fs/btrfs/extent-tree.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include "ctree.h"
  21 #include "disk-io.h"
  22 #include "print-tree.h"
  23 #include "transaction.h"
  24
  25 #define BLOCK_GROUP_DATA EXTENT_WRITEBACK
  26 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
  27 #define BLOCK_GROUP_DIRTY EXTENT_DIRTY
  28
  29 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
  30                                  btrfs_root *extent_root);
  31 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
  32                                btrfs_root *extent_root);
  33
  34 static int cache_block_group(struct btrfs_root *root,
  35                              struct btrfs_block_group_cache *block_group)
  36 {
  37         struct btrfs_path *path;
  38         int ret;
  39         struct btrfs_key key;
  40         struct extent_buffer *leaf;
  41         struct extent_map_tree *free_space_cache;
  42         int slot;
  43         u64 last = 0;
  44         u64 hole_size;
  45         u64 first_free;
  46         int found = 0;
  47
  48         root = root->fs_info->extent_root;
  49         free_space_cache = &root->fs_info->free_space_cache;
  50
  51         if (block_group->cached)
  52                 return 0;
  53
  54         path = btrfs_alloc_path();
  55         if (!path)
  56                 return -ENOMEM;
  57
  58         path->reada = 2;
  59         first_free = block_group->key.objectid;
  60         key.objectid = block_group->key.objectid;
  61         key.offset = 0;
  62
  63         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
  64         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  65
  66         if (ret < 0)
  67                 return ret;
  68
  69         if (ret && path->slots[0] > 0)
  70                 path->slots[0]--;
  71
  72         while(1) {
  73                 leaf = path->nodes[0];
  74                 slot = path->slots[0];
  75                 if (slot >= btrfs_header_nritems(leaf)) {
  76                         ret = btrfs_next_leaf(root, path);
  77                         if (ret < 0)
  78                                 goto err;
  79                         if (ret == 0) {
  80                                 continue;
  81                         } else {
  82                                 break;
  83                         }
  84                 }
  85
  86                 btrfs_item_key_to_cpu(leaf, &key, slot);
  87                 if (key.objectid < block_group->key.objectid) {
  88                         if (key.objectid + key.offset > first_free)
  89                                 first_free = key.objectid + key.offset;
  90                         goto next;
  91                 }
  92
  93                 if (key.objectid >= block_group->key.objectid +
  94                     block_group->key.offset) {
  95                         break;
  96                 }
  97
  98                 if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
  99                         if (!found) {
 100                                 last = first_free;
 101                                 found = 1;
 102                         }
 103                         if (key.objectid > last) {
 104                                 hole_size = key.objectid - last;
 105                                 set_extent_dirty(free_space_cache, last,
 106                                                  last + hole_size - 1,
 107                                                  GFP_NOFS);
 108                         }
 109                         last = key.objectid + key.offset;
 110                 }
 111 next:
 112                 path->slots[0]++;
 113         }
 114
 115         if (!found)
 116                 last = first_free;
 117         if (block_group->key.objectid +
 118             block_group->key.offset > last) {
 119                 hole_size = block_group->key.objectid +
 120                         block_group->key.offset - last;
 121                 set_extent_dirty(free_space_cache, last,
 122                                  last + hole_size - 1, GFP_NOFS);
 123         }
 124         block_group->cached = 1;
 125 err:
 126         btrfs_free_path(path);
 127         return 0;
 128 }
 129
 130 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 131                                                          btrfs_fs_info *info,
 132                                                          u64 bytenr)
 133 {
 134         struct extent_map_tree *block_group_cache;
 135         struct btrfs_block_group_cache *block_group = NULL;
 136         u64 ptr;
 137         u64 start;
 138         u64 end;
 139         int ret;
 140
 141         block_group_cache = &info->block_group_cache;
 142         ret = find_first_extent_bit(block_group_cache,
 143                                     bytenr, &start, &end,
 144                                     BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA);
 145         if (ret) {
 146                 return NULL;
 147         }
 148         ret = get_state_private(block_group_cache, start, &ptr);
 149         if (ret)
 150                 return NULL;
 151
 152         block_group = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 153
 154
 155         if (block_group->key.objectid <= bytenr && bytenr <=
 156             block_group->key.objectid + block_group->key.offset)
 157                 return block_group;
 158
 159         return NULL;
 160 }
 161
 162 static u64 find_search_start(struct btrfs_root *root,
 163                              struct btrfs_block_group_cache **cache_ret,
 164                              u64 search_start, int num, int data)
 165 {
 166         int ret;
 167         struct btrfs_block_group_cache *cache = *cache_ret;
 168         u64 last;
 169         u64 start = 0;
 170         u64 end = 0;
 171
 172 again:
 173         ret = cache_block_group(root, cache);
 174         if (ret)
 175                 goto out;
 176         last = max(search_start, cache->key.objectid);
 177
 178         while(1) {
 179                 ret = find_first_extent_bit(&root->fs_info->free_space_cache,
 180                                             last, &start, &end, EXTENT_DIRTY);
 181                 if (ret) {
 182                         goto new_group;
 183                 }
 184
 185                 start = max(last, start);
 186                 last = end + 1;
 187                 if (end + 1 - start < num)
 188                         continue;
 189                 if (start + num >= cache->key.objectid + cache->key.offset)
 190                         goto new_group;
 191                 return start;
 192         }
 193 out:
 194         return search_start;
 195
 196 new_group:
 197         last = cache->key.objectid + cache->key.offset;
 198         cache = btrfs_lookup_block_group(root->fs_info, last);
 199         if (!cache) {
 200                 return search_start;
 201         }
 202         cache = btrfs_find_block_group(root, cache, last, data, 0);
 203         *cache_ret = cache;
 204         goto again;
 205 }
 206
 207 static u64 div_factor(u64 num, int factor)
 208 {
 209         num *= factor;
 210         do_div(num, 10);
 211         return num;
 212 }
 213
 214 struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 215                                                  struct btrfs_block_group_cache
 216                                                  *hint, u64 search_start,
 217                                                  int data, int owner)
 218 {
 219         struct btrfs_block_group_cache *cache;
 220         struct extent_map_tree *block_group_cache;
 221         struct btrfs_block_group_cache *found_group = NULL;
 222         struct btrfs_fs_info *info = root->fs_info;
 223         u64 used;
 224         u64 last = 0;
 225         u64 hint_last;
 226         u64 start;
 227         u64 end;
 228         u64 free_check;
 229         u64 ptr;
 230         int bit;
 231         int ret;
 232         int full_search = 0;
 233         int factor = 8;
 234         int data_swap = 0;
 235
 236         block_group_cache = &info->block_group_cache;
 237
 238         if (!owner)
 239                 factor = 5;
 240
 241         if (data)
 242                 bit = BLOCK_GROUP_DATA;
 243         else
 244                 bit = BLOCK_GROUP_METADATA;
 245
