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 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
  26                                  btrfs_root *extent_root);
  27 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
  28                                btrfs_root *extent_root);
  29
  30 static int cache_block_group(struct btrfs_root *root,
  31                              struct btrfs_block_group_cache *block_group)
  32 {
  33         struct btrfs_path *path;
  34         int ret;
  35         struct btrfs_key key;
  36         struct extent_buffer *leaf;
  37         struct extent_map_tree *free_space_cache;
  38         int slot;
  39         u64 last = 0;
  40         u64 hole_size;
  41         u64 first_free;
  42         int found = 0;
  43
  44         root = root->fs_info->extent_root;
  45         free_space_cache = &root->fs_info->free_space_cache;
  46
  47         if (block_group->cached)
  48                 return 0;
  49
  50         path = btrfs_alloc_path();
  51         if (!path)
  52                 return -ENOMEM;
  53
  54         path->reada = 2;
  55         first_free = block_group->key.objectid;
  56         key.objectid = block_group->key.objectid;
  57         key.offset = 0;
  58
  59         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
  60         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  61
  62         if (ret < 0)
  63                 return ret;
  64
  65         if (ret && path->slots[0] > 0)
  66                 path->slots[0]--;
  67
  68         while(1) {
  69                 leaf = path->nodes[0];
  70                 slot = path->slots[0];
  71                 if (slot >= btrfs_header_nritems(leaf)) {
  72                         ret = btrfs_next_leaf(root, path);
  73                         if (ret < 0)
  74                                 goto err;
  75                         if (ret == 0) {
  76                                 continue;
  77                         } else {
  78                                 break;
  79                         }
  80                 }
  81
  82                 btrfs_item_key_to_cpu(leaf, &key, slot);
  83                 if (key.objectid < block_group->key.objectid) {
  84                         if (key.objectid + key.offset > first_free)
  85                                 first_free = key.objectid + key.offset;
  86                         goto next;
  87                 }
  88
  89                 if (key.objectid >= block_group->key.objectid +
  90                     block_group->key.offset) {
  91                         break;
  92                 }
  93
  94                 if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
  95                         if (!found) {
  96                                 last = first_free;
  97                                 found = 1;
  98                         }
  99                         if (key.objectid > last) {
 100                                 hole_size = key.objectid - last;
 101                                 set_extent_dirty(free_space_cache, last,
 102                                                  last + hole_size - 1,
 103                                                  GFP_NOFS);
 104                         }
 105                         last = key.objectid + key.offset;
 106                 }
 107 next:
 108                 path->slots[0]++;
 109         }
 110
 111         if (!found)
 112                 last = first_free;
 113         if (block_group->key.objectid +
 114             block_group->key.offset > last) {
 115                 hole_size = block_group->key.objectid +
 116                         block_group->key.offset - last;
 117                 set_extent_dirty(free_space_cache, last,
 118                                  last + hole_size - 1, GFP_NOFS);
 119         }
 120         block_group->cached = 1;
 121 err:
 122         btrfs_free_path(path);
 123         return 0;
 124 }
 125
 126 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 127                                                          btrfs_fs_info *info,
 128                                                          u64 blocknr)
 129 {
 130         struct btrfs_block_group_cache *block_group;
 131         int ret;
 132
 133         ret = radix_tree_gang_lookup(&info->block_group_radix,
 134                                      (void **)&block_group,
 135                                      blocknr, 1);
 136         if (ret) {
 137                 if (block_group->key.objectid <= blocknr && blocknr <=
 138                     block_group->key.objectid + block_group->key.offset)
 139                         return block_group;
 140         }
 141         ret = radix_tree_gang_lookup(&info->block_group_data_radix,
 142                                      (void **)&block_group,
 143                                      blocknr, 1);
 144         if (ret) {
 145                 if (block_group->key.objectid <= blocknr && blocknr <=
 146                     block_group->key.objectid + block_group->key.offset)
 147                         return block_group;
 148         }
 149         return NULL;
 150 }
 151
 152 static u64 find_search_start(struct btrfs_root *root,
 153                              struct btrfs_block_group_cache **cache_ret,
 154                              u64 search_start, int num, int data)
 155 {
 156         int ret;
 157         struct btrfs_block_group_cache *cache = *cache_ret;
 158         u64 last = max(search_start, cache->key.objectid);
 159         u64 start = 0;
 160         u64 end = 0;
 161
 162 again:
 163         ret = cache_block_group(root, cache);
 164         if (ret)
 165                 goto out;
 166         while(1) {
 167                 ret = find_first_extent_bit(&root->fs_info->free_space_cache,
 168                                             last, &start, &end, EXTENT_DIRTY);
 169                 if (ret)
 170                         goto out;
 171
 172                 start = max(last, start);
 173                 last = end + 1;
 174                 if (end + 1 - start < num)
 175                         continue;
 176                 if (start + num > cache->key.objectid + cache->key.offset)
 177                         goto new_group;
 178                 return start;
 179         }
 180 out:
 181         return max(cache->last_alloc, search_start);
 182
 183 new_group:
 184         cache = btrfs_lookup_block_group(root->fs_info,
 185                                          last + cache->key.offset - 1);
 186         if (!cache) {
 187                 return max((*cache_ret)->last_alloc, search_start);
 188         }
 189         cache = btrfs_find_block_group(root, cache,
 190                                        last + cache->key.offset - 1, data, 0);
 191         *cache_ret = cache;
 192         goto again;
 193 }
 194
 195 static u64 div_factor(u64 num, int factor)
 196 {
 197         num *= factor;
 198         do_div(num, 10);
 199         return num;
 200 }
 201
 202 struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 203                                                  struct btrfs_block_group_cache
 204                                                  *hint, u64 search_start,
 205                                                  int data, int owner)
 206 {
 207         struct btrfs_block_group_cache *cache[8];
 208         struct btrfs_block_group_cache *found_group = NULL;
 209         struct btrfs_fs_info *info = root->fs_info;
 210         struct radix_tree_root *radix;
 211         struct radix_tree_root *swap_radix;
 212         u64 used;
 213         u64 last = 0;
 214         u64 hint_last;
 215         int i;
 216         int ret;
 217         int full_search = 0;
 218         int factor = 8;
 219         int data_swap = 0;
 220
 221         if (!owner)
 222                 factor = 5;
 223
 224         if (data) {
 225                 radix = &info->block_group_data_radix;
 226                 swap_radix = &info->block_group_radix;
 227         } else {
 228                 radix = &info->block_group_radix;
 229                 swap_radix = &info->block_group_data_radix;
 230         }
 231
 232         if (search_start) {
 233                 struct btrfs_block_group_cache *shint;
 234                 shint = btrfs_lookup_block_group(info, search_start);
 235                 if (shint && shint->data == data) {
 236                         used = btrfs_block_group_used(&shint->item);
 237                         if (used + shint->pinned <
 238                             div_factor(shint->key.offset, factor)) {
 239                                 return shint;
 240                         }
 241                 }
 242         }
 243         if (hint && hint->data == data) {
 244                 used = btrfs_block_group_used(&hint->item);
