uspace/lib/ext4/libext4_balloc.c

   1 /*
   2  * Copyright (c) 2012 Frantisek Princ
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  * - Redistributions in binary form must reproduce the above copyright
  12  *   notice, this list of conditions and the following disclaimer in the
  13  *   documentation and/or other materials provided with the distribution.
  14  * - The name of the author may not be used to endorse or promote products
  15  *   derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /** @addtogroup libext4
  30  * @{
  31  */
  32 /**
  33  * @file  libext4_balloc.c
  34  * @brief Physical block allocator.
  35  */
  36
  37 #include <errno.h>
  38 #include <sys/types.h>
  39 #include "libext4.h"
  40
  41 /** Compute number of block group from block address.
  42  *
  43  * @param sb         Superblock pointer.
  44  * @param block_addr Absolute address of block.
  45  *
  46  * @return Block group index
  47  *
  48  */
  49 static uint32_t ext4_balloc_get_bgid_of_block(ext4_superblock_t *sb,
  50     uint32_t block_addr)
  51 {
  52         uint32_t blocks_per_group =
  53             ext4_superblock_get_blocks_per_group(sb);
  54         uint32_t first_block =
  55             ext4_superblock_get_first_data_block(sb);
  56
  57         /* First block == 0 or 1 */
  58         if (first_block == 0)
  59                 return block_addr / blocks_per_group;
  60         else
  61                 return (block_addr - 1) / blocks_per_group;
  62 }
  63
  64 /** Free block.
  65  *
  66  * @param inode_ref  Inode, where the block is allocated
  67  * @param block_addr Absolute block address to free
  68  *
  69  * @return Error code
  70  *
  71  */
  72 int ext4_balloc_free_block(ext4_inode_ref_t *inode_ref, uint32_t block_addr)
  73 {
  74         ext4_filesystem_t *fs = inode_ref->fs;
  75         ext4_superblock_t *sb = fs->superblock;
  76
  77         /* Compute indexes */
  78         uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, block_addr);
  79         uint32_t index_in_group =
  80             ext4_filesystem_blockaddr2_index_in_group(sb, block_addr);
  81
  82         /* Load block group reference */
  83         ext4_block_group_ref_t *bg_ref;
  84         int rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
  85         if (rc != EOK)
  86                 return rc;
  87
  88         /* Load block with bitmap */
  89         uint32_t bitmap_block_addr =
  90             ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
  91         block_t *bitmap_block;
  92         rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
  93         if (rc != EOK) {
  94                 ext4_filesystem_put_block_group_ref(bg_ref);
  95                 return rc;
  96         }
  97
  98         /* Modify bitmap */
  99         ext4_bitmap_free_bit(bitmap_block->data, index_in_group);
 100         bitmap_block->dirty = true;
 101
 102         /* Release block with bitmap */
 103         rc = block_put(bitmap_block);
 104         if (rc != EOK) {
 105                 /* Error in saving bitmap */
 106                 ext4_filesystem_put_block_group_ref(bg_ref);
 107                 return rc;
 108         }
 109
 110         uint32_t block_size = ext4_superblock_get_block_size(sb);
 111
 112         /* Update superblock free blocks count */
 113         uint32_t sb_free_blocks =
 114             ext4_superblock_get_free_blocks_count(sb);
 115         sb_free_blocks++;
 116         ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
 117
 118         /* Update inode blocks count */
 119         uint64_t ino_blocks =
 120             ext4_inode_get_blocks_count(sb, inode_ref->inode);
 121         ino_blocks -= block_size / EXT4_INODE_BLOCK_SIZE;
 122         ext4_inode_set_blocks_count(sb, inode_ref->inode, ino_blocks);
 123         inode_ref->dirty = true;
 124
 125         /* Update block group free blocks count */
 126         uint32_t free_blocks =
 127             ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
 128         free_blocks++;
 129         ext4_block_group_set_free_blocks_count(bg_ref->block_group,
 130             sb, free_blocks);
 131         bg_ref->dirty = true;
 132
 133         /* Release block group reference */
 134         return ext4_filesystem_put_block_group_ref(bg_ref);
 135 }
 136
 137 /** Free continuous set of blocks.
