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         if (block_group->key.objectid <= bytenr && bytenr <
 154             block_group->key.objectid + block_group->key.offset)
 155                 return block_group;
 156         return NULL;
 157 }
 158 static u64 find_search_start(struct btrfs_root *root,
 159                              struct btrfs_block_group_cache **cache_ret,
 160                              u64 search_start, int num,
 161                              int data, int full_scan)
 162 {
 163         int ret;
 164         struct btrfs_block_group_cache *cache = *cache_ret;
 165         u64 last;
 166         u64 start = 0;
 167         u64 end = 0;
 168         u64 cache_miss = 0;
 169         int wrapped = 0;
 170
 171 again:
 172         ret = cache_block_group(root, cache);
 173         if (ret)
 174                 goto out;
 175
 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                         if (!cache_miss)
 183                                 cache_miss = last;
 184                         goto new_group;
 185                 }
 186
 187                 start = max(last, start);
 188                 last = end + 1;
 189                 if (last - start < num) {
 190                         if (last == cache->key.objectid + cache->key.offset)
 191                                 cache_miss = start;
 192                         continue;
 193                 }
 194                 if (data != BTRFS_BLOCK_GROUP_MIXED &&
 195                     start + num > cache->key.objectid + cache->key.offset)
 196                         goto new_group;
 197                 return start;
 198         }
 199 out:
 200         return search_start;
 201
 202 new_group:
 203         last = cache->key.objectid + cache->key.offset;
 204 wrapped:
 205         cache = btrfs_lookup_block_group(root->fs_info, last);
 206         if (!cache) {
 207                 if (!wrapped) {
 208                         wrapped = 1;
 209                         last = search_start;
 210                         data = BTRFS_BLOCK_GROUP_MIXED;
 211                         goto wrapped;
 212                 }
 213                 return search_start;
 214         }
 215         if (cache_miss && !cache->cached) {
 216                 cache_block_group(root, cache);
 217                 last = cache_miss;
 218                 cache = btrfs_lookup_block_group(root->fs_info, last);
 219         }
 220         if (!full_scan)
 221                 cache = btrfs_find_block_group(root, cache, last, data, 0);
 222         *cache_ret = cache;
 223         cache_miss = 0;
 224         goto again;
 225 }
 226
 227 static u64 div_factor(u64 num, int factor)
 228 {
 229         if (factor == 10)
 230                 return num;
 231         num *= factor;
 232         do_div(num, 10);
 233         return num;
 234 }
 235
 236 struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 237                                                  struct btrfs_block_group_cache
 238                                                  *hint, u64 search_start,
 239                                                  int data, int owner)
 240 {
 241         struct btrfs_block_group_cache *cache;
 242         struct extent_map_tree *block_group_cache;
 243         struct btrfs_block_group_cache *found_group = NULL;
 244         struct btrfs_fs_info *info = root->fs_info;
 245         u64 used;
 246         u64 last = 0;
 247         u64 hint_last;
 248         u64 start;
 249         u64 end;
 250         u64 free_check;
 251         u64 ptr;
 252         int bit;
 253         int ret;
 254         int full_search = 0;
 255         int factor = 8;
 256         int data_swap = 0;
 257
 258         block_group_cache = &info->block_group_cache;
 259
 260         if (!owner)
 261                 factor = 8;
 262
 263         if (data == BTRFS_BLOCK_GROUP_MIXED) {
 264                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 265                 factor = 10;
 266         } else if (data)
 267                 bit = BLOCK_GROUP_DATA;
 268         else
 269                 bit = BLOCK_GROUP_METADATA;
 270
 271         if (search_start) {
 272                 struct btrfs_block_group_cache *shint;
 273                 shint = btrfs_lookup_block_group(info, search_start);
 274                 if (shint && (shint->data == data ||
 275                               shint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 276                         used = btrfs_block_group_used(&shint->item);
 277                         if (used + shint->pinned <
 278                             div_factor(shint->key.offset, factor)) {
 279                                 return shint;
 280                         }
 281                 }
 282         }
 283         if (hint && (hint->data == data ||
 284                      hint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 285                 used = btrfs_block_group_used(&hint->item);
 286                 if (used + hint->pinned <
 287                     div_factor(hint->key.offset, factor)) {
 288                         return hint;
 289                 }
 290                 last = hint->key.objectid + hint->key.offset;
 291                 hint_last = last;
 292         } else {
 293                 if (hint)
 294                         hint_last = max(hint->key.objectid, search_start);
 295                 else
 296                         hint_last = search_start;
 297
 298                 last = hint_last;
 299         }
 300 again:
 301         while(1) {
 302                 ret = find_first_extent_bit(block_group_cache, last,
 303                                             &start, &end, bit);
 304                 if (ret)
 305                         break;
 306
 307                 ret = get_state_private(block_group_cache, start, &ptr);
 308                 if (ret)
 309                         break;
 310
 311                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 312                 last = cache->key.objectid + cache->key.offset;
 313                 used = btrfs_block_group_used(&cache->item);
 314
 315                 if (full_search)
 316                         free_check = cache->key.offset;
 317                 else
 318                         free_check = div_factor(cache->key.offset, factor);
 319                 if (used + cache->pinned < free_check) {
 320                         found_group = cache;
 321                         goto found;
 322                 }
 323                 cond_resched();
 324         }
 325         if (!full_search) {
 326                 last = search_start;
 327                 full_search = 1;
 328                 goto again;
 329         }
 330         if (!data_swap) {
 331                 data_swap = 1;
 332                 bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
 333                 last = search_start;
 334                 goto again;
 335         }
 336 found:
 337         return found_group;
 338 }
 339
 340 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 341                                 struct btrfs_root *root,
 342                                 u64 bytenr, u64 num_bytes)
 343 {
 344         struct btrfs_path *path;
 345         int ret;
 346         struct btrfs_key key;
 347         struct extent_buffer *l;
 348         struct btrfs_extent_item *item;
 349         u32 refs;
 350
 351         WARN_ON(num_bytes < root->sectorsize);
 352         path = btrfs_alloc_path();
 353         if (!path)
 354                 return -ENOMEM;
 355
 356         key.objectid = bytenr;
 357         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 358         key.offset = num_bytes;
 359         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 360                                 0, 1);
 361         if (ret < 0)
 362                 return ret;