 245                 if (used + hint->pinned <
 246                     div_factor(hint->key.offset, factor)) {
 247                         return hint;
 248                 }
 249                 if (used >= div_factor(hint->key.offset, 8)) {
 250                         radix_tree_tag_clear(radix,
 251                                              hint->key.objectid +
 252                                              hint->key.offset - 1,
 253                                              BTRFS_BLOCK_GROUP_AVAIL);
 254                 }
 255                 last = hint->key.offset * 3;
 256                 if (hint->key.objectid >= last)
 257                         last = max(search_start + hint->key.offset - 1,
 258                                    hint->key.objectid - last);
 259                 else
 260                         last = hint->key.objectid + hint->key.offset;
 261                 hint_last = last;
 262         } else {
 263                 if (hint)
 264                         hint_last = max(hint->key.objectid, search_start);
 265                 else
 266                         hint_last = search_start;
 267
 268                 last = hint_last;
 269         }
 270         while(1) {
 271                 ret = radix_tree_gang_lookup_tag(radix, (void **)cache,
 272                                                  last, ARRAY_SIZE(cache),
 273                                                  BTRFS_BLOCK_GROUP_AVAIL);
 274                 if (!ret)
 275                         break;
 276                 for (i = 0; i < ret; i++) {
 277                         last = cache[i]->key.objectid +
 278                                 cache[i]->key.offset;
 279                         used = btrfs_block_group_used(&cache[i]->item);
 280                         if (used + cache[i]->pinned <
 281                             div_factor(cache[i]->key.offset, factor)) {
 282                                 found_group = cache[i];
 283                                 goto found;
 284                         }
 285                         if (used >= div_factor(cache[i]->key.offset, 8)) {
 286                                 radix_tree_tag_clear(radix,
 287                                                      cache[i]->key.objectid +
 288                                                      cache[i]->key.offset - 1,
 289                                                      BTRFS_BLOCK_GROUP_AVAIL);
 290                         }
 291                 }
 292                 cond_resched();
 293         }
 294         last = hint_last;
 295 again:
 296         while(1) {
 297                 ret = radix_tree_gang_lookup(radix, (void **)cache,
 298                                              last, ARRAY_SIZE(cache));
 299                 if (!ret)
 300                         break;
 301                 for (i = 0; i < ret; i++) {
 302                         last = cache[i]->key.objectid +
 303                                 cache[i]->key.offset;
 304                         used = btrfs_block_group_used(&cache[i]->item);
 305                         if (used + cache[i]->pinned < cache[i]->key.offset) {
 306                                 found_group = cache[i];
 307                                 goto found;
 308                         }
 309                         if (used >= cache[i]->key.offset) {
 310                                 radix_tree_tag_clear(radix,
 311                                                      cache[i]->key.objectid +
 312                                                      cache[i]->key.offset - 1,
 313                                                      BTRFS_BLOCK_GROUP_AVAIL);
 314                         }
 315                 }
 316                 cond_resched();
 317         }
 318         if (!full_search) {
 319                 last = search_start;
 320                 full_search = 1;
 321                 goto again;
 322         }
 323         if (!data_swap) {
 324                 struct radix_tree_root *tmp = radix;
 325                 data_swap = 1;
 326                 radix = swap_radix;
 327                 swap_radix = tmp;
 328                 last = search_start;
 329                 goto again;
 330         }
 331         if (!found_group) {
 332                 ret = radix_tree_gang_lookup(radix,
 333                                              (void **)&found_group, 0, 1);
 334                 if (ret == 0) {
 335                         ret = radix_tree_gang_lookup(swap_radix,
 336                                                      (void **)&found_group,
 337                                                      0, 1);
 338                 }
 339                 BUG_ON(ret != 1);
 340         }
 341 found:
 342         return found_group;
 343 }
 344
 345 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 346                                 struct btrfs_root *root,
 347                                 u64 blocknr, u64 num_blocks)
 348 {
 349         struct btrfs_path *path;
 350         int ret;
 351         struct btrfs_key key;
 352         struct extent_buffer *l;
 353         struct btrfs_extent_item *item;
 354         u32 refs;
 355
 356         path = btrfs_alloc_path();
 357         if (!path)
 358                 return -ENOMEM;
 359
 360         key.objectid = blocknr;
 361         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 362         key.offset = num_blocks;
 363         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 364                                 0, 1);
 365         if (ret < 0)
 366                 return ret;
 367         if (ret != 0) {
 368                 BUG();
 369         }
 370         BUG_ON(ret != 0);
 371         l = path->nodes[0];
 372         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 373         refs = btrfs_extent_refs(l, item);
 374         btrfs_set_extent_refs(l, item, refs + 1);
 375         btrfs_mark_buffer_dirty(path->nodes[0]);
 376
 377         btrfs_release_path(root->fs_info->extent_root, path);
 378         btrfs_free_path(path);
 379         finish_current_insert(trans, root->fs_info->extent_root);
 380         del_pending_extents(trans, root->fs_info->extent_root);
 381         return 0;
 382 }
 383
 384 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 385                          struct btrfs_root *root)
 386 {
 387         finish_current_insert(trans, root->fs_info->extent_root);
 388         del_pending_extents(trans, root->fs_info->extent_root);
 389         return 0;
 390 }
 391
 392 static int lookup_extent_ref(struct btrfs_trans_handle *trans,
 393                              struct btrfs_root *root, u64 blocknr,
 394                              u64 num_blocks, u32 *refs)
 395 {
 396         struct btrfs_path *path;
 397         int ret;
 398         struct btrfs_key key;
 399         struct extent_buffer *l;
 400         struct btrfs_extent_item *item;
 401
 402         path = btrfs_alloc_path();
 403         key.objectid = blocknr;
 404         key.offset = num_blocks;
 405         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 406         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
 407                                 0, 0);
 408         if (ret < 0)
 409                 goto out;
 410         if (ret != 0) {
 411                 btrfs_print_leaf(root, path->nodes[0]);
 412                 printk("failed to find block number %Lu\n", blocknr);
 413                 BUG();
 414         }
 415         l = path->nodes[0];
 416         item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
 417         *refs = btrfs_extent_refs(l, item);
 418 out:
 419         btrfs_free_path(path);
 420         return 0;
 421 }
 422
 423 int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
 424                        struct btrfs_root *root)
 425 {
 426         return btrfs_inc_extent_ref(trans, root,
 427                                     extent_buffer_blocknr(root->node), 1);
 428 }
 429
 430 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 431                   struct extent_buffer *buf)
 432 {
 433         u64 blocknr;
 434         u32 nritems;
 435         struct btrfs_key key;
 436         struct btrfs_file_extent_item *fi;
 437         int i;
 438         int leaf;
 439         int ret;
 440         int faili;
 441         int err;
 442
 443         if (!root->ref_cows)
 444                 return 0;
 445
 446         leaf = btrfs_is_leaf(buf);
 447         nritems = btrfs_header_nritems(buf);
 448         for (i = 0; i < nritems; i++) {
 449                 if (leaf) {
 450                         u64 disk_blocknr;
 451                         btrfs_item_key_to_cpu(buf, &key, i);
 452                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 453                                 continue;
