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 #include "block-group.h"
  14
  15 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
  16                                         struct btrfs_block_group *block_group,
  17                                         struct btrfs_path *path);
  18
  19 static struct btrfs_root *btrfs_free_space_root(
  20                                 struct btrfs_block_group *block_group)
  21 {
  22         struct btrfs_key key = {
  23                 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
  24                 .type = BTRFS_ROOT_ITEM_KEY,
  25                 .offset = 0,
  26         };
  27
  28         if (btrfs_fs_incompat(block_group->fs_info, EXTENT_TREE_V2))
  29                 key.offset = block_group->global_root_id;
  30         return btrfs_global_root(block_group->fs_info, &key);
  31 }
  32
  33 void set_free_space_tree_thresholds(struct btrfs_block_group *cache)
  34 {
  35         u32 bitmap_range;
  36         size_t bitmap_size;
  37         u64 num_bitmaps, total_bitmap_size;
  38
  39         if (WARN_ON(cache->length == 0))
  40                 btrfs_warn(cache->fs_info, "block group %llu length is zero",
  41                            cache->start);
  42
  43         /*
  44          * We convert to bitmaps when the disk space required for using extents
  45          * exceeds that required for using bitmaps.
  46          */
  47         bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
  48         num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range);
  49         bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
  50         total_bitmap_size = num_bitmaps * bitmap_size;
  51         cache->bitmap_high_thresh = div_u64(total_bitmap_size,
  52                                             sizeof(struct btrfs_item));
  53
  54         /*
  55          * We allow for a small buffer between the high threshold and low
  56          * threshold to avoid thrashing back and forth between the two formats.
  57          */
  58         if (cache->bitmap_high_thresh > 100)
  59                 cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
  60         else
  61                 cache->bitmap_low_thresh = 0;
  62 }
  63
  64 static int add_new_free_space_info(struct btrfs_trans_handle *trans,
  65                                    struct btrfs_block_group *block_group,
  66                                    struct btrfs_path *path)
  67 {
  68         struct btrfs_root *root = btrfs_free_space_root(block_group);
  69         struct btrfs_free_space_info *info;
  70         struct btrfs_key key;
  71         struct extent_buffer *leaf;
  72         int ret;
  73
  74         key.objectid = block_group->start;
  75         key.type = BTRFS_FREE_SPACE_INFO_KEY;
  76         key.offset = block_group->length;
  77
  78         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
  79         if (ret)
  80                 goto out;
  81
  82         leaf = path->nodes[0];
  83         info = btrfs_item_ptr(leaf, path->slots[0],
  84                               struct btrfs_free_space_info);
  85         btrfs_set_free_space_extent_count(leaf, info, 0);
  86         btrfs_set_free_space_flags(leaf, info, 0);
  87         btrfs_mark_buffer_dirty(leaf);
  88
  89         ret = 0;
  90 out:
  91         btrfs_release_path(path);
  92         return ret;
  93 }
  94
  95 EXPORT_FOR_TESTS
  96 struct btrfs_free_space_info *search_free_space_info(
  97                 struct btrfs_trans_handle *trans,
  98                 struct btrfs_block_group *block_group,
  99                 struct btrfs_path *path, int cow)
 100 {
 101         struct btrfs_fs_info *fs_info = block_group->fs_info;
 102         struct btrfs_root *root = btrfs_free_space_root(block_group);
 103         struct btrfs_key key;
 104         int ret;
 105
 106         key.objectid = block_group->start;
 107         key.type = BTRFS_FREE_SPACE_INFO_KEY;
 108         key.offset = block_group->length;
 109
 110         ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
 111         if (ret < 0)
 112                 return ERR_PTR(ret);
 113         if (ret != 0) {
 114                 btrfs_warn(fs_info, "missing free space info for %llu",
 115                            block_group->start);
 116                 ASSERT(0);
 117                 return ERR_PTR(-ENOENT);
 118         }
 119
 120         return btrfs_item_ptr(path->nodes[0], path->slots[0],
 121                               struct btrfs_free_space_info);
 122 }
 123
 124 /*
 125  * btrfs_search_slot() but we're looking for the greatest key less than the
 126  * passed key.
 127  */
 128 static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
 129                                   struct btrfs_root *root,
 130                                   struct btrfs_key *key, struct btrfs_path *p,
 131                                   int ins_len, int cow)
 132 {
 133         int ret;
 134
 135         ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
 136         if (ret < 0)
 137                 return ret;
 138
 139         if (ret == 0) {
 140                 ASSERT(0);
 141                 return -EIO;
 142         }
 143
 144         if (p->slots[0] == 0) {
 145                 ASSERT(0);
 146                 return -EIO;
 147         }
 148         p->slots[0]--;
 149
 150         return 0;
 151 }
 152
 153 static inline u32 free_space_bitmap_size(const struct btrfs_fs_info *fs_info,
 154                                          u64 size)
 155 {
 156         return DIV_ROUND_UP(size >> fs_info->sectorsize_bits, BITS_PER_BYTE);
 157 }
 158
 159 static unsigned long *alloc_bitmap(u32 bitmap_size)
 160 {
 161         unsigned long *ret;
 162         unsigned int nofs_flag;
 163         u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long));
 164
 165         /*
 166          * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
 167          * into the filesystem as the free space bitmap can be modified in the
 168          * critical section of a transaction commit.
 169          *
 170          * TODO: push the memalloc_nofs_{save,restore}() to the caller where we
 171          * know that recursion is unsafe.