 363         if (ret != 0) {
 364                 BUG();
 365         }
 366         BUG_ON(ret != 0);
 367         l = path->nodes[0];
 368         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 369         refs = btrfs_extent_refs(l, item);
 370         btrfs_set_extent_refs(l, item, refs + 1);
 371         btrfs_mark_buffer_dirty(path->nodes[0]);
 372
 373         btrfs_release_path(root->fs_info->extent_root, path);
 374         btrfs_free_path(path);
 375         finish_current_insert(trans, root->fs_info->extent_root);
 376         del_pending_extents(trans, root->fs_info->extent_root);
 377         return 0;
 378 }
 379
 380 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 381                          struct btrfs_root *root)
 382 {
 383         finish_current_insert(trans, root->fs_info->extent_root);
 384         del_pending_extents(trans, root->fs_info->extent_root);
 385         return 0;
 386 }
 387
 388 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 389                              struct btrfs_root *root, u64 bytenr,
 390                              u64 num_bytes, u32 *refs)
 391 {
 392         struct btrfs_path *path;
 393         int ret;
 394         struct btrfs_key key;
 395         struct extent_buffer *l;
 396         struct btrfs_extent_item *item;
 397
 398         WARN_ON(num_bytes < root->sectorsize);
 399         path = btrfs_alloc_path();
 400         key.objectid = bytenr;
 401         key.offset = num_bytes;
 402         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 403         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 404                                 0, 0);
 405         if (ret < 0)
 406                 goto out;
 407         if (ret != 0) {
 408                 btrfs_print_leaf(root, path->nodes[0]);
 409                 printk("failed to find block number %Lu\n", bytenr);
 410                 BUG();
 411         }
 412         l = path->nodes[0];
 413         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 414         *refs = btrfs_extent_refs(l, item);
 415 out:
 416         btrfs_free_path(path);
 417         return 0;
 418 }
 419
 420 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 421                        struct btrfs_root *root)
 422 {
 423         return btrfs_inc_extent_ref(trans, root, root->node->start,
 424                                     root->node->len);
 425 }
 426
 427 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 428                   struct extent_buffer *buf)
 429 {
 430         u64 bytenr;
 431         u32 nritems;
 432         struct btrfs_key key;
 433         struct btrfs_file_extent_item *fi;
 434         int i;
 435         int level;
 436         int ret;
 437         int faili;
 438         int err;
 439
 440         if (!root->ref_cows)
 441                 return 0;
 442
 443         level = btrfs_header_level(buf);
 444         nritems = btrfs_header_nritems(buf);
 445         for (i = 0; i < nritems; i++) {
 446                 if (level == 0) {
 447                         u64 disk_bytenr;
 448                         btrfs_item_key_to_cpu(buf, &key, i);
 449                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 450                                 continue;
 451                         fi = btrfs_item_ptr(buf, i,
 452                                             struct btrfs_file_extent_item);
 453                         if (btrfs_file_extent_type(buf, fi) ==
 454                             BTRFS_FILE_EXTENT_INLINE)
 455                                 continue;
 456                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 457                         if (disk_bytenr == 0)
 458                                 continue;
 459                         ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
 460                                     btrfs_file_extent_disk_num_bytes(buf, fi));
 461                         if (ret) {
 462                                 faili = i;
 463                                 goto fail;
 464                         }
 465                 } else {
 466                         bytenr = btrfs_node_blockptr(buf, i);
 467                         ret = btrfs_inc_extent_ref(trans, root, bytenr,
 468                                            btrfs_level_size(root, level - 1));
 469                         if (ret) {
 470                                 faili = i;
 471                                 goto fail;
 472                         }
 473                 }
 474         }
 475         return 0;
 476 fail:
 477         WARN_ON(1);
 478         for (i =0; i < faili; i++) {
 479                 if (level == 0) {
 480                         u64 disk_bytenr;
 481                         btrfs_item_key_to_cpu(buf, &key, i);
 482                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 483                                 continue;
 484                         fi = btrfs_item_ptr(buf, i,
 485                                             struct btrfs_file_extent_item);
 486                         if (btrfs_file_extent_type(buf, fi) ==
 487                             BTRFS_FILE_EXTENT_INLINE)
 488                                 continue;
 489                         disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
 490                         if (disk_bytenr == 0)
 491                                 continue;
 492                         err = btrfs_free_extent(trans, root, disk_bytenr,
 493                                     btrfs_file_extent_disk_num_bytes(buf,
 494                                                                       fi), 0);
 495                         BUG_ON(err);
 496                 } else {
 497                         bytenr = btrfs_node_blockptr(buf, i);
 498                         err = btrfs_free_extent(trans, root, bytenr,
 499                                         btrfs_level_size(root, level - 1), 0);
 500                         BUG_ON(err);
 501                 }
 502         }
 503         return ret;
 504 }
 505
 506 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 507                                  struct btrfs_root *root,
 508                                  struct btrfs_path *path,
 509                                  struct btrfs_block_group_cache *cache)
 510 {
 511         int ret;
 512         int pending_ret;
 513         struct btrfs_root *extent_root = root->fs_info->extent_root;
 514         unsigned long bi;
 515         struct extent_buffer *leaf;
 516
 517         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 518         if (ret < 0)
 519                 goto fail;
 520         BUG_ON(ret);
 521
 522         leaf = path->nodes[0];
 523         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 524         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 525         btrfs_mark_buffer_dirty(leaf);
 526         btrfs_release_path(extent_root, path);
 527 fail:
 528         finish_current_insert(trans, extent_root);
 529         pending_ret = del_pending_extents(trans, extent_root);
 530         if (ret)
 531                 return ret;
 532         if (pending_ret)
 533                 return pending_ret;
 534         return 0;
 535
 536 }
 537
 538 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 539                                    struct btrfs_root *root)
 540 {
 541         struct extent_map_tree *block_group_cache;
 542         struct btrfs_block_group_cache *cache;
 543         int ret;
 544         int err = 0;
 545         int werr = 0;
 546         struct btrfs_path *path;
 547         u64 last = 0;
 548         u64 start;
 549         u64 end;
 550         u64 ptr;
 551
 552         block_group_cache = &root->fs_info->block_group_cache;
 553         path = btrfs_alloc_path();
 554         if (!path)
 555                 return -ENOMEM;
 556
 557         while(1) {
