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   1 /*
   2  *  linux/fs/ext4/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@redhat.com), 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/time.h>
  15 #include <linux/capability.h>
  16 #include <linux/fs.h>
  17 #include <linux/jbd2.h>
  18 #include <linux/quotaops.h>
  19 #include <linux/buffer_head.h>
  20 #include "ext4.h"
  21 #include "ext4_jbd2.h"
  22 #include "mballoc.h"
  23
  24 /*
  25  * balloc.c contains the blocks allocation and deallocation routines
  26  */
  27
  28 /*
  29  * Calculate the block group number and offset, given a block number
  30  */
  31 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  32                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  33 {
  34         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  35         ext4_grpblk_t offset;
  36
  37         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  38         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
  39         if (offsetp)
  40                 *offsetp = offset;
  41         if (blockgrpp)
  42                 *blockgrpp = blocknr;
  43
  44 }
  45
  46 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
  47                         ext4_group_t block_group)
  48 {
  49         ext4_group_t actual_group;
  50         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
  51         if (actual_group == block_group)
  52                 return 1;
  53         return 0;
  54 }
  55
  56 static int ext4_group_used_meta_blocks(struct super_block *sb,
  57                                        ext4_group_t block_group,
  58                                        struct ext4_group_desc *gdp)
  59 {
  60         ext4_fsblk_t tmp;
  61         struct ext4_sb_info *sbi = EXT4_SB(sb);
  62         /* block bitmap, inode bitmap, and inode table blocks */
  63         int used_blocks = sbi->s_itb_per_group + 2;
  64
  65         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
  66                 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
  67                                         block_group))
  68                         used_blocks--;
  69
  70                 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
  71                                         block_group))
  72                         used_blocks--;
  73
  74                 tmp = ext4_inode_table(sb, gdp);
  75                 for (; tmp < ext4_inode_table(sb, gdp) +
  76                                 sbi->s_itb_per_group; tmp++) {
  77                         if (!ext4_block_in_group(sb, tmp, block_group))
  78                                 used_blocks -= 1;
  79                 }
  80         }
  81         return used_blocks;
  82 }
  83
  84 /* Initializes an uninitialized block bitmap if given, and returns the
  85  * number of blocks free in the group. */
  86 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
  87                  ext4_group_t block_group, struct ext4_group_desc *gdp)
  88 {
  89         int bit, bit_max;
  90         ext4_group_t ngroups = ext4_get_groups_count(sb);
  91         unsigned free_blocks, group_blocks;
  92         struct ext4_sb_info *sbi = EXT4_SB(sb);
  93
  94         if (bh) {
  95                 J_ASSERT_BH(bh, buffer_locked(bh));
  96
  97                 /* If checksum is bad mark all blocks used to prevent allocation
  98                  * essentially implementing a per-group read-only flag. */
  99                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
 100                         ext4_error(sb, "Checksum bad for group %u",
 101                                         block_group);
 102                         ext4_free_blks_set(sb, gdp, 0);
 103                         ext4_free_inodes_set(sb, gdp, 0);
 104                         ext4_itable_unused_set(sb, gdp, 0);
 105                         memset(bh->b_data, 0xff, sb->s_blocksize);
 106                         return 0;
 107                 }
 108                 memset(bh->b_data, 0, sb->s_blocksize);
 109         }
 110
 111         /* Check for superblock and gdt backups in this group */
 112         bit_max = ext4_bg_has_super(sb, block_group);
 113
 114         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 115             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 116                           sbi->s_desc_per_block) {
 117                 if (bit_max) {
 118                         bit_max += ext4_bg_num_gdb(sb, block_group);
 119                         bit_max +=
 120                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 121                 }
 122         } else { /* For META_BG_BLOCK_GROUPS */
 123                 bit_max += ext4_bg_num_gdb(sb, block_group);
 124         }
 125
 126         if (block_group == ngroups - 1) {
 127                 /*
 128                  * Even though mke2fs always initialize first and last group
 129                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
 130                  * to make sure we calculate the right free blocks
 131                  */
 132                 group_blocks = ext4_blocks_count(sbi->s_es) -
 133                         le32_to_cpu(sbi->s_es->s_first_data_block) -