 172          */
 173         nofs_flag = memalloc_nofs_save();
 174         ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL);
 175         memalloc_nofs_restore(nofs_flag);
 176         return ret;
 177 }
 178
 179 static void le_bitmap_set(unsigned long *map, unsigned int start, int len)
 180 {
 181         u8 *p = ((u8 *)map) + BIT_BYTE(start);
 182         const unsigned int size = start + len;
 183         int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE);
 184         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start);
 185
 186         while (len - bits_to_set >= 0) {
 187                 *p |= mask_to_set;
 188                 len -= bits_to_set;
 189                 bits_to_set = BITS_PER_BYTE;
 190                 mask_to_set = ~0;
 191                 p++;
 192         }
 193         if (len) {
 194                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
 195                 *p |= mask_to_set;
 196         }
 197 }
 198
 199 EXPORT_FOR_TESTS
 200 int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
 201                                   struct btrfs_block_group *block_group,
 202                                   struct btrfs_path *path)
 203 {
 204         struct btrfs_fs_info *fs_info = trans->fs_info;
 205         struct btrfs_root *root = btrfs_free_space_root(block_group);
 206         struct btrfs_free_space_info *info;
 207         struct btrfs_key key, found_key;
 208         struct extent_buffer *leaf;
 209         unsigned long *bitmap;
 210         char *bitmap_cursor;
 211         u64 start, end;
 212         u64 bitmap_range, i;
 213         u32 bitmap_size, flags, expected_extent_count;
 214         u32 extent_count = 0;
 215         int done = 0, nr;
 216         int ret;
 217
 218         bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
 219         bitmap = alloc_bitmap(bitmap_size);
 220         if (!bitmap) {
 221                 ret = -ENOMEM;
 222                 goto out;
 223         }
 224
 225         start = block_group->start;
 226         end = block_group->start + block_group->length;
 227
 228         key.objectid = end - 1;
 229         key.type = (u8)-1;
 230         key.offset = (u64)-1;
 231
 232         while (!done) {
 233                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 234                 if (ret)
 235                         goto out;
 236
 237                 leaf = path->nodes[0];
 238                 nr = 0;
 239                 path->slots[0]++;
 240                 while (path->slots[0] > 0) {
 241                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 242
 243                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
 244                                 ASSERT(found_key.objectid == block_group->start);
 245                                 ASSERT(found_key.offset == block_group->length);
 246                                 done = 1;
 247                                 break;
 248                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
 249                                 u64 first, last;
 250
 251                                 ASSERT(found_key.objectid >= start);
 252                                 ASSERT(found_key.objectid < end);
 253                                 ASSERT(found_key.objectid + found_key.offset <= end);
 254
 255                                 first = div_u64(found_key.objectid - start,
 256                                                 fs_info->sectorsize);
 257                                 last = div_u64(found_key.objectid + found_key.offset - start,
 258                                                fs_info->sectorsize);
 259                                 le_bitmap_set(bitmap, first, last - first);
 260
 261                                 extent_count++;
 262                                 nr++;
 263                                 path->slots[0]--;
 264                         } else {
 265                                 ASSERT(0);
 266                         }
 267                 }
 268
 269                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
 270                 if (ret)
 271                         goto out;
 272                 btrfs_release_path(path);
 273         }
 274
 275         info = search_free_space_info(trans, block_group, path, 1);
 276         if (IS_ERR(info)) {
 277                 ret = PTR_ERR(info);
 278                 goto out;
 279         }
 280         leaf = path->nodes[0];
 281         flags = btrfs_free_space_flags(leaf, info);
 282         flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
 283         btrfs_set_free_space_flags(leaf, info, flags);
 284         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
 285         btrfs_mark_buffer_dirty(leaf);
 286         btrfs_release_path(path);
 287
 288         if (extent_count != expected_extent_count) {
 289                 btrfs_err(fs_info,
 290                           "incorrect extent count for %llu; counted %u, expected %u",
 291                           block_group->start, extent_count,
 292                           expected_extent_count);
 293                 ASSERT(0);
 294                 ret = -EIO;
 295                 goto out;
 296         }
 297
 298         bitmap_cursor = (char *)bitmap;
 299         bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
 300         i = start;
 301         while (i < end) {
 302                 unsigned long ptr;
 303                 u64 extent_size;
 304                 u32 data_size;
 305
 306                 extent_size = min(end - i, bitmap_range);
 307                 data_size = free_space_bitmap_size(fs_info, extent_size);
 308
 309                 key.objectid = i;
 310                 key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
 311                 key.offset = extent_size;
 312
 313                 ret = btrfs_insert_empty_item(trans, root, path, &key,
 314                                               data_size);
 315                 if (ret)
 316                         goto out;
 317
 318                 leaf = path->nodes[0];
 319                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 320                 write_extent_buffer(leaf, bitmap_cursor, ptr,
 321                                     data_size);
 322                 btrfs_mark_buffer_dirty(leaf);
 323                 btrfs_release_path(path);
 324
 325                 i += extent_size;
 326                 bitmap_cursor += data_size;
 327         }
 328
 329         ret = 0;
 330 out:
 331         kvfree(bitmap);
 332         if (ret)
 333                 btrfs_abort_transaction(trans, ret);
 334         return ret;
 335 }
 336
 337 EXPORT_FOR_TESTS
 338 int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
 339                                   struct btrfs_block_group *block_group,
 340                                   struct btrfs_path *path)
 341 {
 342         struct btrfs_fs_info *fs_info = trans->fs_info;
 343         struct btrfs_root *root = btrfs_free_space_root(block_group);
 344         struct btrfs_free_space_info *info;
 345         struct btrfs_key key, found_key;
 346         struct extent_buffer *leaf;
 347         unsigned long *bitmap;
 348         u64 start, end;
 349         u32 bitmap_size, flags, expected_extent_count;
 350         unsigned long nrbits, start_bit, end_bit;
 351         u32 extent_count = 0;
 352         int done = 0, nr;
 353         int ret;
 354
 355         bitmap_size = free_space_bitmap_size(fs_info, block_group->length);
 356         bitmap = alloc_bitmap(bitmap_size);
 357         if (!bitmap) {
 358                 ret = -ENOMEM;
 359                 goto out;
 360         }
 361
 362         start = block_group->start;
 363         end = block_group->start + block_group->length;
 364
 365         key.objectid = end - 1;
 366         key.type = (u8)-1;
 367         key.offset = (u64)-1;
 368
 369         while (!done) {
 370                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 371                 if (ret)
 372                         goto out;
 373
 374                 leaf = path->nodes[0];
 375                 nr = 0;
 376                 path->slots[0]++;
 377                 while (path->slots[0] > 0) {
 378                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