 558                 ret = find_first_extent_bit(block_group_cache, last,
 559                                             &start, &end, BLOCK_GROUP_DIRTY);
 560                 if (ret)
 561                         break;
 562
 563                 last = end + 1;
 564                 ret = get_state_private(block_group_cache, start, &ptr);
 565                 if (ret)
 566                         break;
 567
 568                 cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
 569                 err = write_one_cache_group(trans, root,
 570                                             path, cache);
 571                 /*
 572                  * if we fail to write the cache group, we want
 573                  * to keep it marked dirty in hopes that a later
 574                  * write will work
 575                  */
 576                 if (err) {
 577                         werr = err;
 578                         continue;
 579                 }
 580                 clear_extent_bits(block_group_cache, start, end,
 581                                   BLOCK_GROUP_DIRTY, GFP_NOFS);
 582         }
 583         btrfs_free_path(path);
 584         return werr;
 585 }
 586
 587 static int update_block_group(struct btrfs_trans_handle *trans,
 588                               struct btrfs_root *root,
 589                               u64 bytenr, u64 num_bytes, int alloc,
 590                               int mark_free, int data)
 591 {
 592         struct btrfs_block_group_cache *cache;
 593         struct btrfs_fs_info *info = root->fs_info;
 594         u64 total = num_bytes;
 595         u64 old_val;
 596         u64 byte_in_group;
 597         u64 start;
 598         u64 end;
 599
 600         while(total) {
 601                 cache = btrfs_lookup_block_group(info, bytenr);
 602                 if (!cache) {
 603                         return -1;
 604                 }
 605                 byte_in_group = bytenr - cache->key.objectid;
 606                 WARN_ON(byte_in_group > cache->key.offset);
 607                 start = cache->key.objectid;
 608                 end = start + cache->key.offset - 1;
 609                 set_extent_bits(&info->block_group_cache, start, end,
 610                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
 611
 612                 old_val = btrfs_block_group_used(&cache->item);
 613                 num_bytes = min(total, cache->key.offset - byte_in_group);
 614                 if (alloc) {
 615                         if (cache->data != data &&
 616                             old_val < (cache->key.offset >> 1)) {
 617                                 int bit_to_clear;
 618                                 int bit_to_set;
 619                                 cache->data = data;
 620                                 if (data) {
 621                                         bit_to_clear = BLOCK_GROUP_METADATA;
 622                                         bit_to_set = BLOCK_GROUP_DATA;
 623                                         cache->item.flags &=
 624                                                 ~BTRFS_BLOCK_GROUP_MIXED;
 625                                         cache->item.flags |=
 626                                                 BTRFS_BLOCK_GROUP_DATA;
 627                                 } else {
 628                                         bit_to_clear = BLOCK_GROUP_DATA;
 629                                         bit_to_set = BLOCK_GROUP_METADATA;
 630                                         cache->item.flags &=
 631                                                 ~BTRFS_BLOCK_GROUP_MIXED;
 632                                         cache->item.flags &=
 633                                                 ~BTRFS_BLOCK_GROUP_DATA;
 634                                 }
 635                                 clear_extent_bits(&info->block_group_cache,
 636                                                   start, end, bit_to_clear,
 637                                                   GFP_NOFS);
 638                                 set_extent_bits(&info->block_group_cache,
 639                                                 start, end, bit_to_set,
 640                                                 GFP_NOFS);
 641                         } else if (cache->data != data &&
 642                                    cache->data != BTRFS_BLOCK_GROUP_MIXED) {
 643                                 cache->data = BTRFS_BLOCK_GROUP_MIXED;
 644                                 set_extent_bits(&info->block_group_cache,
 645                                                 start, end,
 646                                                 BLOCK_GROUP_DATA |
 647                                                 BLOCK_GROUP_METADATA,
 648                                                 GFP_NOFS);
 649                         }
 650                         old_val += num_bytes;
 651                 } else {
 652                         old_val -= num_bytes;
 653                         if (mark_free) {
 654                                 set_extent_dirty(&info->free_space_cache,
 655                                                  bytenr, bytenr + num_bytes - 1,
 656                                                  GFP_NOFS);
 657                         }
 658                 }
 659                 btrfs_set_block_group_used(&cache->item, old_val);
 660                 total -= num_bytes;
 661                 bytenr += num_bytes;
 662         }
 663         return 0;
 664 }
 665 static int update_pinned_extents(struct btrfs_root *root,
 666                                 u64 bytenr, u64 num, int pin)
 667 {
 668         u64 len;
 669         struct btrfs_block_group_cache *cache;
 670         struct btrfs_fs_info *fs_info = root->fs_info;
 671
 672         if (pin) {
 673                 set_extent_dirty(&fs_info->pinned_extents,
 674                                 bytenr, bytenr + num - 1, GFP_NOFS);
 675         } else {
 676                 clear_extent_dirty(&fs_info->pinned_extents,
 677                                 bytenr, bytenr + num - 1, GFP_NOFS);
 678         }
 679         while (num > 0) {
 680                 cache = btrfs_lookup_block_group(fs_info, bytenr);
 681                 WARN_ON(!cache);
 682                 len = min(num, cache->key.offset -
 683                           (bytenr - cache->key.objectid));
 684                 if (pin) {
 685                         cache->pinned += len;
 686                         fs_info->total_pinned += len;
 687                 } else {
 688                         cache->pinned -= len;
 689                         fs_info->total_pinned -= len;
 690                 }
 691                 bytenr += len;
 692                 num -= len;
 693         }
 694         return 0;
 695 }
 696
 697 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
 698 {
 699         u64 last = 0;
 700         u64 start;
 701         u64 end;
 702         struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
 703         int ret;
 704
 705         while(1) {
 706                 ret = find_first_extent_bit(pinned_extents, last,
 707                                             &start, &end, EXTENT_DIRTY);
 708                 if (ret)
 709                         break;
 710                 set_extent_dirty(copy, start, end, GFP_NOFS);
 711                 last = end + 1;
 712         }
 713         return 0;
 714 }
 715
 716 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 717                                struct btrfs_root *root,
 718                                struct extent_map_tree *unpin)
 719 {
 720         u64 start;
 721         u64 end;
 722         int ret;
 723         struct extent_map_tree *free_space_cache;
 724         free_space_cache = &root->fs_info->free_space_cache;
 725
 726         while(1) {
