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 #include <trace/events/ext4.h>
  25
  26 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
  27                                             ext4_group_t block_group);
  28 /*
  29  * balloc.c contains the blocks allocation and deallocation routines
  30  */
  31
  32 /*
  33  * Calculate the block group number and offset into the block/cluster
  34  * allocation bitmap, given a block number
  35  */
  36 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  37                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  38 {
  39         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  40         ext4_grpblk_t offset;
  41
  42         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  43         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
  44                 EXT4_SB(sb)->s_cluster_bits;
  45         if (offsetp)
  46                 *offsetp = offset;
  47         if (blockgrpp)
  48                 *blockgrpp = blocknr;
  49
  50 }
  51
  52 /*
  53  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
  54  * and 0 otherwise.
  55  */
  56 static inline int ext4_block_in_group(struct super_block *sb,
  57                                       ext4_fsblk_t block,
  58                                       ext4_group_t block_group)
  59 {
  60         ext4_group_t actual_group;
  61
  62         if (test_opt2(sb, STD_GROUP_SIZE))
  63                 actual_group =
  64                         (le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) +
  65                         block) >>
  66                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
  67         else
  68                 ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
  69         return (actual_group == block_group) ? 1 : 0;
  70 }
  71
  72 /* Return the number of clusters used for file system metadata; this
  73  * represents the overhead needed by the file system.
  74  */
  75 unsigned ext4_num_overhead_clusters(struct super_block *sb,
  76                                     ext4_group_t block_group,
  77                                     struct ext4_group_desc *gdp)
  78 {
  79         unsigned num_clusters;
  80         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
  81         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  82         ext4_fsblk_t itbl_blk;
  83         struct ext4_sb_info *sbi = EXT4_SB(sb);
  84
  85         /* This is the number of clusters used by the superblock,
  86          * block group descriptors, and reserved block group
  87          * descriptor blocks */
  88         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
  89
  90         /*
  91          * For the allocation bitmaps and inode table, we first need
  92          * to check to see if the block is in the block group.  If it
  93          * is, then check to see if the cluster is already accounted
  94          * for in the clusters used for the base metadata cluster, or
  95          * if we can increment the base metadata cluster to include
  96          * that block.  Otherwise, we will have to track the cluster
  97          * used for the allocation bitmap or inode table explicitly.
  98          * Normally all of these blocks are contiguous, so the special
  99          * case handling shouldn't be necessary except for *very*
 100          * unusual file system layouts.
 101          */
 102         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 103                 block_cluster = EXT4_B2C(sbi,
 104                                          ext4_block_bitmap(sb, gdp) - start);
 105                 if (block_cluster < num_clusters)
 106                         block_cluster = -1;
 107                 else if (block_cluster == num_clusters) {
 108                         num_clusters++;
 109                         block_cluster = -1;
 110                 }
 111         }
 112
 113         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 114                 inode_cluster = EXT4_B2C(sbi,
 115                                          ext4_inode_bitmap(sb, gdp) - start);
 116                 if (inode_cluster < num_clusters)
 117                         inode_cluster = -1;
 118                 else if (inode_cluster == num_clusters) {
 119                         num_clusters++;
 120                         inode_cluster = -1;
 121                 }
 122         }
 123
 124         itbl_blk = ext4_inode_table(sb, gdp);
 125         for (i = 0; i < sbi->s_itb_per_group; i++) {
 126                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
 127                         c = EXT4_B2C(sbi, itbl_blk + i - start);
 128                         if ((c < num_clusters) || (c == inode_cluster) ||
 129                             (c == block_cluster) || (c == itbl_cluster))
 130                                 continue;
 131                         if (c == num_clusters) {
 132                                 num_clusters++;
 133                                 continue;
 134                         }
 135                         num_clusters++;
 136                         itbl_cluster = c;
 137                 }
 138         }
 139
 140         if (block_cluster != -1)
 141                 num_clusters++;
 142         if (inode_cluster != -1)
 143                 num_clusters++;
 144
 145         return num_clusters;
 146 }
 147
 148 static unsigned int num_clusters_in_group(struct super_block *sb,
 149                                           ext4_group_t block_group)
 150 {
 151         unsigned int blocks;
 152
 153         if (block_group == ext4_get_groups_count(sb) - 1) {
 154                 /*
 155                  * Even though mke2fs always initializes the first and
 156                  * last group, just in case some other tool was used,
 157                  * we need to make sure we calculate the right free
 158                  * blocks.
