fs/ext4/balloc.c

   1 /*
   2  *  linux/fs/ext4/balloc.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card ([email protected])
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  Enhanced block allocation by Stephen Tweedie ([email protected]), 1993
  10  *  Big-endian to little-endian byte-swapping/bitmaps by
  11  *        David S. Miller ([email protected]), 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 block group number for a given block number
  34  */
  35 ext4_group_t ext4_get_group_number(struct super_block *sb,
  36                                    ext4_fsblk_t block)
  37 {
  38         ext4_group_t group;
  39
  40         if (test_opt2(sb, STD_GROUP_SIZE))
  41                 group = (block -
  42                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
  43                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
  44         else
  45                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
  46         return group;
  47 }
  48
  49 /*
  50  * Calculate the block group number and offset into the block/cluster
  51  * allocation bitmap, given a block number
  52  */
  53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  54                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  55 {
  56         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  57         ext4_grpblk_t offset;
  58
  59         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  60         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
  61                 EXT4_SB(sb)->s_cluster_bits;
  62         if (offsetp)
  63                 *offsetp = offset;
  64         if (blockgrpp)
  65                 *blockgrpp = blocknr;
  66
  67 }
  68
  69 /*
  70  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
  71  * and 0 otherwise.
  72  */
  73 static inline int ext4_block_in_group(struct super_block *sb,
  74                                       ext4_fsblk_t block,
  75                                       ext4_group_t block_group)
  76 {
  77         ext4_group_t actual_group;
  78
  79         actual_group = ext4_get_group_number(sb, block);
  80         return (actual_group == block_group) ? 1 : 0;
  81 }
  82
  83 /* Return the number of clusters used for file system metadata; this
  84  * represents the overhead needed by the file system.
  85  */
  86 unsigned ext4_num_overhead_clusters(struct super_block *sb,
  87                                     ext4_group_t block_group,
  88                                     struct ext4_group_desc *gdp)
  89 {
  90         unsigned num_clusters;
  91         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
  92         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  93         ext4_fsblk_t itbl_blk;
  94         struct ext4_sb_info *sbi = EXT4_SB(sb);
  95
  96         /* This is the number of clusters used by the superblock,
  97          * block group descriptors, and reserved block group
  98          * descriptor blocks */
  99         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
 100
 101         /*
 102          * For the allocation bitmaps and inode table, we first need
 103          * to check to see if the block is in the block group.  If it
 104          * is, then check to see if the cluster is already accounted
 105          * for in the clusters used for the base metadata cluster, or
 106          * if we can increment the base metadata cluster to include
 107          * that block.  Otherwise, we will have to track the cluster
 108          * used for the allocation bitmap or inode table explicitly.
 109          * Normally all of these blocks are contiguous, so the special
 110          * case handling shouldn't be necessary except for *very*
 111          * unusual file system layouts.
 112          */
 113         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 114                 block_cluster = EXT4_B2C(sbi,
 115                                          ext4_block_bitmap(sb, gdp) - start);
 116                 if (block_cluster < num_clusters)
 117                         block_cluster = -1;
 118                 else if (block_cluster == num_clusters) {
 119                         num_clusters++;
 120                         block_cluster = -1;
 121                 }
 122         }
 123
 124         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 125                 inode_cluster = EXT4_B2C(sbi,
 126                                          ext4_inode_bitmap(sb, gdp) - start);
 127                 if (inode_cluster < num_clusters)
 128                         inode_cluster = -1;
 129                 else if (inode_cluster == num_clusters) {
 130                         num_clusters++;
 131                         inode_cluster = -1;
 132                 }
 133         }
 134
 135         itbl_blk = ext4_inode_table(sb, gdp);
 136         for (i = 0; i < sbi->s_itb_per_group; i++) {
 137                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
 138                         c = EXT4_B2C(sbi, itbl_blk + i - start);
 139                         if ((c < num_clusters) || (c == inode_cluster) ||
 140                             (c == block_cluster) || (c == itbl_cluster))
 141                                 continue;
 142                         if (c == num_clusters) {
 143                                 num_clusters++;
 144                                 continue;
 145                         }
 146                         num_clusters++;
 147                         itbl_cluster = c;
 148                 }
 149         }
 150
 151         if (block_cluster != -1)
 152                 num_clusters++;
 153         if (inode_cluster != -1)
 154                 num_clusters++;
 155
 156         return num_clusters;
 157 }
 158
 159 static unsigned int num_clusters_in_group(struct super_block *sb,
 160                                           ext4_group_t block_group)
 161 {
 162         unsigned int blocks;
 163
 164         if (block_group == ext4_get_groups_count(sb) - 1) {
 165                 /*
 166                  * Even though mke2fs always initializes the first and
 167                  * last group, just in case some other tool was used,
 168                  * we need to make sure we calculate the right free
 169                  * blocks.