 727                 ret = find_first_extent_bit(unpin, 0, &start, &end,
 728                                             EXTENT_DIRTY);
 729                 if (ret)
 730                         break;
 731                 update_pinned_extents(root, start, end + 1 - start, 0);
 732                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
 733                 set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
 734         }
 735         return 0;
 736 }
 737
 738 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 739                                  btrfs_root *extent_root)
 740 {
 741         struct btrfs_key ins;
 742         struct btrfs_extent_item extent_item;
 743         int ret;
 744         int err = 0;
 745         u64 start;
 746         u64 end;
 747         struct btrfs_fs_info *info = extent_root->fs_info;
 748
 749         btrfs_set_stack_extent_refs(&extent_item, 1);
 750         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
 751         btrfs_set_stack_extent_owner(&extent_item,
 752                                      extent_root->root_key.objectid);
 753
 754         while(1) {
 755                 ret = find_first_extent_bit(&info->extent_ins, 0, &start,
 756                                             &end, EXTENT_LOCKED);
 757                 if (ret)
 758                         break;
 759
 760                 ins.objectid = start;
 761                 ins.offset = end + 1 - start;
 762                 err = btrfs_insert_item(trans, extent_root, &ins,
 763                                         &extent_item, sizeof(extent_item));
 764                 clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
 765                                   GFP_NOFS);
 766         }
 767         return 0;
 768 }
 769
 770 static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
 771                           int pending)
 772 {
 773         int err = 0;
 774         struct extent_buffer *buf;
 775
 776         if (!pending) {
 777                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
 778                 if (buf) {
 779                         if (btrfs_buffer_uptodate(buf)) {
 780                                 u64 transid =
 781                                     root->fs_info->running_transaction->transid;
 782                                 if (btrfs_header_generation(buf) == transid) {
 783                                         free_extent_buffer(buf);
 784                                         return 1;
 785                                 }
 786                         }
 787                         free_extent_buffer(buf);
 788                 }
 789                 update_pinned_extents(root, bytenr, num_bytes, 1);
 790         } else {
 791                 set_extent_bits(&root->fs_info->pending_del,
 792                                 bytenr, bytenr + num_bytes - 1,
 793                                 EXTENT_LOCKED, GFP_NOFS);
 794         }
 795         BUG_ON(err < 0);
 796         return 0;
 797 }
 798
 799 /*
 800  * remove an extent from the root, returns 0 on success
 801  */
 802 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 803                          *root, u64 bytenr, u64 num_bytes, int pin,
 804                          int mark_free)
 805 {
 806         struct btrfs_path *path;
 807         struct btrfs_key key;
 808         struct btrfs_fs_info *info = root->fs_info;
 809         struct btrfs_root *extent_root = info->extent_root;
 810         struct extent_buffer *leaf;
 811         int ret;
 812         struct btrfs_extent_item *ei;
 813         u32 refs;
 814
 815         key.objectid = bytenr;
 816         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 817         key.offset = num_bytes;
 818
 819         path = btrfs_alloc_path();
 820         if (!path)
 821                 return -ENOMEM;
 822
 823         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
 824         if (ret < 0)
 825                 return ret;
 826         BUG_ON(ret);
 827
 828         leaf = path->nodes[0];
 829         ei = btrfs_item_ptr(leaf, path->slots[0],
 830                             struct btrfs_extent_item);
 831         refs = btrfs_extent_refs(leaf, ei);
 832         BUG_ON(refs == 0);
 833         refs -= 1;
 834         btrfs_set_extent_refs(leaf, ei, refs);
 835         btrfs_mark_buffer_dirty(leaf);
 836
 837         if (refs == 0) {
 838                 u64 super_used;
 839                 u64 root_used;
 840
 841                 if (pin) {
 842                         ret = pin_down_bytes(root, bytenr, num_bytes, 0);
 843                         if (ret > 0)
 844                                 mark_free = 1;
 845                         BUG_ON(ret < 0);
 846                 }
 847
 848                 /* block accounting for super block */
 849                 super_used = btrfs_super_bytes_used(&info->super_copy);
 850                 btrfs_set_super_bytes_used(&info->super_copy,
 851                                            super_used - num_bytes);
 852
 853                 /* block accounting for root item */
 854                 root_used = btrfs_root_used(&root->root_item);
 855                 btrfs_set_root_used(&root->root_item,
 856                                            root_used - num_bytes);
 857
 858                 ret = btrfs_del_item(trans, extent_root, path);
 859                 if (ret) {
 860                         return ret;
 861                 }
 862                 ret = update_block_group(trans, root, bytenr, num_bytes, 0,
 863                                          mark_free, 0);
 864                 BUG_ON(ret);
 865         }
 866         btrfs_free_path(path);
 867         finish_current_insert(trans, extent_root);
 868         return ret;
 869 }
 870
 871 /*
 872  * find all the blocks marked as pending in the radix tree and remove
 873  * them from the extent map
 874  */
 875 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 876                                btrfs_root *extent_root)
 877 {
 878         int ret;
 879         int err = 0;
 880         u64 start;
 881         u64 end;
 882         struct extent_map_tree *pending_del;
 883         struct extent_map_tree *pinned_extents;
 884
 885         pending_del = &extent_root->fs_info->pending_del;
 886         pinned_extents = &extent_root->fs_info->pinned_extents;
 887
 888         while(1) {
 889                 ret = find_first_extent_bit(pending_del, 0, &start, &end,
 890                                             EXTENT_LOCKED);
 891                 if (ret)
 892                         break;
 893                 update_pinned_extents(extent_root, start, end + 1 - start, 1);
 894                 clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
 895                                   GFP_NOFS);
 896                 ret = __free_extent(trans, extent_root,
 897                                      start, end + 1 - start, 0, 0);
 898                 if (ret)
 899                         err = ret;
 900         }
 901         return err;
 902 }
 903
 904 /*
 905  * remove an extent from the root, returns 0 on success
 906  */
 907 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 908                       *root, u64 bytenr, u64 num_bytes, int pin)
 909 {
 910         struct btrfs_root *extent_root = root->fs_info->extent_root;
 911         int pending_ret;
 912         int ret;
 913
 914         WARN_ON(num_bytes < root->sectorsize);
 915         if (root == extent_root) {
 916                 pin_down_bytes(root, bytenr, num_bytes, 1);
 917                 return 0;
 918         }
 919         ret = __free_extent(trans, root, bytenr, num_bytes, pin, pin == 0);
 920         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
 921         return ret ? ret : pending_ret;
 922 }
 923
 924 /*
 925  * walks the btree of allocated extents and find a hole of a given size.
