fs/btrfs/extent-io.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * BTRFS filesystem implementation for U-Boot
   4  *
   5  * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/bug.h>
  10 #include <malloc.h>
  11 #include <memalign.h>
  12 #include "btrfs.h"
  13 #include "ctree.h"
  14 #include "extent-io.h"
  15 #include "disk-io.h"
  16
  17 void extent_io_tree_init(struct extent_io_tree *tree)
  18 {
  19         cache_tree_init(&tree->state);
  20         cache_tree_init(&tree->cache);
  21         tree->cache_size = 0;
  22 }
  23
  24 static struct extent_state *alloc_extent_state(void)
  25 {
  26         struct extent_state *state;
  27
  28         state = malloc(sizeof(*state));
  29         if (!state)
  30                 return NULL;
  31         state->cache_node.objectid = 0;
  32         state->refs = 1;
  33         state->state = 0;
  34         state->xprivate = 0;
  35         return state;
  36 }
  37
  38 static void btrfs_free_extent_state(struct extent_state *state)
  39 {
  40         state->refs--;
  41         BUG_ON(state->refs < 0);
  42         if (state->refs == 0)
  43                 free(state);
  44 }
  45
  46 static void free_extent_state_func(struct cache_extent *cache)
  47 {
  48         struct extent_state *es;
  49
  50         es = container_of(cache, struct extent_state, cache_node);
  51         btrfs_free_extent_state(es);
  52 }
  53
  54 static void free_extent_buffer_final(struct extent_buffer *eb);
  55 void extent_io_tree_cleanup(struct extent_io_tree *tree)
  56 {
  57         cache_tree_free_extents(&tree->state, free_extent_state_func);
  58 }
  59
  60 static inline void update_extent_state(struct extent_state *state)
  61 {
  62         state->cache_node.start = state->start;
  63         state->cache_node.size = state->end + 1 - state->start;
  64 }
  65
  66 /*
  67  * Utility function to look for merge candidates inside a given range.
  68  * Any extents with matching state are merged together into a single
  69  * extent in the tree. Extents with EXTENT_IO in their state field are
  70  * not merged
  71  */
  72 static int merge_state(struct extent_io_tree *tree,
  73                        struct extent_state *state)
  74 {
  75         struct extent_state *other;
  76         struct cache_extent *other_node;
  77
  78         if (state->state & EXTENT_IOBITS)
  79                 return 0;
  80
  81         other_node = prev_cache_extent(&state->cache_node);
  82         if (other_node) {
  83                 other = container_of(other_node, struct extent_state,
  84                                      cache_node);
  85                 if (other->end == state->start - 1 &&
  86                     other->state == state->state) {
  87                         state->start = other->start;
  88                         update_extent_state(state);
  89                         remove_cache_extent(&tree->state, &other->cache_node);
  90                         btrfs_free_extent_state(other);
  91                 }
  92         }
  93         other_node = next_cache_extent(&state->cache_node);
  94         if (other_node) {
  95                 other = container_of(other_node, struct extent_state,
  96                                      cache_node);
  97                 if (other->start == state->end + 1 &&
  98                     other->state == state->state) {
  99                         other->start = state->start;
 100                         update_extent_state(other);
 101                         remove_cache_extent(&tree->state, &state->cache_node);
 102                         btrfs_free_extent_state(state);
 103                 }
 104         }
 105         return 0;
 106 }
 107
 108 /*
 109  * insert an extent_state struct into the tree.  'bits' are set on the
 110  * struct before it is inserted.
 111  */
 112 static int insert_state(struct extent_io_tree *tree,
 113                         struct extent_state *state, u64 start, u64 end,
 114                         int bits)
 115 {
 116         int ret;
 117
 118         BUG_ON(end < start);
 119         state->state |= bits;
 120         state->start = start;
 121         state->end = end;
 122         update_extent_state(state);
 123         ret = insert_cache_extent(&tree->state, &state->cache_node);
 124         BUG_ON(ret);
 125         merge_state(tree, state);
 126         return 0;
 127 }
 128
 129 /*
 130  * split a given extent state struct in two, inserting the preallocated
 131  * struct 'prealloc' as the newly created second half.  'split' indicates an
 132  * offset inside 'orig' where it should be split.
