fs/ext2/balloc.c

   1 /*
   2  *  linux/fs/ext2/balloc.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  Enhanced block allocation by Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
  10  *  Big-endian to little-endian byte-swapping/bitmaps by
  11  *        David S. Miller (davem@caip.rutgers.edu), 1995
  12  */
  13
  14 #include <linux/config.h>
  15 #include "ext2.h"
  16 #include <linux/quotaops.h>
  17 #include <linux/sched.h>
  18 #include <linux/buffer_head.h>
  19 #include <linux/vs_base.h>
  20 #include <linux/vs_dlimit.h>
  21
  22 /*
  23  * balloc.c contains the blocks allocation and deallocation routines
  24  */
  25
  26 /*
  27  * The free blocks are managed by bitmaps.  A file system contains several
  28  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
  29  * block for inodes, N blocks for the inode table and data blocks.
  30  *
  31  * The file system contains group descriptors which are located after the
  32  * super block.  Each descriptor contains the number of the bitmap block and
  33  * the free blocks count in the block.  The descriptors are loaded in memory
  34  * when a file system is mounted (see ext2_read_super).
  35  */
  36
  37
  38 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
  39
  40 struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
  41                                              unsigned int block_group,
  42                                              struct buffer_head ** bh)
  43 {
  44         unsigned long group_desc;
  45         unsigned long offset;
  46         struct ext2_group_desc * desc;
  47         struct ext2_sb_info *sbi = EXT2_SB(sb);
  48
  49         if (block_group >= sbi->s_groups_count) {
  50                 ext2_error (sb, "ext2_get_group_desc",
  51                             "block_group >= groups_count - "
  52                             "block_group = %d, groups_count = %lu",
  53                             block_group, sbi->s_groups_count);
  54
  55                 return NULL;
  56         }
  57
  58         group_desc = block_group / EXT2_DESC_PER_BLOCK(sb);
  59         offset = block_group % EXT2_DESC_PER_BLOCK(sb);
  60         if (!sbi->s_group_desc[group_desc]) {
  61                 ext2_error (sb, "ext2_get_group_desc",
  62                             "Group descriptor not loaded - "
  63                             "block_group = %d, group_desc = %lu, desc = %lu",
  64                              block_group, group_desc, offset);
  65                 return NULL;
  66         }
  67
  68         desc = (struct ext2_group_desc *) sbi->s_group_desc[group_desc]->b_data;
  69         if (bh)
  70                 *bh = sbi->s_group_desc[group_desc];
  71         return desc + offset;
  72 }
  73
  74 /*
  75  * Read the bitmap for a given block_group, reading into the specified
  76  * slot in the superblock's bitmap cache.
  77  *
  78  * Return buffer_head on success or NULL in case of failure.
  79  */
  80 static struct buffer_head *
  81 read_block_bitmap(struct super_block *sb, unsigned int block_group)
  82 {
  83         struct ext2_group_desc * desc;
  84         struct buffer_head * bh = NULL;
  85
  86         desc = ext2_get_group_desc (sb, block_group, NULL);
  87         if (!desc)
  88                 goto error_out;
  89         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
  90         if (!bh)
  91                 ext2_error (sb, "read_block_bitmap",
  92                             "Cannot read block bitmap - "
  93                             "block_group = %d, block_bitmap = %lu",
  94                             block_group, (unsigned long) desc->bg_block_bitmap);
  95 error_out:
  96         return bh;
  97 }
  98
  99 /*
 100  * Set sb->s_dirt here because the superblock was "logically" altered.  We
 101  * need to recalculate its free blocks count and flush it out.