 926  * The key ins is changed to record the hole:
 927  * ins->objectid == block start
 928  * ins->flags = BTRFS_EXTENT_ITEM_KEY
 929  * ins->offset == number of blocks
 930  * Any available blocks before search_start are skipped.
 931  */
 932 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 933                             *orig_root, u64 num_bytes, u64 empty_size,
 934                             u64 search_start, u64 search_end, u64 hint_byte,
 935                             struct btrfs_key *ins, u64 exclude_start,
 936                             u64 exclude_nr, int data)
 937 {
 938         struct btrfs_path *path;
 939         struct btrfs_key key;
 940         int ret;
 941         u64 hole_size = 0;
 942         int slot = 0;
 943         u64 last_byte = 0;
 944         u64 orig_search_start = search_start;
 945         int start_found;
 946         struct extent_buffer *l;
 947         struct btrfs_root * root = orig_root->fs_info->extent_root;
 948         struct btrfs_fs_info *info = root->fs_info;
 949         u64 total_needed = num_bytes;
 950         int level;
 951         struct btrfs_block_group_cache *block_group;
 952         int full_scan = 0;
 953         int wrapped = 0;
 954         u64 cached_start;
 955
 956         WARN_ON(num_bytes < root->sectorsize);
 957         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 958
 959         level = btrfs_header_level(root->node);
 960
 961         if (num_bytes >= 96 * 1024 * 1024 && hint_byte) {
 962                 data = BTRFS_BLOCK_GROUP_MIXED;
 963         }
 964
 965         if (search_end == (u64)-1)
 966                 search_end = btrfs_super_total_bytes(&info->super_copy);
 967         if (hint_byte) {
 968                 block_group = btrfs_lookup_block_group(info, hint_byte);
 969                 block_group = btrfs_find_block_group(root, block_group,
 970                                                      hint_byte, data, 1);
 971         } else {
 972                 block_group = btrfs_find_block_group(root,
 973                                                      trans->block_group, 0,
 974                                                      data, 1);
 975         }
 976
 977         total_needed += empty_size;
 978         path = btrfs_alloc_path();
 979 check_failed:
 980         search_start = find_search_start(root, &block_group, search_start,
 981                                          total_needed, data, full_scan);
 982         cached_start = search_start;
 983         btrfs_init_path(path);
 984         ins->objectid = search_start;
 985         ins->offset = 0;
 986         start_found = 0;
 987         path->reada = 2;
 988
 989         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
 990         if (ret < 0)
 991                 goto error;
 992
 993         if (path->slots[0] > 0) {
 994                 path->slots[0]--;
 995         }
 996
 997         l = path->nodes[0];
 998         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
 999
1000         /*
1001          * a rare case, go back one key if we hit a block group item
1002          * instead of an extent item
1003          */
1004         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY &&
1005             key.objectid + key.offset >= search_start) {
1006                 ins->objectid = key.objectid;
1007                 ins->offset = key.offset - 1;
1008                 btrfs_release_path(root, path);
1009                 ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1010                 if (ret < 0)
1011                         goto error;
1012
1013                 if (path->slots[0] > 0) {
1014                         path->slots[0]--;
1015                 }
1016         }
1017
1018         while (1) {
1019                 l = path->nodes[0];
1020                 slot = path->slots[0];
1021                 if (slot >= btrfs_header_nritems(l)) {
1022                         ret = btrfs_next_leaf(root, path);
1023                         if (ret == 0)
1024                                 continue;
1025                         if (ret < 0)
1026                                 goto error;
1027
1028                         search_start = max(search_start,
1029                                            block_group->key.objectid);
1030                         if (!start_found) {
1031                                 ins->objectid = search_start;
1032                                 ins->offset = search_end - search_start;
1033                                 start_found = 1;
1034                                 goto check_pending;
1035                         }
1036                         ins->objectid = last_byte > search_start ?
