 GFP_NOFS);
1040                         } else if (cache->data != data &&
1041                                    cache->data != BTRFS_BLOCK_GROUP_MIXED) {
1042                                 cache->data = BTRFS_BLOCK_GROUP_MIXED;
1043                                 set_extent_bits(&info->block_group_cache,
1044                                                 start, end,
1045                                                 BLOCK_GROUP_DATA |
1046                                                 BLOCK_GROUP_METADATA,
1047                                                 GFP_NOFS);
1048                         }
1049                         old_val += num_bytes;
1050                 } else {
1051                         old_val -= num_bytes;
1052                         if (mark_free) {
1053                                 set_extent_dirty(&info->free_space_cache,
1054                                                  bytenr, bytenr + num_bytes - 1,
1055                                                  GFP_NOFS);
1056                         }
1057                 }
1058                 btrfs_set_block_group_used(&cache->item, old_val);
1059                 total -= num_bytes;
1060                 bytenr += num_bytes;
1061         }
1062         return 0;
1063 }
1064 static int update_pinned_extents(struct btrfs_root *root,
1065                                 u64 bytenr, u64 num, int pin)
1066 {
1067         u64 len;
1068         struct btrfs_block_group_cache *cache;
1069         struct btrfs_fs_info *fs_info = root->fs_info;
1070
1071         if (pin) {
1072                 set_extent_dirty(&fs_info->pinned_extents,
1073                                 bytenr, bytenr + num - 1, GFP_NOFS);
1074         } else {
1075                 clear_extent_dirty(&fs_info->pinned_extents,
1076                                 bytenr, bytenr + num - 1, GFP_NOFS);
1077         }
1078         while (num > 0) {
1079                 cache = btrfs_lookup_block_group(fs_info, bytenr);
1080                 WARN_ON(!cache);
1081                 len = min(num, cache->key.offset -
1082                           (bytenr - cache->key.objectid));
1083                 if (pin) {
1084                         cache->pinned += len;
1085                         fs_info->total_pinned += len;
1086                 } else {
1087                         cache->pinned -= len;
1088                         fs_info->total_pinned -= len;
1089                 }
1090                 bytenr += len;
1091                 num -= len;
1092         }
1093         return 0;
1094 }
1095
1096 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
1097 {
1098         u64 last = 0;
1099         u64 start;
1100         u64 end;
1101         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
1102         int ret;
1103
1104         while(1) {
1105                 ret = find_first_extent_bit(pinned_extents, last,
1106                                             &start, &end, EXTENT_DIRTY);
1107                 if (ret)
1108                         break;
1109                 set_extent_dirty(copy, start, end, GFP_NOFS);
1110                 last = end + 1;
1111         }
1112         return 0;
1113 }
1114
1115 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
1116                                struct btrfs_root *root,
1117                                struct extent_map_tree *unpin)
1118 {
1119         u64 start;
1120         u64 end;
1121         int ret;
1122         struct extent_map_tree *free_space_cache;
1123         free_space_cache = &root->fs_info->free_space_cache;
1124
1125         while(1) {
1126                 ret = find_first_extent_bit(unpin, 0, &start, &end,
1127                                             EXTENT_DIRTY);
1128                 if (ret)
1129                         break;
1130                 update_pinned_extents(root, start, end + 1 - start, 0);
1131                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
1132                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
1133         }
1134         return 0;
1135 }
1136
1137 static int finish_current_insert(struct btrfs_trans_handle *trans,
1138                                  struct btrfs_root *extent_root)
1139 {
1140         u64 start;
1141         u64 end;
1142         struct btrfs_fs_info *info = extent_root->fs_info;
1143         struct extent_buffer *eb;
1144         struct btrfs_path *path;
1145         struct btrfs_key ins;
1146         struct btrfs_disk_key first;
1147         struct btrfs_extent_item extent_item;
1148         int ret;
1149         int level;
1150         int err = 0;
1151
1152         btrfs_set_stack_extent_refs(&extent_item, 1);
1153         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
1154         path = btrfs_alloc_path();
1155
1156         while(1) {
1157                 ret = find_first_extent_bit(&info->extent_ins, 0, &start,
1158                                             &end, EXTENT_LOCKED);
1159                 if (ret)
1160                         break;
1161
1162                 ins.objectid = start;
1163                 ins.offset = end + 1 - start;
1164                 err = btrfs_insert_item(trans, extent_root, &ins,
1165                                         &extent_item, sizeof(extent_item));
1166                 clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
1167                                   GFP_NOFS);
1168                 eb = read_tree_block(extent_root, ins.objectid, ins.offset);
1169                 level = btrfs_header_level(eb);
1170                 if (level == 0) {
1171                         btrfs_item_key(eb, &first, 0);
1172                 } else {
1173                         btrfs_node_key(eb, &first, 0);
1174                 }
1175                 err = btrfs_insert_extent_backref(trans, extent_root, path,
1176                                           start, extent_root->root_key.objectid,
1177                                           0, level,
1178                                           btrfs_disk_key_objectid(&first));
1179                 BUG_ON(err);
1180                 free_extent_buffer(eb);
1181         }
1182         btrfs_free_path(path);
1183         return 0;
1184 }
1185
1186 static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
1187                           int pending)
1188 {
1189         int err = 0;
1190         struct extent_buffer *buf;
1191
1192         if (!pending) {
1193                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
1194                 if (buf) {
1195                         if (btrfs_buffer_uptodate(buf)) {
1196                                 u64 transid =
1197                                     root->fs_info->running_transaction->transid;
1198                                 if (btrfs_header_generation(buf) == transid) {
1199                                         free_extent_buffer(buf);
1200                                         return 1;
1201                                 }
1202                         }
1203                         free_extent_buffer(buf);