 102  */
 103 static int reserve_blocks(struct super_block *sb, int count)
 104 {
 105         struct ext2_sb_info *sbi = EXT2_SB(sb);
 106         struct ext2_super_block *es = sbi->s_es;
 107         unsigned free_blocks;
 108         unsigned root_blocks;
 109
 110         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
 111         root_blocks = le32_to_cpu(es->s_r_blocks_count);
 112
 113         DLIMIT_ADJUST_BLOCK(sb, vx_current_xid(), &free_blocks, &root_blocks);
 114
 115         if (free_blocks < count)
 116                 count = free_blocks;
 117
 118         if (free_blocks < root_blocks + count && !capable(CAP_SYS_RESOURCE) &&
 119             sbi->s_resuid != current->fsuid &&
 120             (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
 121                 /*
 122                  * We are too close to reserve and we are not privileged.
 123                  * Can we allocate anything at all?
 124                  */
 125                 if (free_blocks > root_blocks)
 126                         count = free_blocks - root_blocks;
 127                 else
 128                         return 0;
 129         }
 130
 131         percpu_counter_mod(&sbi->s_freeblocks_counter, -count);
 132         sb->s_dirt = 1;
 133         return count;
 134 }
 135
 136 static void release_blocks(struct super_block *sb, int count)
 137 {
 138         if (count) {
 139                 struct ext2_sb_info *sbi = EXT2_SB(sb);
 140
 141                 percpu_counter_mod(&sbi->s_freeblocks_counter, count);
 142                 sb->s_dirt = 1;
 143         }
 144 }
 145
 146 static int group_reserve_blocks(struct ext2_sb_info *sbi, int group_no,
 147         struct ext2_group_desc *desc, struct buffer_head *bh, int count)
 148 {
 149         unsigned free_blocks;
 150
 151         if (!desc->bg_free_blocks_count)
 152                 return 0;
 153
 154         spin_lock(sb_bgl_lock(sbi, group_no));
 155         free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
 156         if (free_blocks < count)
 157                 count = free_blocks;
 158         desc->bg_free_blocks_count = cpu_to_le16(free_blocks - count);
 159         spin_unlock(sb_bgl_lock(sbi, group_no));
 160         mark_buffer_dirty(bh);
 161         return count;
 162 }
 163
 164 static void group_release_blocks(struct super_block *sb, int group_no,
 165         struct ext2_group_desc *desc, struct buffer_head *bh, int count)
 166 {
 167         if (count) {
 168                 struct ext2_sb_info *sbi = EXT2_SB(sb);
 169                 unsigned free_blocks;
 170
 171                 spin_lock(sb_bgl_lock(sbi, group_no));
 172                 free_blocks = le16_to_cpu(desc->bg_free_blocks_count);
 173                 desc->bg_free_blocks_count = cpu_to_le16(free_blocks + count);
 174                 spin_unlock(sb_bgl_lock(sbi, group_no));
 175                 sb->s_dirt = 1;
 176                 mark_buffer_dirty(bh);
 177         }
 178 }
 179
 180 /* Free given blocks, update quota and i_blocks field */
 181 void ext2_free_blocks (struct inode * inode, unsigned long block,
 182                        unsigned long count)
 183 {
 184         struct buffer_head *bitmap_bh = NULL;
 185         struct buffer_head * bh2;
 186         unsigned long block_group;
 187         unsigned long bit;
 188         unsigned long i;
 189         unsigned long overflow;
 190         struct super_block * sb = inode->i_sb;
 191         struct ext2_sb_info * sbi = EXT2_SB(sb);
 192         struct ext2_group_desc * desc;
 193         struct ext2_super_block * es = sbi->s_es;
 194         unsigned freed = 0, group_freed;
 195
 196         if (block < le32_to_cpu(es->s_first_data_block) ||
 197             block + count < block ||
 198             block + count > le32_to_cpu(es->s_blocks_count)) {
 199                 ext2_error (sb, "ext2_free_blocks",
 200                             "Freeing blocks not in datazone - "
 201                             "block = %lu, count = %lu", block, count);
 202                 goto error_return;
 203         }
 204
 205         ext2_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
 206
 207 do_more:
 208         overflow = 0;
 209         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
 210                       EXT2_BLOCKS_PER_GROUP(sb);
 211         bit = (block - le32_to_cpu(es->s_first_data_block)) %
 212                       EXT2_BLOCKS_PER_GROUP(sb);
 213         /*
 214          * Check to see if we are freeing blocks across a group
 215          * boundary.