 134                         (EXT4_BLOCKS_PER_GROUP(sb) * (ngroups - 1));
 135         } else {
 136                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
 137         }
 138
 139         free_blocks = group_blocks - bit_max;
 140
 141         if (bh) {
 142                 ext4_fsblk_t start, tmp;
 143                 int flex_bg = 0;
 144
 145                 for (bit = 0; bit < bit_max; bit++)
 146                         ext4_set_bit(bit, bh->b_data);
 147
 148                 start = ext4_group_first_block_no(sb, block_group);
 149
 150                 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
 151                                               EXT4_FEATURE_INCOMPAT_FLEX_BG))
 152                         flex_bg = 1;
 153
 154                 /* Set bits for block and inode bitmaps, and inode table */
 155                 tmp = ext4_block_bitmap(sb, gdp);
 156                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 157                         ext4_set_bit(tmp - start, bh->b_data);
 158
 159                 tmp = ext4_inode_bitmap(sb, gdp);
 160                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 161                         ext4_set_bit(tmp - start, bh->b_data);
 162
 163                 tmp = ext4_inode_table(sb, gdp);
 164                 for (; tmp < ext4_inode_table(sb, gdp) +
 165                                 sbi->s_itb_per_group; tmp++) {
 166                         if (!flex_bg ||
 167                                 ext4_block_in_group(sb, tmp, block_group))
 168                                 ext4_set_bit(tmp - start, bh->b_data);
 169                 }
 170                 /*
 171                  * Also if the number of blocks within the group is
 172                  * less than the blocksize * 8 ( which is the size
 173                  * of bitmap ), set rest of the block bitmap to 1
 174                  */
 175                 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
 176         }
 177         return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
 178 }
 179
 180
 181 /*
 182  * The free blocks are managed by bitmaps.  A file system contains several
 183  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 184  * block for inodes, N blocks for the inode table and data blocks.
 185  *
 186  * The file system contains group descriptors which are located after the
 187  * super block.  Each descriptor contains the number of the bitmap block and
 188  * the free blocks count in the block.  The descriptors are loaded in memory
 189  * when a file system is mounted (see ext4_fill_super).
 190  */
 191
 192
 193 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 194
 195 /**
 196  * ext4_get_group_desc() -- load group descriptor from disk
 197  * @sb:                 super block
 198  * @block_group:        given block group
 199  * @bh:                 pointer to the buffer head to store the block
 200  *                      group descriptor
 201  */
 202 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 203                                              ext4_group_t block_group,
 204                                              struct buffer_head **bh)
 205 {
 206         unsigned int group_desc;
 207         unsigned int offset;
 208         ext4_group_t ngroups = ext4_get_groups_count(sb);
 209         struct ext4_group_desc *desc;
 210         struct ext4_sb_info *sbi = EXT4_SB(sb);
 211
 212         if (block_group >= ngroups) {
 213                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 214                            " groups_count = %u", block_group, ngroups);
 215
 216                 return NULL;
 217         }
 218
 219         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 220         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 221         if (!sbi->s_group_desc[group_desc]) {
 222                 ext4_error(sb, "Group descriptor not loaded - "
 223                            "block_group = %u, group_desc = %u, desc = %u",
 224                            block_group, group_desc, offset);
 225                 return NULL;
 226         }
 227
 228         desc = (struct ext4_group_desc *)(
 229                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 230                 offset * EXT4_DESC_SIZE(sb));
 231         if (bh)
 232                 *bh = sbi->s_group_desc[group_desc];
 233         return desc;
 234 }
 235
 236 static int ext4_valid_block_bitmap(struct super_block *sb,
 237                                         struct ext4_group_desc *desc,
 238                                         unsigned int block_group,
 239                                         struct buffer_head *bh)
 240 {
 241         ext4_grpblk_t offset;
 242         ext4_grpblk_t next_zero_bit;
 243         ext4_fsblk_t bitmap_blk;
 244         ext4_fsblk_t group_first_block;
 245
 246         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 247                 /* with FLEX_BG, the inode/block bitmaps and itable
 248                  * blocks may not be in the group at all
 249                  * so the bitmap validation will be skipped for those groups
 250                  * or it has to also read the block group where the bitmaps
 251                  * are located to verify they are set.