 170                  */
 171                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 172                         ext4_group_first_block_no(sb, block_group);
 173         } else
 174                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 175         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 176 }
 177
 178 /* Initializes an uninitialized block bitmap */
 179 void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 180                             ext4_group_t block_group,
 181                             struct ext4_group_desc *gdp)
 182 {
 183         unsigned int bit, bit_max;
 184         struct ext4_sb_info *sbi = EXT4_SB(sb);
 185         ext4_fsblk_t start, tmp;
 186         int flex_bg = 0;
 187         struct ext4_group_info *grp;
 188
 189         J_ASSERT_BH(bh, buffer_locked(bh));
 190
 191         /* If checksum is bad mark all blocks used to prevent allocation
 192          * essentially implementing a per-group read-only flag. */
 193         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 194                 ext4_error(sb, "Checksum bad for group %u", block_group);
 195                 grp = ext4_get_group_info(sb, block_group);
 196                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 197                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 198                 return;
 199         }
 200         memset(bh->b_data, 0, sb->s_blocksize);
 201
 202         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 203         for (bit = 0; bit < bit_max; bit++)
 204                 ext4_set_bit(bit, bh->b_data);
 205
 206         start = ext4_group_first_block_no(sb, block_group);
 207
 208         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
 209                 flex_bg = 1;
 210
 211         /* Set bits for block and inode bitmaps, and inode table */
 212         tmp = ext4_block_bitmap(sb, gdp);
 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         tmp = ext4_inode_bitmap(sb, gdp);
 217         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 218                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 219
 220         tmp = ext4_inode_table(sb, gdp);
 221         for (; tmp < ext4_inode_table(sb, gdp) +
 222                      sbi->s_itb_per_group; tmp++) {
 223                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 224                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 225         }
 226
 227         /*
 228          * Also if the number of blocks within the group is less than
 229          * the blocksize * 8 ( which is the size of bitmap ), set rest
 230          * of the block bitmap to 1
 231          */
 232         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 233                              sb->s_blocksize * 8, bh->b_data);
 234         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 235         ext4_group_desc_csum_set(sb, block_group, gdp);
 236 }
 237
 238 /* Return the number of free blocks in a block group.  It is used when
 239  * the block bitmap is uninitialized, so we can't just count the bits
 240  * in the bitmap. */
 241 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 242                                        ext4_group_t block_group,
 243                                        struct ext4_group_desc *gdp)
 244 {
 245         return num_clusters_in_group(sb, block_group) -
 246                 ext4_num_overhead_clusters(sb, block_group, gdp);
 247 }
 248
 249 /*
 250  * The free blocks are managed by bitmaps.  A file system contains several
 251  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 252  * block for inodes, N blocks for the inode table and data blocks.
 253  *
 254  * The file system contains group descriptors which are located after the
 255  * super block.  Each descriptor contains the number of the bitmap block and
 256  * the free blocks count in the block.  The descriptors are loaded in memory
 257  * when a file system is mounted (see ext4_fill_super).