 133  */
 134 static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 135                        struct extent_state *prealloc, u64 split)
 136 {
 137         int ret;
 138         prealloc->start = orig->start;
 139         prealloc->end = split - 1;
 140         prealloc->state = orig->state;
 141         update_extent_state(prealloc);
 142         orig->start = split;
 143         update_extent_state(orig);
 144         ret = insert_cache_extent(&tree->state, &prealloc->cache_node);
 145         BUG_ON(ret);
 146         return 0;
 147 }
 148
 149 /*
 150  * clear some bits on a range in the tree.
 151  */
 152 static int clear_state_bit(struct extent_io_tree *tree,
 153                             struct extent_state *state, int bits)
 154 {
 155         int ret = state->state & bits;
 156
 157         state->state &= ~bits;
 158         if (state->state == 0) {
 159                 remove_cache_extent(&tree->state, &state->cache_node);
 160                 btrfs_free_extent_state(state);
 161         } else {
 162                 merge_state(tree, state);
 163         }
 164         return ret;
 165 }
 166
 167 /*
 168  * extent_buffer_bitmap_set - set an area of a bitmap
 169  * @eb: the extent buffer
 170  * @start: offset of the bitmap item in the extent buffer
 171  * @pos: bit number of the first bit
 172  * @len: number of bits to set
 173  */
 174 void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
 175                               unsigned long pos, unsigned long len)
 176 {
 177         u8 *p = (u8 *)eb->data + start + BIT_BYTE(pos);
 178         const unsigned int size = pos + len;
 179         int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
 180         u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos);
 181
 182         while (len >= bits_to_set) {
 183                 *p |= mask_to_set;
 184                 len -= bits_to_set;
 185                 bits_to_set = BITS_PER_BYTE;
 186                 mask_to_set = ~0;
 187                 p++;
 188         }
 189         if (len) {
 190                 mask_to_set &= BITMAP_LAST_BYTE_MASK(size);
 191                 *p |= mask_to_set;
 192         }
 193 }
 194
 195 /*
 196  * extent_buffer_bitmap_clear - clear an area of a bitmap
 197  * @eb: the extent buffer
 198  * @start: offset of the bitmap item in the extent buffer
 199  * @pos: bit number of the first bit
 200  * @len: number of bits to clear
 201  */
 202 void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
 203                                 unsigned long pos, unsigned long len)
 204 {
 205         u8 *p = (u8 *)eb->data + start + BIT_BYTE(pos);
 206         const unsigned int size = pos + len;
 207         int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE);
 208         u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos);
 209
 210         while (len >= bits_to_clear) {
 211                 *p &= ~mask_to_clear;
 212                 len -= bits_to_clear;
 213                 bits_to_clear = BITS_PER_BYTE;
 214                 mask_to_clear = ~0;
 215                 p++;
 216         }
 217         if (len) {
 218                 mask_to_clear &= BITMAP_LAST_BYTE_MASK(size);
 219                 *p &= ~mask_to_clear;
 220         }
 221 }
 222
 223 /*
 224  * clear some bits on a range in the tree.
 225  */
 226 int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 227 {
 228         struct extent_state *state;
 229         struct extent_state *prealloc = NULL;
 230         struct cache_extent *node;
 231         u64 last_end;
 232         int err;
 233         int set = 0;
 234
 235 again:
 236         if (!prealloc) {
 237                 prealloc = alloc_extent_state();
 238                 if (!prealloc)
 239                         return -ENOMEM;
 240         }
 241
 242         /*
 243          * this search will find the extents that end after
 244          * our range starts
 245          */
 246         node = search_cache_extent(&tree->state, start);
 247         if (!node)
 248                 goto out;
 249         state = container_of(node, struct extent_state, cache_node);
 250         if (state->start > end)
 251                 goto out;
 252         last_end = state->end;
 253
 254         /*
 255          *     | ---- desired range ---- |
 256          *  | state | or
 257          *  | ------------- state -------------- |
 258          *
 259          * We need to split the extent we found, and may flip
 260          * bits on second half.
 261          *
 262          * If the extent we found extends past our range, we
 263          * just split and search again.  It'll get split again
 264          * the next time though.
