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