 252                  */
 253                 return 1;
 254         }
 255         group_first_block = ext4_group_first_block_no(sb, block_group);
 256
 257         /* check whether block bitmap block number is set */
 258         bitmap_blk = ext4_block_bitmap(sb, desc);
 259         offset = bitmap_blk - group_first_block;
 260         if (!ext4_test_bit(offset, bh->b_data))
 261                 /* bad block bitmap */
 262                 goto err_out;
 263
 264         /* check whether the inode bitmap block number is set */
 265         bitmap_blk = ext4_inode_bitmap(sb, desc);
 266         offset = bitmap_blk - group_first_block;
 267         if (!ext4_test_bit(offset, bh->b_data))
 268                 /* bad block bitmap */
 269                 goto err_out;
 270
 271         /* check whether the inode table block number is set */
 272         bitmap_blk = ext4_inode_table(sb, desc);
 273         offset = bitmap_blk - group_first_block;
 274         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 275                                 offset + EXT4_SB(sb)->s_itb_per_group,
 276                                 offset);
 277         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
 278                 /* good bitmap for inode tables */
 279                 return 1;
 280
 281 err_out:
 282         ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
 283                         block_group, bitmap_blk);
 284         return 0;
 285 }
 286 /**
 287  * ext4_read_block_bitmap()
 288  * @sb:                 super block
 289  * @block_group:        given block group
 290  *
 291  * Read the bitmap for a given block_group,and validate the
 292  * bits for block/inode/inode tables are set in the bitmaps
 293  *
 294  * Return buffer_head on success or NULL in case of failure.
 295  */
 296 struct buffer_head *
 297 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 298 {
 299         struct ext4_group_desc *desc;
 300         struct buffer_head *bh = NULL;
 301         ext4_fsblk_t bitmap_blk;
 302
 303         desc = ext4_get_group_desc(sb, block_group, NULL);
 304         if (!desc)
 305                 return NULL;
 306         bitmap_blk = ext4_block_bitmap(sb, desc);
 307         bh = sb_getblk(sb, bitmap_blk);
 308         if (unlikely(!bh)) {
 309                 ext4_error(sb, "Cannot read block bitmap - "
 310                             "block_group = %u, block_bitmap = %llu",
 311                             block_group, bitmap_blk);
 312                 return NULL;
 313         }
 314
 315         if (bitmap_uptodate(bh))
 316                 return bh;
 317
 318         lock_buffer(bh);
 319         if (bitmap_uptodate(bh)) {
 320                 unlock_buffer(bh);
 321                 return bh;
 322         }
 323         ext4_lock_group(sb, block_group);
 324         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 325                 ext4_init_block_bitmap(sb, bh, block_group, desc);
 326                 set_bitmap_uptodate(bh);
 327                 set_buffer_uptodate(bh);
 328                 ext4_unlock_group(sb, block_group);
 329                 unlock_buffer(bh);
 330                 return bh;
 331         }
 332         ext4_unlock_group(sb, block_group);
 333         if (buffer_uptodate(bh)) {
 334                 /*
 335                  * if not uninit if bh is uptodate,
 336                  * bitmap is also uptodate
 337                  */
 338                 set_bitmap_uptodate(bh);
 339                 unlock_buffer(bh);
 340                 return bh;
 341         }
 342         /*
 343          * submit the buffer_head for read. We can
 344          * safely mark the bitmap as uptodate now.
 345          * We do it here so the bitmap uptodate bit
 346          * get set with buffer lock held.