 138  *
 139  * @param inode_ref Inode, where the blocks are allocated
 140  * @param first     First block to release
 141  * @param count     Number of blocks to release
 142  *
 143  */
 144 int ext4_balloc_free_blocks(ext4_inode_ref_t *inode_ref,
 145     uint32_t first, uint32_t count)
 146 {
 147         ext4_filesystem_t *fs = inode_ref->fs;
 148         ext4_superblock_t *sb = fs->superblock;
 149
 150         /* Compute indexes */
 151         uint32_t block_group_first =
 152             ext4_balloc_get_bgid_of_block(sb, first);
 153         uint32_t block_group_last =
 154             ext4_balloc_get_bgid_of_block(sb, first + count - 1);
 155
 156         assert(block_group_first == block_group_last);
 157
 158         /* Load block group reference */
 159         ext4_block_group_ref_t *bg_ref;
 160         int rc = ext4_filesystem_get_block_group_ref(fs, block_group_first, &bg_ref);
 161         if (rc != EOK)
 162                 return rc;
 163
 164         uint32_t index_in_group_first =
 165             ext4_filesystem_blockaddr2_index_in_group(sb, first);
 166
 167         /* Load block with bitmap */
 168         uint32_t bitmap_block_addr =
 169             ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
 170
 171         block_t *bitmap_block;
 172         rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
 173         if (rc != EOK) {
 174                 ext4_filesystem_put_block_group_ref(bg_ref);
 175                 return rc;
 176         }
 177
 178         /* Modify bitmap */
 179         ext4_bitmap_free_bits(bitmap_block->data, index_in_group_first, count);
 180         bitmap_block->dirty = true;
 181
 182         /* Release block with bitmap */
 183         rc = block_put(bitmap_block);
 184         if (rc != EOK) {
 185                 /* Error in saving bitmap */
 186                 ext4_filesystem_put_block_group_ref(bg_ref);
 187                 return rc;
 188         }
 189
 190         uint32_t block_size = ext4_superblock_get_block_size(sb);
 191
 192         /* Update superblock free blocks count */
 193         uint32_t sb_free_blocks =
 194             ext4_superblock_get_free_blocks_count(sb);
 195         sb_free_blocks += count;
 196         ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
 197
 198         /* Update inode blocks count */
 199         uint64_t ino_blocks =
 200             ext4_inode_get_blocks_count(sb, inode_ref->inode);
 201         ino_blocks -= count * (block_size / EXT4_INODE_BLOCK_SIZE);
 202         ext4_inode_set_blocks_count(sb, inode_ref->inode, ino_blocks);
 203         inode_ref->dirty = true;
 204
 205         /* Update block group free blocks count */
 206         uint32_t free_blocks =
 207             ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
 208         free_blocks += count;
 209         ext4_block_group_set_free_blocks_count(bg_ref->block_group,
 210             sb, free_blocks);
 211         bg_ref->dirty = true;
 212
 213         /* Release block group reference */
 214         return ext4_filesystem_put_block_group_ref(bg_ref);
 215 }
 216
 217 /** Compute first block for data in block group.
 218  *
 219  * @param sb   Pointer to superblock
 220  * @param bg   Pointer to block group
 221  * @param bgid Index of block group
 222  *
 223  * @return Absolute block index of first block
 224  *
 225  */
 226 uint32_t ext4_balloc_get_first_data_block_in_group(ext4_superblock_t *sb,
 227     ext4_block_group_ref_t *bg_ref)
 228 {
 229         uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
 230         uint32_t inode_table_first_block =
 231             ext4_block_group_get_inode_table_first_block(bg_ref->block_group, sb);
 232         uint16_t inode_table_item_size = ext4_superblock_get_inode_size(sb);
 233         uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
 234         uint32_t block_size = ext4_superblock_get_block_size(sb);
 235         uint32_t inode_table_bytes;
 236
 237         if (bg_ref->index < block_group_count - 1) {
 238                 inode_table_bytes = inodes_per_group * inode_table_item_size;
 239         } else {
 240                 /* Last block group could be smaller */
 241                 uint32_t inodes_count_total = ext4_superblock_get_inodes_count(sb);
 242                 inode_table_bytes =
 243                     (inodes_count_total - ((block_group_count - 1) * inodes_per_group)) *
 244                     inode_table_item_size;
 245         }
 246
 247         uint32_t inode_table_blocks = inode_table_bytes / block_size;
 248
 249         if (inode_table_bytes % block_size)
 250                 inode_table_blocks++;
 251
 252         return inode_table_first_block + inode_table_blocks;
 253 }
 254
 255 /** Compute 'goal' for allocation algorithm.