 216          */
 217         if (bit + count > EXT2_BLOCKS_PER_GROUP(sb)) {
 218                 overflow = bit + count - EXT2_BLOCKS_PER_GROUP(sb);
 219                 count -= overflow;
 220         }
 221         brelse(bitmap_bh);
 222         bitmap_bh = read_block_bitmap(sb, block_group);
 223         if (!bitmap_bh)
 224                 goto error_return;
 225
 226         desc = ext2_get_group_desc (sb, block_group, &bh2);
 227         if (!desc)
 228                 goto error_return;
 229
 230         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
 231             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
 232             in_range (block, le32_to_cpu(desc->bg_inode_table),
 233                       sbi->s_itb_per_group) ||
 234             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
 235                       sbi->s_itb_per_group))
 236                 ext2_error (sb, "ext2_free_blocks",
 237                             "Freeing blocks in system zones - "
 238                             "Block = %lu, count = %lu",
 239                             block, count);
 240
 241         for (i = 0, group_freed = 0; i < count; i++) {
 242                 if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 243                                         bit + i, (void *) bitmap_bh->b_data))
 244                         ext2_error (sb, "ext2_free_blocks",
 245                                       "bit already cleared for block %lu",
 246                                       block + i);
 247                 else
 248                         group_freed++;
 249         }
 250
 251         mark_buffer_dirty(bitmap_bh);
 252         if (sb->s_flags & MS_SYNCHRONOUS)
 253                 sync_dirty_buffer(bitmap_bh);
 254
 255         group_release_blocks(sb, block_group, desc, bh2, group_freed);
 256         freed += group_freed;
 257
 258         if (overflow) {
 259                 block += count;
 260                 count = overflow;
 261                 goto do_more;
 262         }
 263 error_return:
 264         brelse(bitmap_bh);
 265         DLIMIT_FREE_BLOCK(sb, inode->i_xid, freed);
 266         release_blocks(sb, freed);
 267         DQUOT_FREE_BLOCK(inode, freed);
 268 }
 269
 270 static int grab_block(spinlock_t *lock, char *map, unsigned size, int goal)
 271 {
 272         int k;
 273         char *p, *r;
 274
 275         if (!ext2_test_bit(goal, map))
 276                 goto got_it;
 277
 278 repeat:
 279         if (goal) {
 280                 /*
 281                  * The goal was occupied; search forward for a free
 282                  * block within the next XX blocks.
 283                  *
 284                  * end_goal is more or less random, but it has to be
 285                  * less than EXT2_BLOCKS_PER_GROUP. Aligning up to the
 286                  * next 64-bit boundary is simple..
 287                  */
 288                 k = (goal + 63) & ~63;
 289                 goal = ext2_find_next_zero_bit(map, k, goal);
 290                 if (goal < k)
 291                         goto got_it;
 292                 /*
 293                  * Search in the remainder of the current group.
 294                  */
 295         }
 296
 297         p = map + (goal >> 3);
 298         r = memscan(p, 0, (size - goal + 7) >> 3);
 299         k = (r - map) << 3;
 300         if (k < size) {
 301                 /*
 302                  * We have succeeded in finding a free byte in the block
 303                  * bitmap.  Now search backwards to find the start of this
 304                  * group of free blocks - won't take more than 7 iterations.
 305                  */
 306                 for (goal = k; goal && !ext2_test_bit (goal - 1, map); goal--)
 307                         ;
 308                 goto got_it;
 309         }
 310
 311         k = ext2_find_next_zero_bit ((u32 *)map, size, goal);
 312         if (k < size) {
 313                 goal = k;
 314                 goto got_it;
 315         }
 316         return -1;
 317 got_it:
 318         if (ext2_set_bit_atomic(lock, goal, (void *) map))
 319                 goto repeat;
 320         return goal;
 321 }
 322
 323 /*
 324  * ext2_new_block uses a goal block to assist allocation.  If the goal is
 325  * free, or there is a free block within 32 blocks of the goal, that block
 326  * is allocated.  Otherwise a forward search is made for a free block; within
 327  * each block group the search first looks for an entire free byte in the block
 328  * bitmap, and then for any free bit if that fails.
