fs/btrfs/free-space-tree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2015 Facebook.  All rights reserved.
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/sched/mm.h>
   8 #include "ctree.h"
   9 #include "disk-io.h"
  10 #include "locking.h"
  11 #include "free-space-tree.h"
  12 #include "transaction.h"
  13
  14 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
  15                                         struct btrfs_block_group_cache *block_group,
  16                                         struct btrfs_path *path);
  17
  18 void set_free_space_tree_thresholds(struct btrfs_block_group_cache *cache)
  19 {
  20         u32 bitmap_range;
  21         size_t bitmap_size;
  22         u64 num_bitmaps, total_bitmap_size;
  23
  24         /*
  25          * We convert to bitmaps when the disk space required for using extents
  26          * exceeds that required for using bitmaps.
  27          */
  28         bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
  29         num_bitmaps = div_u64(cache->key.offset + bitmap_range - 1,
  30                               bitmap_range);
  31         bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
  32         total_bitmap_size = num_bitmaps * bitmap_size;
  33         cache->bitmap_high_thresh = div_u64(total_bitmap_size,
  34                                             sizeof(struct btrfs_item));
  35
  36         /*
  37          * We allow for a small buffer between the high threshold and low
  38          * threshold to avoid thrashing back and forth between the two formats.
  39          */
  40         if (cache->bitmap_high_thresh > 100)
  41                 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
  42         else
  43                 cache->bitmap_low_thresh = 0;
  44 }
  45
  46 static int add_new_free_space_info(struct btrfs_trans_handle *trans,
  47                                    struct btrfs_block_group_cache *block_group,
  48                                    struct btrfs_path *path)
  49 {
  50         struct btrfs_root *root = trans->fs_info->free_space_root;
  51         struct btrfs_free_space_info *info;
  52         struct btrfs_key key;
  53         struct extent_buffer *leaf;
  54         int ret;
  55
  56         key.objectid = block_group->key.objectid;
  57         key.type = BTRFS_FREE_SPACE_INFO_KEY;
  58         key.offset = block_group->key.offset;
  59
  60         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
  61         if (ret)
  62                 goto out;
  63
  64         leaf = path->nodes[0];
  65         info = btrfs_item_ptr(leaf, path->slots[0],
  66                               struct btrfs_free_space_info);
  67         btrfs_set_free_space_extent_count(leaf, info, 0);
  68         btrfs_set_free_space_flags(leaf, info, 0);
  69         btrfs_mark_buffer_dirty(leaf);
  70
  71         ret = 0;
  72 out:
  73         btrfs_release_path(path);
  74         return ret;
  75 }
  76
  77 EXPORT_FOR_TESTS
  78 struct btrfs_free_space_info *search_free_space_info(
  79                 struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info,
  80                 struct btrfs_block_group_cache *block_group,
  81                 struct btrfs_path *path, int cow)
  82 {
  83         struct btrfs_root *root = fs_info->free_space_root;
  84         struct btrfs_key key;
  85         int ret;
  86
  87         key.objectid = block_group->key.objectid;
  88         key.type = BTRFS_FREE_SPACE_INFO_KEY;
  89         key.offset = block_group->key.offset;
  90
  91         ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
  92         if (ret < 0)
  93                 return ERR_PTR(ret);
  94         if (ret != 0) {
  95                 btrfs_warn(fs_info, "missing free space info for %llu",
  96                            block_group->key.objectid);
  97                 ASSERT(0);
  98                 return ERR_PTR(-ENOENT);
  99         }
 100
 101         return btrfs_item_ptr(path->nodes[0], path->slots[0],
 102                               struct btrfs_free_space_info);
 103 }
 104
 105 /*
 106  * btrfs_search_slot() but we're looking for the greatest key less than the
 107  * passed key.
 108  */
 109 static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
 110                                   struct btrfs_root *root,
 111                                   struct btrfs_key *key, struct btrfs_path *p,
 112                                   int ins_len, int cow)
 113 {
 114         int ret;
 115
 116         ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
 117         if (ret < 0)
 118                 return ret;
 119
 120         if (ret == 0) {
 121                 ASSERT(0);
 122                 return -EIO;
 123         }
 124
 125         if (p->slots[0] == 0) {
 126                 ASSERT(0);
 127                 return -EIO;
 128         }
 129         p->slots[0]--;
 130
 131         return 0;
 132 }
 133
 134 static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize)
 135 {
 136         return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE);
 137 }
 138
 139 static unsigned long *alloc_bitmap(u32 bitmap_size)
 140 {
 141         unsigned long *ret;
 142         unsigned int nofs_flag;
 143         u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
 144
 145         /*
 146          * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
 147          * into the filesystem as the free space bitmap can be modified in the
 148          * critical section of a transaction commit.
 149          *
 150          * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
 151          * know that recursion is unsafe.