 256  *
 257  * @param inode_ref Reference to inode, to allocate block for
 258  *
 259  * @return Goal block number
 260  *
 261  */
 262 static int ext4_balloc_find_goal(ext4_inode_ref_t *inode_ref, uint32_t *goal)
 263 {
 264         *goal = 0;
 265         ext4_superblock_t *sb = inode_ref->fs->superblock;
 266
 267         uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
 268         uint32_t block_size = ext4_superblock_get_block_size(sb);
 269         uint32_t inode_block_count = inode_size / block_size;
 270
 271         if (inode_size % block_size != 0)
 272                 inode_block_count++;
 273
 274         /* If inode has some blocks, get last block address + 1 */
 275         if (inode_block_count > 0) {
 276                 int rc = ext4_filesystem_get_inode_data_block_index(inode_ref,
 277                     inode_block_count - 1, goal);
 278                 if (rc != EOK)
 279                         return rc;
 280
 281                 if (goal != 0) {
 282                         (*goal)++;
 283                         return EOK;
 284                 }
 285
 286                 /* If goal == 0, sparse file -> continue */
 287         }
 288
 289         /* Identify block group of inode */
 290         uint32_t inodes_per_group = ext4_superblock_get_inodes_per_group(sb);
 291         uint32_t block_group = (inode_ref->index - 1) / inodes_per_group;
 292         block_size = ext4_superblock_get_block_size(sb);
 293
 294         /* Load block group reference */
 295         ext4_block_group_ref_t *bg_ref;
 296         int rc = ext4_filesystem_get_block_group_ref(inode_ref->fs,
 297             block_group, &bg_ref);
 298         if (rc != EOK)
 299                 return rc;
 300
 301         /* Compute indexes */
 302         uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
 303         uint32_t inode_table_first_block =
 304             ext4_block_group_get_inode_table_first_block(bg_ref->block_group, sb);
 305         uint16_t inode_table_item_size = ext4_superblock_get_inode_size(sb);
 306         uint32_t inode_table_bytes;
 307
 308         /* Check for last block group */
 309         if (block_group < block_group_count - 1) {
 310                 inode_table_bytes = inodes_per_group * inode_table_item_size;
 311         } else {
 312                 /* Last block group could be smaller */
 313                 uint32_t inodes_count_total = ext4_superblock_get_inodes_count(sb);
 314                 inode_table_bytes =
 315                     (inodes_count_total - ((block_group_count - 1) * inodes_per_group)) *
 316                     inode_table_item_size;
 317         }
 318
 319         uint32_t inode_table_blocks = inode_table_bytes / block_size;
 320
 321         if (inode_table_bytes % block_size)
 322                 inode_table_blocks++;
 323
 324         *goal = inode_table_first_block + inode_table_blocks;
 325
 326         return ext4_filesystem_put_block_group_ref(bg_ref);
 327 }
 328
 329 /** Data block allocation algorithm.