 379
 380                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
 381                                 ASSERT(found_key.objectid == block_group->start);
 382                                 ASSERT(found_key.offset == block_group->length);
 383                                 done = 1;
 384                                 break;
 385                         } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
 386                                 unsigned long ptr;
 387                                 char *bitmap_cursor;
 388                                 u32 bitmap_pos, data_size;
 389
 390                                 ASSERT(found_key.objectid >= start);
 391                                 ASSERT(found_key.objectid < end);
 392                                 ASSERT(found_key.objectid + found_key.offset <= end);
 393
 394                                 bitmap_pos = div_u64(found_key.objectid - start,
 395                                                      fs_info->sectorsize *
 396                                                      BITS_PER_BYTE);
 397                                 bitmap_cursor = ((char *)bitmap) + bitmap_pos;
 398                                 data_size = free_space_bitmap_size(fs_info,
 399                                                                 found_key.offset);
 400
 401                                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
 402                                 read_extent_buffer(leaf, bitmap_cursor, ptr,
 403                                                    data_size);
 404
 405                                 nr++;
 406                                 path->slots[0]--;
 407                         } else {
 408                                 ASSERT(0);
 409                         }
 410                 }
 411
 412                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
 413                 if (ret)
 414                         goto out;
 415                 btrfs_release_path(path);
 416         }
 417
 418         info = search_free_space_info(trans, block_group, path, 1);
 419         if (IS_ERR(info)) {
 420                 ret = PTR_ERR(info);
 421                 goto out;
 422         }
 423         leaf = path->nodes[0];
 424         flags = btrfs_free_space_flags(leaf, info);
 425         flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
 426         btrfs_set_free_space_flags(leaf, info, flags);
 427         expected_extent_count = btrfs_free_space_extent_count(leaf, info);
 428         btrfs_mark_buffer_dirty(leaf);
 429         btrfs_release_path(path);
 430
 431         nrbits = block_group->length >> block_group->fs_info->sectorsize_bits;
 432         start_bit = find_next_bit_le(bitmap, nrbits, 0);
 433
 434         while (start_bit < nrbits) {
 435                 end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit);
 436                 ASSERT(start_bit < end_bit);
 437
 438                 key.objectid = start + start_bit * block_group->fs_info->sectorsize;
 439                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 440                 key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize;
 441
 442                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 443                 if (ret)
 444                         goto out;
 445                 btrfs_release_path(path);
 446
 447                 extent_count++;
 448
 449                 start_bit = find_next_bit_le(bitmap, nrbits, end_bit);
 450         }
 451
 452         if (extent_count != expected_extent_count) {
 453                 btrfs_err(fs_info,
 454                           "incorrect extent count for %llu; counted %u, expected %u",
 455                           block_group->start, extent_count,
 456                           expected_extent_count);
 457                 ASSERT(0);
 458                 ret = -EIO;
 459                 goto out;
 460         }
 461
 462         ret = 0;
 463 out:
 464         kvfree(bitmap);
 465         if (ret)
 466                 btrfs_abort_transaction(trans, ret);
 467         return ret;
 468 }
 469
 470 static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
 471                                           struct btrfs_block_group *block_group,
 472                                           struct btrfs_path *path,
 473                                           int new_extents)
 474 {
 475         struct btrfs_free_space_info *info;
 476         u32 flags;
 477         u32 extent_count;
 478         int ret = 0;
 479
 480         if (new_extents == 0)
 481                 return 0;
 482
 483         info = search_free_space_info(trans, block_group, path, 1);
 484         if (IS_ERR(info)) {
 485                 ret = PTR_ERR(info);
 486                 goto out;
 487         }
 488         flags = btrfs_free_space_flags(path->nodes[0], info);
 489         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
 490
 491         extent_count += new_extents;
 492         btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
 493         btrfs_mark_buffer_dirty(path->nodes[0]);
 494         btrfs_release_path(path);
 495
 496         if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
 497             extent_count > block_group->bitmap_high_thresh) {
 498                 ret = convert_free_space_to_bitmaps(trans, block_group, path);
 499         } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
 500                    extent_count < block_group->bitmap_low_thresh) {
 501                 ret = convert_free_space_to_extents(trans, block_group, path);
 502         }
 503
 504 out:
 505         return ret;
 506 }
 507
 508 EXPORT_FOR_TESTS
 509 int free_space_test_bit(struct btrfs_block_group *block_group,
 510                         struct btrfs_path *path, u64 offset)
 511 {
 512         struct extent_buffer *leaf;
 513         struct btrfs_key key;
 514         u64 found_start, found_end;
 515         unsigned long ptr, i;
 516
 517         leaf = path->nodes[0];
 518         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 519         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
 520
 521         found_start = key.objectid;
 522         found_end = key.objectid + key.offset;
 523         ASSERT(offset >= found_start && offset < found_end);
 524
 525         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 526         i = div_u64(offset - found_start,
 527                     block_group->fs_info->sectorsize);
 528         return !!extent_buffer_test_bit(leaf, ptr, i);
 529 }
 530
 531 static void free_space_set_bits(struct btrfs_block_group *block_group,
 532                                 struct btrfs_path *path, u64 *start, u64 *size,
 533                                 int bit)
 534 {
 535         struct btrfs_fs_info *fs_info = block_group->fs_info;
 536         struct extent_buffer *leaf;
 537         struct btrfs_key key;
 538         u64 end = *start + *size;
 539         u64 found_start, found_end;
 540         unsigned long ptr, first, last;
 541
 542         leaf = path->nodes[0];
 543         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 544         ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
 545
 546         found_start = key.objectid;
 547         found_end = key.objectid + key.offset;
 548         ASSERT(*start >= found_start && *start < found_end);
 549         ASSERT(end > found_start);
 550
 551         if (end > found_end)
 552                 end = found_end;
 553
 554         ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
 555         first = (*start - found_start) >> fs_info->sectorsize_bits;
 556         last = (end - found_start) >> fs_info->sectorsize_bits;
 557         if (bit)
 558                 extent_buffer_bitmap_set(leaf, ptr, first, last - first);
 559         else
 560                 extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
 561         btrfs_mark_buffer_dirty(leaf);
 562
 563         *size -= end - *start;
 564         *start = end;
 565 }
 566
 567 /*
 568  * We can't use btrfs_next_item() in modify_free_space_bitmap() because
 569  * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
 570  * tree walking in btrfs_next_leaf() anyways because we know exactly what we're
 571  * looking for.