 329  * This function also updates quota and i_blocks field.
 330  */
 331 int ext2_new_block(struct inode *inode, unsigned long goal,
 332                         u32 *prealloc_count, u32 *prealloc_block, int *err)
 333 {
 334         struct buffer_head *bitmap_bh = NULL;
 335         struct buffer_head *gdp_bh;     /* bh2 */
 336         struct ext2_group_desc *desc;
 337         int group_no;                   /* i */
 338         int ret_block;                  /* j */
 339         int group_idx;                  /* k */
 340         int target_block;               /* tmp */
 341         int block = 0;
 342         struct super_block *sb = inode->i_sb;
 343         struct ext2_sb_info *sbi = EXT2_SB(sb);
 344         struct ext2_super_block *es = sbi->s_es;
 345         unsigned group_size = EXT2_BLOCKS_PER_GROUP(sb);
 346         unsigned prealloc_goal = es->s_prealloc_blocks;
 347         unsigned group_alloc = 0, es_alloc, dq_alloc;
 348         int nr_scanned_groups;
 349
 350         if (!prealloc_goal--)
 351                 prealloc_goal = EXT2_DEFAULT_PREALLOC_BLOCKS - 1;
 352         if (!prealloc_count || *prealloc_count)
 353                 prealloc_goal = 0;
 354
 355         if (DQUOT_ALLOC_BLOCK(inode, 1)) {
 356                 *err = -EDQUOT;
 357                 goto out;
 358         }
 359
 360         while (prealloc_goal && DQUOT_PREALLOC_BLOCK(inode, prealloc_goal))
 361                 prealloc_goal--;
 362
 363         dq_alloc = prealloc_goal + 1;
 364         es_alloc = reserve_blocks(sb, dq_alloc);
 365         if (!es_alloc) {
 366                 *err = -ENOSPC;
 367                 goto out_dquot;
 368         }
 369         if (DLIMIT_ALLOC_BLOCK(sb, inode->i_xid, es_alloc)) {
 370                 *err = -ENOSPC;
 371                 goto out_dlimit;
 372         }
 373
 374         ext2_debug ("goal=%lu.\n", goal);
 375
 376         if (goal < le32_to_cpu(es->s_first_data_block) ||
 377             goal >= le32_to_cpu(es->s_blocks_count))
 378                 goal = le32_to_cpu(es->s_first_data_block);
 379         group_no = (goal - le32_to_cpu(es->s_first_data_block)) / group_size;
 380         desc = ext2_get_group_desc (sb, group_no, &gdp_bh);
 381         if (!desc) {
 382                 /*
 383                  * gdp_bh may still be uninitialised.  But group_release_blocks
 384                  * will not touch it because group_alloc is zero.
 385                  */
 386                 goto io_error;
 387         }
 388
 389         group_alloc = group_reserve_blocks(sbi, group_no, desc,
 390                                         gdp_bh, es_alloc);
 391         if (group_alloc) {
 392                 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
 393                                         group_size);
 394                 brelse(bitmap_bh);
 395                 bitmap_bh = read_block_bitmap(sb, group_no);
 396                 if (!bitmap_bh)
 397                         goto io_error;
 398
 399                 ext2_debug("goal is at %d:%d.\n", group_no, ret_block);
 400
 401                 ret_block = grab_block(sb_bgl_lock(sbi, group_no),
 402                                 bitmap_bh->b_data, group_size, ret_block);
 403                 if (ret_block >= 0)
 404                         goto got_block;
 405                 group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
 406                 group_alloc = 0;
 407         }
 408
 409         ext2_debug ("Bit not found in block group %d.\n", group_no);
 410
 411         /*
 412          * Now search the rest of the groups.  We assume that
 413          * i and desc correctly point to the last group visited.