 454                         fi = btrfs_item_ptr(buf, i,
 455                                             struct btrfs_file_extent_item);
 456                         if (btrfs_file_extent_type(buf, fi) ==
 457                             BTRFS_FILE_EXTENT_INLINE)
 458                                 continue;
 459                         disk_blocknr = btrfs_file_extent_disk_blocknr(buf, fi);
 460                         if (disk_blocknr == 0)
 461                                 continue;
 462                         ret = btrfs_inc_extent_ref(trans, root, disk_blocknr,
 463                                     btrfs_file_extent_disk_num_blocks(buf, fi));
 464                         if (ret) {
 465                                 faili = i;
 466                                 goto fail;
 467                         }
 468                 } else {
 469                         blocknr = btrfs_node_blockptr(buf, i);
 470                         ret = btrfs_inc_extent_ref(trans, root, blocknr, 1);
 471                         if (ret) {
 472                                 faili = i;
 473                                 goto fail;
 474                         }
 475                 }
 476         }
 477         return 0;
 478 fail:
 479         WARN_ON(1);
 480         for (i =0; i < faili; i++) {
 481                 if (leaf) {
 482                         u64 disk_blocknr;
 483                         btrfs_item_key_to_cpu(buf, &key, i);
 484                         if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
 485                                 continue;
 486                         fi = btrfs_item_ptr(buf, i,
 487                                             struct btrfs_file_extent_item);
 488                         if (btrfs_file_extent_type(buf, fi) ==
 489                             BTRFS_FILE_EXTENT_INLINE)
 490                                 continue;
 491                         disk_blocknr = btrfs_file_extent_disk_blocknr(buf, fi);
 492                         if (disk_blocknr == 0)
 493                                 continue;
 494                         err = btrfs_free_extent(trans, root, disk_blocknr,
 495                                     btrfs_file_extent_disk_num_blocks(buf,
 496                                                                       fi), 0);
 497                         BUG_ON(err);
 498                 } else {
 499                         blocknr = btrfs_node_blockptr(buf, i);
 500                         err = btrfs_free_extent(trans, root, blocknr, 1, 0);
 501                         BUG_ON(err);
 502                 }
 503         }
 504         return ret;
 505 }
 506
 507 static int write_one_cache_group(struct btrfs_trans_handle *trans,
 508                                  struct btrfs_root *root,
 509                                  struct btrfs_path *path,
 510                                  struct btrfs_block_group_cache *cache)
 511 {
 512         int ret;
 513         int pending_ret;
 514         struct btrfs_root *extent_root = root->fs_info->extent_root;
 515         unsigned long bi;
 516         struct extent_buffer *leaf;
 517
 518         ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
 519         if (ret < 0)
 520                 goto fail;
 521         BUG_ON(ret);
 522
 523         leaf = path->nodes[0];
 524         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
 525         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
 526         btrfs_mark_buffer_dirty(leaf);
 527         btrfs_release_path(extent_root, path);
 528 fail:
 529         finish_current_insert(trans, extent_root);
 530         pending_ret = del_pending_extents(trans, extent_root);
 531         if (ret)
 532                 return ret;
 533         if (pending_ret)
 534                 return pending_ret;
 535         if (cache->data)
 536                 cache->last_alloc = cache->first_free;
 537         return 0;
 538
 539 }
 540
 541 static int write_dirty_block_radix(struct btrfs_trans_handle *trans,
 542                                    struct btrfs_root *root,
 543                                    struct radix_tree_root *radix)
 544 {
 545         struct btrfs_block_group_cache *cache[8];
 546         int ret;
 547         int err = 0;
 548         int werr = 0;
 549         int i;
 550         struct btrfs_path *path;
 551         unsigned long off = 0;
 552
 553         path = btrfs_alloc_path();
 554         if (!path)
 555                 return -ENOMEM;
 556
 557         while(1) {
 558                 ret = radix_tree_gang_lookup_tag(radix, (void **)cache,
 559                                                  off, ARRAY_SIZE(cache),
 560                                                  BTRFS_BLOCK_GROUP_DIRTY);
 561                 if (!ret)
 562                         break;
 563                 for (i = 0; i < ret; i++) {
 564                         err = write_one_cache_group(trans, root,
 565                                                     path, cache[i]);
 566                         /*
 567                          * if we fail to write the cache group, we want
 568                          * to keep it marked dirty in hopes that a later
 569                          * write will work
 570                          */
 571                         if (err) {
 572                                 werr = err;
 573                                 off = cache[i]->key.objectid +
 574                                         cache[i]->key.offset;
 575                                 continue;
 576                         }
 577
 578                         radix_tree_tag_clear(radix, cache[i]->key.objectid +
 579                                              cache[i]->key.offset - 1,
 580                                              BTRFS_BLOCK_GROUP_DIRTY);
 581                 }
 582         }
 583         btrfs_free_path(path);
 584         return werr;
 585 }
 586
 587 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 588                                    struct btrfs_root *root)
 589 {
 590         int ret;
 591         int ret2;
 592         ret = write_dirty_block_radix(trans, root,
 593                                       &root->fs_info->block_group_radix);
 594         ret2 = write_dirty_block_radix(trans, root,
 595                                       &root->fs_info->block_group_data_radix);
 596         if (ret)
 597                 return ret;
 598         if (ret2)
 599                 return ret2;
 600         return 0;
 601 }
 602
 603 static int update_block_group(struct btrfs_trans_handle *trans,
 604                               struct btrfs_root *root,
 605                               u64 blocknr, u64 num, int alloc, int mark_free,
 606                               int data)
 607 {
 608         struct btrfs_block_group_cache *cache;
 609         struct btrfs_fs_info *info = root->fs_info;
 610         u64 total = num;
 611         u64 old_val;
 612         u64 block_in_group;
 613         int ret;
 614
 615         while(total) {
 616                 cache = btrfs_lookup_block_group(info, blocknr);
 617                 if (!cache) {
 618                         return -1;
 619                 }
 620                 block_in_group = blocknr - cache->key.objectid;
 621                 WARN_ON(block_in_group > cache->key.offset);
 622                 radix_tree_tag_set(cache->radix, cache->key.objectid +
 623                                    cache->key.offset - 1,
 624                                    BTRFS_BLOCK_GROUP_DIRTY);
 625
 626                 old_val = btrfs_block_group_used(&cache->item);
 627                 num = min(total, cache->key.offset - block_in_group);
 628                 if (alloc) {
 629                         if (blocknr > cache->last_alloc)
 630                                 cache->last_alloc = blocknr;
 631                         if (cache->data != data &&
 632                             old_val < (cache->key.offset >> 1)) {
 633                                 cache->data = data;
 634                                 radix_tree_delete(cache->radix,
 635                                                   cache->key.objectid +
 636                                                   cache->key.offset - 1);
 637
 638                                 if (data) {
 639                                         cache->radix =
 640                                                 &info->block_group_data_radix;
 641                                         cache->item.flags |=
 642                                                 BTRFS_BLOCK_GROUP_DATA;
 643                                 } else {
 644                                         cache->radix = &info->block_group_radix;