 246         if (search_start) {
 247                 struct btrfs_block_group_cache *shint;
 248                 shint = btrfs_lookup_block_group(info, search_start);
 249                 if (shint && shint->data == data) {
 250                         used = btrfs_block_group_used(&shint->item);
 251                         if (used < div_factor(shint->key.offset, factor)) {
 252                                 return shint;
 253                         }
 254                 }
 255         }
 256         if (hint && hint->data == data) {
 257                 used = btrfs_block_group_used(&hint->item);
 258                 if (used < div_factor(hint->key.offset, factor)) {
 259                         return hint;
 260                 }
 261                 last = hint->key.objectid + hint->key.offset;
 262                 hint_last = last;
 263         } else {
 264                 if (hint)
 265                         hint_last = max(hint->key.objectid, search_start);
 266                 else
 267                         hint_last = search_start;
 268
 269                 last = hint_last;
 270         }
 271 again:
 272         while(1) {
 273                 ret = find_first_extent_bit(block_group_cache, last,
 274                                             &start, &end, bit);
 275                 if (ret)
 276                         break;
 277
 278                 ret = get_state_private(block_group_cache, start, &ptr);
 279                 if (ret)
 280                         break;
 281
 282                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 283                 last = cache->key.objectid + cache->key.offset;
 284                 used = btrfs_block_group_used(&cache->item);
 285
 286                 if (full_search)
 287                         free_check = cache->key.offset;
 288                 else
 289                         free_check = div_factor(cache->key.offset, factor);
 290
 291                 if (used < free_check) {
 292                         found_group = cache;
 293                         goto found;
 294                 }
 295                 cond_resched();
 296         }
 297         if (!full_search) {
 298                 last = search_start;
 299                 full_search = 1;
 300                 goto again;
 301         }
 302         if (!data_swap) {
 303                 data_swap = 1;
 304                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 305                 last = search_start;
 306                 goto again;
 307         }
 308 found:
 309         return found_group;
 310 }
 311
 312 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 313                                 struct btrfs_root *root,
 314                                 u64 bytenr, u64 num_bytes)
 315 {
 316         struct btrfs_path *path;
 317         int ret;
 318         struct btrfs_key key;
 319         struct extent_buffer *l;
 320         struct btrfs_extent_item *item;
 321         u32 refs;
 322
 323         WARN_ON(num_bytes < root->sectorsize);
 324         path = btrfs_alloc_path();
 325         if (!path)
 326                 return -ENOMEM;
 327
 328         key.objectid = bytenr;
 329         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 330         key.offset = num_bytes;
 331         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 332                                 0, 1);
 333         if (ret < 0)
 334                 return ret;
 335         if (ret != 0) {
 336                 BUG();
 337         }
 338         BUG_ON(ret != 0);
 339         l = path->nodes[0];
 340         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 341         refs = btrfs_extent_refs(l, item);
 342         btrfs_set_extent_refs(l, item, refs + 1);
 343         btrfs_mark_buffer_dirty(path->nodes[0]);
 344
 345         btrfs_release_path(root->fs_info->extent_root, path);
 346         btrfs_free_path(path);
 347         finish_current_insert(trans, root->fs_info->extent_root);
 348         del_pending_extents(trans, root->fs_info->extent_root);
 349         return 0;
 350 }
 351
 352 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 353                          struct btrfs_root *root)
 354 {
 355         finish_current_insert(trans, root->fs_info->extent_root);
 356         del_pending_extents(trans, root->fs_info->extent_root);
 357         return 0;
 358 }
 359
 360 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 361                              struct btrfs_root *root, u64 bytenr,
 362                              u64 num_bytes, u32 *refs)
 363 {
 364         struct btrfs_path *path;
 365         int ret;
 366         struct btrfs_key key;
 367         struct extent_buffer *l;
 368         struct btrfs_extent_item *item;
 369
 370         WARN_ON(num_bytes < root->sectorsize);
 371         path = btrfs_alloc_path();
 372         key.objectid = bytenr;
 373         key.offset = num_bytes;
 374         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 375         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 376                                 0, 0);
 377         if (ret < 0)
 378                 goto out;
 379         if (ret != 0) {
 380                 btrfs_print_leaf(root, path->nodes[0]);
 381                 printk("failed to find block number %Lu\n", bytenr);
 382                 BUG();
 383         }
 384         l = path->nodes[0];
 385         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 386         *refs = btrfs_extent_refs(l, item);
 387 out:
 388         btrfs_free_path(path);
 389         return 0;
 390 }
 391
 392 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 393                        struct btrfs_root *root)
 394 {
 395         return btrfs_inc_extent_ref(trans, root, root->node->start,
 396                                     root->node->len);
 397 }
 398
 399 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 400                   struct extent_buffer *buf)
 401 {
 402         u64 bytenr;
 403         u32 nritems;
 404         struct btrfs_key key;
 405         struct btrfs_file_extent_item *fi;
 406         int i;
 407         int level;
 408         int ret;
 409         int faili;
 410         int err;
 411
 412         if (!root->ref_cows)
 413                 return 0;
 414
 415         level = btrfs_header_level(buf);
 416         nritems = btrfs_header_nritems(buf);
 417         for (i = 0; i < nritems; i++) {
 418                 if (level == 0) {
 419                         u64 disk_bytenr;
 420                         btrfs_item_key_to_cpu(buf, &key, i);
 421                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 422                                 continue;
 423                         fi = btrfs_item_ptr(buf, i,
 424                                             struct btrfs_file_extent_item);
 425                         if (btrfs_file_extent_type(buf, fi) ==
 426                             BTRFS_FILE_EXTENT_INLINE)
 427                                 continue;
 428                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 429                         if (disk_bytenr == 0)
 430                                 continue;
 431                         ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
 432                                     btrfs_file_extent_disk_num_bytes(buf, fi));
 433                         if (ret) {
 434                                 faili = i;
 435                                 goto fail;
 436                         }
 437                 } else {
 438                         bytenr = btrfs_node_blockptr(buf, i);
 439                         ret = btrfs_inc_extent_ref(trans, root, bytenr,
 440                                            btrfs_level_size(root, level - 1));
 441                         if (ret) {
 442                                 faili = i;
 443                                 goto fail;
 444                         }
 445                 }
 446         }
 447         return 0;
 448 fail:
 449         WARN_ON(1);
 450         for (i =0; i < faili; i++) {
 451                 if (level == 0) {
 452                         u64 disk_bytenr;
 453                         btrfs_item_key_to_cpu(buf, &key, i);
 454                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 455                                 continue;