 414          */
 415         nr_scanned_groups = 0;
 416 retry:
 417         for (group_idx = 0; !group_alloc &&
 418                         group_idx < sbi->s_groups_count; group_idx++) {
 419                 group_no++;
 420                 if (group_no >= sbi->s_groups_count)
 421                         group_no = 0;
 422                 desc = ext2_get_group_desc(sb, group_no, &gdp_bh);
 423                 if (!desc)
 424                         goto io_error;
 425                 group_alloc = group_reserve_blocks(sbi, group_no, desc,
 426                                                 gdp_bh, es_alloc);
 427         }
 428         if (!group_alloc) {
 429                 *err = -ENOSPC;
 430                 goto out_release;
 431         }
 432         brelse(bitmap_bh);
 433         bitmap_bh = read_block_bitmap(sb, group_no);
 434         if (!bitmap_bh)
 435                 goto io_error;
 436
 437         ret_block = grab_block(sb_bgl_lock(sbi, group_no), bitmap_bh->b_data,
 438                                 group_size, 0);
 439         if (ret_block < 0) {
 440                 /*
 441                  * If a free block counter is corrupted we can loop inifintely.
 442                  * Detect that here.
 443                  */
 444                 nr_scanned_groups++;
 445                 if (nr_scanned_groups > 2 * sbi->s_groups_count) {
 446                         ext2_error(sb, "ext2_new_block",
 447                                 "corrupted free blocks counters");
 448                         goto io_error;
 449                 }
 450                 /*
 451                  * Someone else grabbed the last free block in this blockgroup
 452                  * before us.  Retry the scan.
 453                  */
 454                 group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
 455                 group_alloc = 0;
 456                 goto retry;
 457         }
 458
 459 got_block:
 460         ext2_debug("using block group %d(%d)\n",
 461                 group_no, desc->bg_free_blocks_count);
 462
 463         target_block = ret_block + group_no * group_size +
 464                         le32_to_cpu(es->s_first_data_block);
 465
 466         if (target_block == le32_to_cpu(desc->bg_block_bitmap) ||
 467             target_block == le32_to_cpu(desc->bg_inode_bitmap) ||
 468             in_range(target_block, le32_to_cpu(desc->bg_inode_table),
 469                       sbi->s_itb_per_group))
 470                 ext2_error (sb, "ext2_new_block",
 471                             "Allocating block in system zone - "
 472                             "block = %u", target_block);
 473
 474         if (target_block >= le32_to_cpu(es->s_blocks_count)) {
 475                 ext2_error (sb, "ext2_new_block",
 476                             "block(%d) >= blocks count(%d) - "
 477                             "block_group = %d, es == %p ", ret_block,
 478                         le32_to_cpu(es->s_blocks_count), group_no, es);
 479                 goto io_error;
 480         }
 481         block = target_block;
 482
 483         /* OK, we _had_ allocated something */
 484         ext2_debug("found bit %d\n", ret_block);
 485
 486         dq_alloc--;
 487         es_alloc--;
 488         group_alloc--;
 489
 490         /*
 491          * Do block preallocation now if required.
