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