 645                                         cache->item.flags &=
 646                                                 ~BTRFS_BLOCK_GROUP_DATA;
 647                                 }
 648                                 ret = radix_tree_insert(cache->radix,
 649                                                         cache->key.objectid +
 650                                                         cache->key.offset - 1,
 651                                                         (void *)cache);
 652                         }
 653                         old_val += num;
 654                 } else {
 655                         old_val -= num;
 656                         if (blocknr < cache->first_free)
 657                                 cache->first_free = blocknr;
 658                         if (mark_free) {
 659                                 set_extent_dirty(&info->free_space_cache,
 660                                                  blocknr, blocknr + num - 1,
 661                                                  GFP_NOFS);
 662                         }
 663                         if (old_val < (cache->key.offset >> 1) &&
 664                             old_val + num >= (cache->key.offset >> 1)) {
 665                                 radix_tree_tag_set(cache->radix,
 666                                                    cache->key.objectid +
 667                                                    cache->key.offset - 1,
 668                                                    BTRFS_BLOCK_GROUP_AVAIL);
 669                         }
 670                 }
 671                 btrfs_set_block_group_used(&cache->item, old_val);
 672                 total -= num;
 673                 blocknr += num;
 674         }
 675         return 0;
 676 }
 677
 678 int btrfs_copy_pinned(struct btrfs_root *root, struct radix_tree_root *copy)
 679 {
 680         unsigned long gang[8];
 681         u64 last = 0;
 682         struct radix_tree_root *pinned_radix = &root->fs_info->pinned_radix;
 683         int ret;
 684         int i;
 685
 686         while(1) {
 687                 ret = find_first_radix_bit(pinned_radix, gang, last,
 688                                            ARRAY_SIZE(gang));
 689                 if (!ret)
 690                         break;
 691                 for (i = 0 ; i < ret; i++) {
 692                         set_radix_bit(copy, gang[i]);
 693                         last = gang[i] + 1;
 694                 }
 695         }
 696         ret = find_first_radix_bit(&root->fs_info->extent_ins_radix, gang, 0,
 697                                    ARRAY_SIZE(gang));
 698         WARN_ON(ret);
 699         return 0;
 700 }
 701
 702 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 703                                struct btrfs_root *root,
 704                                struct radix_tree_root *unpin_radix)
 705 {
 706         unsigned long gang[8];
 707         struct btrfs_block_group_cache *block_group;
 708         u64 first = 0;
 709         int ret;
 710         int i;
 711         struct radix_tree_root *pinned_radix = &root->fs_info->pinned_radix;
 712         struct extent_map_tree *free_space_cache;
 713
 714         free_space_cache = &root->fs_info->free_space_cache;
 715
 716         while(1) {
 717                 ret = find_first_radix_bit(unpin_radix, gang, 0,
 718                                            ARRAY_SIZE(gang));
 719                 if (!ret)
 720                         break;
 721                 if (!first)
 722                         first = gang[0];
 723                 for (i = 0; i < ret; i++) {
 724                         clear_radix_bit(pinned_radix, gang[i]);
 725                         clear_radix_bit(unpin_radix, gang[i]);
 726                         block_group = btrfs_lookup_block_group(root->fs_info,
 727                                                                gang[i]);
 728                         if (block_group) {
 729                                 WARN_ON(block_group->pinned == 0);
 730                                 block_group->pinned--;
 731                                 if (gang[i] < block_group->last_alloc)
 732                                         block_group->last_alloc = gang[i];
 733                                 if (!block_group->data) {
 734                                         set_extent_dirty(free_space_cache,
 735                                                          gang[i], gang[i],
 736                                                          GFP_NOFS);
 737                                 }
 738                         }
 739                 }
 740         }
 741         return 0;
 742 }
 743
 744 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
 745                                  btrfs_root *extent_root)
 746 {
 747         struct btrfs_key ins;
 748         struct btrfs_extent_item extent_item;
 749         int i;
 750         int ret;
 751         int err;
 752         unsigned long gang[8];
 753         struct btrfs_fs_info *info = extent_root->fs_info;
 754
 755         btrfs_set_stack_extent_refs(&extent_item, 1);
 756         ins.offset = 1;
 757         btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
 758         btrfs_set_stack_extent_owner(&extent_item,
 759                                      extent_root->root_key.objectid);
 760
 761         while(1) {
 762                 ret = find_first_radix_bit(&info->extent_ins_radix, gang, 0,
 763                                            ARRAY_SIZE(gang));
 764                 if (!ret)
 765                         break;
 766
 767                 for (i = 0; i < ret; i++) {
 768                         ins.objectid = gang[i];
 769                         err = btrfs_insert_item(trans, extent_root, &ins,
 770                                                 &extent_item,
 771                                                 sizeof(extent_item));
 772                         clear_radix_bit(&info->extent_ins_radix, gang[i]);
 773                         WARN_ON(err);
 774                 }
 775         }
 776         return 0;
 777 }
 778
 779 static int pin_down_block(struct btrfs_root *root, u64 blocknr, int pending)
 780 {
 781         int err;
 782         struct extent_buffer *buf;
 783
 784         if (!pending) {
 785                 buf = btrfs_find_tree_block(root, blocknr);
 786                 if (buf) {
 787                         if (btrfs_buffer_uptodate(buf)) {
 788                                 u64 transid =
 789                                     root->fs_info->running_transaction->transid;
 790                                 if (btrfs_header_generation(buf) == transid) {
 791                                         free_extent_buffer(buf);
 792                                         return 0;
 793                                 }
 794                         }
 795                         free_extent_buffer(buf);
 796                 }
 797                 err = set_radix_bit(&root->fs_info->pinned_radix, blocknr);
 798                 if (!err) {
 799                         struct btrfs_block_group_cache *cache;
 800                         cache = btrfs_lookup_block_group(root->fs_info,
 801                                                          blocknr);
 802                         if (cache)
 803                                 cache->pinned++;
 804                 }
 805         } else {
 806                 err = set_radix_bit(&root->fs_info->pending_del_radix, blocknr);
 807         }
 808         BUG_ON(err < 0);
 809         return 0;
 810 }
 811
 812 /*
 813  * remove an extent from the root, returns 0 on success
 814  */
 815 static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 816                          *root, u64 blocknr, u64 num_blocks, int pin,
 817                          int mark_free)
 818 {
 819         struct btrfs_path *path;
 820         struct btrfs_key key;
 821         struct btrfs_fs_info *info = root->fs_info;
 822         struct btrfs_root *extent_root = info->extent_root;
 823         struct extent_buffer *leaf;
 824         int ret;
 825         struct btrfs_extent_item *ei;
 826         u32 refs;
 827
 828         key.objectid = blocknr;
 829         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
 830         key.offset = num_blocks;
 831
 832         path = btrfs_alloc_path();
 833         if (!path)
 834                 return -ENOMEM;
 835
 836         ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
 837         if (ret < 0)
 838                 return ret;
 839         BUG_ON(ret);
 840
 841         leaf = path->nodes[0];
 842         ei = btrfs_item_ptr(leaf, path->slots[0],
 843                             struct btrfs_extent_item);
 844         refs = btrfs_extent_refs(leaf, ei);
 845         BUG_ON(refs == 0);