 456                         fi = btrfs_item_ptr(buf, i,
 457                                             struct btrfs_file_extent_item);
 458                         if (btrfs_file_extent_type(buf, fi) ==
 459                             BTRFS_FILE_EXTENT_INLINE)
 460                                 continue;
 461                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 462                         if (disk_bytenr == 0)
 463                                 continue;
 464                         err = btrfs_free_extent(trans, root, disk_bytenr,
 465                                     btrfs_file_extent_disk_num_bytes(buf,
 466                                                                       fi), 0);
 467                         BUG_ON(err);
 468                 } else {
 469                         bytenr = btrfs_node_blockptr(buf, i);
 470                         err = btrfs_free_extent(trans, root, bytenr,
 471                                         btrfs_level_size(root, level - 1), 0);
 472                         BUG_ON(err);
 473                 }
 474         }
 475         return ret;
 476 }
 477
 478 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 479                                  struct btrfs_root *root,
 480                                  struct btrfs_path *path,
 481                                  struct btrfs_block_group_cache *cache)
 482 {
 483         int ret;
 484         int pending_ret;
 485         struct btrfs_root *extent_root = root->fs_info->extent_root;
 486         unsigned long bi;
 487         struct extent_buffer *leaf;
 488
 489         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 490         if (ret < 0)
 491                 goto fail;
 492         BUG_ON(ret);
 493
 494         leaf = path->nodes[0];
 495         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 496         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 497         btrfs_mark_buffer_dirty(leaf);
 498         btrfs_release_path(extent_root, path);
 499 fail:
 500         finish_current_insert(trans, extent_root);
 501         pending_ret = del_pending_extents(trans, extent_root);
 502         if (ret)
 503                 return ret;
 504         if (pending_ret)
 505                 return pending_ret;
 506         return 0;
 507
 508 }
 509
 510 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 511                                    struct btrfs_root *root)
 512 {
 513         struct extent_map_tree *block_group_cache;
 514         struct btrfs_block_group_cache *cache;
 515         int ret;
 516         int err = 0;
 517         int werr = 0;
 518         struct btrfs_path *path;
 519         u64 last = 0;
 520         u64 start;
 521         u64 end;
 522         u64 ptr;
 523
 524         block_group_cache = &root->fs_info->block_group_cache;
 525         path = btrfs_alloc_path();
 526         if (!path)
 527                 return -ENOMEM;
 528
 529         while(1) {
 530                 ret = find_first_extent_bit(block_group_cache, last,
 531                                             &start, &end, BLOCK_GROUP_DIRTY);
 532                 if (ret)
 533                         break;
 534
 535                 last = end + 1;
 536                 ret = get_state_private(block_group_cache, start, &ptr);
 537                 if (ret)
 538                         break;
 539
 540                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 541                 err = write_one_cache_group(trans, root,
 542                                             path, cache);
 543                 /*
 544                  * if we fail to write the cache group, we want
 545                  * to keep it marked dirty in hopes that a later
 546                  * write will work
 547                  */
 548                 if (err) {
 549                         werr = err;
 550                         continue;
 551                 }
 552                 clear_extent_bits(block_group_cache, start, end,
 553                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
 554         }
 555         btrfs_free_path(path);
 556         return werr;
 557 }
 558
 559 static int update_block_group(struct btrfs_trans_handle *trans,
 560                               struct btrfs_root *root,
 561                               u64 bytenr, u64 num_bytes, int alloc,
 562                               int mark_free, int data)
 563 {
 564         struct btrfs_block_group_cache *cache;
 565         struct btrfs_fs_info *info = root->fs_info;
 566         u64 total = num_bytes;
 567         u64 old_val;
 568         u64 byte_in_group;
 569         u64 start;
 570         u64 end;
 571
 572         while(total) {
 573                 cache = btrfs_lookup_block_group(info, bytenr);
 574                 if (!cache) {
 575                         return -1;
 576                 }
 577                 byte_in_group = bytenr - cache->key.objectid;
 578                 WARN_ON(byte_in_group > cache->key.offset);
 579                 start = cache->key.objectid;
 580                 end = start + cache->key.offset - 1;
 581                 set_extent_bits(&info->block_group_cache, start, end,
 582                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
 583
 584                 old_val = btrfs_block_group_used(&cache->item);
 585                 num_bytes = min(total, cache->key.offset - byte_in_group);
 586                 if (alloc) {
 587                         if (cache->data != data &&
 588                             old_val < (cache->key.offset >> 1)) {
 589                                 int bit_to_clear;
 590                                 int bit_to_set;
 591                                 cache->data = data;
 592                                 if (data) {
 593                                         bit_to_clear = BLOCK_GROUP_METADATA;
 594                                         bit_to_set = BLOCK_GROUP_DATA;
 595                                         cache->item.flags |=
 596                                                 BTRFS_BLOCK_GROUP_DATA;
 597                                 } else {
 598                                         bit_to_clear = BLOCK_GROUP_DATA;
 599                                         bit_to_set = BLOCK_GROUP_METADATA;
 600                                         cache->item.flags &=
 601                                                 ~BTRFS_BLOCK_GROUP_DATA;
 602                                 }
 603                                 clear_extent_bits(&info->block_group_cache,
 604                                                   start, end, bit_to_clear,
 605                                                   GFP_NOFS);
 606                                 set_extent_bits(&info->block_group_cache,
 607                                                 start, end, bit_to_set,
 608                                                 GFP_NOFS);
 609                         }
 610                         old_val += num_bytes;
 611                 } else {
 612                         old_val -= num_bytes;
 613                         if (mark_free) {
 614                                 set_extent_dirty(&info->free_space_cache,
 615                                                  bytenr, bytenr + num_bytes - 1,
 616                                                  GFP_NOFS);
 617                         }
 618                 }
 619                 btrfs_set_block_group_used(&cache->item, old_val);
 620                 total -= num_bytes;
 621                 bytenr += num_bytes;
 622         }
 623         return 0;
 624 }
 625
 626 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
 627 {
 628         u64 last = 0;
 629         u64 start;
 630         u64 end;
 631         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
 632         int ret;
 633
 634         while(1) {
 635                 ret = find_first_extent_bit(pinned_extents, last,
 636                                             &start, &end, EXTENT_DIRTY);
 637                 if (ret)
 638                         break;
 639                 set_extent_dirty(copy, start, end, GFP_NOFS);
 640                 last = end + 1;
 641         }
 642         return 0;
 643 }
 644
 645 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 646                                struct btrfs_root *root,