 265          *
 266          * If the extent we found is inside our range, we clear
 267          * the desired bit on it.
 268          */
 269         if (state->start < start) {
 270                 err = split_state(tree, state, prealloc, start);
 271                 BUG_ON(err == -EEXIST);
 272                 prealloc = NULL;
 273                 if (err)
 274                         goto out;
 275                 if (state->end <= end) {
 276                         set |= clear_state_bit(tree, state, bits);
 277                         if (last_end == (u64)-1)
 278                                 goto out;
 279                         start = last_end + 1;
 280                 } else {
 281                         start = state->start;
 282                 }
 283                 goto search_again;
 284         }
 285         /*
 286          * | ---- desired range ---- |
 287          *                        | state |
 288          * We need to split the extent, and clear the bit
 289          * on the first half
 290          */
 291         if (state->start <= end && state->end > end) {
 292                 err = split_state(tree, state, prealloc, end + 1);
 293                 BUG_ON(err == -EEXIST);
 294
 295                 set |= clear_state_bit(tree, prealloc, bits);
 296                 prealloc = NULL;
 297                 goto out;
 298         }
 299
 300         start = state->end + 1;
 301         set |= clear_state_bit(tree, state, bits);
 302         if (last_end == (u64)-1)
 303                 goto out;
 304         start = last_end + 1;
 305         goto search_again;
 306 out:
 307         if (prealloc)
 308                 btrfs_free_extent_state(prealloc);
 309         return set;
 310
 311 search_again:
 312         if (start > end)
 313                 goto out;
 314         goto again;
 315 }
 316
 317 /*
 318  * set some bits on a range in the tree.
 319  */
 320 int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, int bits)
 321 {
 322         struct extent_state *state;
 323         struct extent_state *prealloc = NULL;
 324         struct cache_extent *node;
 325         int err = 0;
 326         u64 last_start;
 327         u64 last_end;
 328 again:
 329         if (!prealloc) {
 330                 prealloc = alloc_extent_state();
 331                 if (!prealloc)
 332                         return -ENOMEM;
 333         }
 334
 335         /*
 336          * this search will find the extents that end after
 337          * our range starts
 338          */
 339         node = search_cache_extent(&tree->state, start);
 340         if (!node) {
 341                 err = insert_state(tree, prealloc, start, end, bits);
 342                 BUG_ON(err == -EEXIST);
 343                 prealloc = NULL;
 344                 goto out;
 345         }
 346
 347         state = container_of(node, struct extent_state, cache_node);
 348         last_start = state->start;
 349         last_end = state->end;
 350
 351         /*
 352          * | ---- desired range ---- |
 353          * | state |
 354          *
 355          * Just lock what we found and keep going
 356          */
 357         if (state->start == start && state->end <= end) {
 358                 state->state |= bits;
 359                 merge_state(tree, state);
 360                 if (last_end == (u64)-1)
 361                         goto out;
 362                 start = last_end + 1;
 363                 goto search_again;
 364         }
 365         /*
 366          *     | ---- desired range ---- |
 367          * | state |
 368          *   or
 369          * | ------------- state -------------- |
 370          *
 371          * We need to split the extent we found, and may flip bits on
 372          * second half.
 373          *
 374          * If the extent we found extends past our
 375          * range, we just split and search again.  It'll get split
 376          * again the next time though.
 377          *
 378          * If the extent we found is inside our range, we set the
 379          * desired bit on it.
 380          */
 381         if (state->start < start) {
 382                 err = split_state(tree, state, prealloc, start);
 383                 BUG_ON(err == -EEXIST);
 384                 prealloc = NULL;
 385                 if (err)
 386                         goto out;
 387                 if (state->end <= end) {
 388                         state->state |= bits;
 389                         start = state->end + 1;
 390                         merge_state(tree, state);
 391                         if (last_end == (u64)-1)
 392                                 goto out;
 393                         start = last_end + 1;
 394                 } else {
 395                         start = state->start;
 396                 }
 397                 goto search_again;
 398         }
 399         /*
 400          * | ---- desired range ---- |
 401          *     | state | or               | state |
 402          *
 403          * There's a hole, we need to insert something in it and
 404          * ignore the extent we found.