 330  *
 331  * @param inode_ref Inode to allocate block for
 332  * @param fblock    Allocated block address
 333  *
 334  * @return Error code
 335  *
 336  */
 337 int ext4_balloc_alloc_block(ext4_inode_ref_t *inode_ref, uint32_t *fblock)
 338 {
 339         uint32_t allocated_block = 0;
 340
 341         uint32_t bitmap_block_addr;
 342         block_t *bitmap_block;
 343         uint32_t rel_block_idx = 0;
 344         uint32_t goal;
 345
 346         /* Find GOAL */
 347         int rc = ext4_balloc_find_goal(inode_ref, &goal);
 348         if (rc != EOK)
 349                 return rc;
 350         else if (goal == 0) {
 351                 /* no goal found => partition is full */
 352                 return ENOMEM;
 353         }
 354
 355         ext4_superblock_t *sb = inode_ref->fs->superblock;
 356
 357         /* Load block group number for goal and relative index */
 358         uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, goal);
 359         uint32_t index_in_group =
 360             ext4_filesystem_blockaddr2_index_in_group(sb, goal);
 361
 362         /* Load block group reference */
 363         ext4_block_group_ref_t *bg_ref;
 364         rc = ext4_filesystem_get_block_group_ref(inode_ref->fs,
 365             block_group, &bg_ref);
 366         if (rc != EOK)
 367                 return rc;
 368
 369         /* Compute indexes */
 370         uint32_t first_in_group =
 371             ext4_balloc_get_first_data_block_in_group(sb, bg_ref);
 372
 373         uint32_t first_in_group_index =
 374             ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
 375
 376         if (index_in_group < first_in_group_index)
 377                 index_in_group = first_in_group_index;
 378
 379         /* Load block with bitmap */
 380         bitmap_block_addr =
 381             ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
 382
 383         rc = block_get(&bitmap_block, inode_ref->fs->device,
 384             bitmap_block_addr, BLOCK_FLAGS_NONE);
 385         if (rc != EOK) {
 386                 ext4_filesystem_put_block_group_ref(bg_ref);
 387                 return rc;
 388         }
 389
 390         /* Check if goal is free */
 391         if (ext4_bitmap_is_free_bit(bitmap_block->data, index_in_group)) {
 392                 ext4_bitmap_set_bit(bitmap_block->data, index_in_group);
 393                 bitmap_block->dirty = true;
 394                 rc = block_put(bitmap_block);
 395                 if (rc != EOK) {
 396                         ext4_filesystem_put_block_group_ref(bg_ref);
 397                         return rc;
 398                 }
 399
 400                 allocated_block =
 401                     ext4_filesystem_index_in_group2blockaddr(sb, index_in_group,
 402                     block_group);
 403
 404                 goto success;
 405         }
 406
 407         uint32_t blocks_in_group =
 408             ext4_superblock_get_blocks_in_group(sb, block_group);
 409
 410         uint32_t end_idx = (index_in_group + 63) & ~63;
 411         if (end_idx > blocks_in_group)
 412                 end_idx = blocks_in_group;
 413
 414         /* Try to find free block near to goal */
 415         for (uint32_t tmp_idx = index_in_group + 1; tmp_idx < end_idx;
 416             ++tmp_idx) {
 417                 if (ext4_bitmap_is_free_bit(bitmap_block->data, tmp_idx)) {
 418                         ext4_bitmap_set_bit(bitmap_block->data, tmp_idx);
 419                         bitmap_block->dirty = true;
 420                         rc = block_put(bitmap_block);
 421                         if (rc != EOK)
 422                                 return rc;
 423
 424                         allocated_block =
 425                             ext4_filesystem_index_in_group2blockaddr(sb, tmp_idx,
 426                             block_group);
 427
 428                         goto success;
 429                 }
 430         }
 431
 432         /* Find free BYTE in bitmap */
 433         rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data,
 434             index_in_group, &rel_block_idx, blocks_in_group);
 435         if (rc == EOK) {
 436                 bitmap_block->dirty = true;
 437                 rc = block_put(bitmap_block);
 438                 if (rc != EOK)
 439                         return rc;
 440
 441                 allocated_block =
 442                     ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
 443                     block_group);
 444
 445                 goto success;
 446         }
 447
 448         /* Find free bit in bitmap */
 449         rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data,
 450             index_in_group, &rel_block_idx, blocks_in_group);
 451         if (rc == EOK) {
 452                 bitmap_block->dirty = true;
 453                 rc = block_put(bitmap_block);
 454                 if (rc != EOK)
 455                         return rc;
 456
 457                 allocated_block =
 458                     ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
 459                     block_group);
 460
 461                 goto success;
 462         }
 463
 464         /* No free block found yet */
 465         rc = block_put(bitmap_block);
 466         if (rc != EOK) {
 467                 ext4_filesystem_put_block_group_ref(bg_ref);