 152          */
 153         nofs_flag = memalloc_nofs_save();
 154         ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
 155         memalloc_nofs_restore(nofs_flag);
 156         return ret;
 157 }
 158
 159 static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
 160 {
 161         u8 *p = ((u8 *)map) + BIT_BYTE(start);
 162         const unsigned int size = start + len;
 163         int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
 164         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
 165
 166         while (len - bits_to_set >= 0) {
 167                 *p |= mask_to_set;
 168                 len -= bits_to_set;
 169                 bits_to_set = BITS_PER_BYTE;
 170                 mask_to_set = ~0;
 171                 p++;
 172         }
 173         if (len) {
 174                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
 175                 *p |= mask_to_set;
 176         }
 177 }
 178
 179 EXPORT_FOR_TESTS
 180 int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 181                                   struct btrfs_block_group_cache *block_group,
 182                                   struct btrfs_path *path)
 183 {
 184         struct btrfs_fs_info *fs_info = trans->fs_info;
 185         struct btrfs_root *root = fs_info->free_space_root;
 186         struct btrfs_free_space_info *info;
 187         struct btrfs_key key, found_key;
 188         struct extent_buffer *leaf;
 189         unsigned long *bitmap;
 190         char *bitmap_cursor;
 191         u64 start, end;
 192         u64 bitmap_range, i;
 193         u32 bitmap_size, flags, expected_extent_count;
 194         u32 extent_count = 0;
 195         int done = 0, nr;
 196         int ret;
 197
 198         bitmap_size = free_space_bitmap_size(block_group->key.offset,
 199                                              fs_info->sectorsize);
 200         bitmap = alloc_bitmap(bitmap_size);
 201         if (!bitmap) {
 202                 ret = -ENOMEM;
 203                 goto out;
 204         }
 205
 206         start = block_group->key.objectid;
 207         end = block_group->key.objectid + block_group->key.offset;
 208
 209         key.objectid = end - 1;
 210         key.type = (u8)-1;
 211         key.offset = (u64)-1;
 212
 213         while (!done) {
 214                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 215                 if (ret)
 216                         goto out;
 217
 218                 leaf = path->nodes[0];
 219                 nr = 0;
 220                 path->slots[0]++;
 221                 while (path->slots[0] > 0) {
 222                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 223
 224                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
 225                                 ASSERT(found_key.objectid == block_group->key.objectid);
 226                                 ASSERT(found_key.offset == block_group->key.offset);
 227                                 done = 1;
 228                                 break;
 229                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
 230                                 u64 first, last;
 231
 232                                 ASSERT(found_key.objectid >= start);
 233                                 ASSERT(found_key.objectid < end);
 234                                 ASSERT(found_key.objectid + found_key.offset <= end);
 235
 236                                 first = div_u64(found_key.objectid - start,
 237                                                 fs_info->sectorsize);
 238                                 last = div_u64(found_key.objectid + found_key.offset - start,
 239                                                fs_info->sectorsize);
 240                                 le_bitmap_set(bitmap, first, last - first);
 241
 242                                 extent_count++;
 243                                 nr++;
 244                                 path->slots[0]--;
 245                         } else {
 246                                 ASSERT(0);
 247                         }
 248                 }
 249
 250                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
 251                 if (ret)
 252                         goto out;
 253                 btrfs_release_path(path);
 254         }
 255
 256         info = search_free_space_info(trans, fs_info, block_group, path, 1);
 257         if (IS_ERR(info)) {
 258                 ret = PTR_ERR(info);
 259                 goto out;
 260         }
 261         leaf = path->nodes[0];
 262         flags = btrfs_free_space_flags(leaf, info);
 263         flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
 264         btrfs_set_free_space_flags(leaf, info, flags);
 265         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
 266         btrfs_mark_buffer_dirty(leaf);
 267         btrfs_release_path(path);
 268
 269         if (extent_count != expected_extent_count) {
 270                 btrfs_err(fs_info,
 271                           "incorrect extent count for %llu; counted %u, expected %u",
 272                           block_group->key.objectid, extent_count,
 273                           expected_extent_count);
 274                 ASSERT(0);
 275                 ret = -EIO;
 276                 goto out;
 277         }
 278
 279         bitmap_cursor = (char *)bitmap;
 280         bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
 281         i = start;
 282         while (i < end) {
 283                 unsigned long ptr;
 284                 u64 extent_size;
 285                 u32 data_size;
 286
 287                 extent_size = min(end - i, bitmap_range);
 288                 data_size = free_space_bitmap_size(extent_size,
 289                                                    fs_info->sectorsize);
 290
 291                 key.objectid = i;
 292                 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
 293                 key.offset = extent_size;
 294
 295                 ret = btrfs_insert_empty_item(trans, root, path, &key,
 296                                               data_size);
 297                 if (ret)
 298                         goto out;
 299
 300                 leaf = path->nodes[0];
 301                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 302                 write_extent_buffer(leaf, bitmap_cursor, ptr,
 303                                     data_size);
 304                 btrfs_mark_buffer_dirty(leaf);
 305                 btrfs_release_path(path);
 306
 307                 i += extent_size;
 308                 bitmap_cursor += data_size;
 309         }
 310
 311         ret = 0;
 312 out:
 313         kvfree(bitmap);
 314         if (ret)
 315                 btrfs_abort_transaction(trans, ret);
 316         return ret;
 317 }
 318
 319 EXPORT_FOR_TESTS
 320 int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 321                                   struct btrfs_block_group_cache *block_group,
 322                                   struct btrfs_path *path)
 323 {
 324         struct btrfs_fs_info *fs_info = trans->fs_info;
 325         struct btrfs_root *root = fs_info->free_space_root;
 326         struct btrfs_free_space_info *info;
 327         struct btrfs_key key, found_key;
 328         struct extent_buffer *leaf;
 329         unsigned long *bitmap;
 330         u64 start, end;
 331         u32 bitmap_size, flags, expected_extent_count;
 332         unsigned long nrbits, start_bit, end_bit;
 333         u32 extent_count = 0;
 334         int done = 0, nr;
 335         int ret;
 336
 337         bitmap_size = free_space_bitmap_size(block_group->key.offset,
 338                                              fs_info->sectorsize);
 339         bitmap = alloc_bitmap(bitmap_size);
 340         if (!bitmap) {
 341                 ret = -ENOMEM;
 342                 goto out;
 343         }
 344
 345         start = block_group->key.objectid;
 346         end = block_group->key.objectid + block_group->key.offset;
 347
 348         key.objectid = end - 1;
 349         key.type = (u8)-1;
 350         key.offset = (u64)-1;
 351
 352         while (!done) {
 353                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 354                 if (ret)
 355                         goto out;
 356
 357                 leaf = path->nodes[0];
 358                 nr = 0;
 359                 path->slots[0]++;
 360                 while (path->slots[0] > 0) {
 361                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 362
 363                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
 364                                 ASSERT(found_key.objectid == block_group->key.objectid);
 365                                 ASSERT(found_key.offset == block_group->key.offset);
 366                                 done = 1;