 405          */
 406         if (state->start > start) {
 407                 u64 this_end;
 408                 if (end < last_start)
 409                         this_end = end;
 410                 else
 411                         this_end = last_start -1;
 412                 err = insert_state(tree, prealloc, start, this_end,
 413                                 bits);
 414                 BUG_ON(err == -EEXIST);
 415                 prealloc = NULL;
 416                 if (err)
 417                         goto out;
 418                 start = this_end + 1;
 419                 goto search_again;
 420         }
 421         /*
 422          * | ---- desired range ---- |
 423          * | ---------- state ---------- |
 424          * We need to split the extent, and set the bit
 425          * on the first half
 426          */
 427         err = split_state(tree, state, prealloc, end + 1);
 428         BUG_ON(err == -EEXIST);
 429
 430         state->state |= bits;
 431         merge_state(tree, prealloc);
 432         prealloc = NULL;
 433 out:
 434         if (prealloc)
 435                 btrfs_free_extent_state(prealloc);
 436         return err;
 437 search_again:
 438         if (start > end)
 439                 goto out;
 440         goto again;
 441 }
 442
 443 int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end)
 444 {
 445         return set_extent_bits(tree, start, end, EXTENT_DIRTY);
 446 }
 447
 448 int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end)
 449 {
 450         return clear_extent_bits(tree, start, end, EXTENT_DIRTY);
 451 }
 452
 453 int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
 454                           u64 *start_ret, u64 *end_ret, int bits)
 455 {
 456         struct cache_extent *node;
 457         struct extent_state *state;
 458         int ret = 1;
 459
 460         /*
 461          * this search will find all the extents that end after
 462          * our range starts.
 463          */
 464         node = search_cache_extent(&tree->state, start);
 465         if (!node)
 466                 goto out;
 467
 468         while(1) {
 469                 state = container_of(node, struct extent_state, cache_node);
 470                 if (state->end >= start && (state->state & bits)) {
 471                         *start_ret = state->start;
 472                         *end_ret = state->end;
 473                         ret = 0;
 474                         break;
 475                 }
 476                 node = next_cache_extent(node);
 477                 if (!node)
 478                         break;
 479         }
 480 out:
 481         return ret;
 482 }
 483
 484 int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
 485                    int bits, int filled)
 486 {
 487         struct extent_state *state = NULL;
 488         struct cache_extent *node;
 489         int bitset = 0;
 490
 491         node = search_cache_extent(&tree->state, start);
 492         while (node && start <= end) {
 493                 state = container_of(node, struct extent_state, cache_node);
 494
 495                 if (filled && state->start > start) {
 496                         bitset = 0;
 497                         break;
 498                 }
 499                 if (state->start > end)
 500                         break;
 501                 if (state->state & bits) {
 502                         bitset = 1;
 503                         if (!filled)
 504                                 break;
 505                 } else if (filled) {
 506                         bitset = 0;
 507                         break;
 508                 }
 509                 start = state->end + 1;
 510                 if (start > end)
 511                         break;
 512                 node = next_cache_extent(node);
 513                 if (!node) {
 514                         if (filled)
 515                                 bitset = 0;
 516                         break;
 517                 }
 518         }
 519         return bitset;
 520 }
 521
 522 int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
 523 {
 524         struct cache_extent *node;
 525         struct extent_state *state;
 526         int ret = 0;
 527
 528         node = search_cache_extent(&tree->state, start);
 529         if (!node) {
 530                 ret = -ENOENT;
 531                 goto out;
 532         }
 533         state = container_of(node, struct extent_state, cache_node);
 534         if (state->start != start) {
 535                 ret = -ENOENT;
 536                 goto out;
 537         }
 538         state->xprivate = private;
 539 out:
 540         return ret;
 541 }
 542
 543 int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
 544 {
 545         struct cache_extent *node;
 546         struct extent_state *state;
 547         int ret = 0;
 548
 549         node = search_cache_extent(&tree->state, start);
 550         if (!node) {
 551                 ret = -ENOENT;
 552                 goto out;
 553         }
 554         state = container_of(node, struct extent_state, cache_node);
 555         if (state->start != start) {
 556                 ret = -ENOENT;