 846         refs -= 1;
 847         btrfs_set_extent_refs(leaf, ei, refs);
 848         btrfs_mark_buffer_dirty(leaf);
 849
 850         if (refs == 0) {
 851                 u64 super_blocks_used, root_blocks_used;
 852
 853                 if (pin) {
 854                         ret = pin_down_block(root, blocknr, 0);
 855                         BUG_ON(ret);
 856                 }
 857
 858                 /* block accounting for super block */
 859                 super_blocks_used = btrfs_super_blocks_used(&info->super_copy);
 860                 btrfs_set_super_blocks_used(&info->super_copy,
 861                                             super_blocks_used - num_blocks);
 862
 863                 /* block accounting for root item */
 864                 root_blocks_used = btrfs_root_used(&root->root_item);
 865                 btrfs_set_root_used(&root->root_item,
 866                                            root_blocks_used - num_blocks);
 867
 868                 ret = btrfs_del_item(trans, extent_root, path);
 869                 if (ret) {
 870                         return ret;
 871                 }
 872                 ret = update_block_group(trans, root, blocknr, num_blocks, 0,
 873                                          mark_free, 0);
 874                 BUG_ON(ret);
 875         }
 876         btrfs_free_path(path);
 877         finish_current_insert(trans, extent_root);
 878         return ret;
 879 }
 880
 881 /*
 882  * find all the blocks marked as pending in the radix tree and remove
 883  * them from the extent map
 884  */
 885 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 886                                btrfs_root *extent_root)
 887 {
 888         int ret;
 889         int wret;
 890         int err = 0;
 891         unsigned long gang[4];
 892         int i;
 893         struct radix_tree_root *pending_radix;
 894         struct radix_tree_root *pinned_radix;
 895         struct btrfs_block_group_cache *cache;
 896
 897         pending_radix = &extent_root->fs_info->pending_del_radix;
 898         pinned_radix = &extent_root->fs_info->pinned_radix;
 899
 900         while(1) {
 901                 ret = find_first_radix_bit(pending_radix, gang, 0,
 902                                            ARRAY_SIZE(gang));
 903                 if (!ret)
 904                         break;
 905                 for (i = 0; i < ret; i++) {
 906                         wret = set_radix_bit(pinned_radix, gang[i]);
 907                         if (wret == 0) {
 908                                 cache =
 909                                   btrfs_lookup_block_group(extent_root->fs_info,
 910                                                            gang[i]);
 911                                 if (cache)
 912                                         cache->pinned++;
 913                         }
 914                         if (wret < 0) {
 915                                 printk(KERN_CRIT "set_radix_bit, err %d\n",
 916                                        wret);
 917                                 BUG_ON(wret < 0);
 918                         }
 919                         wret = clear_radix_bit(pending_radix, gang[i]);
 920                         BUG_ON(wret);
 921                         wret = __free_extent(trans, extent_root,
 922                                              gang[i], 1, 0, 0);
 923                         if (wret)
 924                                 err = wret;
 925                 }
 926         }
 927         return err;
 928 }
 929
 930 /*
 931  * remove an extent from the root, returns 0 on success
 932  */
 933 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 934                       *root, u64 blocknr, u64 num_blocks, int pin)
 935 {
 936         struct btrfs_root *extent_root = root->fs_info->extent_root;
 937         int pending_ret;
 938         int ret;
 939
 940         if (root == extent_root) {
 941                 pin_down_block(root, blocknr, 1);
 942                 return 0;
 943         }
 944         ret = __free_extent(trans, root, blocknr, num_blocks, pin, pin == 0);
 945         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
 946         return ret ? ret : pending_ret;
 947 }
 948
 949 /*
 950  * walks the btree of allocated extents and find a hole of a given size.
 951  * The key ins is changed to record the hole:
 952  * ins->objectid == block start
 953  * ins->flags = BTRFS_EXTENT_ITEM_KEY
 954  * ins->offset == number of blocks
 955  * Any available blocks before search_start are skipped.
 956  */
 957 static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 958                             *orig_root, u64 num_blocks, u64 empty_size,
 959                             u64 search_start, u64 search_end, u64 hint_block,
 960                             struct btrfs_key *ins, u64 exclude_start,
 961                             u64 exclude_nr, int data)
 962 {
 963         struct btrfs_path *path;
 964         struct btrfs_key key;
 965         int ret;
 966         u64 hole_size = 0;
 967         int slot = 0;
 968         u64 last_block = 0;
 969         u64 test_block;
 970         u64 orig_search_start = search_start;
 971         int start_found;
 972         struct extent_buffer *l;
 973         struct btrfs_root * root = orig_root->fs_info->extent_root;
 974         struct btrfs_fs_info *info = root->fs_info;
 975         int total_needed = num_blocks;
 976         int level;
 977         struct btrfs_block_group_cache *block_group;
 978         int full_scan = 0;
 979         int wrapped = 0;
 980         u64 cached_search_start = 0;
 981
 982         WARN_ON(num_blocks < 1);
 983         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 984
 985         level = btrfs_header_level(root->node);
 986
 987         if (search_end == (u64)-1)
 988                 search_end = btrfs_super_total_blocks(&info->super_copy);
 989         if (hint_block) {
 990                 block_group = btrfs_lookup_block_group(info, hint_block);
 991                 block_group = btrfs_find_block_group(root, block_group,
 992                                                      hint_block, data, 1);
 993         } else {
 994                 block_group = btrfs_find_block_group(root,
 995                                                      trans->block_group, 0,
 996                                                      data, 1);
 997         }
 998
 999         total_needed += empty_size;
1000         path = btrfs_alloc_path();
1001
1002 check_failed:
1003         search_start = find_search_start(root, &block_group,
1004                                          search_start, total_needed, data);
1005         cached_search_start = search_start;
1006
1007         btrfs_init_path(path);
1008         ins->objectid = search_start;
1009         ins->offset = 0;
1010         start_found = 0;
1011         path->reada = 2;
1012
1013         ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1014         if (ret < 0)
1015                 goto error;
1016
1017         if (path->slots[0] > 0) {
1018                 path->slots[0]--;
1019         }
1020
1021         l = path->nodes[0];
1022         btrfs_item_key_to_cpu(l, &key, path->slots[0]);
1023
1024         /*
1025          * a rare case, go back one key if we hit a block group item
1026          * instead of an extent item
1027          */
1028         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY &&
1029             key.objectid + key.offset >= search_start) {
1030                 ins->objectid = key.objectid;
1031                 ins->offset = key.offset - 1;
1032                 btrfs_release_path(root, path);
1033                 ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
1034                 if (ret < 0)
1035                         goto error;
1036
1037                 if (path->slots[0] > 0) {
1038                         path->slots[0]--;
1039                 }
1040         }
1041
1042         while (1) {
1043                 l = path->nodes[0];
1044                 slot = path->slots[0];
1045                 if (slot >= btrfs_header_nritems(l)) {
1046                         ret = btrfs_next_leaf(root, path);
1047                         if (ret == 0)
1048                                 continue;
1049                         if (ret < 0)
1050                                 goto error;
1051                         if (!start_found) {
1052                                 ins->objectid = search_start;
1053                                 ins->offset = search_end - search_start;
1054                                 start_found = 1;
1055                                 goto check_pending;
1056                         }
1057                         ins->objectid = last_block > search_start ?