 367                                 break;
 368                         } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
 369                                 unsigned long ptr;
 370                                 char *bitmap_cursor;
 371                                 u32 bitmap_pos, data_size;
 372
 373                                 ASSERT(found_key.objectid >= start);
 374                                 ASSERT(found_key.objectid < end);
 375                                 ASSERT(found_key.objectid + found_key.offset <= end);
 376
 377                                 bitmap_pos = div_u64(found_key.objectid - start,
 378                                                      fs_info->sectorsize *
 379                                                      BITS_PER_BYTE);
 380                                 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
 381                                 data_size = free_space_bitmap_size(found_key.offset,
 382                                                                    fs_info->sectorsize);
 383
 384                                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
 385                                 read_extent_buffer(leaf, bitmap_cursor, ptr,
 386                                                    data_size);
 387
 388                                 nr++;
 389                                 path->slots[0]--;
 390                         } else {
 391                                 ASSERT(0);
 392                         }
 393                 }
 394
 395                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
 396                 if (ret)
 397                         goto out;
 398                 btrfs_release_path(path);
 399         }
 400
 401         info = search_free_space_info(trans, fs_info, block_group, path, 1);
 402         if (IS_ERR(info)) {
 403                 ret = PTR_ERR(info);
 404                 goto out;
 405         }
 406         leaf = path->nodes[0];
 407         flags = btrfs_free_space_flags(leaf, info);
 408         flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
 409         btrfs_set_free_space_flags(leaf, info, flags);
 410         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
 411         btrfs_mark_buffer_dirty(leaf);
 412         btrfs_release_path(path);
 413
 414         nrbits = div_u64(block_group->key.offset, block_group->fs_info->sectorsize);
 415         start_bit = find_next_bit_le(bitmap, nrbits, 0);
 416
 417         while (start_bit < nrbits) {
 418                 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
 419                 ASSERT(start_bit < end_bit);
 420
 421                 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
 422                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 423                 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
 424
 425                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 426                 if (ret)
 427                         goto out;
 428                 btrfs_release_path(path);
 429
 430                 extent_count++;
 431
 432                 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
 433         }
 434
 435         if (extent_count != expected_extent_count) {
 436                 btrfs_err(fs_info,
 437                           "incorrect extent count for %llu; counted %u, expected %u",
 438                           block_group->key.objectid, extent_count,
 439                           expected_extent_count);
 440                 ASSERT(0);
 441                 ret = -EIO;
 442                 goto out;
 443         }
 444
 445         ret = 0;
 446 out:
 447         kvfree(bitmap);
 448         if (ret)
 449                 btrfs_abort_transaction(trans, ret);
 450         return ret;
 451 }
 452
 453 static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
 454                                           struct btrfs_block_group_cache *block_group,
 455                                           struct btrfs_path *path,
 456                                           int new_extents)
 457 {
 458         struct btrfs_free_space_info *info;
 459         u32 flags;
 460         u32 extent_count;
 461         int ret = 0;
 462
 463         if (new_extents == 0)
 464                 return 0;
 465
 466         info = search_free_space_info(trans, trans->fs_info, block_group, path,
 467                                       1);
 468         if (IS_ERR(info)) {
 469                 ret = PTR_ERR(info);
 470                 goto out;
 471         }
 472         flags = btrfs_free_space_flags(path->nodes[0], info);
 473         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
 474
 475         extent_count += new_extents;
 476         btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
 477         btrfs_mark_buffer_dirty(path->nodes[0]);
 478         btrfs_release_path(path);
 479
 480         if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
 481             extent_count > block_group->bitmap_high_thresh) {
 482                 ret = convert_free_space_to_bitmaps(trans, block_group, path);
 483         } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
 484                    extent_count < block_group->bitmap_low_thresh) {
 485                 ret = convert_free_space_to_extents(trans, block_group, path);
 486         }
 487
 488 out:
 489         return ret;
 490 }
 491
 492 EXPORT_FOR_TESTS
 493 int free_space_test_bit(struct btrfs_block_group_cache *block_group,
 494                         struct btrfs_path *path, u64 offset)
 495 {
 496         struct extent_buffer *leaf;
 497         struct btrfs_key key;
 498         u64 found_start, found_end;
 499         unsigned long ptr, i;
 500
 501         leaf = path->nodes[0];
 502         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 503         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
 504
 505         found_start = key.objectid;
 506         found_end = key.objectid + key.offset;
 507         ASSERT(offset >= found_start && offset < found_end);
 508
 509         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 510         i = div_u64(offset - found_start,
 511                     block_group->fs_info->sectorsize);
 512         return !!extent_buffer_test_bit(leaf, ptr, i);
 513 }
 514
 515 static void free_space_set_bits(struct btrfs_block_group_cache *block_group,
 516                                 struct btrfs_path *path, u64 *start, u64 *size,
 517                                 int bit)
 518 {
 519         struct btrfs_fs_info *fs_info = block_group->fs_info;
 520         struct extent_buffer *leaf;
 521         struct btrfs_key key;
 522         u64 end = *start + *size;
 523         u64 found_start, found_end;
 524         unsigned long ptr, first, last;
 525
 526         leaf = path->nodes[0];
 527         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 528         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
 529
 530         found_start = key.objectid;
 531         found_end = key.objectid + key.offset;
 532         ASSERT(*start >= found_start && *start < found_end);
 533         ASSERT(end > found_start);
 534
 535         if (end > found_end)
 536                 end = found_end;
 537
 538         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 539         first = div_u64(*start - found_start, fs_info->sectorsize);
 540         last = div_u64(end - found_start, fs_info->sectorsize);
 541         if (bit)
 542                 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
 543         else
 544                 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
 545         btrfs_mark_buffer_dirty(leaf);
 546
 547         *size -= end - *start;
 548         *start = end;
 549 }
 550
 551 /*
 552  * We can't use btrfs_next_item() in modify_free_space_bitmap() because
 553  * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
 554  * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
 555  * looking for.
 556  */
 557 static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
 558                                   struct btrfs_root *root, struct btrfs_path *p)
 559 {
 560         struct btrfs_key key;
 561
 562         if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
 563                 p->slots[0]++;
 564                 return 0;
 565         }
 566
 567         btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
 568         btrfs_release_path(p);
 569
 570         key.objectid += key.offset;
 571         key.type = (u8)-1;
 572         key.offset = (u64)-1;
 573
 574         return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
 575 }
 576
 577 /*
 578  * If remove is 1, then we are removing free space, thus clearing bits in the
 579  * bitmap. If remove is 0, then we are adding free space, thus setting bits in
 580  * the bitmap.