 572  */
 573 static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
 574                                   struct btrfs_root *root, struct btrfs_path *p)
 575 {
 576         struct btrfs_key key;
 577
 578         if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
 579                 p->slots[0]++;
 580                 return 0;
 581         }
 582
 583         btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
 584         btrfs_release_path(p);
 585
 586         key.objectid += key.offset;
 587         key.type = (u8)-1;
 588         key.offset = (u64)-1;
 589
 590         return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
 591 }
 592
 593 /*
 594  * If remove is 1, then we are removing free space, thus clearing bits in the
 595  * bitmap. If remove is 0, then we are adding free space, thus setting bits in
 596  * the bitmap.
 597  */
 598 static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
 599                                     struct btrfs_block_group *block_group,
 600                                     struct btrfs_path *path,
 601                                     u64 start, u64 size, int remove)
 602 {
 603         struct btrfs_root *root = btrfs_free_space_root(block_group);
 604         struct btrfs_key key;
 605         u64 end = start + size;
 606         u64 cur_start, cur_size;
 607         int prev_bit, next_bit;
 608         int new_extents;
 609         int ret;
 610
 611         /*
 612          * Read the bit for the block immediately before the extent of space if
 613          * that block is within the block group.
 614          */
 615         if (start > block_group->start) {
 616                 u64 prev_block = start - block_group->fs_info->sectorsize;
 617
 618                 key.objectid = prev_block;
 619                 key.type = (u8)-1;
 620                 key.offset = (u64)-1;
 621
 622                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
 623                 if (ret)
 624                         goto out;
 625
 626                 prev_bit = free_space_test_bit(block_group, path, prev_block);
 627
 628                 /* The previous block may have been in the previous bitmap. */
 629                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 630                 if (start >= key.objectid + key.offset) {
 631                         ret = free_space_next_bitmap(trans, root, path);
 632                         if (ret)
 633                                 goto out;
 634                 }
 635         } else {
 636                 key.objectid = start;
 637                 key.type = (u8)-1;
 638                 key.offset = (u64)-1;
 639
 640                 ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
 641                 if (ret)
 642                         goto out;
 643
 644                 prev_bit = -1;
 645         }
 646
 647         /*
 648          * Iterate over all of the bitmaps overlapped by the extent of space,
 649          * clearing/setting bits as required.
 650          */
 651         cur_start = start;
 652         cur_size = size;
 653         while (1) {
 654                 free_space_set_bits(block_group, path, &cur_start, &cur_size,
 655                                     !remove);
 656                 if (cur_size == 0)
 657                         break;
 658                 ret = free_space_next_bitmap(trans, root, path);
 659                 if (ret)
 660                         goto out;
 661         }
 662
 663         /*
 664          * Read the bit for the block immediately after the extent of space if
 665          * that block is within the block group.
 666          */
 667         if (end < block_group->start + block_group->length) {
 668                 /* The next block may be in the next bitmap. */
 669                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 670                 if (end >= key.objectid + key.offset) {
 671                         ret = free_space_next_bitmap(trans, root, path);
 672                         if (ret)
 673                                 goto out;
 674                 }
 675
 676                 next_bit = free_space_test_bit(block_group, path, end);
 677         } else {
 678                 next_bit = -1;
 679         }
 680
 681         if (remove) {
 682                 new_extents = -1;
 683                 if (prev_bit == 1) {
 684                         /* Leftover on the left. */
 685                         new_extents++;
 686                 }
 687                 if (next_bit == 1) {
 688                         /* Leftover on the right. */
 689                         new_extents++;
 690                 }
 691         } else {
 692                 new_extents = 1;
 693                 if (prev_bit == 1) {
 694                         /* Merging with neighbor on the left. */
 695                         new_extents--;
 696                 }
 697                 if (next_bit == 1) {
 698                         /* Merging with neighbor on the right. */
 699                         new_extents--;
 700                 }
 701         }
 702
 703         btrfs_release_path(path);
 704         ret = update_free_space_extent_count(trans, block_group, path,
 705                                              new_extents);
 706
 707 out:
 708         return ret;
 709 }
 710
 711 static int remove_free_space_extent(struct btrfs_trans_handle *trans,
 712                                     struct btrfs_block_group *block_group,
 713                                     struct btrfs_path *path,
 714                                     u64 start, u64 size)
 715 {
 716         struct btrfs_root *root = btrfs_free_space_root(block_group);
 717         struct btrfs_key key;
 718         u64 found_start, found_end;
 719         u64 end = start + size;
 720         int new_extents = -1;
 721         int ret;
 722
 723         key.objectid = start;
 724         key.type = (u8)-1;
 725         key.offset = (u64)-1;
 726
 727         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 728         if (ret)
 729                 goto out;
 730
 731         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 732
 733         ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
 734
 735         found_start = key.objectid;
 736         found_end = key.objectid + key.offset;
 737         ASSERT(start >= found_start && end <= found_end);
 738
 739         /*
 740          * Okay, now that we've found the free space extent which contains the
 741          * free space that we are removing, there are four cases:
 742          *
 743          * 1. We're using the whole extent: delete the key we found and
 744          * decrement the free space extent count.
 745          * 2. We are using part of the extent starting at the beginning: delete
 746          * the key we found and insert a new key representing the leftover at
 747          * the end. There is no net change in the number of extents.
 748          * 3. We are using part of the extent ending at the end: delete the key
 749          * we found and insert a new key representing the leftover at the
 750          * beginning. There is no net change in the number of extents.
 751          * 4. We are using part of the extent in the middle: delete the key we
 752          * found and insert two new keys representing the leftovers on each
 753          * side. Where we used to have one extent, we now have two, so increment
 754          * the extent count. We may need to convert the block group to bitmaps
 755          * as a result.