1037                                         last_byte : search_start;
1038                         ins->offset = search_end - ins->objectid;
1039                         BUG_ON(ins->objectid >= search_end);
1040                         goto check_pending;
1041                 }
1042                 btrfs_item_key_to_cpu(l, &key, slot);
1043
1044                 if (key.objectid >= search_start && key.objectid > last_byte &&
1045                     start_found) {
1046                         if (last_byte < search_start)
1047                                 last_byte = search_start;
1048                         hole_size = key.objectid - last_byte;
1049                         if (hole_size >= num_bytes) {
1050                                 ins->objectid = last_byte;
1051                                 ins->offset = hole_size;
1052                                 goto check_pending;
1053                         }
1054                 }
1055                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY) {
1056                         if (!start_found) {
1057                                 last_byte = key.objectid;
1058                                 start_found = 1;
1059                         }
1060                         goto next;
1061                 }
1062
1063
1064                 start_found = 1;
1065                 last_byte = key.objectid + key.offset;
1066
1067                 if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1068                     last_byte >= block_group->key.objectid +
1069                     block_group->key.offset) {
1070                         btrfs_release_path(root, path);
1071                         search_start = block_group->key.objectid +
1072                                 block_group->key.offset;
1073                         goto new_group;
1074                 }
1075 next:
1076                 path->slots[0]++;
1077                 cond_resched();
1078         }
1079 check_pending:
1080         /* we have to make sure we didn't find an extent that has already
1081          * been allocated by the map tree or the original allocation
1082          */
1083         btrfs_release_path(root, path);
1084         BUG_ON(ins->objectid < search_start);
1085
1086         if (ins->objectid + num_bytes >= search_end)
1087                 goto enospc;
1088         if (!full_scan && data != BTRFS_BLOCK_GROUP_MIXED &&
1089             ins->objectid + num_bytes > block_group->
1090             key.objectid + block_group->key.offset) {
1091                 search_start = block_group->key.objectid +
1092                         block_group->key.offset;
1093                 goto new_group;
1094         }
1095         if (test_range_bit(&info->extent_ins, ins->objectid,
1096                            ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
1097                 search_start = ins->objectid + num_bytes;
1098                 goto new_group;
1099         }
1100         if (test_range_bit(&info->pinned_extents, ins->objectid,
1101                            ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
1102                 search_start = ins->objectid + num_bytes;
1103                 goto new_group;
1104         }
1105         if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
1106             ins->objectid < exclude_start + exclude_nr)) {
1107                 search_start = exclude_start + exclude_nr;
1108                 goto new_group;
1109         }
1110         if (!data) {
1111                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1112                 if (block_group)
1113                         trans->block_group = block_group;
1114         }
1115         ins->offset = num_bytes;
1116         btrfs_free_path(path);
1117         return 0;
1118
1119 new_group:
1120         if (search_start + num_bytes >= search_end) {
1121 enospc:
1122                 search_start = orig_search_start;
1123                 if (full_scan) {
1124                         ret = -ENOSPC;
1125                         goto error;
1126                 }
1127                 if (wrapped) {
1128                         if (!full_scan)
1129                                 total_needed -= empty_size;
1130                         full_scan = 1;
1131                 } else
1132                         wrapped = 1;
1133         }
1134         block_group = btrfs_lookup_block_group(info, search_start);
1135         cond_resched();
1136         if (!full_scan)
1137                 block_group = btrfs_find_block_group(root, block_group,
1138                                                      search_start, data, 0);
1139         goto check_failed;
1140
1141 error:
1142         btrfs_release_path(root, path);
1143         btrfs_free_path(path);
1144         return ret;
1145 }
1146 /*
1147  * finds a free extent and does all the dirty work required for allocation
1148  * returns the key for the extent through ins, and a tree buffer for
1149  * the first block of the extent through buf.
1150  *
1151  * returns 0 if everything worked, non-zero otherwise.
1152  */
1153 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1154                        struct btrfs_root *root, u64 owner,
1155                        u64 num_bytes, u64 empty_size, u64 hint_byte,
1156                        u64 search_end, struct btrfs_key *ins, int data)
1157 {
1158         int ret;
1159         int pending_ret;
1160         u64 super_used, root_used;
1161         u64 search_start = 0;
1162         struct btrfs_fs_info *info = root->fs_info;
1163         struct btrfs_root *extent_root = info->extent_root;
1164         struct btrfs_extent_item extent_item;
1165
1166         btrfs_set_stack_extent_refs(&extent_item, 1);
1167         btrfs_set_stack_extent_owner(&extent_item, owner);
1168
1169         WARN_ON(num_bytes < root->sectorsize);
1170         ret = find_free_extent(trans, root, num_bytes, empty_size,
1171                                search_start, search_end, hint_byte, ins,
1172                                trans->alloc_exclude_start,
1173                                trans->alloc_exclude_nr, data);
1174         BUG_ON(ret);
1175         if (ret)
1176                 return ret;
1177
1178         /* block accounting for super block */
1179         super_used = btrfs_super_bytes_used(&info->super_copy);
1180         btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
1181
1182         /* block accounting for root item */
1183         root_used = btrfs_root_used(&root->root_item);
1184         btrfs_set_root_used(&root->root_item, root_used + num_bytes);
1185
1186         clear_extent_dirty(&root->fs_info->free_space_cache,
1187                            ins->objectid, ins->objectid + ins->offset - 1,
1188                            GFP_NOFS);
1189
1190         if (root == extent_root) {
1191                 set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
1192                                 ins->objectid + ins->offset - 1,
1193                                 EXTENT_LOCKED, GFP_NOFS);
1194                 WARN_ON(data == 1);
1195                 goto update_block;
1196         }
1197
1198         WARN_ON(trans->alloc_exclude_nr);
1199         trans->alloc_exclude_start = ins->objectid;
1200         trans->alloc_exclude_nr = ins->offset;
1201         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1202                                 sizeof(extent_item));
1203
1204         trans->alloc_exclude_start = 0;
1205         trans->alloc_exclude_nr = 0;
1206
1207         BUG_ON(ret);
1208         finish_current_insert(trans, extent_root);
1209         pending_ret = del_pending_extents(trans, extent_root);
1210
1211         if (ret) {
1212                 return ret;
1213         }
1214         if (pending_ret) {
1215                 return pending_ret;
1216         }
1217
1218 update_block:
1219         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1220                                  data);
1221         BUG_ON(ret);
1222         return 0;
1223 }
1224
1225 /*
1226  * helper function to allocate a block for a given tree
1227  * returns the tree buffer or NULL.