 159                  */
 160                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 161                         ext4_group_first_block_no(sb, block_group);
 162         } else
 163                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 164         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 165 }
 166
 167 /* Initializes an uninitialized block bitmap */
 168 void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 169                             ext4_group_t block_group,
 170                             struct ext4_group_desc *gdp)
 171 {
 172         unsigned int bit, bit_max;
 173         struct ext4_sb_info *sbi = EXT4_SB(sb);
 174         ext4_fsblk_t start, tmp;
 175         int flex_bg = 0;
 176
 177         J_ASSERT_BH(bh, buffer_locked(bh));
 178
 179         /* If checksum is bad mark all blocks used to prevent allocation
 180          * essentially implementing a per-group read-only flag. */
 181         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 182                 ext4_error(sb, "Checksum bad for group %u", block_group);
 183                 ext4_free_group_clusters_set(sb, gdp, 0);
 184                 ext4_free_inodes_set(sb, gdp, 0);
 185                 ext4_itable_unused_set(sb, gdp, 0);
 186                 memset(bh->b_data, 0xff, sb->s_blocksize);
 187                 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 188                 return;
 189         }
 190         memset(bh->b_data, 0, sb->s_blocksize);
 191
 192         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 193         for (bit = 0; bit < bit_max; bit++)
 194                 ext4_set_bit(bit, bh->b_data);
 195
 196         start = ext4_group_first_block_no(sb, block_group);
 197
 198         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
 199                 flex_bg = 1;
 200
 201         /* Set bits for block and inode bitmaps, and inode table */
 202         tmp = ext4_block_bitmap(sb, gdp);
 203         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 204                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 205
 206         tmp = ext4_inode_bitmap(sb, gdp);
 207         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 208                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 209
 210         tmp = ext4_inode_table(sb, gdp);
 211         for (; tmp < ext4_inode_table(sb, gdp) +
 212                      sbi->s_itb_per_group; tmp++) {
 213                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 214                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 215         }
 216
 217         /*
 218          * Also if the number of blocks within the group is less than
 219          * the blocksize * 8 ( which is the size of bitmap ), set rest
 220          * of the block bitmap to 1
 221          */
 222         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 223                              sb->s_blocksize * 8, bh->b_data);
 224         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 225         ext4_group_desc_csum_set(sb, block_group, gdp);
 226 }
 227
 228 /* Return the number of free blocks in a block group.  It is used when
 229  * the block bitmap is uninitialized, so we can't just count the bits
 230  * in the bitmap. */
 231 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 232                                        ext4_group_t block_group,
 233                                        struct ext4_group_desc *gdp)
 234 {
 235         return num_clusters_in_group(sb, block_group) -
 236                 ext4_num_overhead_clusters(sb, block_group, gdp);
 237 }
 238
 239 /*
 240  * The free blocks are managed by bitmaps.  A file system contains several
 241  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 242  * block for inodes, N blocks for the inode table and data blocks.
 243  *
 244  * The file system contains group descriptors which are located after the
 245  * super block.  Each descriptor contains the number of the bitmap block and
 246  * the free blocks count in the block.  The descriptors are loaded in memory
 247  * when a file system is mounted (see ext4_fill_super).