 581  */
 582 static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
 583                                     struct btrfs_block_group_cache *block_group,
 584                                     struct btrfs_path *path,
 585                                     u64 start, u64 size, int remove)
 586 {
 587         struct btrfs_root *root = block_group->fs_info->free_space_root;
 588         struct btrfs_key key;
 589         u64 end = start + size;
 590         u64 cur_start, cur_size;
 591         int prev_bit, next_bit;
 592         int new_extents;
 593         int ret;
 594
 595         /*
 596          * Read the bit for the block immediately before the extent of space if
 597          * that block is within the block group.
 598          */
 599         if (start > block_group->key.objectid) {
 600                 u64 prev_block = start - block_group->fs_info->sectorsize;
 601
 602                 key.objectid = prev_block;
 603                 key.type = (u8)-1;
 604                 key.offset = (u64)-1;
 605
 606                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
 607                 if (ret)
 608                         goto out;
 609
 610                 prev_bit = free_space_test_bit(block_group, path, prev_block);
 611
 612                 /* The previous block may have been in the previous bitmap. */
 613                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 614                 if (start >= key.objectid + key.offset) {
 615                         ret = free_space_next_bitmap(trans, root, path);
 616                         if (ret)
 617                                 goto out;
 618                 }
 619         } else {
 620                 key.objectid = start;
 621                 key.type = (u8)-1;
 622                 key.offset = (u64)-1;
 623
 624                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
 625                 if (ret)
 626                         goto out;
 627
 628                 prev_bit = -1;
 629         }
 630
 631         /*
 632          * Iterate over all of the bitmaps overlapped by the extent of space,
 633          * clearing/setting bits as required.
 634          */
 635         cur_start = start;
 636         cur_size = size;
 637         while (1) {
 638                 free_space_set_bits(block_group, path, &cur_start, &cur_size,
 639                                     !remove);
 640                 if (cur_size == 0)
 641                         break;
 642                 ret = free_space_next_bitmap(trans, root, path);
 643                 if (ret)
 644                         goto out;
 645         }
 646
 647         /*
 648          * Read the bit for the block immediately after the extent of space if
 649          * that block is within the block group.
 650          */
 651         if (end < block_group->key.objectid + block_group->key.offset) {
 652                 /* The next block may be in the next bitmap. */
 653                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 654                 if (end >= key.objectid + key.offset) {
 655                         ret = free_space_next_bitmap(trans, root, path);
 656                         if (ret)
 657                                 goto out;
 658                 }
 659
 660                 next_bit = free_space_test_bit(block_group, path, end);
 661         } else {
 662                 next_bit = -1;
 663         }
 664
 665         if (remove) {
 666                 new_extents = -1;
 667                 if (prev_bit == 1) {
 668                         /* Leftover on the left. */
 669                         new_extents++;
 670                 }
 671                 if (next_bit == 1) {
 672                         /* Leftover on the right. */
 673                         new_extents++;
 674                 }
 675         } else {
 676                 new_extents = 1;
 677                 if (prev_bit == 1) {
 678                         /* Merging with neighbor on the left. */
 679                         new_extents--;
 680                 }
 681                 if (next_bit == 1) {
 682                         /* Merging with neighbor on the right. */
 683                         new_extents--;
 684                 }
 685         }
 686
 687         btrfs_release_path(path);
 688         ret = update_free_space_extent_count(trans, block_group, path,
 689                                              new_extents);
 690
 691 out:
 692         return ret;
 693 }
 694
 695 static int remove_free_space_extent(struct btrfs_trans_handle *trans,
 696                                     struct btrfs_block_group_cache *block_group,
 697                                     struct btrfs_path *path,
 698                                     u64 start, u64 size)
 699 {
 700         struct btrfs_root *root = trans->fs_info->free_space_root;
 701         struct btrfs_key key;
 702         u64 found_start, found_end;
 703         u64 end = start + size;
 704         int new_extents = -1;
 705         int ret;
 706
 707         key.objectid = start;
 708         key.type = (u8)-1;
 709         key.offset = (u64)-1;
 710
 711         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 712         if (ret)
 713                 goto out;
 714
 715         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 716
 717         ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
 718
 719         found_start = key.objectid;
 720         found_end = key.objectid + key.offset;
 721         ASSERT(start >= found_start && end <= found_end);
 722
 723         /*
 724          * Okay, now that we've found the free space extent which contains the
 725          * free space that we are removing, there are four cases:
 726          *
 727          * 1. We're using the whole extent: delete the key we found and
 728          * decrement the free space extent count.
 729          * 2. We are using part of the extent starting at the beginning: delete
 730          * the key we found and insert a new key representing the leftover at
 731          * the end. There is no net change in the number of extents.
 732          * 3. We are using part of the extent ending at the end: delete the key
 733          * we found and insert a new key representing the leftover at the
 734          * beginning. There is no net change in the number of extents.
 735          * 4. We are using part of the extent in the middle: delete the key we
 736          * found and insert two new keys representing the leftovers on each
 737          * side. Where we used to have one extent, we now have two, so increment
 738          * the extent count. We may need to convert the block group to bitmaps
 739          * as a result.