 647                                struct extent_map_tree *unpin)
 648 {
 649         u64 start;
 650         u64 end;
 651         int ret;
 652         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
 653         struct extent_map_tree *free_space_cache;
 654
 655         free_space_cache = &root->fs_info->free_space_cache;
 656
 657         while(1) {
 658                 ret = find_first_extent_bit(unpin, 0, &start, &end,
 659                                             EXTENT_DIRTY);
 660                 if (ret)
 661                         break;
 662
 663                 clear_extent_dirty(pinned_extents, start, end,
 664                                    GFP_NOFS);
 665                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
 666                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
 667         }
 668         return 0;
 669 }
 670
 671 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 672                                  btrfs_root *extent_root)
 673 {
 674         struct btrfs_key ins;
 675         struct btrfs_extent_item extent_item;
 676         int ret;
 677         int err = 0;
 678         u64 start;
 679         u64 end;
 680         struct btrfs_fs_info *info = extent_root->fs_info;
 681
 682         btrfs_set_stack_extent_refs(&extent_item, 1);
 683         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
 684         btrfs_set_stack_extent_owner(&extent_item,
 685                                      extent_root->root_key.objectid);
 686
 687         while(1) {
 688                 ret = find_first_extent_bit(&info->extent_ins, 0, &start,
 689                                             &end, EXTENT_LOCKED);
 690                 if (ret)
 691                         break;
 692
 693                 ins.objectid = start;
 694                 ins.offset = end + 1 - start;
 695                 err = btrfs_insert_item(trans, extent_root, &ins,
 696                                         &extent_item, sizeof(extent_item));
 697                 clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
 698                                   GFP_NOFS);
 699         }
 700         return 0;
 701 }
 702
 703 static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
 704                           int pending)
 705 {
 706         int err = 0;
 707         struct extent_buffer *buf;
 708
 709         if (!pending) {
 710                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
 711                 if (buf) {
 712                         if (btrfs_buffer_uptodate(buf)) {
 713                                 u64 transid =
 714                                     root->fs_info->running_transaction->transid;
 715                                 if (btrfs_header_generation(buf) == transid) {
 716                                         free_extent_buffer(buf);
 717                                         return 1;
 718                                 }
 719                         }
 720                         free_extent_buffer(buf);
 721                 }
 722                 set_extent_dirty(&root->fs_info->pinned_extents,
 723                                  bytenr, bytenr + num_bytes - 1, GFP_NOFS);
 724         } else {
 725                 set_extent_bits(&root->fs_info->pending_del,
 726                                 bytenr, bytenr + num_bytes - 1,
 727                                 EXTENT_LOCKED, GFP_NOFS);
 728         }
 729         BUG_ON(err < 0);
 730         return 0;
 731 }
 732
 733 /*
 734  * remove an extent from the root, returns 0 on success
 735  */
 736 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 737                          *root, u64 bytenr, u64 num_bytes, int pin,
 738                          int mark_free)
 739 {
 740         struct btrfs_path *path;
 741         struct btrfs_key key;
 742         struct btrfs_fs_info *info = root->fs_info;
 743         struct btrfs_root *extent_root = info->extent_root;
 744         struct extent_buffer *leaf;
 745         int ret;
 746         struct btrfs_extent_item *ei;
 747         u32 refs;
 748
 749         key.objectid = bytenr;
 750         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 751         key.offset = num_bytes;
 752
 753         path = btrfs_alloc_path();
 754         if (!path)
 755                 return -ENOMEM;
 756
 757         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
 758         if (ret < 0)
 759                 return ret;
 760         BUG_ON(ret);
 761
 762         leaf = path->nodes[0];
 763         ei = btrfs_item_ptr(leaf, path->slots[0],
 764                             struct btrfs_extent_item);
 765         refs = btrfs_extent_refs(leaf, ei);
 766         BUG_ON(refs == 0);
 767         refs -= 1;
 768         btrfs_set_extent_refs(leaf, ei, refs);
 769         btrfs_mark_buffer_dirty(leaf);
 770
 771         if (refs == 0) {
 772                 u64 super_used;
 773                 u64 root_used;
 774
 775                 if (pin) {
 776                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
 777                         if (ret > 0)
 778                                 mark_free = 1;
 779                         BUG_ON(ret < 0);
 780                 }
 781
 782                 /* block accounting for super block */
 783                 super_used = btrfs_super_bytes_used(&info->super_copy);
 784                 btrfs_set_super_bytes_used(&info->super_copy,
 785                                            super_used - num_bytes);
 786
 787                 /* block accounting for root item */
 788                 root_used = btrfs_root_used(&root->root_item);
 789                 btrfs_set_root_used(&root->root_item,
 790                                            root_used - num_bytes);
 791
 792                 ret = btrfs_del_item(trans, extent_root, path);
 793                 if (ret) {
 794                         return ret;
 795                 }
 796                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
 797                                          mark_free, 0);
 798                 BUG_ON(ret);
 799         }
 800         btrfs_free_path(path);
 801         finish_current_insert(trans, extent_root);
 802         return ret;
 803 }
 804
 805 /*
 806  * find all the blocks marked as pending in the radix tree and remove
 807  * them from the extent map
 808  */
 809 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 810                                btrfs_root *extent_root)
 811 {
 812         int ret;
 813         int err = 0;
 814         u64 start;
 815         u64 end;
 816         struct extent_map_tree *pending_del;
 817         struct extent_map_tree *pinned_extents;
 818
 819         pending_del = &extent_root->fs_info->pending_del;
 820         pinned_extents = &extent_root->fs_info->pinned_extents;
 821
 822         while(1) {
 823                 ret = find_first_extent_bit(pending_del, 0, &start, &end,
 824                                             EXTENT_LOCKED);
 825                 if (ret)
 826                         break;
 827
 828                 set_extent_dirty(pinned_extents, start, end, GFP_NOFS);
 829                 clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
 830                                   GFP_NOFS);
 831                 ret = __free_extent(trans, extent_root,
 832                                      start, end + 1 - start, 0, 0);
 833                 if (ret)
 834                         err = ret;
 835         }
 836         return err;
 837 }
 838
 839 /*
 840  * remove an extent from the root, returns 0 on success
 841  */
 842 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 843                       *root, u64 bytenr, u64 num_bytes, int pin)
 844 {
 845         struct btrfs_root *extent_root = root->fs_info->extent_root;
 846         int pending_ret;
 847         int ret;
 848
 849         WARN_ON(num_bytes < root->sectorsize);
 850         if (root == extent_root) {
 851                 pin_down_bytes(root, bytenr, num_bytes, 1);
 852                 return 0;
 853         }
 854         ret = __free_extent(trans, root, bytenr, num_bytes, pin, pin == 0);
 855         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
 856         return ret ? ret : pending_ret;
 857 }
 858
 859 /*
 860  * walks the btree of allocated extents and find a hole of a given size.