 248  */
 249
 250 /**
 251  * ext4_get_group_desc() -- load group descriptor from disk
 252  * @sb:                 super block
 253  * @block_group:        given block group
 254  * @bh:                 pointer to the buffer head to store the block
 255  *                      group descriptor
 256  */
 257 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 258                                              ext4_group_t block_group,
 259                                              struct buffer_head **bh)
 260 {
 261         unsigned int group_desc;
 262         unsigned int offset;
 263         ext4_group_t ngroups = ext4_get_groups_count(sb);
 264         struct ext4_group_desc *desc;
 265         struct ext4_sb_info *sbi = EXT4_SB(sb);
 266
 267         if (block_group >= ngroups) {
 268                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 269                            " groups_count = %u", block_group, ngroups);
 270
 271                 return NULL;
 272         }
 273
 274         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 275         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 276         if (!sbi->s_group_desc[group_desc]) {
 277                 ext4_error(sb, "Group descriptor not loaded - "
 278                            "block_group = %u, group_desc = %u, desc = %u",
 279                            block_group, group_desc, offset);
 280                 return NULL;
 281         }
 282
 283         desc = (struct ext4_group_desc *)(
 284                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 285                 offset * EXT4_DESC_SIZE(sb));
 286         if (bh)
 287                 *bh = sbi->s_group_desc[group_desc];
 288         return desc;
 289 }
 290
 291 /*
 292  * Return the block number which was discovered to be invalid, or 0 if
 293  * the block bitmap is valid.
 294  */
 295 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 296                                             struct ext4_group_desc *desc,
 297                                             unsigned int block_group,
 298                                             struct buffer_head *bh)
 299 {
 300         ext4_grpblk_t offset;
 301         ext4_grpblk_t next_zero_bit;
 302         ext4_fsblk_t blk;
 303         ext4_fsblk_t group_first_block;
 304
 305         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 306                 /* with FLEX_BG, the inode/block bitmaps and itable
 307                  * blocks may not be in the group at all
 308                  * so the bitmap validation will be skipped for those groups
 309                  * or it has to also read the block group where the bitmaps
 310                  * are located to verify they are set.
 311                  */
 312                 return 0;
 313         }
 314         group_first_block = ext4_group_first_block_no(sb, block_group);
 315
 316         /* check whether block bitmap block number is set */
 317         blk = ext4_block_bitmap(sb, desc);
 318         offset = blk - group_first_block;
 319         if (!ext4_test_bit(offset, bh->b_data))
 320                 /* bad block bitmap */
 321                 return blk;
 322
 323         /* check whether the inode bitmap block number is set */
 324         blk = ext4_inode_bitmap(sb, desc);
 325         offset = blk - group_first_block;
 326         if (!ext4_test_bit(offset, bh->b_data))
 327                 /* bad block bitmap */
 328                 return blk;
 329
 330         /* check whether the inode table block number is set */
 331         blk = ext4_inode_table(sb, desc);
 332         offset = blk - group_first_block;
 333         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 334                                 offset + EXT4_SB(sb)->s_itb_per_group,
 335                                 offset);
 336         if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
 337                 /* bad bitmap for inode tables */
 338                 return blk;
 339         return 0;
 340 }
 341
 342 void ext4_validate_block_bitmap(struct super_block *sb,
 343                                struct ext4_group_desc *desc,
 344                                unsigned int block_group,
 345                                struct buffer_head *bh)
 346 {
 347         ext4_fsblk_t    blk;
 348
 349         if (buffer_verified(bh))
 350                 return;
 351
 352         ext4_lock_group(sb, block_group);
 353         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 354         if (unlikely(blk != 0)) {
 355                 ext4_unlock_group(sb, block_group);
 356                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 357                            block_group, blk);
 358                 return;
 359         }
 360         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 361                         desc, bh))) {
 362                 ext4_unlock_group(sb, block_group);
 363                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 364                 return;
 365         }
 366         set_buffer_verified(bh);
 367         ext4_unlock_group(sb, block_group);
 368 }
 369
 370 /**
 371  * ext4_read_block_bitmap_nowait()
 372  * @sb:                 super block
 373  * @block_group:        given block group
 374  *
 375  * Read the bitmap for a given block_group,and validate the
 376  * bits for block/inode/inode tables are set in the bitmaps
 377  *
 378  * Return buffer_head on success or NULL in case of failure.