 258  */
 259
 260 /**
 261  * ext4_get_group_desc() -- load group descriptor from disk
 262  * @sb:                 super block
 263  * @block_group:        given block group
 264  * @bh:                 pointer to the buffer head to store the block
 265  *                      group descriptor
 266  */
 267 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 268                                              ext4_group_t block_group,
 269                                              struct buffer_head **bh)
 270 {
 271         unsigned int group_desc;
 272         unsigned int offset;
 273         ext4_group_t ngroups = ext4_get_groups_count(sb);
 274         struct ext4_group_desc *desc;
 275         struct ext4_sb_info *sbi = EXT4_SB(sb);
 276
 277         if (block_group >= ngroups) {
 278                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 279                            " groups_count = %u", block_group, ngroups);
 280
 281                 return NULL;
 282         }
 283
 284         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 285         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 286         if (!sbi->s_group_desc[group_desc]) {
 287                 ext4_error(sb, "Group descriptor not loaded - "
 288                            "block_group = %u, group_desc = %u, desc = %u",
 289                            block_group, group_desc, offset);
 290                 return NULL;
 291         }
 292
 293         desc = (struct ext4_group_desc *)(
 294                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 295                 offset * EXT4_DESC_SIZE(sb));
 296         if (bh)
 297                 *bh = sbi->s_group_desc[group_desc];
 298         return desc;
 299 }
 300
 301 /*
 302  * Return the block number which was discovered to be invalid, or 0 if
 303  * the block bitmap is valid.
 304  */
 305 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 306                                             struct ext4_group_desc *desc,
 307                                             ext4_group_t block_group,
 308                                             struct buffer_head *bh)
 309 {
 310         ext4_grpblk_t offset;
 311         ext4_grpblk_t next_zero_bit;
 312         ext4_fsblk_t blk;
 313         ext4_fsblk_t group_first_block;
 314
 315         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 316                 /* with FLEX_BG, the inode/block bitmaps and itable
 317                  * blocks may not be in the group at all
 318                  * so the bitmap validation will be skipped for those groups
 319                  * or it has to also read the block group where the bitmaps
 320                  * are located to verify they are set.
 321                  */
 322                 return 0;
 323         }
 324         group_first_block = ext4_group_first_block_no(sb, block_group);
 325
 326         /* check whether block bitmap block number is set */
 327         blk = ext4_block_bitmap(sb, desc);
 328         offset = blk - group_first_block;
 329         if (!ext4_test_bit(offset, bh->b_data))
 330                 /* bad block bitmap */
 331                 return blk;
 332
 333         /* check whether the inode bitmap block number is set */
 334         blk = ext4_inode_bitmap(sb, desc);
 335         offset = blk - group_first_block;
 336         if (!ext4_test_bit(offset, bh->b_data))
 337                 /* bad block bitmap */
 338                 return blk;
 339
 340         /* check whether the inode table block number is set */
 341         blk = ext4_inode_table(sb, desc);
 342         offset = blk - group_first_block;
 343         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 344                                 offset + EXT4_SB(sb)->s_itb_per_group,
 345                                 offset);
 346         if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
 347                 /* bad bitmap for inode tables */
 348                 return blk;
 349         return 0;
 350 }
 351
 352 void ext4_validate_block_bitmap(struct super_block *sb,
 353                                struct ext4_group_desc *desc,
 354                                ext4_group_t block_group,
 355                                struct buffer_head *bh)
 356 {
 357         ext4_fsblk_t    blk;
 358         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
 359
 360         if (buffer_verified(bh))
 361                 return;
 362
 363         ext4_lock_group(sb, block_group);
 364         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 365         if (unlikely(blk != 0)) {
 366                 ext4_unlock_group(sb, block_group);
 367                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 368                            block_group, blk);
 369                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 370                 return;
 371         }
 372         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 373                         desc, bh))) {
 374                 ext4_unlock_group(sb, block_group);
 375                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 376                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 377                 return;
 378         }
 379         set_buffer_verified(bh);
 380         ext4_unlock_group(sb, block_group);
 381 }
 382
 383 /**
 384  * ext4_read_block_bitmap_nowait()
 385  * @sb:                 super block
 386  * @block_group:        given block group
 387  *
 388  * Read the bitmap for a given block_group,and validate the
 389  * bits for block/inode/inode tables are set in the bitmaps
 390  *
 391  * Return buffer_head on success or NULL in case of failure.
