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