 347          */
 348         set_bitmap_uptodate(bh);
 349         if (bh_submit_read(bh) < 0) {
 350                 put_bh(bh);
 351                 ext4_error(sb, "Cannot read block bitmap - "
 352                             "block_group = %u, block_bitmap = %llu",
 353                             block_group, bitmap_blk);
 354                 return NULL;
 355         }
 356         ext4_valid_block_bitmap(sb, desc, block_group, bh);
 357         /*
 358          * file system mounted not to panic on error,
 359          * continue with corrupt bitmap
 360          */
 361         return bh;
 362 }
 363
 364 /**
 365  * ext4_add_groupblocks() -- Add given blocks to an existing group
 366  * @handle:                     handle to this transaction
 367  * @sb:                         super block
 368  * @block:                      start physcial block to add to the block group
 369  * @count:                      number of blocks to free
 370  *
 371  * This marks the blocks as free in the bitmap. We ask the
 372  * mballoc to reload the buddy after this by setting group
 373  * EXT4_GROUP_INFO_NEED_INIT_BIT flag
 374  */
 375 void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 376                          ext4_fsblk_t block, unsigned long count)
 377 {
 378         struct buffer_head *bitmap_bh = NULL;
 379         struct buffer_head *gd_bh;
 380         ext4_group_t block_group;
 381         ext4_grpblk_t bit;
 382         unsigned int i;
 383         struct ext4_group_desc *desc;
 384         struct ext4_super_block *es;
 385         struct ext4_sb_info *sbi;
 386         int err = 0, ret, blk_free_count;
 387         ext4_grpblk_t blocks_freed;
 388         struct ext4_group_info *grp;
 389
 390         sbi = EXT4_SB(sb);
 391         es = sbi->s_es;
 392         ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 393
 394         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
 395         grp = ext4_get_group_info(sb, block_group);
 396         /*
 397          * Check to see if we are freeing blocks across a group
 398          * boundary.
 399          */
 400         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
 401                 goto error_return;
 402         }
 403         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
 404         if (!bitmap_bh)
 405                 goto error_return;
 406         desc = ext4_get_group_desc(sb, block_group, &gd_bh);
 407         if (!desc)
 408                 goto error_return;
 409
 410         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
 411             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
 412             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
 413             in_range(block + count - 1, ext4_inode_table(sb, desc),
 414                      sbi->s_itb_per_group)) {
 415                 ext4_error(sb, "Adding blocks in system zones - "
 416                            "Block = %llu, count = %lu",
 417                            block, count);
 418                 goto error_return;
 419         }
 420
 421         /*
 422          * We are about to add blocks to the bitmap,
 423          * so we need undo access.
 424          */
 425         BUFFER_TRACE(bitmap_bh, "getting undo access");
 426         err = ext4_journal_get_undo_access(handle, bitmap_bh);
 427         if (err)
 428                 goto error_return;
 429
 430         /*
 431          * We are about to modify some metadata.  Call the journal APIs
 432          * to unshare ->b_data if a currently-committing transaction is
 433          * using it
 434          */
 435         BUFFER_TRACE(gd_bh, "get_write_access");
 436         err = ext4_journal_get_write_access(handle, gd_bh);
 437         if (err)
 438                 goto error_return;
 439         /*
 440          * make sure we don't allow a parallel init on other groups in the
 441          * same buddy cache
 442          */
 443         down_write(&grp->alloc_sem);
 444         for (i = 0, blocks_freed = 0; i < count; i++) {
 445                 BUFFER_TRACE(bitmap_bh, "clear bit");
 446                 if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
 447                                                 bit + i, bitmap_bh->b_data)) {
 448                         ext4_error(sb, "bit already cleared for block %llu",
 449                                    (ext4_fsblk_t)(block + i));
 450                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 451                 } else {
 452                         blocks_freed++;
 453                 }
 454         }
 455         ext4_lock_group(sb, block_group);
 456         blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
 457         ext4_free_blks_set(sb, desc, blk_free_count);
 458         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
 459         ext4_unlock_group(sb, block_group);
 460         percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
 461
 462         if (sbi->s_log_groups_per_flex) {
 463                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
 464                 atomic_add(blocks_freed,
 465                            &sbi->s_flex_groups[flex_group].free_blocks);
 466         }
 467         /*
 468          * request to reload the buddy with the
 469          * new bitmap information
 470          */
 471         set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
 472         grp->bb_free += blocks_freed;
 473         up_write(&grp->alloc_sem);
 474
 475         /* We dirtied the bitmap block */
 476         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 477         err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
 478
 479         /* And the group descriptor block */
 480         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 481         ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
 482         if (!err)
 483                 err = ret;
 484         sb->s_dirt = 1;
 485
 486 error_return:
 487         brelse(bitmap_bh);
 488         ext4_std_error(sb, err);
 489         return;
 490 }
 491
 492 /**
 493  * ext4_has_free_blocks()
 494  * @sbi:        in-core super block structure.