 392  */
 393 struct buffer_head *
 394 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 395 {
 396         struct ext4_group_desc *desc;
 397         struct buffer_head *bh;
 398         ext4_fsblk_t bitmap_blk;
 399
 400         desc = ext4_get_group_desc(sb, block_group, NULL);
 401         if (!desc)
 402                 return NULL;
 403         bitmap_blk = ext4_block_bitmap(sb, desc);
 404         bh = sb_getblk(sb, bitmap_blk);
 405         if (unlikely(!bh)) {
 406                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 407                            "block_group = %u, block_bitmap = %llu",
 408                            block_group, bitmap_blk);
 409                 return NULL;
 410         }
 411
 412         if (bitmap_uptodate(bh))
 413                 goto verify;
 414
 415         lock_buffer(bh);
 416         if (bitmap_uptodate(bh)) {
 417                 unlock_buffer(bh);
 418                 goto verify;
 419         }
 420         ext4_lock_group(sb, block_group);
 421         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 422                 ext4_init_block_bitmap(sb, bh, block_group, desc);
 423                 set_bitmap_uptodate(bh);
 424                 set_buffer_uptodate(bh);
 425                 ext4_unlock_group(sb, block_group);
 426                 unlock_buffer(bh);
 427                 return bh;
 428         }
 429         ext4_unlock_group(sb, block_group);
 430         if (buffer_uptodate(bh)) {
 431                 /*
 432                  * if not uninit if bh is uptodate,
 433                  * bitmap is also uptodate
 434                  */
 435                 set_bitmap_uptodate(bh);
 436                 unlock_buffer(bh);
 437                 goto verify;
 438         }
 439         /*
 440          * submit the buffer_head for reading
 441          */
 442         set_buffer_new(bh);
 443         trace_ext4_read_block_bitmap_load(sb, block_group);
 444         bh->b_end_io = ext4_end_bitmap_read;
 445         get_bh(bh);
 446         submit_bh(READ | REQ_META | REQ_PRIO, bh);
 447         return bh;
 448 verify:
 449         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 450         if (buffer_verified(bh))
 451                 return bh;
 452         put_bh(bh);
 453         return NULL;
 454 }
 455
 456 /* Returns 0 on success, 1 on error */
 457 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 458                            struct buffer_head *bh)
 459 {
 460         struct ext4_group_desc *desc;
 461
 462         if (!buffer_new(bh))
 463                 return 0;
 464         desc = ext4_get_group_desc(sb, block_group, NULL);
 465         if (!desc)
 466                 return 1;
 467         wait_on_buffer(bh);
 468         if (!buffer_uptodate(bh)) {
 469                 ext4_error(sb, "Cannot read block bitmap - "
 470                            "block_group = %u, block_bitmap = %llu",
 471                            block_group, (unsigned long long) bh->b_blocknr);
 472                 return 1;
 473         }
 474         clear_buffer_new(bh);
 475         /* Panic or remount fs read-only if block bitmap is invalid */
 476         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 477         /* ...but check for error just in case errors=continue. */
 478         return !buffer_verified(bh);
 479 }
 480
 481 struct buffer_head *
 482 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 483 {
 484         struct buffer_head *bh;
 485
 486         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 487         if (!bh)
 488                 return NULL;
 489         if (ext4_wait_block_bitmap(sb, block_group, bh)) {
 490                 put_bh(bh);
 491                 return NULL;
 492         }
 493         return bh;
 494 }
 495
 496 /**
 497  * ext4_has_free_clusters()
 498  * @sbi:        in-core super block structure.
 499  * @nclusters:  number of needed blocks
 500  * @flags:      flags from ext4_mb_new_blocks()
 501  *
 502  * Check if filesystem has nclusters free & available for allocation.
 503  * On success return 1, return 0 on failure.
 504  */
 505 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 506                                   s64 nclusters, unsigned int flags)
 507 {
 508         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 509         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 510         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 511
 512         free_clusters  = percpu_counter_read_positive(fcc);
 513         dirty_clusters = percpu_counter_read_positive(dcc);
 514         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 515
 516         /*
 517          * r_blocks_count should always be multiple of the cluster ratio so
 518          * we are safe to do a plane bit shift only.
 519          */
 520         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 521               resv_clusters;
 522
 523         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 524                                         EXT4_FREECLUSTERS_WATERMARK) {
 525                 free_clusters  = percpu_counter_sum_positive(fcc);
 526                 dirty_clusters = percpu_counter_sum_positive(dcc);
 527         }
 528         /* Check whether we have space after accounting for current
 529          * dirty clusters & root reserved clusters.