 740          */
 741
 742         /* Delete the existing key (cases 1-4). */
 743         ret = btrfs_del_item(trans, root, path);
 744         if (ret)
 745                 goto out;
 746
 747         /* Add a key for leftovers at the beginning (cases 3 and 4). */
 748         if (start > found_start) {
 749                 key.objectid = found_start;
 750                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 751                 key.offset = start - found_start;
 752
 753                 btrfs_release_path(path);
 754                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 755                 if (ret)
 756                         goto out;
 757                 new_extents++;
 758         }
 759
 760         /* Add a key for leftovers at the end (cases 2 and 4). */
 761         if (end < found_end) {
 762                 key.objectid = end;
 763                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 764                 key.offset = found_end - end;
 765
 766                 btrfs_release_path(path);
 767                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 768                 if (ret)
 769                         goto out;
 770                 new_extents++;
 771         }
 772
 773         btrfs_release_path(path);
 774         ret = update_free_space_extent_count(trans, block_group, path,
 775                                              new_extents);
 776
 777 out:
 778         return ret;
 779 }
 780
 781 EXPORT_FOR_TESTS
 782 int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
 783                                   struct btrfs_block_group_cache *block_group,
 784                                   struct btrfs_path *path, u64 start, u64 size)
 785 {
 786         struct btrfs_free_space_info *info;
 787         u32 flags;
 788         int ret;
 789
 790         if (block_group->needs_free_space) {
 791                 ret = __add_block_group_free_space(trans, block_group, path);
 792                 if (ret)
 793                         return ret;
 794         }
 795
 796         info = search_free_space_info(NULL, trans->fs_info, block_group, path,
 797                                       0);
 798         if (IS_ERR(info))
 799                 return PTR_ERR(info);
 800         flags = btrfs_free_space_flags(path->nodes[0], info);
 801         btrfs_release_path(path);
 802
 803         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
 804                 return modify_free_space_bitmap(trans, block_group, path,
 805                                                 start, size, 1);
 806         } else {
 807                 return remove_free_space_extent(trans, block_group, path,
 808                                                 start, size);
 809         }
 810 }
 811
 812 int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
 813                                 u64 start, u64 size)
 814 {
 815         struct btrfs_block_group_cache *block_group;
 816         struct btrfs_path *path;
 817         int ret;
 818
 819         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
 820                 return 0;
 821
 822         path = btrfs_alloc_path();
 823         if (!path) {
 824                 ret = -ENOMEM;
 825                 goto out;
 826         }
 827
 828         block_group = btrfs_lookup_block_group(trans->fs_info, start);
 829         if (!block_group) {
 830                 ASSERT(0);
 831                 ret = -ENOENT;
 832                 goto out;
 833         }
 834
 835         mutex_lock(&block_group->free_space_lock);
 836         ret = __remove_from_free_space_tree(trans, block_group, path, start,
 837                                             size);
 838         mutex_unlock(&block_group->free_space_lock);
 839
 840         btrfs_put_block_group(block_group);
 841 out:
 842         btrfs_free_path(path);
 843         if (ret)
 844                 btrfs_abort_transaction(trans, ret);
 845         return ret;
 846 }
 847
 848 static int add_free_space_extent(struct btrfs_trans_handle *trans,
 849                                  struct btrfs_block_group_cache *block_group,
 850                                  struct btrfs_path *path,
 851                                  u64 start, u64 size)
 852 {
 853         struct btrfs_root *root = trans->fs_info->free_space_root;
 854         struct btrfs_key key, new_key;
 855         u64 found_start, found_end;
 856         u64 end = start + size;
 857         int new_extents = 1;
 858         int ret;
 859
 860         /*
 861          * We are adding a new extent of free space, but we need to merge
 862          * extents. There are four cases here:
 863          *
 864          * 1. The new extent does not have any immediate neighbors to merge
 865          * with: add the new key and increment the free space extent count. We
 866          * may need to convert the block group to bitmaps as a result.
 867          * 2. The new extent has an immediate neighbor before it: remove the
 868          * previous key and insert a new key combining both of them. There is no
 869          * net change in the number of extents.
 870          * 3. The new extent has an immediate neighbor after it: remove the next
 871          * key and insert a new key combining both of them. There is no net
 872          * change in the number of extents.
 873          * 4. The new extent has immediate neighbors on both sides: remove both
 874          * of the keys and insert a new key combining all of them. Where we used
 875          * to have two extents, we now have one, so decrement the extent count.
 876          */
 877
 878         new_key.objectid = start;
 879         new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 880         new_key.offset = size;
 881
 882         /* Search for a neighbor on the left. */
 883         if (start == block_group->key.objectid)
 884                 goto right;
 885         key.objectid = start - 1;
 886         key.type = (u8)-1;
 887         key.offset = (u64)-1;
 888
 889         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 890         if (ret)
 891                 goto out;
 892
 893         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 894
 895         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
 896                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
 897                 btrfs_release_path(path);
 898                 goto right;
 899         }
 900
 901         found_start = key.objectid;
 902         found_end = key.objectid + key.offset;
 903         ASSERT(found_start >= block_group->key.objectid &&
 904                found_end > block_group->key.objectid);
 905         ASSERT(found_start < start && found_end <= start);
 906
 907         /*
 908          * Delete the neighbor on the left and absorb it into the new key (cases
 909          * 2 and 4).
 910          */
 911         if (found_end == start) {
 912                 ret = btrfs_del_item(trans, root, path);
 913                 if (ret)
 914                         goto out;
 915                 new_key.objectid = found_start;
 916                 new_key.offset += key.offset;
 917                 new_extents--;
 918         }
 919         btrfs_release_path(path);
 920
 921 right:
 922         /* Search for a neighbor on the right. */
 923         if (end == block_group->key.objectid + block_group->key.offset)
 924                 goto insert;
 925         key.objectid = end;
 926         key.type = (u8)-1;
 927         key.offset = (u64)-1;
 928
 929         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 930         if (ret)
 931                 goto out;
 932
 933         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 934
 935         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
 936                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
 937                 btrfs_release_path(path);
 938                 goto insert;
 939         }
 940
 941         found_start = key.objectid;
 942         found_end = key.objectid + key.offset;
 943         ASSERT(found_start >= block_group->key.objectid &&
 944                found_end > block_group->key.objectid);
 945         ASSERT((found_start < start && found_end <= start) ||
 946                (found_start >= end && found_end > end));
 947
 948         /*
 949          * Delete the neighbor on the right and absorb it into the new key
 950          * (cases 3 and 4).