1058                                         last_block : search_start;
1059                         ins->offset = search_end - ins->objectid;
1060                         goto check_pending;
1061                 }
1062
1063                 btrfs_item_key_to_cpu(l, &key, slot);
1064                 if (key.objectid >= search_start && key.objectid > last_block &&
1065                     start_found) {
1066                         if (last_block < search_start)
1067                                 last_block = search_start;
1068                         hole_size = key.objectid - last_block;
1069                         if (hole_size >= num_blocks) {
1070                                 ins->objectid = last_block;
1071                                 ins->offset = hole_size;
1072                                 goto check_pending;
1073                         }
1074                 }
1075
1076                 if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
1077                         goto next;
1078
1079                 start_found = 1;
1080                 last_block = key.objectid + key.offset;
1081
1082                 if (!full_scan && last_block >= block_group->key.objectid +
1083                     block_group->key.offset) {
1084                         btrfs_release_path(root, path);
1085                         search_start = block_group->key.objectid +
1086                                 block_group->key.offset * 2;
1087                         goto new_group;
1088                 }
1089 next:
1090                 path->slots[0]++;
1091                 cond_resched();
1092         }
1093 check_pending:
1094         /* we have to make sure we didn't find an extent that has already
1095          * been allocated by the map tree or the original allocation
1096          */
1097         btrfs_release_path(root, path);
1098         BUG_ON(ins->objectid < search_start);
1099
1100         if (ins->objectid + num_blocks >= search_end)
1101                 goto enospc;
1102
1103         for (test_block = ins->objectid;
1104              test_block < ins->objectid + num_blocks; test_block++) {
1105                 if (test_radix_bit(&info->pinned_radix, test_block) ||
1106                     test_radix_bit(&info->extent_ins_radix, test_block)) {
1107                         search_start = test_block + 1;
1108                         goto new_group;
1109                 }
1110         }
1111         if (exclude_nr > 0 && (ins->objectid + num_blocks > exclude_start &&
1112             ins->objectid < exclude_start + exclude_nr)) {
1113                 search_start = exclude_start + exclude_nr;
1114                 goto new_group;
1115         }
1116         if (!data) {
1117                 block_group = btrfs_lookup_block_group(info, ins->objectid);
1118                 if (block_group)
1119                         trans->block_group = block_group;
1120         }
1121         ins->offset = num_blocks;
1122         btrfs_free_path(path);
1123         if (0 && ins->objectid != cached_search_start) {
1124 printk("\tcached was %Lu found %Lu\n", cached_search_start, ins->objectid);
1125         }
1126         return 0;
1127
1128 new_group:
1129         if (search_start + num_blocks >= search_end) {
1130 enospc:
1131                 search_start = orig_search_start;
1132                 if (full_scan) {
1133                         ret = -ENOSPC;
1134                         goto error;
1135                 }
1136                 if (wrapped) {
1137                         if (!full_scan)
1138                                 total_needed -= empty_size;
1139                         full_scan = 1;
1140                 } else
1141                         wrapped = 1;
1142         }
1143         block_group = btrfs_lookup_block_group(info, search_start);
1144         cond_resched();
1145         if (!full_scan)
1146                 block_group = btrfs_find_block_group(root, block_group,
1147                                                      search_start, data, 0);
1148         goto check_failed;
1149
1150 error:
1151         btrfs_release_path(root, path);
1152         btrfs_free_path(path);
1153         return ret;
1154 }
1155 /*
1156  * finds a free extent and does all the dirty work required for allocation
1157  * returns the key for the extent through ins, and a tree buffer for
1158  * the first block of the extent through buf.
1159  *
1160  * returns 0 if everything worked, non-zero otherwise.
1161  */
1162 int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
1163                        struct btrfs_root *root, u64 owner,
1164                        u64 num_blocks, u64 empty_size, u64 hint_block,
1165                        u64 search_end, struct btrfs_key *ins, int data)
1166 {
1167         int ret;
1168         int pending_ret;
1169         u64 super_blocks_used, root_blocks_used;
1170         u64 search_start = 0;
1171         struct btrfs_fs_info *info = root->fs_info;
1172         struct btrfs_root *extent_root = info->extent_root;
1173         struct btrfs_extent_item extent_item;
1174
1175         btrfs_set_stack_extent_refs(&extent_item, 1);
1176         btrfs_set_stack_extent_owner(&extent_item, owner);
1177
1178         WARN_ON(num_blocks < 1);
1179         ret = find_free_extent(trans, root, num_blocks, empty_size,
1180                                search_start, search_end, hint_block, ins,
1181                                trans->alloc_exclude_start,
1182                                trans->alloc_exclude_nr, data);
1183         BUG_ON(ret);
1184         if (ret)
1185                 return ret;
1186
1187         /* block accounting for super block */
1188         super_blocks_used = btrfs_super_blocks_used(&info->super_copy);
1189         btrfs_set_super_blocks_used(&info->super_copy, super_blocks_used +
1190                                     num_blocks);
1191
1192         /* block accounting for root item */
1193         root_blocks_used = btrfs_root_used(&root->root_item);
1194         btrfs_set_root_used(&root->root_item, root_blocks_used +
1195                                    num_blocks);
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                 BUG_ON(num_blocks != 1);
1203                 set_radix_bit(&root->fs_info->extent_ins_radix, ins->objectid);
1204                 goto update_block;
1205         }
1206
1207         WARN_ON(trans->alloc_exclude_nr);
1208         trans->alloc_exclude_start = ins->objectid;
1209         trans->alloc_exclude_nr = ins->offset;
1210         ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
1211                                 sizeof(extent_item));
1212
1213         trans->alloc_exclude_start = 0;
1214         trans->alloc_exclude_nr = 0;
1215
1216         BUG_ON(ret);
1217         finish_current_insert(trans, extent_root);
1218         pending_ret = del_pending_extents(trans, extent_root);
1219
1220         if (ret) {
1221                 return ret;
1222         }
1223         if (pending_ret) {
1224                 return pending_ret;
1225         }
1226
1227 update_block:
1228         ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0,
1229                                  data);
1230         BUG_ON(ret);
1231         return 0;
1232 }
1233
1234 /*
1235  * helper function to allocate a block for a given tree
1236  * returns the tree buffer or NULL.
1237  */
1238 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
1239                                              struct btrfs_root *root, u64 hint,
1240                                              u64 empty_size)
1241 {
1242         struct btrfs_key ins;
1243         int ret;
1244         struct extent_buffer *buf;
1245
1246         ret = btrfs_alloc_extent(trans, root, root->root_key.objectid,
1247                                  1, empty_size, hint, (u64)-1, &ins, 0);
1248         if (ret) {
1249                 BUG_ON(ret > 0);
1250                 return ERR_PTR(ret);
1251         }
1252         buf = btrfs_find_create_tree_block(root, ins.objectid);
1253         if (!buf) {
1254                 btrfs_free_extent(trans, root, ins.objectid, 1, 0);
1255                 return ERR_PTR(-ENOMEM);
1256         }
1257         btrfs_set_buffer_uptodate(buf);
1258         buf->alloc_addr = (unsigned long)__builtin_return_address(0);
1259         set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
1260                          buf->start + buf->len - 1, GFP_NOFS);
1261         /*
1262         set_buffer_checked(buf);
1263         set_buffer_defrag(buf);
1264         */
1265         /* FIXME!!!!!!!!!!!!!!!!