 756          */
 757
 758         /* Delete the existing key (cases 1-4). */
 759         ret = btrfs_del_item(trans, root, path);
 760         if (ret)
 761                 goto out;
 762
 763         /* Add a key for leftovers at the beginning (cases 3 and 4). */
 764         if (start > found_start) {
 765                 key.objectid = found_start;
 766                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 767                 key.offset = start - found_start;
 768
 769                 btrfs_release_path(path);
 770                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 771                 if (ret)
 772                         goto out;
 773                 new_extents++;
 774         }
 775
 776         /* Add a key for leftovers at the end (cases 2 and 4). */
 777         if (end < found_end) {
 778                 key.objectid = end;
 779                 key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 780                 key.offset = found_end - end;
 781
 782                 btrfs_release_path(path);
 783                 ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 784                 if (ret)
 785                         goto out;
 786                 new_extents++;
 787         }
 788
 789         btrfs_release_path(path);
 790         ret = update_free_space_extent_count(trans, block_group, path,
 791                                              new_extents);
 792
 793 out:
 794         return ret;
 795 }
 796
 797 EXPORT_FOR_TESTS
 798 int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
 799                                   struct btrfs_block_group *block_group,
 800                                   struct btrfs_path *path, u64 start, u64 size)
 801 {
 802         struct btrfs_free_space_info *info;
 803         u32 flags;
 804         int ret;
 805
 806         if (block_group->needs_free_space) {
 807                 ret = __add_block_group_free_space(trans, block_group, path);
 808                 if (ret)
 809                         return ret;
 810         }
 811
 812         info = search_free_space_info(NULL, block_group, path, 0);
 813         if (IS_ERR(info))
 814                 return PTR_ERR(info);
 815         flags = btrfs_free_space_flags(path->nodes[0], info);
 816         btrfs_release_path(path);
 817
 818         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
 819                 return modify_free_space_bitmap(trans, block_group, path,
 820                                                 start, size, 1);
 821         } else {
 822                 return remove_free_space_extent(trans, block_group, path,
 823                                                 start, size);
 824         }
 825 }
 826
 827 int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
 828                                 u64 start, u64 size)
 829 {
 830         struct btrfs_block_group *block_group;
 831         struct btrfs_path *path;
 832         int ret;
 833
 834         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
 835                 return 0;
 836
 837         path = btrfs_alloc_path();
 838         if (!path) {
 839                 ret = -ENOMEM;
 840                 goto out;
 841         }
 842
 843         block_group = btrfs_lookup_block_group(trans->fs_info, start);
 844         if (!block_group) {
 845                 ASSERT(0);
 846                 ret = -ENOENT;
 847                 goto out;
 848         }
 849
 850         mutex_lock(&block_group->free_space_lock);
 851         ret = __remove_from_free_space_tree(trans, block_group, path, start,
 852                                             size);
 853         mutex_unlock(&block_group->free_space_lock);
 854
 855         btrfs_put_block_group(block_group);
 856 out:
 857         btrfs_free_path(path);
 858         if (ret)
 859                 btrfs_abort_transaction(trans, ret);
 860         return ret;
 861 }
 862
 863 static int add_free_space_extent(struct btrfs_trans_handle *trans,
 864                                  struct btrfs_block_group *block_group,
 865                                  struct btrfs_path *path,
 866                                  u64 start, u64 size)
 867 {
 868         struct btrfs_root *root = btrfs_free_space_root(block_group);
 869         struct btrfs_key key, new_key;
 870         u64 found_start, found_end;
 871         u64 end = start + size;
 872         int new_extents = 1;
 873         int ret;
 874
 875         /*
 876          * We are adding a new extent of free space, but we need to merge
 877          * extents. There are four cases here:
 878          *
 879          * 1. The new extent does not have any immediate neighbors to merge
 880          * with: add the new key and increment the free space extent count. We
 881          * may need to convert the block group to bitmaps as a result.
 882          * 2. The new extent has an immediate neighbor before it: remove the
 883          * previous key and insert a new key combining both of them. There is no
 884          * net change in the number of extents.
 885          * 3. The new extent has an immediate neighbor after it: remove the next
 886          * key and insert a new key combining both of them. There is no net
 887          * change in the number of extents.
 888          * 4. The new extent has immediate neighbors on both sides: remove both
 889          * of the keys and insert a new key combining all of them. Where we used
 890          * to have two extents, we now have one, so decrement the extent count.
 891          */
 892
 893         new_key.objectid = start;
 894         new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
 895         new_key.offset = size;
 896
 897         /* Search for a neighbor on the left. */
 898         if (start == block_group->start)
 899                 goto right;
 900         key.objectid = start - 1;
 901         key.type = (u8)-1;
 902         key.offset = (u64)-1;
 903
 904         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 905         if (ret)
 906                 goto out;
 907
 908         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 909
 910         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
 911                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
 912                 btrfs_release_path(path);
 913                 goto right;
 914         }
 915
 916         found_start = key.objectid;
 917         found_end = key.objectid + key.offset;
 918         ASSERT(found_start >= block_group->start &&
 919                found_end > block_group->start);
 920         ASSERT(found_start < start && found_end <= start);
 921
 922         /*
 923          * Delete the neighbor on the left and absorb it into the new key (cases
 924          * 2 and 4).
 925          */
 926         if (found_end == start) {
 927                 ret = btrfs_del_item(trans, root, path);
 928                 if (ret)
 929                         goto out;
 930                 new_key.objectid = found_start;
 931                 new_key.offset += key.offset;
 932                 new_extents--;
 933         }
 934         btrfs_release_path(path);
 935
 936 right:
 937         /* Search for a neighbor on the right. */
 938         if (end == block_group->start + block_group->length)
 939                 goto insert;
 940         key.objectid = end;
 941         key.type = (u8)-1;
 942         key.offset = (u64)-1;
 943
 944         ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
 945         if (ret)
 946                 goto out;
 947
 948         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 949
 950         if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
 951                 ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
 952                 btrfs_release_path(path);
 953                 goto insert;
 954         }
 955
 956         found_start = key.objectid;
 957         found_end = key.objectid + key.offset;
 958         ASSERT(found_start >= block_group->start &&
 959                found_end > block_group->start);
 960         ASSERT((found_start < start && found_end <= start) ||
 961                (found_start >= end && found_end > end));
 962
 963         /*
 964          * Delete the neighbor on the right and absorb it into the new key
 965          * (cases 3 and 4).