 492          */
 493         write_lock(&EXT2_I(inode)->i_meta_lock);
 494         if (group_alloc && !*prealloc_count) {
 495                 unsigned n;
 496
 497                 for (n = 0; n < group_alloc && ++ret_block < group_size; n++) {
 498                         if (ext2_set_bit_atomic(sb_bgl_lock(sbi, group_no),
 499                                                 ret_block,
 500                                                 (void*) bitmap_bh->b_data))
 501                                 break;
 502                 }
 503                 *prealloc_block = block + 1;
 504                 *prealloc_count = n;
 505                 es_alloc -= n;
 506                 dq_alloc -= n;
 507                 group_alloc -= n;
 508         }
 509         write_unlock(&EXT2_I(inode)->i_meta_lock);
 510
 511         mark_buffer_dirty(bitmap_bh);
 512         if (sb->s_flags & MS_SYNCHRONOUS)
 513                 sync_dirty_buffer(bitmap_bh);
 514
 515         ext2_debug ("allocating block %d. ", block);
 516
 517         *err = 0;
 518 out_release:
 519         group_release_blocks(sb, group_no, desc, gdp_bh, group_alloc);
 520         DLIMIT_FREE_BLOCK(sb, inode->i_xid, es_alloc);
 521 out_dlimit:
 522         release_blocks(sb, es_alloc);
 523 out_dquot:
 524         DQUOT_FREE_BLOCK(inode, dq_alloc);
 525 out:
 526         brelse(bitmap_bh);
 527         return block;
 528
 529 io_error:
 530         *err = -EIO;
 531         goto out_release;
 532 }
 533
 534 unsigned long ext2_count_free_blocks (struct super_block * sb)
 535 {
 536         struct ext2_group_desc * desc;
 537         unsigned long desc_count = 0;
 538         int i;
 539 #ifdef EXT2FS_DEBUG
 540         unsigned long bitmap_count, x;
 541         struct ext2_super_block *es;
 542
 543         lock_super (sb);
 544         es = EXT2_SB(sb)->s_es;
 545         desc_count = 0;
 546         bitmap_count = 0;
 547         desc = NULL;
 548         for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
 549                 struct buffer_head *bitmap_bh;
 550                 desc = ext2_get_group_desc (sb, i, NULL);
 551                 if (!desc)
 552                         continue;
 553                 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
 554                 bitmap_bh = read_block_bitmap(sb, i);
 555                 if (!bitmap_bh)
 556                         continue;
 557
 558                 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
 559                 printk ("group %d: stored = %d, counted = %lu\n",
 560                         i, le16_to_cpu(desc->bg_free_blocks_count), x);
 561                 bitmap_count += x;
 562                 brelse(bitmap_bh);
 563         }
 564         printk("ext2_count_free_blocks: stored = %lu, computed = %lu, %lu\n",
 565                 (long)le32_to_cpu(es->s_free_blocks_count),
 566                 desc_count, bitmap_count);
 567         unlock_super (sb);
 568         return bitmap_count;
 569 #else
 570         for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
 571                 desc = ext2_get_group_desc (sb, i, NULL);
 572                 if (!desc)
 573                         continue;
 574                 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
 575         }
 576         return desc_count;
 577 #endif
 578 }
 579
 580 static inline int
 581 block_in_use(unsigned long block, struct super_block *sb, unsigned char *map)
 582 {
 583         return ext2_test_bit ((block - le32_to_cpu(EXT2_SB(sb)->s_es->s_first_data_block)) %
 584                          EXT2_BLOCKS_PER_GROUP(sb), map);
 585 }
 586
 587 static inline int test_root(int a, int b)
 588 {
 589         if (a == 0)
 590                 return 1;
 591         while (1) {
 592                 if (a == 1)
 593                         return 1;
 594                 if (a % b)
 595                         return 0;
 596                 a = a / b;
 597         }
 598 }
 599
 600 static int ext2_group_sparse(int group)
 601 {
 602         return (test_root(group, 3) || test_root(group, 5) ||
 603                 test_root(group, 7));
 604 }
 605
 606 /**
 607  *      ext2_bg_has_super - number of blocks used by the superblock in group
 608  *      @sb: superblock for filesystem
 609  *      @group: group number to check
 610  *
 611  *      Return the number of blocks used by the superblock (primary or backup)
 612  *      in this group.  Currently this will be only 0 or 1.
 613  */
 614 int ext2_bg_has_super(struct super_block *sb, int group)
 615 {
 616         if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
 617             !ext2_group_sparse(group))
 618                 return 0;
 619         return 1;
 620 }
 621
 622 /**
 623  *      ext2_bg_num_gdb - number of blocks used by the group table in group
 624  *      @sb: superblock for filesystem
 625  *      @group: group number to check
 626  *
 627  *      Return the number of blocks used by the group descriptor table
 628  *      (primary or backup) in this group.  In the future there may be a
 629  *      different number of descriptor blocks in each group.