1266         set_radix_bit(&trans->transaction->dirty_pages, buf->pages[0]->index);
1267         */
1268         trans->blocks_used++;
1269         return buf;
1270 }
1271
1272 static int drop_leaf_ref(struct btrfs_trans_handle *trans,
1273                          struct btrfs_root *root, struct extent_buffer *leaf)
1274 {
1275         struct btrfs_key key;
1276         struct btrfs_file_extent_item *fi;
1277         int i;
1278         int nritems;
1279         int ret;
1280
1281         BUG_ON(!btrfs_is_leaf(leaf));
1282         nritems = btrfs_header_nritems(leaf);
1283         for (i = 0; i < nritems; i++) {
1284                 u64 disk_blocknr;
1285
1286                 btrfs_item_key_to_cpu(leaf, &key, i);
1287                 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
1288                         continue;
1289                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1290                 if (btrfs_file_extent_type(leaf, fi) ==
1291                     BTRFS_FILE_EXTENT_INLINE)
1292                         continue;
1293                 /*
1294                  * FIXME make sure to insert a trans record that
1295                  * repeats the snapshot del on crash
1296                  */
1297                 disk_blocknr = btrfs_file_extent_disk_blocknr(leaf, fi);
1298                 if (disk_blocknr == 0)
1299                         continue;
1300                 ret = btrfs_free_extent(trans, root, disk_blocknr,
1301                                 btrfs_file_extent_disk_num_blocks(leaf, fi), 0);
1302                 BUG_ON(ret);
1303         }
1304         return 0;
1305 }
1306
1307 static void reada_walk_down(struct btrfs_root *root,
1308                             struct extent_buffer *node)
1309 {
1310         int i;
1311         u32 nritems;
1312         u64 blocknr;
1313         int ret;
1314         u32 refs;
1315
1316         nritems = btrfs_header_nritems(node);
1317         for (i = 0; i < nritems; i++) {
1318                 blocknr = btrfs_node_blockptr(node, i);
1319                 ret = lookup_extent_ref(NULL, root, blocknr, 1, &refs);
1320                 BUG_ON(ret);
1321                 if (refs != 1)
1322                         continue;
1323                 mutex_unlock(&root->fs_info->fs_mutex);
1324                 ret = readahead_tree_block(root, blocknr);
1325                 cond_resched();
1326                 mutex_lock(&root->fs_info->fs_mutex);
1327                 if (ret)
1328                         break;
1329         }
1330 }
1331
1332 /*
1333  * helper function for drop_snapshot, this walks down the tree dropping ref
1334  * counts as it goes.
1335  */
1336 static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1337                           *root, struct btrfs_path *path, int *level)
1338 {
1339         struct extent_buffer *next;
1340         struct extent_buffer *cur;
1341         u64 blocknr;
1342         int ret;
1343         u32 refs;
1344
1345         WARN_ON(*level < 0);
1346         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1347         ret = lookup_extent_ref(trans, root,
1348                                 extent_buffer_blocknr(path->nodes[*level]),
1349                                 1, &refs);
1350         BUG_ON(ret);
1351         if (refs > 1)
1352                 goto out;
1353
1354         /*
1355          * walk down to the last node level and free all the leaves
1356          */
1357         while(*level >= 0) {
1358                 WARN_ON(*level < 0);
1359                 WARN_ON(*level >= BTRFS_MAX_LEVEL);
1360                 cur = path->nodes[*level];
1361
1362                 if (*level > 0 && path->slots[*level] == 0)
1363                         reada_walk_down(root, cur);
1364
1365                 if (btrfs_header_level(cur) != *level)
1366                         WARN_ON(1);
1367
1368                 if (path->slots[*level] >=
1369                     btrfs_header_nritems(cur))
1370                         break;
1371                 if (*level == 0) {
1372                         ret = drop_leaf_ref(trans, root, cur);
1373                         BUG_ON(ret);
1374                         break;
1375                 }
1376                 blocknr = btrfs_node_blockptr(cur, path->slots[*level]);
1377                 ret = lookup_extent_ref(trans, root, blocknr, 1, &refs);
1378                 BUG_ON(ret);
1379                 if (refs != 1) {
1380                         path->slots[*level]++;
1381                         ret = btrfs_free_extent(trans, root, blocknr, 1, 1);
1382                         BUG_ON(ret);
1383                         continue;
1384                 }
1385                 next = btrfs_find_tree_block(root, blocknr);
1386                 if (!next || !btrfs_buffer_uptodate(next)) {
1387                         free_extent_buffer(next);
1388                         mutex_unlock(&root->fs_info->fs_mutex);
1389                         next = read_tree_block(root, blocknr);
1390                         mutex_lock(&root->fs_info->fs_mutex);
1391
1392                         /* we dropped the lock, check one more time */
1393                         ret = lookup_extent_ref(trans, root, blocknr, 1, &refs);
1394                         BUG_ON(ret);
1395                         if (refs != 1) {
1396                                 path->slots[*level]++;
1397                                 free_extent_buffer(next);
1398                                 ret = btrfs_free_extent(trans, root,
1399                                                         blocknr, 1, 1);
1400                                 BUG_ON(ret);
1401                                 continue;
1402                         }
1403                 }
1404                 WARN_ON(*level <= 0);
1405                 if (path->nodes[*level-1])
1406                         free_extent_buffer(path->nodes[*level-1]);
1407                 path->nodes[*level-1] = next;
1408                 *level = btrfs_header_level(next);
1409                 path->slots[*level] = 0;
1410         }
1411 out:
1412         WARN_ON(*level < 0);
1413         WARN_ON(*level >= BTRFS_MAX_LEVEL);
1414         ret = btrfs_free_extent(trans, root,
1415                         extent_buffer_blocknr(path->nodes[*level]), 1, 1);
1416         free_extent_buffer(path->nodes[*level]);
1417         path->nodes[*level] = NULL;
1418         *level += 1;
1419         BUG_ON(ret);
1420         return 0;
1421 }
1422
1423 /*
1424  * helper for dropping snapshots.  This walks back up the tree in the path
1425  * to find the first node higher up where we haven't yet gone through
1426  * all the slots
1427  */
1428 static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
1429                         *root, struct btrfs_path *path, int *level)
1430 {
1431         int i;
1432         int slot;
1433         int ret;
1434         struct btrfs_root_item *root_item = &root->root_item;
1435
1436         for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
1437                 slot = path->slots[i];
1438                 if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
1439                         struct extent_buffer *node;
1440                         struct btrfs_disk_key disk_key;
1441                         node = path->nodes[i];
1442                         path->slots[i]++;
1443                         *level = i;
1444                         WARN_ON(*level == 0);
1445                         btrfs_node_key(node, &disk_key, path->slots[i]);
1446                         memcpy(&root_item->drop_progress,
1447                                &disk_key, sizeof(disk_key));
1448                         root_item->drop_level = i;
1449                         return 0;
1450                 } else {
1451                         ret = btrfs_free_extent(trans, root,
1452                                     extent_buffer_blocknr(path->nodes[*level]),
1453                                     1, 1);
1454                         BUG_ON(ret);
1455                         free_extent_buffer(path->nodes[*level]);
1456                         path->nodes[*level] = NULL;
1457                         *level = i + 1;
1458                 }
1459         }
1460         return 1;
1461 }
1462
1463 /*
1464  * drop the reference count on the tree rooted at 'snap'.  This traverses
1465  * the tree freeing any blocks that have a ref count of zero after being
1466  * decremented.