 966          */
 967         if (found_start == end) {
 968                 ret = btrfs_del_item(trans, root, path);
 969                 if (ret)
 970                         goto out;
 971                 new_key.offset += key.offset;
 972                 new_extents--;
 973         }
 974         btrfs_release_path(path);
 975
 976 insert:
 977         /* Insert the new key (cases 1-4). */
 978         ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
 979         if (ret)
 980                 goto out;
 981
 982         btrfs_release_path(path);
 983         ret = update_free_space_extent_count(trans, block_group, path,
 984                                              new_extents);
 985
 986 out:
 987         return ret;
 988 }
 989
 990 EXPORT_FOR_TESTS
 991 int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
 992                              struct btrfs_block_group *block_group,
 993                              struct btrfs_path *path, u64 start, u64 size)
 994 {
 995         struct btrfs_free_space_info *info;
 996         u32 flags;
 997         int ret;
 998
 999         if (block_group->needs_free_space) {
1000                 ret = __add_block_group_free_space(trans, block_group, path);
1001                 if (ret)
1002                         return ret;
1003         }
1004
1005         info = search_free_space_info(NULL, block_group, path, 0);
1006         if (IS_ERR(info))
1007                 return PTR_ERR(info);
1008         flags = btrfs_free_space_flags(path->nodes[0], info);
1009         btrfs_release_path(path);
1010
1011         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
1012                 return modify_free_space_bitmap(trans, block_group, path,
1013                                                 start, size, 0);
1014         } else {
1015                 return add_free_space_extent(trans, block_group, path, start,
1016                                              size);
1017         }
1018 }
1019
1020 int add_to_free_space_tree(struct btrfs_trans_handle *trans,
1021                            u64 start, u64 size)
1022 {
1023         struct btrfs_block_group *block_group;
1024         struct btrfs_path *path;
1025         int ret;
1026
1027         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1028                 return 0;
1029
1030         path = btrfs_alloc_path();
1031         if (!path) {
1032                 ret = -ENOMEM;
1033                 goto out;
1034         }
1035
1036         block_group = btrfs_lookup_block_group(trans->fs_info, start);
1037         if (!block_group) {
1038                 ASSERT(0);
1039                 ret = -ENOENT;
1040                 goto out;
1041         }
1042
1043         mutex_lock(&block_group->free_space_lock);
1044         ret = __add_to_free_space_tree(trans, block_group, path, start, size);
1045         mutex_unlock(&block_group->free_space_lock);
1046
1047         btrfs_put_block_group(block_group);
1048 out:
1049         btrfs_free_path(path);
1050         if (ret)
1051                 btrfs_abort_transaction(trans, ret);
1052         return ret;
1053 }
1054
1055 /*
1056  * Populate the free space tree by walking the extent tree. Operations on the
1057  * extent tree that happen as a result of writes to the free space tree will go
1058  * through the normal add/remove hooks.
1059  */
1060 static int populate_free_space_tree(struct btrfs_trans_handle *trans,
1061                                     struct btrfs_block_group *block_group)
1062 {
1063         struct btrfs_root *extent_root;
1064         struct btrfs_path *path, *path2;
1065         struct btrfs_key key;
1066         u64 start, end;
1067         int ret;
1068
1069         path = btrfs_alloc_path();
1070         if (!path)
1071                 return -ENOMEM;
1072         path->reada = READA_FORWARD;
1073
1074         path2 = btrfs_alloc_path();
1075         if (!path2) {
1076                 btrfs_free_path(path);
1077                 return -ENOMEM;
1078         }
1079
1080         ret = add_new_free_space_info(trans, block_group, path2);
1081         if (ret)
1082                 goto out;
1083
1084         mutex_lock(&block_group->free_space_lock);
1085
1086         /*
1087          * Iterate through all of the extent and metadata items in this block
1088          * group, adding the free space between them and the free space at the
1089          * end. Note that EXTENT_ITEM and METADATA_ITEM are less than
1090          * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
1091          * contained in.
1092          */
1093         key.objectid = block_group->start;
1094         key.type = BTRFS_EXTENT_ITEM_KEY;
1095         key.offset = 0;
1096
1097         extent_root = btrfs_extent_root(trans->fs_info, key.objectid);
1098         ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
1099         if (ret < 0)
1100                 goto out_locked;
1101         ASSERT(ret == 0);
1102
1103         start = block_group->start;
1104         end = block_group->start + block_group->length;
1105         while (1) {
1106                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1107
1108                 if (key.type == BTRFS_EXTENT_ITEM_KEY ||
1109                     key.type == BTRFS_METADATA_ITEM_KEY) {
1110                         if (key.objectid >= end)
1111                                 break;
1112
1113                         if (start < key.objectid) {
1114                                 ret = __add_to_free_space_tree(trans,
1115                                                                block_group,
1116                                                                path2, start,
1117                                                                key.objectid -
1118                                                                start);
1119                                 if (ret)
1120                                         goto out_locked;
1121                         }
1122                         start = key.objectid;
1123                         if (key.type == BTRFS_METADATA_ITEM_KEY)
1124                                 start += trans->fs_info->nodesize;
1125                         else
1126                                 start += key.offset;
1127                 } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
1128                         if (key.objectid != block_group->start)
1129                                 break;
1130                 }
1131
1132                 ret = btrfs_next_item(extent_root, path);
1133                 if (ret < 0)
1134                         goto out_locked;
1135                 if (ret)
1136                         break;
1137         }
1138         if (start < end) {
1139                 ret = __add_to_free_space_tree(trans, block_group, path2,
1140                                                start, end - start);
1141                 if (ret)
1142                         goto out_locked;
1143         }
1144
1145         ret = 0;
1146 out_locked:
1147         mutex_unlock(&block_group->free_space_lock);
1148 out:
1149         btrfs_free_path(path2);
1150         btrfs_free_path(path);
1151         return ret;
1152 }
1153
1154 int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
1155 {
1156         struct btrfs_trans_handle *trans;
1157         struct btrfs_root *tree_root = fs_info->tree_root;
1158         struct btrfs_root *free_space_root;
1159         struct btrfs_block_group *block_group;
1160         struct rb_node *node;
1161         int ret;
1162
1163         trans = btrfs_start_transaction(tree_root, 0);
1164         if (IS_ERR(trans))
1165                 return PTR_ERR(trans);
1166
1167         set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1168         set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1169         free_space_root = btrfs_create_tree(trans,
1170                                             BTRFS_FREE_SPACE_TREE_OBJECTID);
1171         if (IS_ERR(free_space_root)) {
1172                 ret = PTR_ERR(free_space_root);
1173                 goto abort;
1174         }
1175         ret = btrfs_global_root_insert(free_space_root);
1176         if (ret) {
1177                 btrfs_put_root(free_space_root);
1178                 goto abort;
1179         }
1180
1181         node = rb_first_cached(&fs_info->block_group_cache_tree);
1182         while (node) {
1183                 block_group = rb_entry(node, struct btrfs_block_group,
1184                                        cache_node);
1185                 ret = populate_free_space_tree(trans, block_group);
1186                 if (ret)
1187                         goto abort;
1188                 node = rb_next(node);
1189         }
1190
1191         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1192         btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1193         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1194         ret = btrfs_commit_transaction(trans);
1195
1196         /*
1197          * Now that we've committed the transaction any reading of our commit
1198          * root will be safe, so we can cache from the free space tree now.