 495  * @nblocks:    number of needed blocks
 496  *
 497  * Check if filesystem has nblocks free & available for allocation.
 498  * On success return 1, return 0 on failure.
 499  */
 500 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
 501 {
 502         s64 free_blocks, dirty_blocks, root_blocks;
 503         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
 504         struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
 505
 506         free_blocks  = percpu_counter_read_positive(fbc);
 507         dirty_blocks = percpu_counter_read_positive(dbc);
 508         root_blocks = ext4_r_blocks_count(sbi->s_es);
 509
 510         if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
 511                                                 EXT4_FREEBLOCKS_WATERMARK) {
 512                 free_blocks  = percpu_counter_sum_positive(fbc);
 513                 dirty_blocks = percpu_counter_sum_positive(dbc);
 514                 if (dirty_blocks < 0) {
 515                         printk(KERN_CRIT "Dirty block accounting "
 516                                         "went wrong %lld\n",
 517                                         (long long)dirty_blocks);
 518                 }
 519         }
 520         /* Check whether we have space after
 521          * accounting for current dirty blocks & root reserved blocks.
 522          */
 523         if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
 524                 return 1;
 525
 526         /* Hm, nope.  Are (enough) root reserved blocks available? */
 527         if (sbi->s_resuid == current_fsuid() ||
 528             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
 529             capable(CAP_SYS_RESOURCE)) {
 530                 if (free_blocks >= (nblocks + dirty_blocks))
 531                         return 1;
 532         }
 533
 534         return 0;
 535 }
 536
 537 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
 538                                                 s64 nblocks)
 539 {
 540         if (ext4_has_free_blocks(sbi, nblocks)) {
 541                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
 542                 return 0;
 543         } else
 544                 return -ENOSPC;
 545 }
 546
 547 /**
 548  * ext4_should_retry_alloc()
 549  * @sb:                 super block
 550  * @retries             number of attemps has been made
 551  *
 552  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 553  * it is profitable to retry the operation, this function will wait
 554  * for the current or commiting transaction to complete, and then
 555  * return TRUE.
 556  *
 557  * if the total number of retries exceed three times, return FALSE.
 558  */
 559 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 560 {
 561         if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
 562             (*retries)++ > 3 ||
 563             !EXT4_SB(sb)->s_journal)
 564                 return 0;
 565
 566         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 567
 568         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 569 }
 570
 571 /*
 572  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 573  *
 574  * @handle:             handle to this transaction
 575  * @inode:              file inode
 576  * @goal:               given target block(filesystem wide)
 577  * @count:              pointer to total number of blocks needed
 578  * @errp:               error code
 579  *
 580  * Return 1st allocated block number on success, *count stores total account
 581  * error stores in errp pointer
 582  */
 583 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 584                 ext4_fsblk_t goal, unsigned long *count, int *errp)
 585 {
 586         struct ext4_allocation_request ar;
 587         ext4_fsblk_t ret;
 588
 589         memset(&ar, 0, sizeof(ar));
 590         /* Fill with neighbour allocated blocks */
 591         ar.inode = inode;
 592         ar.goal = goal;
 593         ar.len = count ? *count : 1;
 594
 595         ret = ext4_mb_new_blocks(handle, &ar, errp);
 596         if (count)
 597                 *count = ar.len;
 598
 599         /*
 600          * Account for the allocated meta blocks
 601          */
 602         if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
 603                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 604                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 605                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 606         }
 607         return ret;
 608 }
 609
 610 /**
 611  * ext4_count_free_blocks() -- count filesystem free blocks
 612  * @sb:         superblock
 613  *
 614  * Adds up the number of free blocks from each block group.