1204                 }
1205                 update_pinned_extents(root, bytenr, num_bytes, 1);
1206         } else {
1207                 set_extent_bits(&root->fs_info->pending_del,
1208                                 bytenr, bytenr + num_bytes - 1,
1209                                 EXTENT_LOCKED, GFP_NOFS);
1210         }
1211         BUG_ON(err < 0);
1212         return 0;
1213 }
1214
1215 /*
1216  * remove an extent from the root, returns 0 on success
1217  */
1218 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1219                          *root, u64 bytenr, u64 num_bytes,
1220                          u64 root_objectid, u64 ref_generation,
1221                          u64 owner_objectid, u64 owner_offset, int pin,
1222                          int mark_free)
1223 {
1224         struct btrfs_path *path;
1225         struct btrfs_key key;
1226         struct btrfs_fs_info *info = root->fs_info;
1227         struct btrfs_extent_ops *ops = info->extent_ops;
1228         struct btrfs_root *extent_root = info->extent_root;
1229         struct extent_buffer *leaf;
1230         int ret;
1231         struct btrfs_extent_item *ei;
1232         u32 refs;
1233
1234         key.objectid = bytenr;
1235         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
1236         key.offset = num_bytes;
1237
1238         path = btrfs_alloc_path();
1239         if (!path)
1240                 return -ENOMEM;
1241
1242         ret = lookup_extent_backref(trans, extent_root, path,
1243                                     bytenr, root_objectid,
1244                                     ref_generation,
1245                                     owner_objectid, owner_offset, 1);
1246         if (ret == 0) {
1247                 ret = btrfs_del_item(trans, extent_root, path);
1248         } else {
1249                 btrfs_print_leaf(extent_root, path->nodes[0]);
1250                 WARN_ON(1);
1251                 printk("Unable to find ref byte nr %Lu root %Lu "
1252                        " gen %Lu owner %Lu offset %Lu\n", bytenr,
1253                        root_objectid, ref_generation, owner_objectid,
1254                        owner_offset);
1255         }
1256         btrfs_release_path(extent_root, path);
1257         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
1258         if (ret < 0)
1259                 return ret;
1260         BUG_ON(ret);
1261
1262         leaf = path->nodes[0];
1263         ei = btrfs_item_ptr(leaf, path->slots[0],
1264                             struct btrfs_extent_item);
1265         refs = btrfs_extent_refs(leaf, ei);
1266         BUG_ON(refs == 0);
1267         refs -= 1;
1268         btrfs_set_extent_refs(leaf, ei, refs);
1269         btrfs_mark_buffer_dirty(leaf);
1270
1271         if (refs == 0) {
1272                 u64 super_used;
1273                 u64 root_used;
1274
1275                 if (pin) {
1276                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
1277                         if (ret > 0)
1278                                 mark_free = 1;
1279                         BUG_ON(ret < 0);
1280                 }
1281
1282                 /* block accounting for super block */
1283                 super_used = btrfs_super_bytes_used(&info->super_copy);
1284                 btrfs_set_super_bytes_used(&info->super_copy,
1285                                            super_used - num_bytes);
1286
1287                 /* block accounting for root item */
1288                 root_used = btrfs_root_used(&root->root_item);
1289                 btrfs_set_root_used(&root->root_item,
1290                                            root_used - num_bytes);
1291                 ret = btrfs_del_item(trans, extent_root, path);
1292                 if (ret)
1293                         return ret;
1294
1295                 if (ops && ops->free_extent)
1296                         ops->free_extent(root, bytenr, num_bytes);
1297
1298                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
1299                                          mark_free, 0);
1300                 BUG_ON(ret);
1301         }
1302         btrfs_free_path(path);
1303         finish_current_insert(trans, extent_root);
1304         return ret;
1305 }
1306
1307 /*
1308  * find all the blocks marked as pending in the radix tree and remove
1309  * them from the extent map
1310  */
1311 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
1312                                btrfs_root *extent_root)
1313 {
1314         int ret;
1315         int err = 0;
1316         u64 start;
1317         u64 end;
1318         struct extent_map_tree *pending_del;
1319         struct extent_map_tree *pinned_extents;
1320
1321         pending_del = &extent_root->fs_info->pending_del;
1322         pinned_extents = &extent_root->fs_info->pinned_extents;
1323
1324         while(1) {
1325                 ret = find_first_extent_bit(pending_del, 0, &start, &end,
1326                                             EXTENT_LOCKED);
1327                 if (ret)
1328                         break;
1329                 update_pinned_extents(extent_root, start, end + 1 - start, 1);
1330                 clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
1331                                   GFP_NOFS);
1332                 ret = __free_extent(trans, extent_root,
1333                                      start, end + 1 - start,
1334                                      extent_root->root_key.objectid,
1335                                      0, 0, 0, 0, 0);
1336                 if (ret)
1337                         err = ret;
1338         }
1339         return err;
1340 }
1341
1342 /*
1343  * remove an extent from the root, returns 0 on success
1344  */
1345 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
1346                       *root, u64 bytenr, u64 num_bytes,
1347                       u64 root_objectid, u64 ref_generation,
1348                       u64 owner_objectid, u64 owner_offset, int pin)
1349 {
1350         struct btrfs_root *extent_root = root->fs_info->extent_root;
1351         int pending_ret;
1352         int ret;
1353
1354         WARN_ON(num_bytes < root->sectorsize);
1355         if (!root->ref_cows)
1356                 ref_generation = 0;
1357
1358         if (root == extent_root) {
1359                 pin_down_bytes(root, bytenr, num_bytes, 1);
1360                 return 0;
1361         }
1362         ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
1363                             ref_generation, owner_objectid, owner_offset,
1364                             pin, pin == 0);
1365         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
1366         return ret ? ret : pending_ret;
1367 }
1368
1369 static u64 stripe_align(struct btrfs_root *root, u64 val)
1370 {
1371         u64 mask = ((u64)root->stripesize - 1);
1372         u64 ret = (val + mask) & ~mask;
1373         return ret;
1374 }
1375
1376 /*
1377  * walks the btree of allocated extents and find a hole of a given size.