 951          */
 952         if (found_start == end) {
 953                 ret = btrfs_del_item(trans, root, path);
 954                 if (ret)
 955                         goto out;
 956                 new_key.offset += key.offset;
 957                 new_extents--;
 958         }
 959         btrfs_release_path(path);
 960
 961 insert:
 962         /* Insert the new key (cases 1-4). */
 963         ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
 964         if (ret)
 965                 goto out;
 966
 967         btrfs_release_path(path);
 968         ret = update_free_space_extent_count(trans, block_group, path,
 969                                              new_extents);
 970
 971 out:
 972         return ret;
 973 }
 974
 975 EXPORT_FOR_TESTS
 976 int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
 977                              struct btrfs_block_group_cache *block_group,
 978                              struct btrfs_path *path, u64 start, u64 size)
 979 {
 980         struct btrfs_fs_info *fs_info = trans->fs_info;
 981         struct btrfs_free_space_info *info;
 982         u32 flags;
 983         int ret;
 984
 985         if (block_group->needs_free_space) {
 986                 ret = __add_block_group_free_space(trans, block_group, path);
 987                 if (ret)
 988                         return ret;
 989         }
 990
 991         info = search_free_space_info(NULL, fs_info, block_group, path, 0);
 992         if (IS_ERR(info))
 993                 return PTR_ERR(info);
 994         flags = btrfs_free_space_flags(path->nodes[0], info);
 995         btrfs_release_path(path);
 996
 997         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
 998                 return modify_free_space_bitmap(trans, block_group, path,
 999                                                 start, size, 0);
1000         } else {
1001                 return add_free_space_extent(trans, block_group, path, start,
1002                                              size);
1003         }
1004 }
1005
1006 int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1007                            u64 start, u64 size)
1008 {
1009         struct btrfs_block_group_cache *block_group;
1010         struct btrfs_path *path;
1011         int ret;
1012
1013         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1014                 return 0;
1015
1016         path = btrfs_alloc_path();
1017         if (!path) {
1018                 ret = -ENOMEM;
1019                 goto out;
1020         }
1021
1022         block_group = btrfs_lookup_block_group(trans->fs_info, start);
1023         if (!block_group) {
1024                 ASSERT(0);
1025                 ret = -ENOENT;
1026                 goto out;
1027         }
1028
1029         mutex_lock(&block_group->free_space_lock);
1030         ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1031         mutex_unlock(&block_group->free_space_lock);
1032
1033         btrfs_put_block_group(block_group);
1034 out:
1035         btrfs_free_path(path);
1036         if (ret)
1037                 btrfs_abort_transaction(trans, ret);
1038         return ret;
1039 }
1040
1041 /*
1042  * Populate the free space tree by walking the extent tree. Operations on the
1043  * extent tree that happen as a result of writes to the free space tree will go
1044  * through the normal add/remove hooks.
1045  */
1046 static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1047                                     struct btrfs_block_group_cache *block_group)
1048 {
1049         struct btrfs_root *extent_root = trans->fs_info->extent_root;
1050         struct btrfs_path *path, *path2;
1051         struct btrfs_key key;
1052         u64 start, end;
1053         int ret;
1054
1055         path = btrfs_alloc_path();
1056         if (!path)
1057                 return -ENOMEM;
1058         path->reada = READA_FORWARD;
1059
1060         path2 = btrfs_alloc_path();
1061         if (!path2) {
1062                 btrfs_free_path(path);
1063                 return -ENOMEM;
1064         }
1065
1066         ret = add_new_free_space_info(trans, block_group, path2);
1067         if (ret)
1068                 goto out;
1069
1070         mutex_lock(&block_group->free_space_lock);
1071
1072         /*
1073          * Iterate through all of the extent and metadata items in this block
1074          * group, adding the free space between them and the free space at the
1075          * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1076          * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1077          * contained in.
1078          */
1079         key.objectid = block_group->key.objectid;
1080         key.type = BTRFS_EXTENT_ITEM_KEY;
1081         key.offset = 0;
1082
1083         ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1084         if (ret < 0)
1085                 goto out_locked;
1086         ASSERT(ret == 0);
1087
1088         start = block_group->key.objectid;
1089         end = block_group->key.objectid + block_group->key.offset;
1090         while (1) {
1091                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1092
1093                 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1094                     key.type == BTRFS_METADATA_ITEM_KEY) {
1095                         if (key.objectid >= end)
1096                                 break;
1097
1098                         if (start < key.objectid) {
1099                                 ret = __add_to_free_space_tree(trans,
1100                                                                block_group,
1101                                                                path2, start,
1102                                                                key.objectid -
1103                                                                start);
1104                                 if (ret)
1105                                         goto out_locked;
1106                         }
1107                         start = key.objectid;
1108                         if (key.type == BTRFS_METADATA_ITEM_KEY)
1109                                 start += trans->fs_info->nodesize;
1110                         else
1111                                 start += key.offset;
1112                 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1113                         if (key.objectid != block_group->key.objectid)
1114                                 break;
1115                 }
1116
1117                 ret = btrfs_next_item(extent_root, path);
1118                 if (ret < 0)
1119                         goto out_locked;
1120                 if (ret)
1121                         break;
1122         }
1123         if (start < end) {
1124                 ret = __add_to_free_space_tree(trans, block_group, path2,
1125                                                start, end - start);
1126                 if (ret)
1127                         goto out_locked;
1128         }
1129
1130         ret = 0;
1131 out_locked:
1132         mutex_unlock(&block_group->free_space_lock);
1133 out:
1134         btrfs_free_path(path2);
1135         btrfs_free_path(path);
1136         return ret;
1137 }
1138
1139 int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1140 {
1141         struct btrfs_trans_handle *trans;
1142         struct btrfs_root *tree_root = fs_info->tree_root;
1143         struct btrfs_root *free_space_root;
1144         struct btrfs_block_group_cache *block_group;
1145         struct rb_node *node;
1146         int ret;
1147
1148         trans = btrfs_start_transaction(tree_root, 0);
1149         if (IS_ERR(trans))
1150                 return PTR_ERR(trans);
1151
1152         set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1153         free_space_root = btrfs_create_tree(trans, fs_info,
1154                                             BTRFS_FREE_SPACE_TREE_OBJECTID);