 615  */
 616 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
 617 {
 618         ext4_fsblk_t desc_count;
 619         struct ext4_group_desc *gdp;
 620         ext4_group_t i;
 621         ext4_group_t ngroups = ext4_get_groups_count(sb);
 622 #ifdef EXT4FS_DEBUG
 623         struct ext4_super_block *es;
 624         ext4_fsblk_t bitmap_count;
 625         unsigned int x;
 626         struct buffer_head *bitmap_bh = NULL;
 627
 628         es = EXT4_SB(sb)->s_es;
 629         desc_count = 0;
 630         bitmap_count = 0;
 631         gdp = NULL;
 632
 633         for (i = 0; i < ngroups; i++) {
 634                 gdp = ext4_get_group_desc(sb, i, NULL);
 635                 if (!gdp)
 636                         continue;
 637                 desc_count += ext4_free_blks_count(sb, gdp);
 638                 brelse(bitmap_bh);
 639                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 640                 if (bitmap_bh == NULL)
 641                         continue;
 642
 643                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
 644                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 645                         i, ext4_free_blks_count(sb, gdp), x);
 646                 bitmap_count += x;
 647         }
 648         brelse(bitmap_bh);
 649         printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
 650                 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
 651                desc_count, bitmap_count);
 652         return bitmap_count;
 653 #else
 654         desc_count = 0;
 655         for (i = 0; i < ngroups; i++) {
 656                 gdp = ext4_get_group_desc(sb, i, NULL);
 657                 if (!gdp)
 658                         continue;
 659                 desc_count += ext4_free_blks_count(sb, gdp);
 660         }
 661
 662         return desc_count;
 663 #endif
 664 }
 665
 666 static inline int test_root(ext4_group_t a, int b)
 667 {
 668         int num = b;
 669
 670         while (a > num)
 671                 num *= b;
 672         return num == a;
 673 }
 674
 675 static int ext4_group_sparse(ext4_group_t group)
 676 {
 677         if (group <= 1)
 678                 return 1;
 679         if (!(group & 1))
 680                 return 0;
 681         return (test_root(group, 7) || test_root(group, 5) ||
 682                 test_root(group, 3));
 683 }
 684
 685 /**
 686  *      ext4_bg_has_super - number of blocks used by the superblock in group
 687  *      @sb: superblock for filesystem
 688  *      @group: group number to check
 689  *
 690  *      Return the number of blocks used by the superblock (primary or backup)
 691  *      in this group.  Currently this will be only 0 or 1.
 692  */
 693 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 694 {
 695         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
 696                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
 697                         !ext4_group_sparse(group))
 698                 return 0;
 699         return 1;
 700 }
 701
 702 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 703                                         ext4_group_t group)
 704 {
 705         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 706         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 707         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 708
 709         if (group == first || group == first + 1 || group == last)
 710                 return 1;
 711         return 0;
 712 }
 713
 714 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 715                                         ext4_group_t group)
 716 {
 717         if (!ext4_bg_has_super(sb, group))
 718                 return 0;
 719
 720         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
 721                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 722         else
 723                 return EXT4_SB(sb)->s_gdb_count;
 724 }
 725
 726 /**
 727  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 728  *      @sb: superblock for filesystem
 729  *      @group: group number to check
 730  *
 731  *      Return the number of blocks used by the group descriptor table
 732  *      (primary or backup) in this group.  In the future there may be a
 733  *      different number of descriptor blocks in each group.
 734  */
 735 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 736 {
 737         unsigned long first_meta_bg =
 738                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 739         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 740
 741         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 742                         metagroup < first_meta_bg)
 743                 return ext4_bg_num_gdb_nometa(sb, group);
 744
 745         return ext4_bg_num_gdb_meta(sb,group);
 746
 747 }
 748