 379  */
 380 struct buffer_head *
 381 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 382 {
 383         struct ext4_group_desc *desc;
 384         struct buffer_head *bh;
 385         ext4_fsblk_t bitmap_blk;
 386
 387         desc = ext4_get_group_desc(sb, block_group, NULL);
 388         if (!desc)
 389                 return NULL;
 390         bitmap_blk = ext4_block_bitmap(sb, desc);
 391         bh = sb_getblk(sb, bitmap_blk);
 392         if (unlikely(!bh)) {
 393                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 394                            "block_group = %u, block_bitmap = %llu",
 395                            block_group, bitmap_blk);
 396                 return NULL;
 397         }
 398
 399         if (bitmap_uptodate(bh))
 400                 goto verify;
 401
 402         lock_buffer(bh);
 403         if (bitmap_uptodate(bh)) {
 404                 unlock_buffer(bh);
 405                 goto verify;
 406         }
 407         ext4_lock_group(sb, block_group);
 408         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 409                 ext4_init_block_bitmap(sb, bh, block_group, desc);
 410                 set_bitmap_uptodate(bh);
 411                 set_buffer_uptodate(bh);
 412                 ext4_unlock_group(sb, block_group);
 413                 unlock_buffer(bh);
 414                 return bh;
 415         }
 416         ext4_unlock_group(sb, block_group);
 417         if (buffer_uptodate(bh)) {
 418                 /*
 419                  * if not uninit if bh is uptodate,
 420                  * bitmap is also uptodate
 421                  */
 422                 set_bitmap_uptodate(bh);
 423                 unlock_buffer(bh);
 424                 goto verify;
 425         }
 426         /*
 427          * submit the buffer_head for reading
 428          */
 429         set_buffer_new(bh);
 430         trace_ext4_read_block_bitmap_load(sb, block_group);
 431         bh->b_end_io = ext4_end_bitmap_read;
 432         get_bh(bh);
 433         submit_bh(READ, bh);
 434         return bh;
 435 verify:
 436         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 437         return bh;
 438 }
 439
 440 /* Returns 0 on success, 1 on error */
 441 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 442                            struct buffer_head *bh)
 443 {
 444         struct ext4_group_desc *desc;
 445
 446         if (!buffer_new(bh))
 447                 return 0;
 448         desc = ext4_get_group_desc(sb, block_group, NULL);
 449         if (!desc)
 450                 return 1;
 451         wait_on_buffer(bh);
 452         if (!buffer_uptodate(bh)) {
 453                 ext4_error(sb, "Cannot read block bitmap - "
 454                            "block_group = %u, block_bitmap = %llu",
 455                            block_group, (unsigned long long) bh->b_blocknr);
 456                 return 1;
 457         }
 458         clear_buffer_new(bh);
 459         /* Panic or remount fs read-only if block bitmap is invalid */
 460         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 461         return 0;
 462 }
 463
 464 struct buffer_head *
 465 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 466 {
 467         struct buffer_head *bh;
 468
 469         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 470         if (!bh)
 471                 return NULL;
 472         if (ext4_wait_block_bitmap(sb, block_group, bh)) {
 473                 put_bh(bh);
 474                 return NULL;
 475         }
 476         return bh;
 477 }
 478
 479 /**
 480  * ext4_has_free_clusters()
 481  * @sbi:        in-core super block structure.
 482  * @nclusters:  number of needed blocks
 483  * @flags:      flags from ext4_mb_new_blocks()
 484  *
 485  * Check if filesystem has nclusters free & available for allocation.
 486  * On success return 1, return 0 on failure.
 487  */
 488 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 489                                   s64 nclusters, unsigned int flags)
 490 {
 491         s64 free_clusters, dirty_clusters, root_clusters;
 492         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 493         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 494
 495         free_clusters  = percpu_counter_read_positive(fcc);
 496         dirty_clusters = percpu_counter_read_positive(dcc);
 497
 498         /*
 499          * r_blocks_count should always be multiple of the cluster ratio so
 500          * we are safe to do a plane bit shift only.
 501          */
 502         root_clusters = ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits;
 503
 504         if (free_clusters - (nclusters + root_clusters + dirty_clusters) <
 505                                         EXT4_FREECLUSTERS_WATERMARK) {
 506                 free_clusters  = percpu_counter_sum_positive(fcc);
 507                 dirty_clusters = percpu_counter_sum_positive(dcc);
 508         }
 509         /* Check whether we have space after accounting for current
 510          * dirty clusters & root reserved clusters.