 468                 return rc;
 469         }
 470
 471         rc = ext4_filesystem_put_block_group_ref(bg_ref);
 472         if (rc != EOK)
 473                 return rc;
 474
 475         /* Try other block groups */
 476         uint32_t block_group_count = ext4_superblock_get_block_group_count(sb);
 477
 478         uint32_t bgid = (block_group + 1) % block_group_count;
 479         uint32_t count = block_group_count;
 480
 481         while (count > 0) {
 482                 rc = ext4_filesystem_get_block_group_ref(inode_ref->fs, bgid,
 483                     &bg_ref);
 484                 if (rc != EOK)
 485                         return rc;
 486
 487                 /* Load block with bitmap */
 488                 bitmap_block_addr =
 489                     ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
 490
 491                 rc = block_get(&bitmap_block, inode_ref->fs->device,
 492                     bitmap_block_addr, 0);
 493                 if (rc != EOK) {
 494                         ext4_filesystem_put_block_group_ref(bg_ref);
 495                         return rc;
 496                 }
 497
 498                 /* Compute indexes */
 499                 first_in_group =
 500                     ext4_balloc_get_first_data_block_in_group(sb, bg_ref);
 501                 index_in_group =
 502                     ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
 503                 blocks_in_group = ext4_superblock_get_blocks_in_group(sb, bgid);
 504
 505                 first_in_group_index =
 506                     ext4_filesystem_blockaddr2_index_in_group(sb, first_in_group);
 507
 508                 if (index_in_group < first_in_group_index)
 509                         index_in_group = first_in_group_index;
 510
 511                 /* Try to find free byte in bitmap */
 512                 rc = ext4_bitmap_find_free_byte_and_set_bit(bitmap_block->data,
 513                     index_in_group, &rel_block_idx, blocks_in_group);
 514                 if (rc == EOK) {
 515                         bitmap_block->dirty = true;
 516                         rc = block_put(bitmap_block);
 517                         if (rc != EOK) {
 518                                 ext4_filesystem_put_block_group_ref(bg_ref);
 519                                 return rc;
 520                         }
 521
 522                         allocated_block =
 523                             ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
 524                             bgid);
 525
 526                         goto success;
 527                 }
 528
 529                 /* Try to find free bit in bitmap */
 530                 rc = ext4_bitmap_find_free_bit_and_set(bitmap_block->data,
 531                     index_in_group, &rel_block_idx, blocks_in_group);
 532                 if (rc == EOK) {
 533                         bitmap_block->dirty = true;
 534                         rc = block_put(bitmap_block);
 535                         if (rc != EOK) {
 536                                 ext4_filesystem_put_block_group_ref(bg_ref);
 537                                 return rc;
 538                         }
 539
 540                         allocated_block =
 541                             ext4_filesystem_index_in_group2blockaddr(sb, rel_block_idx,
 542                             bgid);
 543
 544                         goto success;
 545                 }
 546
 547                 rc = block_put(bitmap_block);
 548                 if (rc != EOK) {
 549                         ext4_filesystem_put_block_group_ref(bg_ref);
 550                         return rc;
 551                 }
 552
 553                 rc = ext4_filesystem_put_block_group_ref(bg_ref);
 554                 if (rc != EOK)
 555                         return rc;
 556
 557                 /* Goto next group */
 558                 bgid = (bgid + 1) % block_group_count;
 559                 count--;
 560         }
 561
 562         return ENOSPC;
 563
 564 success:
 565         /* Empty command - because of syntax */
 566         ;
 567
 568         uint32_t block_size = ext4_superblock_get_block_size(sb);
 569
 570         /* Update superblock free blocks count */
 571         uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(sb);
 572         sb_free_blocks--;
 573         ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
 574
 575         /* Update inode blocks (different block size!) count */
 576         uint64_t ino_blocks =
 577             ext4_inode_get_blocks_count(sb, inode_ref->inode);
 578         ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
 579         ext4_inode_set_blocks_count(sb, inode_ref->inode, ino_blocks);
 580         inode_ref->dirty = true;
 581
 582         /* Update block group free blocks count */
 583         uint32_t bg_free_blocks =
 584             ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
 585         bg_free_blocks--;
 586         ext4_block_group_set_free_blocks_count(bg_ref->block_group, sb,
 587             bg_free_blocks);
 588         bg_ref->dirty = true;
 589
 590         rc = ext4_filesystem_put_block_group_ref(bg_ref);
 591
 592         *fblock = allocated_block;
 593         return rc;
 594 }
 595
 596 /** Try to allocate concrete block.