 630  */
 631 unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
 632 {
 633         if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
 634             !ext2_group_sparse(group))
 635                 return 0;
 636         return EXT2_SB(sb)->s_gdb_count;
 637 }
 638
 639 #ifdef CONFIG_EXT2_CHECK
 640 /* Called at mount-time, super-block is locked */
 641 void ext2_check_blocks_bitmap (struct super_block * sb)
 642 {
 643         struct buffer_head *bitmap_bh = NULL;
 644         struct ext2_super_block * es;
 645         unsigned long desc_count, bitmap_count, x, j;
 646         unsigned long desc_blocks;
 647         struct ext2_group_desc * desc;
 648         int i;
 649
 650         es = EXT2_SB(sb)->s_es;
 651         desc_count = 0;
 652         bitmap_count = 0;
 653         desc = NULL;
 654         for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++) {
 655                 desc = ext2_get_group_desc (sb, i, NULL);
 656                 if (!desc)
 657                         continue;
 658                 desc_count += le16_to_cpu(desc->bg_free_blocks_count);
 659                 brelse(bitmap_bh);
 660                 bitmap_bh = read_block_bitmap(sb, i);
 661                 if (!bitmap_bh)
 662                         continue;
 663
 664                 if (ext2_bg_has_super(sb, i) &&
 665                                 !ext2_test_bit(0, bitmap_bh->b_data))
 666                         ext2_error(sb, __FUNCTION__,
 667                                    "Superblock in group %d is marked free", i);
 668
 669                 desc_blocks = ext2_bg_num_gdb(sb, i);
 670                 for (j = 0; j < desc_blocks; j++)
 671                         if (!ext2_test_bit(j + 1, bitmap_bh->b_data))
 672                                 ext2_error(sb, __FUNCTION__,
 673                                            "Descriptor block #%ld in group "
 674                                            "%d is marked free", j, i);
 675
 676                 if (!block_in_use(le32_to_cpu(desc->bg_block_bitmap),
 677                                         sb, bitmap_bh->b_data))
 678                         ext2_error(sb, "ext2_check_blocks_bitmap",
 679                                     "Block bitmap for group %d is marked free",
 680                                     i);
 681
 682                 if (!block_in_use(le32_to_cpu(desc->bg_inode_bitmap),
 683                                         sb, bitmap_bh->b_data))
 684                         ext2_error(sb, "ext2_check_blocks_bitmap",
 685                                     "Inode bitmap for group %d is marked free",
 686                                     i);
 687
 688                 for (j = 0; j < EXT2_SB(sb)->s_itb_per_group; j++)
 689                         if (!block_in_use(le32_to_cpu(desc->bg_inode_table) + j,
 690                                                 sb, bitmap_bh->b_data))
 691                                 ext2_error (sb, "ext2_check_blocks_bitmap",
 692                                             "Block #%ld of the inode table in "
 693                                             "group %d is marked free", j, i);
 694
 695                 x = ext2_count_free(bitmap_bh, sb->s_blocksize);
 696                 if (le16_to_cpu(desc->bg_free_blocks_count) != x)
 697                         ext2_error (sb, "ext2_check_blocks_bitmap",
 698                                     "Wrong free blocks count for group %d, "
 699                                     "stored = %d, counted = %lu", i,
 700                                     le16_to_cpu(desc->bg_free_blocks_count), x);
 701                 bitmap_count += x;
 702         }
 703         if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
 704                 ext2_error (sb, "ext2_check_blocks_bitmap",
 705                         "Wrong free blocks count in super block, "
 706                         "stored = %lu, counted = %lu",
 707                         (unsigned long)le32_to_cpu(es->s_free_blocks_count),
 708                         bitmap_count);
 709         brelse(bitmap_bh);
 710 }
 711 #endif