 511          */
 512         if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters))
 513                 return 1;
 514
 515         /* Hm, nope.  Are (enough) root reserved clusters available? */
 516         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 517             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 518             capable(CAP_SYS_RESOURCE) ||
 519                 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 520
 521                 if (free_clusters >= (nclusters + dirty_clusters))
 522                         return 1;
 523         }
 524
 525         return 0;
 526 }
 527
 528 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 529                              s64 nclusters, unsigned int flags)
 530 {
 531         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 532                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 533                 return 0;
 534         } else
 535                 return -ENOSPC;
 536 }
 537
 538 /**
 539  * ext4_should_retry_alloc()
 540  * @sb:                 super block
 541  * @retries             number of attemps has been made
 542  *
 543  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 544  * it is profitable to retry the operation, this function will wait
 545  * for the current or committing transaction to complete, and then
 546  * return TRUE.
 547  *
 548  * if the total number of retries exceed three times, return FALSE.
 549  */
 550 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 551 {
 552         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 553             (*retries)++ > 3 ||
 554             !EXT4_SB(sb)->s_journal)
 555                 return 0;
 556
 557         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 558
 559         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 560 }
 561
 562 /*
 563  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 564  *
 565  * @handle:             handle to this transaction
 566  * @inode:              file inode
 567  * @goal:               given target block(filesystem wide)
 568  * @count:              pointer to total number of clusters needed
 569  * @errp:               error code
 570  *
 571  * Return 1st allocated block number on success, *count stores total account
 572  * error stores in errp pointer
 573  */
 574 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 575                                   ext4_fsblk_t goal, unsigned int flags,
 576                                   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         ar.flags = flags;
 587
 588         ret = ext4_mb_new_blocks(handle, &ar, errp);
 589         if (count)
 590                 *count = ar.len;
 591         /*
 592          * Account for the allocated meta blocks.  We will never
 593          * fail EDQUOT for metdata, but we do account for it.
 594          */
 595         if (!(*errp) &&
 596             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
 597                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 598                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 599                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 600                 dquot_alloc_block_nofail(inode,
 601                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 602         }
 603         return ret;
 604 }
 605
 606 /**
 607  * ext4_count_free_clusters() -- count filesystem free clusters
 608  * @sb:         superblock
 609  *
 610  * Adds up the number of free clusters from each block group.
 611  */
 612 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 613 {
 614         ext4_fsblk_t desc_count;
 615         struct ext4_group_desc *gdp;
 616         ext4_group_t i;
 617         ext4_group_t ngroups = ext4_get_groups_count(sb);
 618 #ifdef EXT4FS_DEBUG
 619         struct ext4_super_block *es;
 620         ext4_fsblk_t bitmap_count;
 621         unsigned int x;
 622         struct buffer_head *bitmap_bh = NULL;
 623
 624         es = EXT4_SB(sb)->s_es;
 625         desc_count = 0;
 626         bitmap_count = 0;
 627         gdp = NULL;
 628
 629         for (i = 0; i < ngroups; i++) {
 630                 gdp = ext4_get_group_desc(sb, i, NULL);
 631                 if (!gdp)
 632                         continue;
 633                 desc_count += ext4_free_group_clusters(sb, gdp);
 634                 brelse(bitmap_bh);
 635                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 636                 if (bitmap_bh == NULL)
 637                         continue;
 638
 639                 x = ext4_count_free(bitmap_bh->b_data,
 640                                     EXT4_BLOCKS_PER_GROUP(sb) / 8);
 641                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 642                         i, ext4_free_group_clusters(sb, gdp), x);
 643                 bitmap_count += x;
 644         }
 645         brelse(bitmap_bh);
 646         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 647                ", computed = %llu, %llu\n",
 648                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 649                desc_count, bitmap_count);
 650         return bitmap_count;
 651 #else
 652         desc_count = 0;
 653         for (i = 0; i < ngroups; i++) {
 654                 gdp = ext4_get_group_desc(sb, i, NULL);
 655                 if (!gdp)
 656                         continue;
 657                 desc_count += ext4_free_group_clusters(sb, gdp);
 658         }
 659
 660         return desc_count;
 661 #endif
 662 }
 663
 664 static inline int test_root(ext4_group_t a, int b)
 665 {
 666         int num = b;
 667
 668         while (a > num)
 669                 num *= b;
 670         return num == a;
 671 }
 672
 673 static int ext4_group_sparse(ext4_group_t group)
 674 {
 675         if (group <= 1)
 676                 return 1;
 677         if (!(group & 1))
 678                 return 0;
 679         return (test_root(group, 7) || test_root(group, 5) ||
 680                 test_root(group, 3));
 681 }
 682
 683 /**
 684  *      ext4_bg_has_super - number of blocks used by the superblock in group
 685  *      @sb: superblock for filesystem
 686  *      @group: group number to check
 687  *
 688  *      Return the number of blocks used by the superblock (primary or backup)
 689  *      in this group.  Currently this will be only 0 or 1.