1467  */
1468 int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
1469                         *root)
1470 {
1471         int ret = 0;
1472         int wret;
1473         int level;
1474         struct btrfs_path *path;
1475         int i;
1476         int orig_level;
1477         struct btrfs_root_item *root_item = &root->root_item;
1478
1479         path = btrfs_alloc_path();
1480         BUG_ON(!path);
1481
1482         level = btrfs_header_level(root->node);
1483         orig_level = level;
1484         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
1485                 path->nodes[level] = root->node;
1486                 extent_buffer_get(root->node);
1487                 path->slots[level] = 0;
1488         } else {
1489                 struct btrfs_key key;
1490                 struct btrfs_disk_key found_key;
1491                 struct extent_buffer *node;
1492
1493                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
1494                 level = root_item->drop_level;
1495                 path->lowest_level = level;
1496                 wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1497                 if (wret < 0) {
1498                         ret = wret;
1499                         goto out;
1500                 }
1501                 node = path->nodes[level];
1502                 btrfs_node_key(node, &found_key, path->slots[level]);
1503                 WARN_ON(memcmp(&found_key, &root_item->drop_progress,
1504                                sizeof(found_key)));
1505         }
1506         while(1) {
1507                 wret = walk_down_tree(trans, root, path, &level);
1508                 if (wret > 0)
1509                         break;
1510                 if (wret < 0)
1511                         ret = wret;
1512
1513                 wret = walk_up_tree(trans, root, path, &level);
1514                 if (wret > 0)
1515                         break;
1516                 if (wret < 0)
1517                         ret = wret;
1518                 ret = -EAGAIN;
1519                 break;
1520         }
1521         for (i = 0; i <= orig_level; i++) {
1522                 if (path->nodes[i]) {
1523                         free_extent_buffer(path->nodes[i]);
1524                         path->nodes[i] = 0;
1525                 }
1526         }
1527 out:
1528         btrfs_free_path(path);
1529         return ret;
1530 }
1531
1532 static int free_block_group_radix(struct radix_tree_root *radix)
1533 {
1534         int ret;
1535         struct btrfs_block_group_cache *cache[8];
1536         int i;
1537
1538         while(1) {
1539                 ret = radix_tree_gang_lookup(radix, (void **)cache, 0,
1540                                              ARRAY_SIZE(cache));
1541                 if (!ret)
1542                         break;
1543                 for (i = 0; i < ret; i++) {
1544                         radix_tree_delete(radix, cache[i]->key.objectid +
1545                                           cache[i]->key.offset - 1);
1546                         kfree(cache[i]);
1547                 }
1548         }
1549         return 0;
1550 }
1551
1552 int btrfs_free_block_groups(struct btrfs_fs_info *info)
1553 {
1554         int ret;
1555         int ret2;
1556         u64 start;
1557         u64 end;
1558
1559         ret = free_block_group_radix(&info->block_group_radix);
1560         ret2 = free_block_group_radix(&info->block_group_data_radix);
1561         if (ret)
1562                 return ret;
1563         if (ret2)
1564                 return ret2;
1565
1566         while(1) {
1567                 ret = find_first_extent_bit(&info->free_space_cache, 0,
1568                                             &start, &end, EXTENT_DIRTY);
1569                 if (ret)
1570                         break;
1571                 clear_extent_dirty(&info->free_space_cache, start,
1572                                    end, GFP_NOFS);
1573         }
1574         return 0;
1575 }
1576
1577 int btrfs_read_block_groups(struct btrfs_root *root)
1578 {
1579         struct btrfs_path *path;
1580         int ret;
1581         int err = 0;
1582         struct btrfs_block_group_cache *cache;
1583         struct btrfs_fs_info *info = root->fs_info;
1584         struct radix_tree_root *radix;
1585         struct btrfs_key key;
1586         struct btrfs_key found_key;
1587         struct extent_buffer *leaf;
1588         u64 group_size_blocks;
1589         u64 used;
1590
1591         group_size_blocks = BTRFS_BLOCK_GROUP_SIZE >>
1592                 root->fs_info->sb->s_blocksize_bits;
1593         root = info->extent_root;
1594         key.objectid = 0;
1595         key.offset = group_size_blocks;
1596         btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
1597
1598         path = btrfs_alloc_path();
1599         if (!path)
1600                 return -ENOMEM;
1601
1602         while(1) {
1603                 ret = btrfs_search_slot(NULL, info->extent_root,
1604                                         &key, path, 0, 0);
1605                 if (ret != 0) {
1606                         err = ret;
1607                         break;
1608                 }
1609                 leaf = path->nodes[0];
1610                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1611                 cache = kmalloc(sizeof(*cache), GFP_NOFS);
1612                 if (!cache) {
1613                         err = -1;
1614                         break;
1615                 }
1616
1617                 read_extent_buffer(leaf, &cache->item,
1618                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
1619                                    sizeof(cache->item));
1620                 if (cache->item.flags & BTRFS_BLOCK_GROUP_DATA) {
1621                         radix = &info->block_group_data_radix;
1622                         cache->data = 1;
1623                 } else {
1624                         radix = &info->block_group_radix;
1625                         cache->data = 0;
1626                 }
1627
1628                 memcpy(&cache->key, &found_key, sizeof(found_key));
1629                 cache->last_alloc = cache->key.objectid;
1630                 cache->first_free = cache->key.objectid;
1631                 cache->pinned = 0;
1632                 cache->cached = 0;
1633
1634                 cache->radix = radix;
1635
1636                 key.objectid = found_key.objectid + found_key.offset;
1637                 btrfs_release_path(root, path);
1638
1639                 ret = radix_tree_insert(radix, found_key.objectid +
1640                                         found_key.offset - 1,
1641                                         (void *)cache);
1642                 BUG_ON(ret);
1643                 used = btrfs_block_group_used(&cache->item);
1644                 if (used < div_factor(key.offset, 8)) {
1645                         radix_tree_tag_set(radix, found_key.objectid +
1646                                            found_key.offset - 1,
1647                                            BTRFS_BLOCK_GROUP_AVAIL);
1648                 }
1649                 if (key.objectid >=
1650                     btrfs_super_total_blocks(&info->super_copy))
1651                         break;
1652         }
1653
1654         btrfs_free_path(path);
1655         return 0;
1656 }