1199          */
1200         clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1201         return ret;
1202
1203 abort:
1204         clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
1205         clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags);
1206         btrfs_abort_transaction(trans, ret);
1207         btrfs_end_transaction(trans);
1208         return ret;
1209 }
1210
1211 static int clear_free_space_tree(struct btrfs_trans_handle *trans,
1212                                  struct btrfs_root *root)
1213 {
1214         struct btrfs_path *path;
1215         struct btrfs_key key;
1216         int nr;
1217         int ret;
1218
1219         path = btrfs_alloc_path();
1220         if (!path)
1221                 return -ENOMEM;
1222
1223         key.objectid = 0;
1224         key.type = 0;
1225         key.offset = 0;
1226
1227         while (1) {
1228                 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1229                 if (ret < 0)
1230                         goto out;
1231
1232                 nr = btrfs_header_nritems(path->nodes[0]);
1233                 if (!nr)
1234                         break;
1235
1236                 path->slots[0] = 0;
1237                 ret = btrfs_del_items(trans, root, path, 0, nr);
1238                 if (ret)
1239                         goto out;
1240
1241                 btrfs_release_path(path);
1242         }
1243
1244         ret = 0;
1245 out:
1246         btrfs_free_path(path);
1247         return ret;
1248 }
1249
1250 int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
1251 {
1252         struct btrfs_trans_handle *trans;
1253         struct btrfs_root *tree_root = fs_info->tree_root;
1254         struct btrfs_key key = {
1255                 .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID,
1256                 .type = BTRFS_ROOT_ITEM_KEY,
1257                 .offset = 0,
1258         };
1259         struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key);
1260         int ret;
1261
1262         trans = btrfs_start_transaction(tree_root, 0);
1263         if (IS_ERR(trans))
1264                 return PTR_ERR(trans);
1265
1266         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
1267         btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
1268
1269         ret = clear_free_space_tree(trans, free_space_root);
1270         if (ret)
1271                 goto abort;
1272
1273         ret = btrfs_del_root(trans, &free_space_root->root_key);
1274         if (ret)
1275                 goto abort;
1276
1277         btrfs_global_root_delete(free_space_root);
1278         list_del(&free_space_root->dirty_list);
1279
1280         btrfs_tree_lock(free_space_root->node);
1281         btrfs_clean_tree_block(free_space_root->node);
1282         btrfs_tree_unlock(free_space_root->node);
1283         btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
1284                               free_space_root->node, 0, 1);
1285
1286         btrfs_put_root(free_space_root);
1287
1288         return btrfs_commit_transaction(trans);
1289
1290 abort:
1291         btrfs_abort_transaction(trans, ret);
1292         btrfs_end_transaction(trans);
1293         return ret;
1294 }
1295
1296 static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
1297                                         struct btrfs_block_group *block_group,
1298                                         struct btrfs_path *path)
1299 {
1300         int ret;
1301
1302         block_group->needs_free_space = 0;
1303
1304         ret = add_new_free_space_info(trans, block_group, path);
1305         if (ret)
1306                 return ret;
1307
1308         return __add_to_free_space_tree(trans, block_group, path,
1309                                         block_group->start,
1310                                         block_group->length);
1311 }
1312
1313 int add_block_group_free_space(struct btrfs_trans_handle *trans,
1314                                struct btrfs_block_group *block_group)
1315 {
1316         struct btrfs_fs_info *fs_info = trans->fs_info;
1317         struct btrfs_path *path = NULL;
1318         int ret = 0;
1319
1320         if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
1321                 return 0;
1322
1323         mutex_lock(&block_group->free_space_lock);
1324         if (!block_group->needs_free_space)
1325                 goto out;
1326
1327         path = btrfs_alloc_path();
1328         if (!path) {
1329                 ret = -ENOMEM;
1330                 goto out;
1331         }
1332
1333         ret = __add_block_group_free_space(trans, block_group, path);
1334
1335 out:
1336         btrfs_free_path(path);
1337         mutex_unlock(&block_group->free_space_lock);
1338         if (ret)
1339                 btrfs_abort_transaction(trans, ret);
1340         return ret;
1341 }
1342
1343 int remove_block_group_free_space(struct btrfs_trans_handle *trans,
1344                                   struct btrfs_block_group *block_group)
1345 {
1346         struct btrfs_root *root = btrfs_free_space_root(block_group);
1347         struct btrfs_path *path;
1348         struct btrfs_key key, found_key;
1349         struct extent_buffer *leaf;
1350         u64 start, end;
1351         int done = 0, nr;
1352         int ret;
1353
1354         if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE))
1355                 return 0;
1356
1357         if (block_group->needs_free_space) {
1358                 /* We never added this block group to the free space tree. */
1359                 return 0;
1360         }
1361
1362         path = btrfs_alloc_path();
1363         if (!path) {
1364                 ret = -ENOMEM;
1365                 goto out;
1366         }
1367
1368         start = block_group->start;
1369         end = block_group->start + block_group->length;
1370
1371         key.objectid = end - 1;
1372         key.type = (u8)-1;
1373         key.offset = (u64)-1;
1374
1375         while (!done) {
1376                 ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
1377                 if (ret)
1378                         goto out;
1379
1380                 leaf = path->nodes[0];
1381                 nr = 0;
1382                 path->slots[0]++;
1383                 while (path->slots[0] > 0) {
1384                         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
1385
1386                         if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
1387                                 ASSERT(found_key.objectid == block_group->start);
1388                                 ASSERT(found_key.offset == block_group->length);
1389                                 done = 1;
1390                                 nr++;
1391                                 path->slots[0]--;
1392                                 break;
1393                         } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
1394                                    found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
1395                                 ASSERT(found_key.objectid >= start);
1396                                 ASSERT(found_key.objectid < end);
1397                                 ASSERT(found_key.objectid + found_key.offset <= end);
1398                                 nr++;
1399                                 path->slots[0]--;
1400                         } else {
1401                                 ASSERT(0);
1402                         }
1403                 }
1404
1405                 ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
1406                 if (ret)