1378  * The key ins is changed to record the hole:
1379  * ins->objectid == block start
1380  * ins->flags = BTRFS_EXTENT_ITEM_KEY
1381  * ins->offset == number of blocks
1382  * Any available blocks before search_start are skipped.
1383  */
1384 static int noinline find_free_extent(struct btrfs_trans_handle *trans,
1385                                      struct btrfs_root *orig_root,
1386                                      u64 num_bytes, u64 empty_size,
1387                                      u64 search_start, u64 search_end,
1388                                      u64 hint_byte, struct btrfs_key *ins,
1389                                      u64 exclude_start, u64 exclude_nr,
1390                                      int data)
1391 {
1392         struct btrfs_path *path;
1393         struct btrfs_key key;
1394         u64 hole_size = 0;
1395         u64 aligned;
1396         int ret;
1397         int slot = 0;
1398         u64 last_byte = 0;
1399         u64 orig_search_start = search_start;
1400         int start_found;
1401         struct extent_buffer *l;
1402         struct btrfs_root * root = orig_root->fs_info->extent_root;
1403         struct btrfs_fs_info *info = root->fs_info;
1404         u64 total_needed = num_bytes;
1405         int level;
1406         struct btrfs_block_group_cache *block_group;
1407         int full_scan = 0;
1408         int wrapped = 0;
1409         u64 cached_start;
1410
1411         WARN_ON(num_bytes < root->sectorsize);
1412         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
1413
1414         level = btrfs_header_level(root->node);
1415
1416         if (num_bytes >= 32 * 1024 * 1024 && hint_byte) {
1417                 data = BTRFS_BLOCK_GROUP_MIXED;
1418         }
1419
1420         if (search_end == (u64)-1)
1421                 search_end = btrfs_super_total_bytes(&info->super_copy);
1422         if (hint_byte) {
1423                 block_group = btrfs_lookup_block_group(info, hint_byte);
1424                 if (!block_group)
1425                         hint_byte = search_start;
1426                 block_group = btrfs_find_block_group(root, block_group,
1427                                                      hint_byte, data, 1);
1428         } else {
1429                 block_group = btrfs_find_block_group(root,
1430                                                      trans->block_group,
1431                                                      search_start, data, 1);
1432         }
1433
1434         total_needed += empty_size;
1435         path = btrfs_alloc_path();
1436 check_failed:
1437         if (!block_group) {
1438                 block_group = btrfs_lookup_block_group(info, search_start);
1439                 if (!block_group)
1440                         block_group = btrfs_lookup_block_group(info,
1441                                                        orig_search_start);
1442         }
1443         search_start = find_search_start(root, &block_group, search_start,
1444                                          total_needed, data);
1445         search_start = stripe_align(root, search_start);
1446         cached_start = search_start;
1447         btrfs_init_path(path);
1448         ins->objectid = search_start;
1449         ins->offset = 0;
1450         start_found = 0;
1451         path->reada = 2;
1452
1453         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1454         if (ret < 0)
1455                 goto error;
1456         ret = find_previous_extent(root, path);
1457         if (ret < 0)
1458                 goto error;
1459         l = path->nodes[0];
1460         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
1461         while (1) {
1462                 l = path->nodes[0];
1463                 slot = path->slots[0];
1464                 if (slot >= btrfs_header_nritems(l)) {
1465                         ret = btrfs_next_leaf(root, path);
1466                         if (ret == 0)
1467                                 continue;
1468                         if (ret < 0)
1469                                 goto error;
1470
1471                         search_start = max(search_start,
1472                                            block_group->key.objectid);
1473                         if (!start_found) {
1474                                 aligned = stripe_align(root, search_start);
1475                                 ins->objectid = aligned;
1476                                 if (aligned >= search_end) {
1477                                         ret = -ENOSPC;
1478                                         goto error;
1479                                 }
1480                                 ins->offset = search_end - aligned;
1481                                 start_found = 1;
1482                                 goto check_pending;
1483                         }
1484                         ins->objectid = stripe_align(root,
1485                                                      last_byte > search_start ?