1228  */
1229 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1230                                              struct btrfs_root *root,
1231                                              u32 blocksize, u64 hint,
1232                                              u64 empty_size)
1233 {
1234         struct btrfs_key ins;
1235         int ret;
1236         struct extent_buffer *buf;
1237
1238         ret = btrfs_alloc_extent(trans, root, root->root_key.objectid,
1239                                  blocksize, empty_size, hint,
1240                                  (u64)-1, &ins, 0);
1241         if (ret) {
1242                 BUG_ON(ret > 0);
1243                 return ERR_PTR(ret);
1244         }
1245         buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
1246         if (!buf) {
1247                 btrfs_free_extent(trans, root, ins.objectid, blocksize, 0);
1248                 return ERR_PTR(-ENOMEM);
1249         }
1250         btrfs_set_buffer_uptodate(buf);
1251         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1252                          buf->start + buf->len - 1, GFP_NOFS);
1253         set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
1254                         buf->start, buf->start + buf->len - 1,
1255                         EXTENT_CSUM, GFP_NOFS);
1256         buf->flags |= EXTENT_CSUM;
1257         btrfs_set_buffer_defrag(buf);
1258         trans->blocks_used++;
1259         return buf;
1260 }
1261
1262 static int drop_leaf_ref(struct btrfs_trans_handle *trans,
1263                          struct btrfs_root *root, struct extent_buffer *leaf)
1264 {
1265         struct btrfs_key key;
1266         struct btrfs_file_extent_item *fi;
1267         int i;
1268         int nritems;
1269         int ret;
1270
1271         BUG_ON(!btrfs_is_leaf(leaf));
1272         nritems = btrfs_header_nritems(leaf);
1273         for (i = 0; i < nritems; i++) {
1274                 u64 disk_bytenr;
1275
1276                 btrfs_item_key_to_cpu(leaf, &key, i);
1277                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1278                         continue;
1279                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1280                 if (btrfs_file_extent_type(leaf, fi) ==
1281                     BTRFS_FILE_EXTENT_INLINE)
1282                         continue;
1283                 /*
1284                  * FIXME make sure to insert a trans record that
1285                  * repeats the snapshot del on crash
1286                  */
1287                 disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1288                 if (disk_bytenr == 0)
1289                         continue;
1290                 ret = btrfs_free_extent(trans, root, disk_bytenr,
1291                                 btrfs_file_extent_disk_num_bytes(leaf, fi), 0);
1292                 BUG_ON(ret);
1293         }
1294         return 0;
1295 }
1296
1297 static void reada_walk_down(struct btrfs_root *root,
1298                             struct extent_buffer *node)
1299 {
1300         int i;
1301         u32 nritems;
1302         u64 bytenr;
1303         int ret;
1304         u32 refs;
1305         int level;
1306         u32 blocksize;
1307
1308         nritems = btrfs_header_nritems(node);
1309         level = btrfs_header_level(node);
1310         for (i = 0; i < nritems; i++) {
1311                 bytenr = btrfs_node_blockptr(node, i);
1312                 blocksize = btrfs_level_size(root, level - 1);
1313                 ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);
1314                 BUG_ON(ret);
1315                 if (refs != 1)
1316                         continue;
1317                 mutex_unlock(&root->fs_info->fs_mutex);
1318                 ret = readahead_tree_block(root, bytenr, blocksize);
1319                 cond_resched();
1320                 mutex_lock(&root->fs_info->fs_mutex);
1321                 if (ret)
1322                         break;
1323         }
1324 }
1325
1326 /*
1327  * helper function for drop_snapshot, this walks down the tree dropping ref
1328  * counts as it goes.
1329  */
1330 static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1331                           *root, struct btrfs_path *path, int *level)
1332 {
1333         struct extent_buffer *next;
1334         struct extent_buffer *cur;
1335         u64 bytenr;
1336         u32 blocksize;
1337         int ret;
1338         u32 refs;
1339
1340         WARN_ON(*level < 0);
1341         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1342         ret = lookup_extent_ref(trans, root,
1343                                 path->nodes[*level]->start,
1344                                 path->nodes[*level]->len, &refs);
1345         BUG_ON(ret);
1346         if (refs > 1)
1347                 goto out;
1348
1349         /*
1350          * walk down to the last node level and free all the leaves
1351          */
1352         while(*level >= 0) {
1353                 WARN_ON(*level < 0);
1354                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1355                 cur = path->nodes[*level];
1356
1357                 if (*level > 0 && path->slots[*level] == 0)
1358                         reada_walk_down(root, cur);
1359
1360                 if (btrfs_header_level(cur) != *level)
1361                         WARN_ON(1);
1362
1363                 if (path->slots[*level] >=
1364                     btrfs_header_nritems(cur))
1365                         break;
1366                 if (*level == 0) {
1367                         ret = drop_leaf_ref(trans, root, cur);
1368                         BUG_ON(ret);
1369                         break;
1370                 }
1371                 bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
1372                 blocksize = btrfs_level_size(root, *level - 1);
1373                 ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
1374                 BUG_ON(ret);
1375                 if (refs != 1) {
1376                         path->slots[*level]++;
1377                         ret = btrfs_free_extent(trans, root, bytenr,
1378                                                 blocksize, 1);
1379                         BUG_ON(ret);
1380                         continue;
1381                 }
1382                 next = btrfs_find_tree_block(root, bytenr, blocksize);
1383                 if (!next || !btrfs_buffer_uptodate(next)) {
1384                         free_extent_buffer(next);
1385                         mutex_unlock(&root->fs_info->fs_mutex);
1386                         next = read_tree_block(root, bytenr, blocksize);
1387                         mutex_lock(&root->fs_info->fs_mutex);
1388
1389                         /* we dropped the lock, check one more time */
1390                         ret = lookup_extent_ref(trans, root, bytenr,
1391                                                 blocksize, &refs);
1392                         BUG_ON(ret);
1393                         if (refs != 1) {
1394                                 path->slots[*level]++;
1395                                 free_extent_buffer(next);
1396                                 ret = btrfs_free_extent(trans, root,
1397                                                         bytenr, blocksize, 1);
1398                                 BUG_ON(ret);
1399                                 continue;
1400                         }
1401                 }
1402                 WARN_ON(*level <= 0);
1403                 if (path->nodes[*level-1])
1404                         free_extent_buffer(path->nodes[*level-1]);
1405                 path->nodes[*level-1] = next;
1406                 *level = btrfs_header_level(next);
1407                 path->slots[*level] = 0;
1408         }
1409 out:
1410         WARN_ON(*level < 0);
1411         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1412         ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
1413                                 path->nodes[*level]->len, 1);
1414         free_extent_buffer(path->nodes[*level]);
1415         path->nodes[*level] = NULL;
1416         *level += 1;
1417         BUG_ON(ret);
1418         return 0;
1419 }
1420
1421 /*
1422  * helper for dropping snapshots.  This walks back up the tree in the path
1423  * to find the first node higher up where we haven't yet gone through
1424  * all the slots
1425  */
1426 static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1427                         *root, struct btrfs_path *path, int *level)
1428 {
1429         int i;
1430         int slot;
1431         int ret;
1432         struct btrfs_root_item *root_item = &root->root_item;
1433
1434         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1435                 slot = path->slots[i];
1436                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1437                         struct extent_buffer *node;
1438                         struct btrfs_disk_key disk_key;
1439                         node = path->nodes[i];
1440                         path->slots[i]++;
1441                         *level = i;
1442                         WARN_ON(*level == 0);
1443                         btrfs_node_key(node, &disk_key, path->slots[i]);
1444                         memcpy(&root_item->drop_progress,
1445                                &disk_key, sizeof(disk_key));
1446                         root_item->drop_level = i;
1447                         return 0;
1448                 } else {
1449                         ret = btrfs_free_extent(trans, root,
1450                                                 path->nodes[*level]->start,
1451                                                 path->nodes[*level]->len, 1);
1452                         BUG_ON(ret);
1453                         free_extent_buffer(path->nodes[*level]);
1454                         path->nodes[*level] = NULL;
1455                         *level = i + 1;
1456                 }
1457         }
1458         return 1;
1459 }
1460
1461 /*
1462  * drop the reference count on the tree rooted at 'snap'.  This traverses
1463  * the tree freeing any blocks that have a ref count of zero after being
1464  * decremented.