1407                         goto out;
1408                 btrfs_release_path(path);
1409         }
1410
1411         ret = 0;
1412 out:
1413         btrfs_free_path(path);
1414         if (ret)
1415                 btrfs_abort_transaction(trans, ret);
1416         return ret;
1417 }
1418
1419 static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
1420                                    struct btrfs_path *path,
1421                                    u32 expected_extent_count)
1422 {
1423         struct btrfs_block_group *block_group;
1424         struct btrfs_fs_info *fs_info;
1425         struct btrfs_root *root;
1426         struct btrfs_key key;
1427         int prev_bit = 0, bit;
1428         /* Initialize to silence GCC. */
1429         u64 extent_start = 0;
1430         u64 end, offset;
1431         u64 total_found = 0;
1432         u32 extent_count = 0;
1433         int ret;
1434
1435         block_group = caching_ctl->block_group;
1436         fs_info = block_group->fs_info;
1437         root = btrfs_free_space_root(block_group);
1438
1439         end = block_group->start + block_group->length;
1440
1441         while (1) {
1442                 ret = btrfs_next_item(root, path);
1443                 if (ret < 0)
1444                         goto out;
1445                 if (ret)
1446                         break;
1447
1448                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1449
1450                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1451                         break;
1452
1453                 ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
1454                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1455
1456                 caching_ctl->progress = key.objectid;
1457
1458                 offset = key.objectid;
1459                 while (offset < key.objectid + key.offset) {
1460                         bit = free_space_test_bit(block_group, path, offset);
1461                         if (prev_bit == 0 && bit == 1) {
1462                                 extent_start = offset;
1463                         } else if (prev_bit == 1 && bit == 0) {
1464                                 total_found += add_new_free_space(block_group,
1465                                                                   extent_start,
1466                                                                   offset);
1467                                 if (total_found > CACHING_CTL_WAKE_UP) {
1468                                         total_found = 0;
1469                                         wake_up(&caching_ctl->wait);
1470                                 }
1471                                 extent_count++;
1472                         }
1473                         prev_bit = bit;
1474                         offset += fs_info->sectorsize;
1475                 }
1476         }
1477         if (prev_bit == 1) {
1478                 total_found += add_new_free_space(block_group, extent_start,
1479                                                   end);
1480                 extent_count++;
1481         }
1482
1483         if (extent_count != expected_extent_count) {
1484                 btrfs_err(fs_info,
1485                           "incorrect extent count for %llu; counted %u, expected %u",
1486                           block_group->start, extent_count,
1487                           expected_extent_count);
1488                 ASSERT(0);
1489                 ret = -EIO;
1490                 goto out;
1491         }
1492
1493         caching_ctl->progress = (u64)-1;
1494
1495         ret = 0;
1496 out:
1497         return ret;
1498 }
1499
1500 static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
1501                                    struct btrfs_path *path,
1502                                    u32 expected_extent_count)
1503 {
1504         struct btrfs_block_group *block_group;
1505         struct btrfs_fs_info *fs_info;
1506         struct btrfs_root *root;
1507         struct btrfs_key key;
1508         u64 end;
1509         u64 total_found = 0;
1510         u32 extent_count = 0;
1511         int ret;
1512
1513         block_group = caching_ctl->block_group;
1514         fs_info = block_group->fs_info;
1515         root = btrfs_free_space_root(block_group);
1516
1517         end = block_group->start + block_group->length;
1518
1519         while (1) {
1520                 ret = btrfs_next_item(root, path);
1521                 if (ret < 0)
1522                         goto out;
1523                 if (ret)
1524                         break;
1525
1526                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1527
1528                 if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
1529                         break;
1530
1531                 ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
1532                 ASSERT(key.objectid < end && key.objectid + key.offset <= end);
1533
1534                 caching_ctl->progress = key.objectid;
1535
1536                 total_found += add_new_free_space(block_group, key.objectid,
1537                                                   key.objectid + key.offset);
1538                 if (total_found > CACHING_CTL_WAKE_UP) {
1539                         total_found = 0;
1540                         wake_up(&caching_ctl->wait);
1541                 }
1542                 extent_count++;
1543         }
1544
1545         if (extent_count != expected_extent_count) {
1546                 btrfs_err(fs_info,
1547                           "incorrect extent count for %llu; counted %u, expected %u",
1548                           block_group->start, extent_count,
1549                           expected_extent_count);
1550                 ASSERT(0);
1551                 ret = -EIO;
1552                 goto out;
1553         }
1554
1555         caching_ctl->progress = (u64)-1;
1556
1557         ret = 0;
1558 out:
1559         return ret;
1560 }
1561
1562 int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
1563 {
1564         struct btrfs_block_group *block_group;
1565         struct btrfs_free_space_info *info;
1566         struct btrfs_path *path;
1567         u32 extent_count, flags;
1568         int ret;
1569
1570         block_group = caching_ctl->block_group;
1571
1572         path = btrfs_alloc_path();
1573         if (!path)
1574                 return -ENOMEM;
1575
1576         /*
1577          * Just like caching_thread() doesn't want to deadlock on the extent
1578          * tree, we don't want to deadlock on the free space tree.
1579          */
1580         path->skip_locking = 1;
1581         path->search_commit_root = 1;
1582         path->reada = READA_FORWARD;
1583
1584         info = search_free_space_info(NULL, block_group, path, 0);
1585         if (IS_ERR(info)) {
1586                 ret = PTR_ERR(info);
1587                 goto out;
1588         }
1589         extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
1590         flags = btrfs_free_space_flags(path->nodes[0], info);
1591
1592         /*
1593          * We left path pointing to the free space info item, so now
1594          * load_free_space_foo can just iterate through the free space tree from
1595          * there.
1596          */
1597         if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
1598                 ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
1599         else
1600                 ret = load_free_space_extents(caching_ctl, path, extent_count);
1601
1602 out:
1603         btrfs_free_path(path);
1604         return ret;
1605 }