1486                                                      last_byte : search_start);
1487                         if (search_end <= ins->objectid) {
1488                                 ret = -ENOSPC;
1489                                 goto error;
1490                         }
1491                         ins->offset = search_end - ins->objectid;
1492                         BUG_ON(ins->objectid >= search_end);
1493                         goto check_pending;
1494                 }
1495                 btrfs_item_key_to_cpu(l, &key, slot);
1496
1497                 if (key.objectid >= search_start && key.objectid > last_byte &&
1498                     start_found) {
1499                         if (last_byte < search_start)
1500                                 last_byte = search_start;
1501                         aligned = stripe_align(root, last_byte);
1502                         hole_size = key.objectid - aligned;
1503                         if (key.objectid > aligned && hole_size >= num_bytes) {
1504                                 ins->objectid = aligned;
1505                                 ins->offset = hole_size;
1506                                 goto check_pending;
1507                         }
1508                 }
1509                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
1510                         if (!start_found && btrfs_key_type(&key) ==
1511                             BTRFS_BLOCK_GROUP_ITEM_KEY) {
1512                                 last_byte = key.objectid;
1513                                 start_found = 1;
1514                         }
1515                         goto next;
1516                 }
1517
1518
1519                 start_found = 1;
1520                 last_byte = key.objectid + key.offset;
1521
1522                 if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1523                     last_byte >= block_group->key.objectid +
1524                     block_group->key.offset) {
1525                         btrfs_release_path(root, path);
1526                         search_start = block_group->key.objectid +
1527                                 block_group->key.offset;
1528                         goto new_group;
1529                 }
1530 next:
1531                 path->slots[0]++;
1532                 cond_resched();
1533         }
1534 check_pending:
1535         /* we have to make sure we didn't find an extent that has already
1536          * been allocated by the map tree or the original allocation
1537          */
1538         btrfs_release_path(root, path);
1539         BUG_ON(ins->objectid < search_start);
1540
1541         if (ins->objectid + num_bytes >= search_end)
1542                 goto enospc;
1543         if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1544             ins->objectid + num_bytes > block_group->
1545             key.objectid + block_group->key.offset) {
1546                 search_start = block_group->key.objectid +
1547                         block_group->key.offset;
1548                 goto new_group;
1549         }
1550         if (test_range_bit(&info->extent_ins, ins->objectid,
1551                            ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
1552                 search_start = ins->objectid + num_bytes;
1553                 goto new_group;
1554         }
1555         if (test_range_bit(&info->pinned_extents, ins->objectid,
1556                            ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
1557                 search_start = ins->objectid + num_bytes;
1558                 goto new_group;
1559         }
1560         if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
1561             ins->objectid < exclude_start + exclude_nr)) {
1562                 search_start = exclude_start + exclude_nr;
1563                 goto new_group;
1564         }
1565         if (!data) {
1566                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1567                 if (block_group)
1568                         trans->block_group = block_group;
1569         }
1570         ins->offset = num_bytes;
1571         btrfs_free_path(path);
1572         return 0;
1573
1574 new_group:
1575         if (search_start + num_bytes >= search_end) {
1576 enospc:
1577                 search_start = orig_search_start;
1578                 if (full_scan) {
1579                         ret = -ENOSPC;
1580                         goto error;
1581                 }
1582                 if (wrapped) {
1583                         if (!full_scan)
1584                                 total_needed -= empty_size;
1585                         full_scan = 1;
1586                         data = BTRFS_BLOCK_GROUP_MIXED;
1587                 } else
1588                         wrapped = 1;
1589         }
1590         block_group = btrfs_lookup_block_group(info, search_start);
1591         cond_resched();
1592         block_group = btrfs_find_block_group(root, block_group,
1593                                              search_start, data, 0);
1594         goto check_failed;
1595
1596 error:
1597         btrfs_release_path(root, path);
1598         btrfs_free_path(path);
1599         return ret;
1600 }
1601 /*
1602  * finds a free extent and does all the dirty work required for allocation
1603  * returns the key for the extent through ins, and a tree buffer for
1604  * the first block of the extent through buf.
1605  *
1606  * returns 0 if everything worked, non-zero otherwise.
1607  */
1608 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1609                        struct btrfs_root *root,
1610                        u64 num_bytes, u64 root_objectid, u64 ref_generation,
1611                        u64 owner, u64 owner_offset,
1612                        u64 empty_size, u64 hint_byte,
1613                        u64 search_end, struct btrfs_key *ins, int data)
1614 {
1615         int ret;
1616         int pending_ret;
1617         u64 super_used, root_used;
1618         u64 search_start = 0;
1619         /*
1620         u64 new_hint;
1621         */
1622         struct btrfs_fs_info *info = root->fs_info;
1623         struct btrfs_extent_ops *ops = info->extent_ops;
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         /*
1631         new_hint = max(hint_byte, root->fs_info->alloc_start);
1632         if (new_hint < btrfs_super_total_bytes(&info->super_copy))
1633                 hint_byte = new_hint;
1634         */
1635         WARN_ON(num_bytes < root->sectorsize);
1636         if (ops && ops->alloc_extent) {
1637                 ret = ops->alloc_extent(root, num_bytes, hint_byte, ins);
1638         } else {
1639                 ret = find_free_extent(trans, root, num_bytes, empty_size,
1640                                         search_start, search_end, hint_byte,
1641                                         ins, trans->alloc_exclude_start,
1642                                         trans->alloc_exclude_nr, data);
1643         }
1644         BUG_ON(ret);
1645         if (ret)
1646                 return ret;
1647
1648         /* block accounting for super block */
1649         super_used = btrfs_super_bytes_used(&info->super_copy);
1650         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
1651
1652         /* block accounting for root item */
1653         root_used = btrfs_root_used(&root->root_item);
1654         btrfs_set_root_used(&root->root_item, root_used + num_bytes);
1655
1656         clear_extent_dirty(&root->fs_info->free_space_cache,
1657                            ins->objectid, ins->objectid + ins->offset - 1,
1658                            GFP_NOFS);
1659
1660         if (root == extent_root) {
1661                 set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
1662                                 ins->objectid + ins->offset - 1,
1663                                 EXTENT_LOCKED, GFP_NOFS);
1664                 WARN_ON(data == 1);
1665                 goto update_block;
1666         }
1667
1668         WARN_ON(trans->alloc_exclude_nr);
1669         trans->alloc_exclude_start = ins->objectid;
1670         trans->alloc_exclude_nr = ins->offset;
1671         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1672                                 sizeof(extent_item));
1673
1674         trans->alloc_exclude_start = 0;
1675         trans->alloc_exclude_nr = 0;
1676         BUG_ON(ret);
1677
1678         path = btrfs_alloc_path();
1679         BUG_ON(!path);
1680         ret = btrfs_insert_extent_backref(trans, extent_root, path,
1681                                           ins->objectid, root_objectid,
1682                                           ref_generation, owner, owner_offset);
1683
1684         BUG_ON(ret);
1685         btrfs_free_path(path);
1686         finish_current_insert(trans, extent_root);
1687         pending_ret = del_pending_extents(trans, extent_root);
1688
1689         if (ret) {
1690                 return ret;
1691         }
1692         if (pending_ret) {
1693                 return pending_ret;
1694         }
1695
1696 update_block:
1697         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1698                                  data);
1699         BUG_ON(ret);
1700         return 0;
1701 }
1702
1703 /*
1704  * helper function to allocate a block for a given tree
1705  * returns the tree buffer or NULL.