 861  * The key ins is changed to record the hole:
 862  * ins->objectid == block start
 863  * ins->flags = BTRFS_EXTENT_ITEM_KEY
 864  * ins->offset == number of blocks
 865  * Any available blocks before search_start are skipped.
 866  */
 867 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 868                             *orig_root, u64 num_bytes, u64 empty_size,
 869                             u64 search_start, u64 search_end, u64 hint_byte,
 870                             struct btrfs_key *ins, u64 exclude_start,
 871                             u64 exclude_nr, int data)
 872 {
 873         struct btrfs_path *path;
 874         struct btrfs_key key;
 875         int ret;
 876         u64 hole_size = 0;
 877         int slot = 0;
 878         u64 last_byte = 0;
 879         u64 orig_search_start = search_start;
 880         int start_found;
 881         struct extent_buffer *l;
 882         struct btrfs_root * root = orig_root->fs_info->extent_root;
 883         struct btrfs_fs_info *info = root->fs_info;
 884         u64 total_needed = num_bytes;
 885         int level;
 886         struct btrfs_block_group_cache *block_group;
 887         int full_scan = 0;
 888         int wrapped = 0;
 889
 890         WARN_ON(num_bytes < root->sectorsize);
 891         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 892
 893         level = btrfs_header_level(root->node);
 894
 895         if (search_end == (u64)-1)
 896                 search_end = btrfs_super_total_bytes(&info->super_copy);
 897         if (hint_byte) {
 898                 block_group = btrfs_lookup_block_group(info, hint_byte);
 899                 block_group = btrfs_find_block_group(root, block_group,
 900                                                      hint_byte, data, 1);
 901         } else {
 902                 block_group = btrfs_find_block_group(root,
 903                                                      trans->block_group, 0,
 904                                                      data, 1);
 905         }
 906
 907         total_needed += empty_size;
 908         path = btrfs_alloc_path();
 909
 910 check_failed:
 911         search_start = find_search_start(root, &block_group,
 912                                          search_start, total_needed, data);
 913         btrfs_init_path(path);
 914         ins->objectid = search_start;
 915         ins->offset = 0;
 916         start_found = 0;
 917         path->reada = 2;
 918
 919         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
 920         if (ret < 0)
 921                 goto error;
 922
 923         if (path->slots[0] > 0) {
 924                 path->slots[0]--;
 925         }
 926
 927         l = path->nodes[0];
 928         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
 929
 930         /*
 931          * a rare case, go back one key if we hit a block group item
 932          * instead of an extent item
 933          */
 934         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY &&
 935             key.objectid + key.offset >= search_start) {
 936                 ins->objectid = key.objectid;
 937                 ins->offset = key.offset - 1;
 938                 btrfs_release_path(root, path);
 939                 ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
 940                 if (ret < 0)
 941                         goto error;
 942
 943                 if (path->slots[0] > 0) {
 944                         path->slots[0]--;
 945                 }
 946         }
 947
 948         while (1) {
 949                 l = path->nodes[0];
 950                 slot = path->slots[0];
 951                 if (slot >= btrfs_header_nritems(l)) {
 952                         ret = btrfs_next_leaf(root, path);
 953                         if (ret == 0)
 954                                 continue;
 955                         if (ret < 0)
 956                                 goto error;
 957
 958                         search_start = max(search_start,
 959                                            block_group->key.objectid);
 960                         if (!start_found) {
 961                                 ins->objectid = search_start;
 962                                 ins->offset = search_end - search_start;
 963                                 start_found = 1;
 964                                 goto check_pending;
 965                         }
 966                         ins->objectid = last_byte > search_start ?
