fs/ext4/balloc.c

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