1706  */
1707 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1708                                              struct btrfs_root *root,
1709                                              u32 blocksize,
1710                                              u64 root_objectid, u64 hint,
1711                                              u64 empty_size)
1712 {
1713         u64 ref_generation;
1714
1715         if (root->ref_cows)
1716                 ref_generation = trans->transid;
1717         else
1718                 ref_generation = 0;
1719
1720
1721         return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
1722                                         ref_generation, 0, 0, hint, empty_size);
1723 }
1724
1725 /*
1726  * helper function to allocate a block for a given tree
1727  * returns the tree buffer or NULL.
1728  */
1729 struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1730                                              struct btrfs_root *root,
1731                                              u32 blocksize,
1732                                              u64 root_objectid,
1733                                              u64 ref_generation,
1734                                              u64 first_objectid,
1735                                              int level,
1736                                              u64 hint,
1737                                              u64 empty_size)
1738 {
1739         struct btrfs_key ins;
1740         int ret;
1741         struct extent_buffer *buf;
1742
1743         ret = btrfs_alloc_extent(trans, root, blocksize,
1744                                  root_objectid, ref_generation,
1745                                  level, first_objectid, empty_size, hint,
1746                                  (u64)-1, &ins, 0);
1747         if (ret) {
1748                 BUG_ON(ret > 0);
1749                 return ERR_PTR(ret);
1750         }
1751         buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
1752         if (!buf) {
1753                 btrfs_free_extent(trans, root, ins.objectid, blocksize,
1754                                   root->root_key.objectid, ref_generation,
1755                                   0, 0, 0);
1756                 return ERR_PTR(-ENOMEM);
1757         }
1758         btrfs_set_buffer_uptodate(buf);
1759         /*
1760         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1761                          buf->start + buf->len - 1, GFP_NOFS);
1762         set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
1763                         buf->start, buf->start + buf->len - 1,
1764                         EXTENT_CSUM, GFP_NOFS);
1765         buf->flags |= EXTENT_CSUM;
1766         btrfs_set_buffer_defrag(buf);
1767         */
1768         trans->blocks_used++;
1769         return buf;
1770 }
1771
1772 static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
1773                                   struct btrfs_root *root,
1774                                   struct extent_buffer *leaf)
1775 {
1776         u64 leaf_owner;
1777         u64 leaf_generation;
1778         struct btrfs_key key;
1779         struct btrfs_file_extent_item *fi;
1780         int i;
1781         int nritems;
1782         int ret;
1783
1784         BUG_ON(!btrfs_is_leaf(leaf));
1785         nritems = btrfs_header_nritems(leaf);
1786         leaf_owner = btrfs_header_owner(leaf);
1787         leaf_generation = btrfs_header_generation(leaf);
1788
1789         for (i = 0; i < nritems; i++) {
1790                 u64 disk_bytenr;
1791
1792                 btrfs_item_key_to_cpu(leaf, &key, i);
1793                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1794                         continue;
1795                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1796                 if (btrfs_file_extent_type(leaf, fi) ==
1797                     BTRFS_FILE_EXTENT_INLINE)
1798                         continue;
1799                 /*
1800                  * FIXME make sure to insert a trans record that
1801                  * repeats the snapshot del on crash
1802                  */
1803                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1804                 if (disk_bytenr == 0)
1805                         continue;
1806                 ret = btrfs_free_extent(trans, root, disk_bytenr,
1807                                 btrfs_file_extent_disk_num_bytes(leaf, fi),
1808                                 leaf_owner, leaf_generation,
1809                                 key.objectid, key.offset, 0);
1810                 BUG_ON(ret);
1811         }
1812         return 0;
1813 }
1814
1815 static void noinline reada_walk_down(struct btrfs_root *root,
1816                                      struct extent_buffer *node)
1817 {
1818         int i;
1819         u32 nritems;
1820         u64 bytenr;
1821         int ret;
1822         u32 refs;
1823         int level;
1824         u32 blocksize;
1825
1826         nritems = btrfs_header_nritems(node);
1827         level = btrfs_header_level(node);
1828         for (i = 0; i < nritems; i++) {
1829                 bytenr = btrfs_node_blockptr(node, i);
1830                 blocksize = btrfs_level_size(root, level - 1);
1831                 ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
1832                 BUG_ON(ret);
1833                 if (refs != 1)
1834                         continue;
1835                 mutex_unlock(&root->fs_info->fs_mutex);
1836                 ret = readahead_tree_block(root, bytenr, blocksize);
1837                 cond_resched();
1838                 mutex_lock(&root->fs_info->fs_mutex);
1839                 if (ret)
1840                         break;
1841         }
1842 }
1843
1844 /*
1845  * helper function for drop_snapshot, this walks down the tree dropping ref
1846  * counts as it goes.