1155         if (IS_ERR(free_space_root)) {
1156                 ret = PTR_ERR(free_space_root);
1157                 goto abort;
1158         }
1159         fs_info->free_space_root = free_space_root;
1160
1161         node = rb_first(&fs_info->block_group_cache_tree);
1162         while (node) {
1163                 block_group = rb_entry(node, struct btrfs_block_group_cache,
1164                                        cache_node);
1165                 ret = populate_free_space_tree(trans, block_group);
1166                 if (ret)
1167                         goto abort;
1168                 node = rb_next(node);
1169         }
1170
1171         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1172         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1173         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1174
1175         return btrfs_commit_transaction(trans);
1176
1177 abort:
1178         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1179         btrfs_abort_transaction(trans, ret);
1180         btrfs_end_transaction(trans);
1181         return ret;
1182 }
1183
1184 static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1185                                  struct btrfs_root *root)
1186 {
1187         struct btrfs_path *path;
1188         struct btrfs_key key;
1189         int nr;
1190         int ret;
1191
1192         path = btrfs_alloc_path();
1193         if (!path)
1194                 return -ENOMEM;
1195
1196         path->leave_spinning = 1;
1197
1198         key.objectid = 0;
1199         key.type = 0;
1200         key.offset = 0;
1201
1202         while (1) {
1203                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1204                 if (ret < 0)
1205                         goto out;
1206
1207                 nr = btrfs_header_nritems(path->nodes[0]);
1208                 if (!nr)
1209                         break;
1210
1211                 path->slots[0] = 0;
1212                 ret = btrfs_del_items(trans, root, path, 0, nr);
1213                 if (ret)
1214                         goto out;
1215
1216                 btrfs_release_path(path);
1217         }
1218
1219         ret = 0;
1220 out:
1221         btrfs_free_path(path);
1222         return ret;
1223 }
1224
1225 int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1226 {
1227         struct btrfs_trans_handle *trans;
1228         struct btrfs_root *tree_root = fs_info->tree_root;
1229         struct btrfs_root *free_space_root = fs_info->free_space_root;
1230         int ret;
1231
1232         trans = btrfs_start_transaction(tree_root, 0);
1233         if (IS_ERR(trans))
1234                 return PTR_ERR(trans);
1235
1236         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1237         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1238         fs_info->free_space_root = NULL;
1239
1240         ret = clear_free_space_tree(trans, free_space_root);
1241         if (ret)
1242                 goto abort;
1243
1244         ret = btrfs_del_root(trans, &free_space_root->root_key);
1245         if (ret)
1246                 goto abort;
1247
1248         list_del(&free_space_root->dirty_list);
1249
1250         btrfs_tree_lock(free_space_root->node);
1251         clean_tree_block(fs_info, free_space_root->node);
1252         btrfs_tree_unlock(free_space_root->node);
1253         btrfs_free_tree_block(trans, free_space_root, free_space_root->node,
1254                               0, 1);
1255
1256         free_extent_buffer(free_space_root->node);
1257         free_extent_buffer(free_space_root->commit_root);
1258         kfree(free_space_root);
1259
1260         return btrfs_commit_transaction(trans);
1261
1262 abort:
1263         btrfs_abort_transaction(trans, ret);
1264         btrfs_end_transaction(trans);
1265         return ret;
1266 }
1267
1268 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1269                                         struct btrfs_block_group_cache *block_group,
1270                                         struct btrfs_path *path)
1271 {
1272         int ret;
1273
1274         block_group->needs_free_space = 0;
1275
1276         ret = add_new_free_space_info(trans, block_group, path);
1277         if (ret)
1278                 return ret;
1279
1280         return __add_to_free_space_tree(trans, block_group, path,
1281                                         block_group->key.objectid,
1282                                         block_group->key.offset);
1283 }
1284
1285 int add_block_group_free_space(struct btrfs_trans_handle *trans,
1286                                struct btrfs_block_group_cache *block_group)
1287 {
1288         struct btrfs_fs_info *fs_info = trans->fs_info;
1289         struct btrfs_path *path = NULL;
1290         int ret = 0;
1291
1292         if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1293                 return 0;
1294
1295         mutex_lock(&block_group->free_space_lock);
1296         if (!block_group->needs_free_space)
1297                 goto out;
1298
1299         path = btrfs_alloc_path();
1300         if (!path) {
1301                 ret = -ENOMEM;
1302                 goto out;
1303         }
1304
1305         ret = __add_block_group_free_space(trans, block_group, path);
1306
1307 out:
1308         btrfs_free_path(path);
1309         mutex_unlock(&block_group->free_space_lock);
1310         if (ret)
1311                 btrfs_abort_transaction(trans, ret);
1312         return ret;
1313 }
1314
1315 int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1316                                   struct btrfs_block_group_cache *block_group)
1317 {
1318         struct btrfs_root *root = trans->fs_info->free_space_root;
1319         struct btrfs_path *path;
1320         struct btrfs_key key, found_key;
1321         struct extent_buffer *leaf;
1322         u64 start, end;
1323         int done = 0, nr;
1324         int ret;
1325
1326         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1327                 return 0;
1328
1329         if (block_group->needs_free_space) {
1330                 /* We never added this block group to the free space tree. */
1331                 return 0;
1332         }
1333
1334         path = btrfs_alloc_path();
1335         if (!path) {
1336                 ret = -ENOMEM;
1337                 goto out;
1338         }
1339
1340         start = block_group->key.objectid;
1341         end = block_group->key.objectid + block_group->key.offset;
1342
1343         key.objectid = end - 1;
1344         key.type = (u8)-1;
1345         key.offset = (u64)-1;
1346
1347         while (!done) {
1348                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1349                 if (ret)
1350                         goto out;
1351
1352                 leaf = path->nodes[0];
1353                 nr = 0;
1354                 path->slots[0]++;
1355                 while (path->slots[0] > 0) {
1356                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1357
1358                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1359                                 ASSERT(found_key.objectid == block_group->key.objectid);
1360                                 ASSERT(found_key.offset == block_group->key.offset);
1361                                 done = 1;
1362                                 nr++;
1363                                 path->slots[0]--;
1364                                 break;
1365                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1366                                    found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1367                                 ASSERT(found_key.objectid >= start);
1368                                 ASSERT(found_key.objectid < end);
1369                                 ASSERT(found_key.objectid + found_key.offset <= end);
1370                                 nr++;
1371                                 path->slots[0]--;