 530          */
 531         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 532                 return 1;
 533
 534         /* Hm, nope.  Are (enough) root reserved clusters available? */
 535         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 536             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 537             capable(CAP_SYS_RESOURCE) ||
 538             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 539
 540                 if (free_clusters >= (nclusters + dirty_clusters +
 541                                       resv_clusters))
 542                         return 1;
 543         }
 544         /* No free blocks. Let's see if we can dip into reserved pool */
 545         if (flags & EXT4_MB_USE_RESERVED) {
 546                 if (free_clusters >= (nclusters + dirty_clusters))
 547                         return 1;
 548         }
 549
 550         return 0;
 551 }
 552
 553 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 554                              s64 nclusters, unsigned int flags)
 555 {
 556         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 557                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 558                 return 0;
 559         } else
 560                 return -ENOSPC;
 561 }
 562
 563 /**
 564  * ext4_should_retry_alloc()
 565  * @sb:                 super block
 566  * @retries             number of attemps has been made
 567  *
 568  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 569  * it is profitable to retry the operation, this function will wait
 570  * for the current or committing transaction to complete, and then
 571  * return TRUE.
 572  *
 573  * if the total number of retries exceed three times, return FALSE.
 574  */
 575 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 576 {
 577         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 578             (*retries)++ > 3 ||
 579             !EXT4_SB(sb)->s_journal)
 580                 return 0;
 581
 582         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 583
 584         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 585 }
 586
 587 /*
 588  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 589  *
 590  * @handle:             handle to this transaction
 591  * @inode:              file inode
 592  * @goal:               given target block(filesystem wide)
 593  * @count:              pointer to total number of clusters needed
 594  * @errp:               error code
 595  *
 596  * Return 1st allocated block number on success, *count stores total account
 597  * error stores in errp pointer
 598  */
 599 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 600                                   ext4_fsblk_t goal, unsigned int flags,
 601                                   unsigned long *count, int *errp)
 602 {
 603         struct ext4_allocation_request ar;
 604         ext4_fsblk_t ret;
 605
 606         memset(&ar, 0, sizeof(ar));
 607         /* Fill with neighbour allocated blocks */
 608         ar.inode = inode;
 609         ar.goal = goal;
 610         ar.len = count ? *count : 1;
 611         ar.flags = flags;
 612
 613         ret = ext4_mb_new_blocks(handle, &ar, errp);
 614         if (count)
 615                 *count = ar.len;
 616         /*
 617          * Account for the allocated meta blocks.  We will never
 618          * fail EDQUOT for metdata, but we do account for it.
 619          */
 620         if (!(*errp) &&
 621             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
 622                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 623                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 624                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 625                 dquot_alloc_block_nofail(inode,
 626                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 627         }
 628         return ret;
 629 }
 630
 631 /**
 632  * ext4_count_free_clusters() -- count filesystem free clusters
 633  * @sb:         superblock
 634  *
 635  * Adds up the number of free clusters from each block group.