 597  *
 598  * @param inode_ref Inode to allocate block for
 599  * @param fblock    Block address to allocate
 600  * @param free      Output value - if target block is free
 601  *
 602  * @return Error code
 603  *
 604  */
 605 int ext4_balloc_try_alloc_block(ext4_inode_ref_t *inode_ref, uint32_t fblock,
 606     bool *free)
 607 {
 608         int rc;
 609
 610         ext4_filesystem_t *fs = inode_ref->fs;
 611         ext4_superblock_t *sb = fs->superblock;
 612
 613         /* Compute indexes */
 614         uint32_t block_group = ext4_balloc_get_bgid_of_block(sb, fblock);
 615         uint32_t index_in_group =
 616             ext4_filesystem_blockaddr2_index_in_group(sb, fblock);
 617
 618         /* Load block group reference */
 619         ext4_block_group_ref_t *bg_ref;
 620         rc = ext4_filesystem_get_block_group_ref(fs, block_group, &bg_ref);
 621         if (rc != EOK)
 622                 return rc;
 623
 624         /* Load block with bitmap */
 625         uint32_t bitmap_block_addr =
 626             ext4_block_group_get_block_bitmap(bg_ref->block_group, sb);
 627         block_t *bitmap_block;
 628         rc = block_get(&bitmap_block, fs->device, bitmap_block_addr, 0);
 629         if (rc != EOK) {
 630                 ext4_filesystem_put_block_group_ref(bg_ref);
 631                 return rc;
 632         }
 633
 634         /* Check if block is free */
 635         *free = ext4_bitmap_is_free_bit(bitmap_block->data, index_in_group);
 636
 637         /* Allocate block if possible */
 638         if (*free) {
 639                 ext4_bitmap_set_bit(bitmap_block->data, index_in_group);
 640                 bitmap_block->dirty = true;
 641         }
 642
 643         /* Release block with bitmap */
 644         rc = block_put(bitmap_block);
 645         if (rc != EOK) {
 646                 /* Error in saving bitmap */
 647                 ext4_filesystem_put_block_group_ref(bg_ref);
 648                 return rc;
 649         }
 650
 651         /* If block is not free, return */
 652         if (!(*free))
 653                 goto terminate;
 654
 655         uint32_t block_size = ext4_superblock_get_block_size(sb);
 656
 657         /* Update superblock free blocks count */
 658         uint32_t sb_free_blocks = ext4_superblock_get_free_blocks_count(sb);
 659         sb_free_blocks--;
 660         ext4_superblock_set_free_blocks_count(sb, sb_free_blocks);
 661
 662         /* Update inode blocks count */
 663         uint64_t ino_blocks =
 664             ext4_inode_get_blocks_count(sb, inode_ref->inode);
 665         ino_blocks += block_size / EXT4_INODE_BLOCK_SIZE;
 666         ext4_inode_set_blocks_count(sb, inode_ref->inode, ino_blocks);
 667         inode_ref->dirty = true;
 668
 669         /* Update block group free blocks count */
 670         uint32_t free_blocks =
 671             ext4_block_group_get_free_blocks_count(bg_ref->block_group, sb);
 672         free_blocks--;
 673         ext4_block_group_set_free_blocks_count(bg_ref->block_group,
 674             sb, free_blocks);
 675         bg_ref->dirty = true;
 676
 677 terminate:
 678         return ext4_filesystem_put_block_group_ref(bg_ref);
 679 }
 680
 681 /**
 682  * @}
 683  */