1372                         } else {
1373                                 ASSERT(0);
1374                         }
1375                 }
1376
1377                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1378                 if (ret)
1379                         goto out;
1380                 btrfs_release_path(path);
1381         }
1382
1383         ret = 0;
1384 out:
1385         btrfs_free_path(path);
1386         if (ret)
1387                 btrfs_abort_transaction(trans, ret);
1388         return ret;
1389 }
1390
1391 static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1392                                    struct btrfs_path *path,
1393                                    u32 expected_extent_count)
1394 {
1395         struct btrfs_block_group_cache *block_group;
1396         struct btrfs_fs_info *fs_info;
1397         struct btrfs_root *root;
1398         struct btrfs_key key;
1399         int prev_bit = 0, bit;
1400         /* Initialize to silence GCC. */
1401         u64 extent_start = 0;
1402         u64 end, offset;
1403         u64 total_found = 0;
1404         u32 extent_count = 0;
1405         int ret;
1406
1407         block_group = caching_ctl->block_group;
1408         fs_info = block_group->fs_info;
1409         root = fs_info->free_space_root;
1410
1411         end = block_group->key.objectid + block_group->key.offset;
1412
1413         while (1) {
1414                 ret = btrfs_next_item(root, path);
1415                 if (ret < 0)
1416                         goto out;
1417                 if (ret)
1418                         break;
1419
1420                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1421
1422                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1423                         break;
1424
1425                 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1426                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1427
1428                 caching_ctl->progress = key.objectid;
1429
1430                 offset = key.objectid;
1431                 while (offset < key.objectid + key.offset) {
1432                         bit = free_space_test_bit(block_group, path, offset);
1433                         if (prev_bit == 0 && bit == 1) {
1434                                 extent_start = offset;
1435                         } else if (prev_bit == 1 && bit == 0) {
1436                                 total_found += add_new_free_space(block_group,
1437                                                                   extent_start,
1438                                                                   offset);
1439                                 if (total_found > CACHING_CTL_WAKE_UP) {
1440                                         total_found = 0;
1441                                         wake_up(&caching_ctl->wait);
1442                                 }
1443                                 extent_count++;
1444                         }
1445                         prev_bit = bit;
1446                         offset += fs_info->sectorsize;
1447                 }
1448         }
1449         if (prev_bit == 1) {
1450                 total_found += add_new_free_space(block_group, extent_start,
1451                                                   end);
1452                 extent_count++;
1453         }
1454
1455         if (extent_count != expected_extent_count) {
1456                 btrfs_err(fs_info,
1457                           "incorrect extent count for %llu; counted %u, expected %u",
1458                           block_group->key.objectid, extent_count,
1459                           expected_extent_count);
1460                 ASSERT(0);
1461                 ret = -EIO;
1462                 goto out;
1463         }
1464
1465         caching_ctl->progress = (u64)-1;
1466
1467         ret = 0;
1468 out:
1469         return ret;
1470 }
1471
1472 static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1473                                    struct btrfs_path *path,
1474                                    u32 expected_extent_count)
1475 {
1476         struct btrfs_block_group_cache *block_group;
1477         struct btrfs_fs_info *fs_info;
1478         struct btrfs_root *root;
1479         struct btrfs_key key;
1480         u64 end;
1481         u64 total_found = 0;
1482         u32 extent_count = 0;
1483         int ret;
1484
1485         block_group = caching_ctl->block_group;
1486         fs_info = block_group->fs_info;
1487         root = fs_info->free_space_root;
1488
1489         end = block_group->key.objectid + block_group->key.offset;
1490
1491         while (1) {
1492                 ret = btrfs_next_item(root, path);
1493                 if (ret < 0)
1494                         goto out;
1495                 if (ret)
1496                         break;
1497
1498                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1499
1500                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1501                         break;
1502
1503                 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1504                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1505
1506                 caching_ctl->progress = key.objectid;
1507
1508                 total_found += add_new_free_space(block_group, key.objectid,
1509                                                   key.objectid + key.offset);
1510                 if (total_found > CACHING_CTL_WAKE_UP) {
1511                         total_found = 0;
1512                         wake_up(&caching_ctl->wait);
1513                 }
1514                 extent_count++;
1515         }
1516
1517         if (extent_count != expected_extent_count) {
1518                 btrfs_err(fs_info,
1519                           "incorrect extent count for %llu; counted %u, expected %u",
1520                           block_group->key.objectid, extent_count,
1521                           expected_extent_count);
1522                 ASSERT(0);
1523                 ret = -EIO;
1524                 goto out;
1525         }
1526
1527         caching_ctl->progress = (u64)-1;
1528
1529         ret = 0;
1530 out:
1531         return ret;
1532 }
1533
1534 int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1535 {
1536         struct btrfs_block_group_cache *block_group;
1537         struct btrfs_fs_info *fs_info;
1538         struct btrfs_free_space_info *info;
1539         struct btrfs_path *path;
1540         u32 extent_count, flags;
1541         int ret;
1542
1543         block_group = caching_ctl->block_group;
1544         fs_info = block_group->fs_info;
1545
1546         path = btrfs_alloc_path();
1547         if (!path)
1548                 return -ENOMEM;
1549
1550         /*
1551          * Just like caching_thread() doesn't want to deadlock on the extent
1552          * tree, we don't want to deadlock on the free space tree.
1553          */
1554         path->skip_locking = 1;
1555         path->search_commit_root = 1;
1556         path->reada = READA_FORWARD;
1557
1558         info = search_free_space_info(NULL, fs_info, block_group, path, 0);
1559         if (IS_ERR(info)) {
1560                 ret = PTR_ERR(info);
1561                 goto out;
1562         }
1563         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1564         flags = btrfs_free_space_flags(path->nodes[0], info);
1565
1566         /*
1567          * We left path pointing to the free space info item, so now
1568          * load_free_space_foo can just iterate through the free space tree from
1569          * there.
1570          */
1571         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1572                 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1573         else
1574                 ret = load_free_space_extents(caching_ctl, path, extent_count);
1575
1576 out:
1577         btrfs_free_path(path);
1578         return ret;
1579 }