 557                 goto out;
 558         }
 559         *private = state->xprivate;
 560 out:
 561         return ret;
 562 }
 563
 564 static struct extent_buffer *__alloc_extent_buffer(struct btrfs_fs_info *info,
 565                                                    u64 bytenr, u32 blocksize)
 566 {
 567         struct extent_buffer *eb;
 568
 569         eb = calloc(1, sizeof(struct extent_buffer));
 570         if (!eb)
 571                 return NULL;
 572         eb->data = malloc_cache_aligned(blocksize);
 573         if (!eb->data) {
 574                 free(eb);
 575                 return NULL;
 576         }
 577
 578         eb->start = bytenr;
 579         eb->len = blocksize;
 580         eb->refs = 1;
 581         eb->flags = 0;
 582         eb->cache_node.start = bytenr;
 583         eb->cache_node.size = blocksize;
 584         eb->fs_info = info;
 585         memset_extent_buffer(eb, 0, 0, blocksize);
 586
 587         return eb;
 588 }
 589
 590 struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
 591 {
 592         struct extent_buffer *new;
 593
 594         new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
 595         if (!new)
 596                 return NULL;
 597
 598         copy_extent_buffer(new, src, 0, 0, src->len);
 599         new->flags |= EXTENT_BUFFER_DUMMY;
 600
 601         return new;
 602 }
 603
 604 static void free_extent_buffer_final(struct extent_buffer *eb)
 605 {
 606         BUG_ON(eb->refs);
 607         if (!(eb->flags & EXTENT_BUFFER_DUMMY)) {
 608                 struct extent_io_tree *tree = &eb->fs_info->extent_cache;
 609
 610                 remove_cache_extent(&tree->cache, &eb->cache_node);
 611                 BUG_ON(tree->cache_size < eb->len);
 612                 tree->cache_size -= eb->len;
 613         }
 614         free(eb->data);
 615         free(eb);
 616 }
 617
 618 static void free_extent_buffer_internal(struct extent_buffer *eb, bool free_now)
 619 {
 620         if (!eb || IS_ERR(eb))
 621                 return;
 622
 623         eb->refs--;
 624         BUG_ON(eb->refs < 0);
 625         if (eb->refs == 0) {
 626                 if (eb->flags & EXTENT_DIRTY) {
 627                         error(
 628                         "dirty eb leak (aborted trans): start %llu len %u",
 629                                 eb->start, eb->len);
 630                 }
 631                 if (eb->flags & EXTENT_BUFFER_DUMMY || free_now)
 632                         free_extent_buffer_final(eb);
 633         }
 634 }
 635
 636 void free_extent_buffer(struct extent_buffer *eb)
 637 {
 638         free_extent_buffer_internal(eb, 1);
 639 }
 640
 641 struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
 642                                          u64 bytenr, u32 blocksize)
 643 {
 644         struct extent_buffer *eb = NULL;
 645         struct cache_extent *cache;
 646
 647         cache = lookup_cache_extent(&tree->cache, bytenr, blocksize);
 648         if (cache && cache->start == bytenr &&
 649             cache->size == blocksize) {
 650                 eb = container_of(cache, struct extent_buffer, cache_node);
 651                 eb->refs++;
 652         }
 653         return eb;
 654 }
 655
 656 struct extent_buffer *find_first_extent_buffer(struct extent_io_tree *tree,
 657                                                u64 start)
 658 {
 659         struct extent_buffer *eb = NULL;
 660         struct cache_extent *cache;
 661
 662         cache = search_cache_extent(&tree->cache, start);
 663         if (cache) {
 664                 eb = container_of(cache, struct extent_buffer, cache_node);
 665                 eb->refs++;
 666         }
 667         return eb;
 668 }
 669
 670 struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 671                                           u64 bytenr, u32 blocksize)
 672 {
 673         struct extent_buffer *eb;
 674         struct extent_io_tree *tree = &fs_info->extent_cache;
 675         struct cache_extent *cache;
 676
 677         cache = lookup_cache_extent(&tree->cache, bytenr, blocksize);
 678         if (cache && cache->start == bytenr &&
 679             cache->size == blocksize) {
 680                 eb = container_of(cache, struct extent_buffer, cache_node);
 681                 eb->refs++;
 682         } else {
 683                 int ret;
 684
 685                 if (cache) {
 686                         eb = container_of(cache, struct extent_buffer,
 687                                           cache_node);
 688                         free_extent_buffer(eb);
 689                 }
 690                 eb = __alloc_extent_buffer(fs_info, bytenr, blocksize);
 691                 if (!eb)
 692                         return NULL;
 693                 ret = insert_cache_extent(&tree->cache, &eb->cache_node);
 694                 if (ret) {
 695                         free(eb);
 696                         return NULL;
 697                 }
 698                 tree->cache_size += blocksize;
 699         }
 700         return eb;
 701 }
 702
 703 /*
 704  * Allocate a dummy extent buffer which won't be inserted into extent buffer
 705  * cache.