1847  */
1848 static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
1849                                    struct btrfs_root *root,
1850                                    struct btrfs_path *path, int *level)
1851 {
1852         u64 root_owner;
1853         u64 root_gen;
1854         u64 bytenr;
1855         struct extent_buffer *next;
1856         struct extent_buffer *cur;
1857         struct extent_buffer *parent;
1858         u32 blocksize;
1859         int ret;
1860         u32 refs;
1861
1862         WARN_ON(*level < 0);
1863         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1864         ret = lookup_extent_ref(trans, root,
1865                                 path->nodes[*level]->start,
1866                                 path->nodes[*level]->len, &refs);
1867         BUG_ON(ret);
1868         if (refs > 1)
1869                 goto out;
1870
1871         /*
1872          * walk down to the last node level and free all the leaves
1873          */
1874         while(*level >= 0) {
1875                 WARN_ON(*level < 0);
1876                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1877                 cur = path->nodes[*level];
1878
1879                 if (*level > 0 && path->slots[*level] == 0)
1880                         reada_walk_down(root, cur);
1881
1882                 if (btrfs_header_level(cur) != *level)
1883                         WARN_ON(1);
1884
1885                 if (path->slots[*level] >=
1886                     btrfs_header_nritems(cur))
1887                         break;
1888                 if (*level == 0) {
1889                         ret = drop_leaf_ref(trans, root, cur);
1890                         BUG_ON(ret);
1891                         break;
1892                 }
1893                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
1894                 blocksize = btrfs_level_size(root, *level - 1);
1895                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
1896                 BUG_ON(ret);
1897                 if (refs != 1) {
1898                         parent = path->nodes[*level];
1899                         root_owner = btrfs_header_owner(parent);
1900                         root_gen = btrfs_header_generation(parent);
1901                         path->slots[*level]++;
1902                         ret = btrfs_free_extent(trans, root, bytenr,
1903                                                 blocksize, root_owner,
1904                                                 root_gen, 0, 0, 1);
1905                         BUG_ON(ret);
1906                         continue;
1907                 }
1908                 next = btrfs_find_tree_block(root, bytenr, blocksize);
1909                 if (!next || !btrfs_buffer_uptodate(next)) {
1910                         free_extent_buffer(next);
1911                         mutex_unlock(&root->fs_info->fs_mutex);
1912                         next = read_tree_block(root, bytenr, blocksize);
1913                         mutex_lock(&root->fs_info->fs_mutex);
1914
1915                         /* we dropped the lock, check one more time */
1916                         ret = lookup_extent_ref(trans, root, bytenr,
1917                                                 blocksize, &refs);
1918                         BUG_ON(ret);
1919                         if (refs != 1) {
1920                                 parent = path->nodes[*level];
1921                                 root_owner = btrfs_header_owner(parent);
1922                                 root_gen = btrfs_header_generation(parent);
1923
1924                                 path->slots[*level]++;
1925                                 free_extent_buffer(next);
1926                                 ret = btrfs_free_extent(trans, root, bytenr,
1927                                                         blocksize,
1928                                                         root_owner,
1929                                                         root_gen, 0, 0, 1);
1930                                 BUG_ON(ret);
1931                                 continue;
1932                         }
1933                 }
1934                 WARN_ON(*level <= 0);
1935                 if (path->nodes[*level-1])
1936                         free_extent_buffer(path->nodes[*level-1]);
1937                 path->nodes[*level-1] = next;
1938                 *level = btrfs_header_level(next);
1939                 path->slots[*level] = 0;
1940         }
1941 out:
1942         WARN_ON(*level < 0);
1943         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1944
1945         if (path->nodes[*level] == root->node) {
1946                 root_owner = root->root_key.objectid;
1947                 parent = path->nodes[*level];
1948         } else {
1949                 parent = path->nodes[*level + 1];
1950                 root_owner = btrfs_header_owner(parent);
1951         }
1952
1953         root_gen = btrfs_header_generation(parent);
1954         ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
1955                                 path->nodes[*level]->len,
1956                                 root_owner, root_gen, 0, 0, 1);
1957         free_extent_buffer(path->nodes[*level]);
1958         path->nodes[*level] = NULL;
1959         *level += 1;
1960         BUG_ON(ret);
1961         return 0;
1962 }
1963
1964 /*
1965  * helper for dropping snapshots.  This walks back up the tree in the path
1966  * to find the first node higher up where we haven't yet gone through
1967  * all the slots
1968  */
1969 static int noinline walk_up_tree(struct btrfs_trans_handle *trans,
1970                                  struct btrfs_root *root,
1971                                  struct btrfs_path *path, int *level)
1972 {
1973         u64 root_owner;
1974         u64 root_gen;
1975         struct btrfs_root_item *root_item = &root->root_item;
1976         int i;
1977         int slot;
1978         int ret;
1979
1980         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1981                 slot = path->slots[i];
1982                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1983                         struct extent_buffer *node;
1984                         struct btrfs_disk_key disk_key;
1985                         node = path->nodes[i];
1986                         path->slots[i]++;
1987                         *level = i;
1988                         WARN_ON(*level == 0);
1989                         btrfs_node_key(node, &disk_key, path->slots[i]);
1990                         memcpy(&root_item->drop_progress,
1991                                &disk_key, sizeof(disk_key));
1992                         root_item->drop_level = i;
1993                         return 0;
1994                 } else {
1995                         if (path->nodes[*level] == root->node) {
1996                                 root_owner = root->root_key.objectid;
1997                                 root_gen =
1998                                    btrfs_header_generation(path->nodes[*level]);
1999                         } else {
2000                                 struct extent_buffer *node;
2001                                 node = path->nodes[*level + 1];
2002                                 root_owner = btrfs_header_owner(node);
2003                                 root_gen = btrfs_header_generation(node);
2004                         }
2005                         ret = btrfs_free_extent(trans, root,
2006                                                 path->nodes[*level]->start,
2007                                                 path->nodes[*level]->len,
2008                                                 root_owner, root_gen, 0, 0, 1);
2009                         BUG_ON(ret);
2010                         free_extent_buffer(path->nodes[*level]);
2011                         path->nodes[*level] = NULL;
2012                         *level = i + 1;
2013                 }
2014         }
2015         return 1;
2016 }
2017
2018 /*
2019  * drop the reference count on the tree rooted at 'snap'.  This traverses
2020  * the tree freeing any blocks that have a ref count of zero after being
2021  * decremented.