 967                                         last_byte : search_start;
 968                         ins->offset = search_end - ins->objectid;
 969                         BUG_ON(ins->objectid >= search_end);
 970                         goto check_pending;
 971                 }
 972                 btrfs_item_key_to_cpu(l, &key, slot);
 973
 974                 if (key.objectid >= search_start && key.objectid > last_byte &&
 975                     start_found) {
 976                         if (last_byte < search_start)
 977                                 last_byte = search_start;
 978                         hole_size = key.objectid - last_byte;
 979                         if (hole_size >= num_bytes) {
 980                                 ins->objectid = last_byte;
 981                                 ins->offset = hole_size;
 982                                 goto check_pending;
 983                         }
 984                 }
 985                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
 986                         if (!start_found) {
 987                                 last_byte = key.objectid;
 988                                 start_found = 1;
 989                         }
 990                         goto next;
 991                 }
 992
 993
 994                 start_found = 1;
 995                 last_byte = key.objectid + key.offset;
 996
 997                 if (!full_scan && last_byte >= block_group->key.objectid +
 998                     block_group->key.offset) {
 999                         btrfs_release_path(root, path);
1000                         search_start = block_group->key.objectid +
1001                                 block_group->key.offset;
1002                         goto new_group;
1003                 }
1004 next:
1005                 path->slots[0]++;
1006                 cond_resched();
1007         }
1008 check_pending:
1009         /* we have to make sure we didn't find an extent that has already
1010          * been allocated by the map tree or the original allocation
1011          */
1012         btrfs_release_path(root, path);
1013         BUG_ON(ins->objectid < search_start);
1014
1015         if (ins->objectid + num_bytes >= search_end)
1016                 goto enospc;
1017
1018         if (!full_scan && ins->objectid + num_bytes >= block_group->
1019             key.objectid + block_group->key.offset) {
1020                 search_start = block_group->key.objectid +
1021                         block_group->key.offset;
1022                 goto new_group;
1023         }
1024         if (test_range_bit(&info->extent_ins, ins->objectid,
1025                            ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
1026                 search_start = ins->objectid + num_bytes;
1027                 goto new_group;
1028         }
1029         if (test_range_bit(&info->pinned_extents, ins->objectid,
1030                            ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
1031                 search_start = ins->objectid + num_bytes;
1032                 goto new_group;
1033         }
1034         if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
1035             ins->objectid < exclude_start + exclude_nr)) {
1036                 search_start = exclude_start + exclude_nr;
1037                 goto new_group;
1038         }
1039         if (!data) {
1040                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1041                 if (block_group)
1042                         trans->block_group = block_group;
1043         }
1044         ins->offset = num_bytes;
1045         btrfs_free_path(path);
1046         return 0;
1047
1048 new_group:
1049         if (search_start + num_bytes >= search_end) {
1050 enospc:
1051                 search_start = orig_search_start;
1052                 if (full_scan) {
1053                         ret = -ENOSPC;
1054                         goto error;
1055                 }
1056                 if (wrapped) {
1057                         if (!full_scan)
1058                                 total_needed -= empty_size;
1059                         full_scan = 1;
1060                 } else
1061                         wrapped = 1;
1062         }
1063         block_group = btrfs_lookup_block_group(info, search_start);
1064         cond_resched();
1065         if (!full_scan)
1066                 block_group = btrfs_find_block_group(root, block_group,
1067                                                      search_start, data, 0);
1068         goto check_failed;
1069
1070 error:
1071         btrfs_release_path(root, path);
1072         btrfs_free_path(path);
1073         return ret;
1074 }
1075 /*
1076  * finds a free extent and does all the dirty work required for allocation
1077  * returns the key for the extent through ins, and a tree buffer for
1078  * the first block of the extent through buf.
1079  *
1080  * returns 0 if everything worked, non-zero otherwise.
1081  */
1082 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1083                        struct btrfs_root *root, u64 owner,
1084                        u64 num_bytes, u64 empty_size, u64 hint_byte,
1085                        u64 search_end, struct btrfs_key *ins, int data)
1086 {
1087         int ret;
1088         int pending_ret;
1089         u64 super_used, root_used;
1090         u64 search_start = 0;
1091         struct btrfs_fs_info *info = root->fs_info;
1092         struct btrfs_root *extent_root = info->extent_root;
1093         struct btrfs_extent_item extent_item;
1094
1095         btrfs_set_stack_extent_refs(&extent_item, 1);
1096         btrfs_set_stack_extent_owner(&extent_item, owner);
1097
1098         WARN_ON(num_bytes < root->sectorsize);
1099         ret = find_free_extent(trans, root, num_bytes, empty_size,
1100                                search_start, search_end, hint_byte, ins,
1101                                trans->alloc_exclude_start,
1102                                trans->alloc_exclude_nr, data);
1103         BUG_ON(ret);
1104         if (ret)
1105                 return ret;
1106
1107         /* block accounting for super block */
1108         super_used = btrfs_super_bytes_used(&info->super_copy);
1109         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
1110
1111         /* block accounting for root item */
1112         root_used = btrfs_root_used(&root->root_item);
1113         btrfs_set_root_used(&root->root_item, root_used + num_bytes);
1114
1115         clear_extent_dirty(&root->fs_info->free_space_cache,
1116                            ins->objectid, ins->objectid + ins->offset - 1,
1117                            GFP_NOFS);
1118
1119         if (root == extent_root) {
1120                 set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
1121                                 ins->objectid + ins->offset - 1,
1122                                 EXTENT_LOCKED, GFP_NOFS);
1123                 WARN_ON(data == 1);
1124                 goto update_block;
1125         }
1126
1127         WARN_ON(trans->alloc_exclude_nr);
1128         trans->alloc_exclude_start = ins->objectid;
1129         trans->alloc_exclude_nr = ins->offset;
1130         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1131                                 sizeof(extent_item));
1132
1133         trans->alloc_exclude_start = 0;
1134         trans->alloc_exclude_nr = 0;
1135
1136         BUG_ON(ret);
1137         finish_current_insert(trans, extent_root);
1138         pending_ret = del_pending_extents(trans, extent_root);
1139
1140         if (ret) {
1141                 return ret;
1142         }
1143         if (pending_ret) {
1144                 return pending_ret;
1145         }
1146
1147 update_block:
1148         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1149                                  data);
1150         BUG_ON(ret);
1151         return 0;
1152 }
1153
1154 /*
1155  * helper function to allocate a block for a given tree
1156  * returns the tree buffer or NULL.