 690  */
 691 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 692 {
 693         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
 694                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
 695                         !ext4_group_sparse(group))
 696                 return 0;
 697         return 1;
 698 }
 699
 700 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 701                                         ext4_group_t group)
 702 {
 703         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 704         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 705         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 706
 707         if (group == first || group == first + 1 || group == last)
 708                 return 1;
 709         return 0;
 710 }
 711
 712 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 713                                         ext4_group_t group)
 714 {
 715         if (!ext4_bg_has_super(sb, group))
 716                 return 0;
 717
 718         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
 719                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 720         else
 721                 return EXT4_SB(sb)->s_gdb_count;
 722 }
 723
 724 /**
 725  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 726  *      @sb: superblock for filesystem
 727  *      @group: group number to check
 728  *
 729  *      Return the number of blocks used by the group descriptor table
 730  *      (primary or backup) in this group.  In the future there may be a
 731  *      different number of descriptor blocks in each group.
 732  */
 733 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 734 {
 735         unsigned long first_meta_bg =
 736                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 737         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 738
 739         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 740                         metagroup < first_meta_bg)
 741                 return ext4_bg_num_gdb_nometa(sb, group);
 742
 743         return ext4_bg_num_gdb_meta(sb,group);
 744
 745 }
 746
 747 /*
 748  * This function returns the number of file system metadata clusters at
 749  * the beginning of a block group, including the reserved gdt blocks.
 750  */
 751 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 752                                      ext4_group_t block_group)
 753 {
 754         struct ext4_sb_info *sbi = EXT4_SB(sb);
 755         unsigned num;
 756
 757         /* Check for superblock and gdt backups in this group */
 758         num = ext4_bg_has_super(sb, block_group);
 759
 760         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 761             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 762                           sbi->s_desc_per_block) {
 763                 if (num) {
 764                         num += ext4_bg_num_gdb(sb, block_group);
 765                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 766                 }
 767         } else { /* For META_BG_BLOCK_GROUPS */
 768                 num += ext4_bg_num_gdb(sb, block_group);
 769         }
 770         return EXT4_NUM_B2C(sbi, num);
 771 }
 772 /**
 773  *      ext4_inode_to_goal_block - return a hint for block allocation
 774  *      @inode: inode for block allocation
 775  *
 776  *      Return the ideal location to start allocating blocks for a
 777  *      newly created inode.
 778  */
 779 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 780 {
 781         struct ext4_inode_info *ei = EXT4_I(inode);
 782         ext4_group_t block_group;
 783         ext4_grpblk_t colour;
 784         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 785         ext4_fsblk_t bg_start;
 786         ext4_fsblk_t last_block;
 787
 788         block_group = ei->i_block_group;
 789         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 790                 /*
 791                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 792                  * block groups per flexgroup, reserve the first block
 793                  * group for directories and special files.  Regular
 794                  * files will start at the second block group.  This
 795                  * tends to speed up directory access and improves
 796                  * fsck times.
 797                  */
 798                 block_group &= ~(flex_size-1);
 799                 if (S_ISREG(inode->i_mode))
 800                         block_group++;
 801         }
 802         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 803         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 804
 805         /*
 806          * If we are doing delayed allocation, we don't need take
 807          * colour into account.
 808          */
 809         if (test_opt(inode->i_sb, DELALLOC))
 810                 return bg_start;
 811
 812         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 813                 colour = (current->pid % 16) *
 814                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 815         else
 816                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 817         return bg_start + colour;
 818 }
 819