2022  */
2023 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
2024                         *root)
2025 {
2026         int ret = 0;
2027         int wret;
2028         int level;
2029         struct btrfs_path *path;
2030         int i;
2031         int orig_level;
2032         struct btrfs_root_item *root_item = &root->root_item;
2033
2034         path = btrfs_alloc_path();
2035         BUG_ON(!path);
2036
2037         level = btrfs_header_level(root->node);
2038         orig_level = level;
2039         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2040                 path->nodes[level] = root->node;
2041                 extent_buffer_get(root->node);
2042                 path->slots[level] = 0;
2043         } else {
2044                 struct btrfs_key key;
2045                 struct btrfs_disk_key found_key;
2046                 struct extent_buffer *node;
2047
2048                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2049                 level = root_item->drop_level;
2050                 path->lowest_level = level;
2051                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2052                 if (wret < 0) {
2053                         ret = wret;
2054                         goto out;
2055                 }
2056                 node = path->nodes[level];
2057                 btrfs_node_key(node, &found_key, path->slots[level]);
2058                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
2059                                sizeof(found_key)));
2060         }
2061         while(1) {
2062                 wret = walk_down_tree(trans, root, path, &level);
2063                 if (wret < 0)
2064                         ret = wret;
2065                 if (wret != 0)
2066                         break;
2067
2068                 wret = walk_up_tree(trans, root, path, &level);
2069                 if (wret < 0)
2070                         ret = wret;
2071                 if (wret != 0)
2072                         break;
2073                 /*
2074                 ret = -EAGAIN;
2075                 break;
2076                 */
2077         }
2078         for (i = 0; i <= orig_level; i++) {
2079                 if (path->nodes[i]) {
2080                         free_extent_buffer(path->nodes[i]);
2081                         path->nodes[i] = NULL;
2082                 }
2083         }
2084 out:
2085         btrfs_free_path(path);
2086         return ret;
2087 }
2088
2089 int btrfs_free_block_groups(struct btrfs_fs_info *info)
2090 {
2091         u64 start;
2092         u64 end;
2093         u64 ptr;
2094         int ret;
2095         while(1) {
2096                 ret = find_first_extent_bit(&info->block_group_cache, 0,
2097                                             &start, &end, (unsigned int)-1);
2098                 if (ret)
2099                         break;
2100                 ret = get_state_private(&info->block_group_cache, start, &ptr);
2101                 if (!ret)
2102                         kfree((void *)(unsigned long)ptr);
2103                 clear_extent_bits(&info->block_group_cache, start,
2104                                   end, (unsigned int)-1, GFP_NOFS);
2105         }
2106         while(1) {
2107                 ret = find_first_extent_bit(&info->free_space_cache, 0,
2108                                             &start, &end, EXTENT_DIRTY);
2109                 if (ret)
2110                         break;
2111                 clear_extent_dirty(&info->free_space_cache, start,
2112                                    end, GFP_NOFS);
2113         }
2114         return 0;
2115 }
2116
2117 int btrfs_read_block_groups(struct btrfs_root *root)
2118 {
2119         struct btrfs_path *path;
2120         int ret;
2121         int err = 0;
2122         int bit;
2123         struct btrfs_block_group_cache *cache;
2124         struct btrfs_fs_info *info = root->fs_info;
2125         struct extent_map_tree *block_group_cache;
2126         struct btrfs_key key;
2127         struct btrfs_key found_key;
2128         struct extent_buffer *leaf;
2129
2130         block_group_cache = &info->block_group_cache;
2131
2132         root = info->extent_root;
2133         key.objectid = 0;
2134         key.offset = BTRFS_BLOCK_GROUP_SIZE;
2135         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
2136
2137         path = btrfs_alloc_path();
2138         if (!path)
2139                 return -ENOMEM;
2140
2141         while(1) {
2142                 ret = btrfs_search_slot(NULL, info->extent_root,
2143                                         &key, path, 0, 0);
2144                 if (ret != 0) {
2145                         err = ret;
2146                         break;
2147                 }
2148                 leaf = path->nodes[0];
2149                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2150                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
2151                 if (!cache) {
2152                         err = -1;
2153                         break;
2154                 }
2155
2156                 read_extent_buffer(leaf, &cache->item,
2157                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
2158                                    sizeof(cache->item));
2159                 memcpy(&cache->key, &found_key, sizeof(found_key));
2160                 cache->cached = 0;
2161                 cache->pinned = 0;