1157  */
1158 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1159                                              struct btrfs_root *root,
1160                                              u32 blocksize, u64 hint,
1161                                              u64 empty_size)
1162 {
1163         struct btrfs_key ins;
1164         int ret;
1165         struct extent_buffer *buf;
1166
1167         ret = btrfs_alloc_extent(trans, root, root->root_key.objectid,
1168                                  blocksize, empty_size, hint,
1169                                  (u64)-1, &ins, 0);
1170         if (ret) {
1171                 BUG_ON(ret > 0);
1172                 return ERR_PTR(ret);
1173         }
1174         buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
1175         if (!buf) {
1176                 btrfs_free_extent(trans, root, ins.objectid, blocksize, 0);
1177                 return ERR_PTR(-ENOMEM);
1178         }
1179         btrfs_set_buffer_uptodate(buf);
1180         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1181                          buf->start + buf->len - 1, GFP_NOFS);
1182         set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
1183                         buf->start, buf->start + buf->len - 1,
1184                         EXTENT_CSUM, GFP_NOFS);
1185         buf->flags |= EXTENT_CSUM;
1186         btrfs_set_buffer_defrag(buf);
1187         trans->blocks_used++;
1188         return buf;
1189 }
1190
1191 static int drop_leaf_ref(struct btrfs_trans_handle *trans,
1192                          struct btrfs_root *root, struct extent_buffer *leaf)
1193 {
1194         struct btrfs_key key;
1195         struct btrfs_file_extent_item *fi;
1196         int i;
1197         int nritems;
1198         int ret;
1199
1200         BUG_ON(!btrfs_is_leaf(leaf));
1201         nritems = btrfs_header_nritems(leaf);
1202         for (i = 0; i < nritems; i++) {
1203                 u64 disk_bytenr;
1204
1205                 btrfs_item_key_to_cpu(leaf, &key, i);
1206                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1207                         continue;
1208                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1209                 if (btrfs_file_extent_type(leaf, fi) ==
1210                     BTRFS_FILE_EXTENT_INLINE)
1211                         continue;
1212                 /*
1213                  * FIXME make sure to insert a trans record that
1214                  * repeats the snapshot del on crash
1215                  */
1216                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1217                 if (disk_bytenr == 0)
1218                         continue;
1219                 ret = btrfs_free_extent(trans, root, disk_bytenr,
1220                                 btrfs_file_extent_disk_num_bytes(leaf, fi), 0);
1221                 BUG_ON(ret);
1222         }
1223         return 0;
1224 }
1225
1226 static void reada_walk_down(struct btrfs_root *root,
1227                             struct extent_buffer *node)
1228 {
1229         int i;
1230         u32 nritems;
1231         u64 bytenr;
1232         int ret;
1233         u32 refs;
1234         int level;
1235         u32 blocksize;
1236
1237         nritems = btrfs_header_nritems(node);
1238         level = btrfs_header_level(node);
1239         for (i = 0; i < nritems; i++) {
1240                 bytenr = btrfs_node_blockptr(node, i);
1241                 blocksize = btrfs_level_size(root, level - 1);
1242                 ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
1243                 BUG_ON(ret);
1244                 if (refs != 1)
1245                         continue;
1246                 mutex_unlock(&root->fs_info->fs_mutex);
1247                 ret = readahead_tree_block(root, bytenr, blocksize);
1248                 cond_resched();
1249                 mutex_lock(&root->fs_info->fs_mutex);
1250                 if (ret)
1251                         break;
1252         }
1253 }
1254
1255 /*
1256  * helper function for drop_snapshot, this walks down the tree dropping ref
1257  * counts as it goes.
1258  */
1259 static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1260                           *root, struct btrfs_path *path, int *level)
1261 {
1262         struct extent_buffer *next;
1263         struct extent_buffer *cur;
1264         u64 bytenr;
1265         u32 blocksize;
1266         int ret;
1267         u32 refs;
1268
1269         WARN_ON(*level < 0);
1270         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1271         ret = lookup_extent_ref(trans, root,
1272                                 path->nodes[*level]->start,
1273                                 path->nodes[*level]->len, &refs);
1274         BUG_ON(ret);
1275         if (refs > 1)
1276                 goto out;
1277
1278         /*
1279          * walk down to the last node level and free all the leaves
1280          */
1281         while(*level >= 0) {
1282                 WARN_ON(*level < 0);
1283                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1284                 cur = path->nodes[*level];
1285
1286                 if (*level > 0 && path->slots[*level] == 0)
1287                         reada_walk_down(root, cur);
1288
1289                 if (btrfs_header_level(cur) != *level)
1290                         WARN_ON(1);
1291
1292                 if (path->slots[*level] >=
1293                     btrfs_header_nritems(cur))
1294                         break;
1295                 if (*level == 0) {
1296                         ret = drop_leaf_ref(trans, root, cur);
1297                         BUG_ON(ret);
1298                         break;
1299                 }
1300                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
1301                 blocksize = btrfs_level_size(root, *level - 1);
1302                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
1303                 BUG_ON(ret);
1304                 if (refs != 1) {
1305                         path->slots[*level]++;
1306                         ret = btrfs_free_extent(trans, root, bytenr,
1307                                                 blocksize, 1);
1308                         BUG_ON(ret);
1309                         continue;
1310                 }
1311                 next = btrfs_find_tree_block(root, bytenr, blocksize);
1312                 if (!next || !btrfs_buffer_uptodate(next)) {
1313                         free_extent_buffer(next);
1314                         mutex_unlock(&root->fs_info->fs_mutex);
1315                         next = read_tree_block(root, bytenr, blocksize);
1316                         mutex_lock(&root->fs_info->fs_mutex);
1317
1318                         /* we dropped the lock, check one more time */
1319                         ret = lookup_extent_ref(trans, root, bytenr,
1320                                                 blocksize, &refs);
1321                         BUG_ON(ret);
1322                         if (refs != 1) {
1323                                 path->slots[*level]++;
1324                                 free_extent_buffer(next);
1325                                 ret = btrfs_free_extent(trans, root,
1326                                                         bytenr, blocksize, 1);
1327                                 BUG_ON(ret);
1328                                 continue;
1329                         }
1330                 }
1331                 WARN_ON(*level <= 0);
1332                 if (path->nodes[*level-1])
1333                         free_extent_buffer(path->nodes[*level-1]);
1334                 path->nodes[*level-1] = next;
1335                 *level = btrfs_header_level(next);
1336                 path->slots[*level] = 0;
1337         }
1338 out:
1339         WARN_ON(*level < 0);
1340         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1341         ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
1342                                 path->nodes[*level]->len, 1);
1343         free_extent_buffer(path->nodes[*level]);
1344         path->nodes[*level] = NULL;
1345         *level += 1;
1346         BUG_ON(ret);
1347         return 0;
1348 }
1349
1350 /*
1351  * helper for dropping snapshots.  This walks back up the tree in the path
1352  * to find the first node higher up where we haven't yet gone through
1353  * all the slots
1354  */
1355 static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1356                         *root, struct btrfs_path *path, int *level)
1357 {
1358         int i;
1359         int slot;
1360         int ret;
1361         struct btrfs_root_item *root_item = &root->root_item;
1362
1363         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1364                 slot = path->slots[i];
1365                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1366                         struct extent_buffer *node;
1367                         struct btrfs_disk_key disk_key;
1368                         node = path->nodes[i];
1369                         path->slots[i]++;
1370                         *level = i;
1371                         WARN_ON(*level == 0);
1372                         btrfs_node_key(node, &disk_key, path->slots[i]);
1373                         memcpy(&root_item->drop_progress,
1374                                &disk_key, sizeof(disk_key));
1375                         root_item->drop_level = i;
1376                         return 0;
1377                 } else {
1378                         ret = btrfs_free_extent(trans, root,
1379                                                 path->nodes[*level]->start,
1380                                                 path->nodes[*level]->len, 1);
1381                         BUG_ON(ret);
1382                         free_extent_buffer(path->nodes[*level]);
1383                         path->nodes[*level] = NULL;
1384                         *level = i + 1;
1385                 }
1386         }
1387         return 1;
1388 }
1389
1390 /*
1391  * drop the reference count on the tree rooted at 'snap'.  This traverses
1392  * the tree freeing any blocks that have a ref count of zero after being
1393  * decremented.