 706  *
 707  * This mostly allows super block read write using existing eb infrastructure
 708  * without pulluting the eb cache.
 709  *
 710  * This is especially important to avoid injecting eb->start == SZ_64K, as
 711  * fuzzed image could have invalid tree bytenr covers super block range,
 712  * and cause ref count underflow.
 713  */
 714 struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
 715                                                 u64 bytenr, u32 blocksize)
 716 {
 717         struct extent_buffer *ret;
 718
 719         ret = __alloc_extent_buffer(fs_info, bytenr, blocksize);
 720         if (!ret)
 721                 return NULL;
 722
 723         ret->flags |= EXTENT_BUFFER_DUMMY;
 724
 725         return ret;
 726 }
 727
 728 int read_extent_from_disk(struct blk_desc *desc, struct disk_partition *part,
 729                           u64 physical, struct extent_buffer *eb,
 730                           unsigned long offset, unsigned long len)
 731 {
 732         int ret;
 733
 734         ret = __btrfs_devread(desc, part, eb->data + offset, len, physical);
 735         if (ret < 0)
 736                 goto out;
 737         if (ret != len) {
 738                 ret = -EIO;
 739                 goto out;
 740         }
 741         ret = 0;
 742 out:
 743         return ret;
 744 }
 745
 746 int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
 747                          unsigned long start, unsigned long len)
 748 {
 749         return memcmp(eb->data + start, ptrv, len);
 750 }
 751
 752 void read_extent_buffer(const struct extent_buffer *eb, void *dst,
 753                         unsigned long start, unsigned long len)
 754 {
 755         memcpy(dst, eb->data + start, len);
 756 }
 757
 758 void write_extent_buffer(struct extent_buffer *eb, const void *src,
 759                          unsigned long start, unsigned long len)
 760 {
 761         memcpy(eb->data + start, src, len);
 762 }
 763
 764 void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
 765                         unsigned long dst_offset, unsigned long src_offset,
 766                         unsigned long len)
 767 {
 768         memcpy(dst->data + dst_offset, src->data + src_offset, len);
 769 }
 770
 771 void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
 772                            unsigned long src_offset, unsigned long len)
 773 {
 774         memmove(dst->data + dst_offset, dst->data + src_offset, len);
 775 }
 776
 777 void memset_extent_buffer(struct extent_buffer *eb, char c,
 778                           unsigned long start, unsigned long len)
 779 {
 780         memset(eb->data + start, c, len);
 781 }
 782
 783 int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
 784                            unsigned long nr)
 785 {
 786         return le_test_bit(nr, (u8 *)eb->data + start);
 787 }
 788
 789 int set_extent_buffer_dirty(struct extent_buffer *eb)
 790 {
 791         struct extent_io_tree *tree = &eb->fs_info->extent_cache;
 792         if (!(eb->flags & EXTENT_DIRTY)) {
 793                 eb->flags |= EXTENT_DIRTY;
 794                 set_extent_dirty(tree, eb->start, eb->start + eb->len - 1);
 795                 extent_buffer_get(eb);
 796         }
 797         return 0;
 798 }
 799
 800 int clear_extent_buffer_dirty(struct extent_buffer *eb)
 801 {
 802         struct extent_io_tree *tree = &eb->fs_info->extent_cache;
 803         if (eb->flags & EXTENT_DIRTY) {
 804                 eb->flags &= ~EXTENT_DIRTY;
 805                 clear_extent_dirty(tree, eb->start, eb->start + eb->len - 1);
 806                 free_extent_buffer(eb);
 807         }
 808         return 0;
 809 }