1465  */
1466 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
1467                         *root)
1468 {
1469         int ret = 0;
1470         int wret;
1471         int level;
1472         struct btrfs_path *path;
1473         int i;
1474         int orig_level;
1475         struct btrfs_root_item *root_item = &root->root_item;
1476
1477         path = btrfs_alloc_path();
1478         BUG_ON(!path);
1479
1480         level = btrfs_header_level(root->node);
1481         orig_level = level;
1482         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
1483                 path->nodes[level] = root->node;
1484                 extent_buffer_get(root->node);
1485                 path->slots[level] = 0;
1486         } else {
1487                 struct btrfs_key key;
1488                 struct btrfs_disk_key found_key;
1489                 struct extent_buffer *node;
1490
1491                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
1492                 level = root_item->drop_level;
1493                 path->lowest_level = level;
1494                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1495                 if (wret < 0) {
1496                         ret = wret;
1497                         goto out;
1498                 }
1499                 node = path->nodes[level];
1500                 btrfs_node_key(node, &found_key, path->slots[level]);
1501                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
1502                                sizeof(found_key)));
1503         }
1504         while(1) {
1505                 wret = walk_down_tree(trans, root, path, &level);
1506                 if (wret > 0)
1507                         break;
1508                 if (wret < 0)
1509                         ret = wret;
1510
1511                 wret = walk_up_tree(trans, root, path, &level);
1512                 if (wret > 0)
1513                         break;
1514                 if (wret < 0)
1515                         ret = wret;
1516                 ret = -EAGAIN;
1517                 break;
1518         }
1519         for (i = 0; i <= orig_level; i++) {
1520                 if (path->nodes[i]) {
1521                         free_extent_buffer(path->nodes[i]);
1522                         path->nodes[i] = NULL;
1523                 }
1524         }
1525 out:
1526         btrfs_free_path(path);
1527         return ret;
1528 }
1529
1530 int btrfs_free_block_groups(struct btrfs_fs_info *info)
1531 {
1532         u64 start;
1533         u64 end;
1534         u64 ptr;
1535         int ret;
1536         while(1) {
1537                 ret = find_first_extent_bit(&info->block_group_cache, 0,
1538                                             &start, &end, (unsigned int)-1);
1539                 if (ret)
1540                         break;
1541                 ret = get_state_private(&info->block_group_cache, start, &ptr);
1542                 if (!ret)
1543                         kfree((void *)(unsigned long)ptr);
1544                 clear_extent_bits(&info->block_group_cache, start,
1545                                   end, (unsigned int)-1, GFP_NOFS);
1546         }
1547         while(1) {
1548                 ret = find_first_extent_bit(&info->free_space_cache, 0,
1549                                             &start, &end, EXTENT_DIRTY);
1550                 if (ret)
1551                         break;
1552                 clear_extent_dirty(&info->free_space_cache, start,
1553                                    end, GFP_NOFS);
1554         }
1555         return 0;
1556 }
1557
1558 int btrfs_read_block_groups(struct btrfs_root *root)
1559 {
1560         struct btrfs_path *path;
1561         int ret;
1562         int err = 0;
1563         int bit;
1564         struct btrfs_block_group_cache *cache;
1565         struct btrfs_fs_info *info = root->fs_info;
1566         struct extent_map_tree *block_group_cache;
1567         struct btrfs_key key;
1568         struct btrfs_key found_key;
1569         struct extent_buffer *leaf;
1570
1571         block_group_cache = &info->block_group_cache;
1572
1573         root = info->extent_root;
1574         key.objectid = 0;
1575         key.offset = BTRFS_BLOCK_GROUP_SIZE;
1576         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
1577
1578         path = btrfs_alloc_path();
1579         if (!path)
1580                 return -ENOMEM;
1581
1582         while(1) {
1583                 ret = btrfs_search_slot(NULL, info->extent_root,
1584                                         &key, path, 0, 0);
1585                 if (ret != 0) {
1586                         err = ret;
1587                         break;
1588                 }
1589                 leaf = path->nodes[0];
1590                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1591                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
1592                 if (!cache) {
1593                         err = -1;
1594                         break;
1595                 }
1596
1597                 read_extent_buffer(leaf, &cache->item,
1598                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
1599                                    sizeof(cache->item));
1600                 memcpy(&cache->key, &found_key, sizeof(found_key));
1601                 cache->cached = 0;
1602                 cache->pinned = 0;
1603                 key.objectid = found_key.objectid + found_key.offset;
1604                 btrfs_release_path(root, path);
1605
1606                 if (cache->item.flags & BTRFS_BLOCK_GROUP_MIXED) {
1607                         bit = BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA;
1608                         cache->data = BTRFS_BLOCK_GROUP_MIXED;
1609                 } else if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
1610                         bit = BLOCK_GROUP_DATA;
1611                         cache->data = BTRFS_BLOCK_GROUP_DATA;
1612                 } else {
1613                         bit = BLOCK_GROUP_METADATA;
1614                         cache->data = 0;
1615                 }
1616
1617                 /* use EXTENT_LOCKED to prevent merging */
1618                 set_extent_bits(block_group_cache, found_key.objectid,
1619                                 found_key.objectid + found_key.offset - 1,
1620                                 bit | EXTENT_LOCKED, GFP_NOFS);
1621                 set_state_private(block_group_cache, found_key.objectid,
1622                                   (unsigned long)cache);
1623
1624                 if (key.objectid >=
1625                     btrfs_super_total_bytes(&info->super_copy))
1626                         break;
1627         }
1628
1629         btrfs_free_path(path);
1630         return 0;
1631 }