1394  */
1395 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
1396                         *root)
1397 {
1398         int ret = 0;
1399         int wret;
1400         int level;
1401         struct btrfs_path *path;
1402         int i;
1403         int orig_level;
1404         struct btrfs_root_item *root_item = &root->root_item;
1405
1406         path = btrfs_alloc_path();
1407         BUG_ON(!path);
1408
1409         level = btrfs_header_level(root->node);
1410         orig_level = level;
1411         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
1412                 path->nodes[level] = root->node;
1413                 extent_buffer_get(root->node);
1414                 path->slots[level] = 0;
1415         } else {
1416                 struct btrfs_key key;
1417                 struct btrfs_disk_key found_key;
1418                 struct extent_buffer *node;
1419
1420                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
1421                 level = root_item->drop_level;
1422                 path->lowest_level = level;
1423                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1424                 if (wret < 0) {
1425                         ret = wret;
1426                         goto out;
1427                 }
1428                 node = path->nodes[level];
1429                 btrfs_node_key(node, &found_key, path->slots[level]);
1430                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
1431                                sizeof(found_key)));
1432         }
1433         while(1) {
1434                 wret = walk_down_tree(trans, root, path, &level);
1435                 if (wret > 0)
1436                         break;
1437                 if (wret < 0)
1438                         ret = wret;
1439
1440                 wret = walk_up_tree(trans, root, path, &level);
1441                 if (wret > 0)
1442                         break;
1443                 if (wret < 0)
1444                         ret = wret;
1445                 ret = -EAGAIN;
1446                 break;
1447         }
1448         for (i = 0; i <= orig_level; i++) {
1449                 if (path->nodes[i]) {
1450                         free_extent_buffer(path->nodes[i]);
1451                         path->nodes[i] = NULL;
1452                 }
1453         }
1454 out:
1455         btrfs_free_path(path);
1456         return ret;
1457 }
1458
1459 int btrfs_free_block_groups(struct btrfs_fs_info *info)
1460 {
1461         u64 start;
1462         u64 end;
1463         u64 ptr;
1464         int ret;
1465         while(1) {
1466                 ret = find_first_extent_bit(&info->block_group_cache, 0,
1467                                             &start, &end, (unsigned int)-1);
1468                 if (ret)
1469                         break;
1470                 ret = get_state_private(&info->block_group_cache, start, &ptr);
1471                 if (!ret)
1472                         kfree((void *)(unsigned long)ptr);
1473                 clear_extent_bits(&info->block_group_cache, start,
1474                                   end, (unsigned int)-1, GFP_NOFS);
1475         }
1476         while(1) {
1477                 ret = find_first_extent_bit(&info->free_space_cache, 0,
1478                                             &start, &end, EXTENT_DIRTY);
1479                 if (ret)
1480                         break;
1481                 clear_extent_dirty(&info->free_space_cache, start,
1482                                    end, GFP_NOFS);
1483         }
1484         return 0;
1485 }
1486
1487 int btrfs_read_block_groups(struct btrfs_root *root)
1488 {
1489         struct btrfs_path *path;
1490         int ret;
1491         int err = 0;
1492         int bit;
1493         struct btrfs_block_group_cache *cache;
1494         struct btrfs_fs_info *info = root->fs_info;
1495         struct extent_map_tree *block_group_cache;
1496         struct btrfs_key key;
1497         struct btrfs_key found_key;
1498         struct extent_buffer *leaf;
1499
1500         block_group_cache = &info->block_group_cache;
1501
1502         root = info->extent_root;
1503         key.objectid = 0;
1504         key.offset = BTRFS_BLOCK_GROUP_SIZE;
1505         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
1506
1507         path = btrfs_alloc_path();
1508         if (!path)
1509                 return -ENOMEM;
1510
1511         while(1) {
1512                 ret = btrfs_search_slot(NULL, info->extent_root,
1513                                         &key, path, 0, 0);
1514                 if (ret != 0) {
1515                         err = ret;
1516                         break;
1517                 }
1518                 leaf = path->nodes[0];
1519                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1520                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
1521                 if (!cache) {
1522                         err = -1;
1523                         break;
1524                 }
1525
1526                 read_extent_buffer(leaf, &cache->item,
1527                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
1528                                    sizeof(cache->item));
1529                 memcpy(&cache->key, &found_key, sizeof(found_key));
1530                 cache->cached = 0;
1531
1532                 key.objectid = found_key.objectid + found_key.offset;
1533                 btrfs_release_path(root, path);
1534
1535                 if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
1536                         bit = BLOCK_GROUP_DATA;
1537                         cache->data = 1;
1538                 } else {
1539                         bit = BLOCK_GROUP_METADATA;
1540                         cache->data = 0;
1541                 }
1542
1543                 /* use EXTENT_LOCKED to prevent merging */
1544                 set_extent_bits(block_group_cache, found_key.objectid,
1545                                 found_key.objectid + found_key.offset - 1,
1546                                 bit | EXTENT_LOCKED, GFP_NOFS);
1547                 set_state_private(block_group_cache, found_key.objectid,
1548                                   (unsigned long)cache);
1549
1550                 if (key.objectid >=
1551                     btrfs_super_total_bytes(&info->super_copy))
1552                         break;
1553         }
1554
1555         btrfs_free_path(path);
1556         return 0;
1557 }