2162                 key.objectid = found_key.objectid + found_key.offset;
2163                 btrfs_release_path(root, path);
2164
2165                 if (cache->item.flags & BTRFS_BLOCK_GROUP_MIXED) {
2166                         bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
2167                         cache->data = BTRFS_BLOCK_GROUP_MIXED;
2168                 } else if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
2169                         bit = BLOCK_GROUP_DATA;
2170                         cache->data = BTRFS_BLOCK_GROUP_DATA;
2171                 } else {
2172                         bit = BLOCK_GROUP_METADATA;
2173                         cache->data = 0;
2174                 }
2175
2176                 /* use EXTENT_LOCKED to prevent merging */
2177                 set_extent_bits(block_group_cache, found_key.objectid,
2178                                 found_key.objectid + found_key.offset - 1,
2179                                 bit | EXTENT_LOCKED, GFP_NOFS);
2180                 set_state_private(block_group_cache, found_key.objectid,
2181                                   (unsigned long)cache);
2182
2183                 if (key.objectid >=
2184                     btrfs_super_total_bytes(&info->super_copy))
2185                         break;
2186         }
2187
2188         btrfs_free_path(path);
2189         return 0;
2190 }
2191
2192 static int btrfs_insert_block_group(struct btrfs_trans_handle *trans,
2193                                     struct btrfs_root *root,
2194                                     struct btrfs_key *key,
2195                                     struct btrfs_block_group_item *bi)
2196 {
2197         int ret;
2198         int pending_ret;
2199         struct btrfs_root *extent_root;
2200
2201         extent_root = root->fs_info->extent_root;
2202         ret = btrfs_insert_item(trans, extent_root, key, bi, sizeof(*bi));
2203         finish_current_insert(trans, extent_root);
2204         pending_ret = del_pending_extents(trans, extent_root);
2205         if (ret)
2206                 return ret;
2207         if (pending_ret)
2208                 return pending_ret;
2209         return 0;
2210 }
2211
2212 int btrfs_make_block_groups(struct btrfs_trans_handle *trans,
2213                             struct btrfs_root *root)
2214 {
2215         u64 group_size;
2216         u64 bytes_used;
2217         u64 total_bytes;
2218         u64 cur_start;
2219         u64 nr = 0;
2220         int ret;
2221         int bit;
2222         struct btrfs_root *extent_root;
2223         struct btrfs_block_group_cache *cache;
2224         struct extent_map_tree *block_group_cache;
2225
2226         extent_root = root->fs_info->extent_root;
2227         block_group_cache = &root->fs_info->block_group_cache;
2228         group_size = BTRFS_BLOCK_GROUP_SIZE;
2229         bytes_used = btrfs_super_bytes_used(&root->fs_info->super_copy);
2230         total_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
2231
2232         cur_start = 0;
2233         while (cur_start < total_bytes) {
2234                 cache = malloc(sizeof(*cache));
2235                 BUG_ON(!cache);
2236                 cache->key.objectid = cur_start;
2237                 cache->key.offset = group_size;
2238                 btrfs_set_key_type(&cache->key, BTRFS_BLOCK_GROUP_ITEM_KEY);
2239                 memset(&cache->item, 0, sizeof(cache->item));
2240                 if (nr == 0)
2241                         btrfs_set_block_group_used(&cache->item, bytes_used);
2242                 if (nr++ % 3) {
2243                         bit = BLOCK_GROUP_DATA;
2244                         cache->data = 1;
2245                         cache->item.flags |= BTRFS_BLOCK_GROUP_DATA;
2246                 } else {
2247                         bit = BLOCK_GROUP_METADATA;
2248                         cache->data = 0;
2249                 }
2250
2251                 set_extent_bits(block_group_cache, cur_start,
2252                                 cur_start + group_size - 1,
2253                                 bit | EXTENT_LOCKED, GFP_NOFS);
2254                 set_state_private(block_group_cache, cur_start,
2255                                   (unsigned long)cache);
2256                 cur_start += group_size;
2257         }
2258         /* then insert all the items */
2259         cur_start = 0;
2260         while(cur_start < total_bytes) {
2261                 cache = btrfs_lookup_block_group(root->fs_info, cur_start);
2262                 BUG_ON(!cache);
2263                 ret = btrfs_insert_block_group(trans, root, &cache->key,
2264                                                &cache->item);
2265                 BUG_ON(ret);
2266                 cur_start += group_size;
2267         }
2268         return 0;
2269 }
2270
2271 u64 btrfs_hash_extent_ref(u64 root_objectid, u64 ref_generation,
2272                           u64 owner, u64 owner_offset)
2273 {
2274         return hash_extent_ref(root_objectid, ref_generation,
2275                                owner, owner_offset);
2276 }
2277
2278 int btrfs_update_block_group(struct btrfs_trans_handle *trans,
2279                              struct btrfs_root *root,
2280                              u64 bytenr, u64 num_bytes, int alloc,
2281                              int mark_free, int data)
2282 {
2283         return update_block_group(trans, root, bytenr, num_bytes,
2284                                   alloc, mark_free, data);
2285 }