 636  */
 637 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 638 {
 639         ext4_fsblk_t desc_count;
 640         struct ext4_group_desc *gdp;
 641         ext4_group_t i;
 642         ext4_group_t ngroups = ext4_get_groups_count(sb);
 643         struct ext4_group_info *grp;
 644 #ifdef EXT4FS_DEBUG
 645         struct ext4_super_block *es;
 646         ext4_fsblk_t bitmap_count;
 647         unsigned int x;
 648         struct buffer_head *bitmap_bh = NULL;
 649
 650         es = EXT4_SB(sb)->s_es;
 651         desc_count = 0;
 652         bitmap_count = 0;
 653         gdp = NULL;
 654
 655         for (i = 0; i < ngroups; i++) {
 656                 gdp = ext4_get_group_desc(sb, i, NULL);
 657                 if (!gdp)
 658                         continue;
 659                 grp = NULL;
 660                 if (EXT4_SB(sb)->s_group_info)
 661                         grp = ext4_get_group_info(sb, i);
 662                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 663                         desc_count += ext4_free_group_clusters(sb, gdp);
 664                 brelse(bitmap_bh);
 665                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 666                 if (bitmap_bh == NULL)
 667                         continue;
 668
 669                 x = ext4_count_free(bitmap_bh->b_data,
 670                                     EXT4_BLOCKS_PER_GROUP(sb) / 8);
 671                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 672                         i, ext4_free_group_clusters(sb, gdp), x);
 673                 bitmap_count += x;
 674         }
 675         brelse(bitmap_bh);
 676         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 677                ", computed = %llu, %llu\n",
 678                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 679                desc_count, bitmap_count);
 680         return bitmap_count;
 681 #else
 682         desc_count = 0;
 683         for (i = 0; i < ngroups; i++) {
 684                 gdp = ext4_get_group_desc(sb, i, NULL);
 685                 if (!gdp)
 686                         continue;
 687                 grp = NULL;
 688                 if (EXT4_SB(sb)->s_group_info)
 689                         grp = ext4_get_group_info(sb, i);
 690                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 691                         desc_count += ext4_free_group_clusters(sb, gdp);
 692         }
 693
 694         return desc_count;
 695 #endif
 696 }
 697
 698 static inline int test_root(ext4_group_t a, int b)
 699 {
 700         while (1) {
 701                 if (a < b)
 702                         return 0;
 703                 if (a == b)
 704                         return 1;
 705                 if ((a % b) != 0)
 706                         return 0;
 707                 a = a / b;
 708         }
 709 }
 710
 711 static int ext4_group_sparse(ext4_group_t group)
 712 {
 713         if (group <= 1)
 714                 return 1;
 715         if (!(group & 1))
 716                 return 0;
 717         return (test_root(group, 7) || test_root(group, 5) ||
 718                 test_root(group, 3));
 719 }
 720
 721 /**
 722  *      ext4_bg_has_super - number of blocks used by the superblock in group
 723  *      @sb: superblock for filesystem
 724  *      @group: group number to check
 725  *
 726  *      Return the number of blocks used by the superblock (primary or backup)
 727  *      in this group.  Currently this will be only 0 or 1.
 728  */
 729 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 730 {
 731         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
 732                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
 733                         !ext4_group_sparse(group))
 734                 return 0;
 735         return 1;
 736 }
 737
 738 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 739                                         ext4_group_t group)
 740 {
 741         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 742         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 743         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 744
 745         if (group == first || group == first + 1 || group == last)
 746                 return 1;
 747         return 0;
 748 }
 749
 750 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 751                                         ext4_group_t group)
 752 {
 753         if (!ext4_bg_has_super(sb, group))
 754                 return 0;
 755
 756         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
 757                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 758         else
 759                 return EXT4_SB(sb)->s_gdb_count;
 760 }
 761
 762 /**
 763  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 764  *      @sb: superblock for filesystem
 765  *      @group: group number to check
 766  *
 767  *      Return the number of blocks used by the group descriptor table
 768  *      (primary or backup) in this group.  In the future there may be a
 769  *      different number of descriptor blocks in each group.
 770  */
 771 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 772 {
 773         unsigned long first_meta_bg =
 774                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 775         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 776
 777         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 778                         metagroup < first_meta_bg)
 779                 return ext4_bg_num_gdb_nometa(sb, group);
 780
 781         return ext4_bg_num_gdb_meta(sb,group);
 782
 783 }
 784
 785 /*
 786  * This function returns the number of file system metadata clusters at
 787  * the beginning of a block group, including the reserved gdt blocks.
 788  */
 789 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 790                                      ext4_group_t block_group)
 791 {
 792         struct ext4_sb_info *sbi = EXT4_SB(sb);
 793         unsigned num;
 794
 795         /* Check for superblock and gdt backups in this group */
 796         num = ext4_bg_has_super(sb, block_group);
 797
 798         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 799             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 800                           sbi->s_desc_per_block) {
 801                 if (num) {
 802                         num += ext4_bg_num_gdb(sb, block_group);
 803                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 804                 }
 805         } else { /* For META_BG_BLOCK_GROUPS */
 806                 num += ext4_bg_num_gdb(sb, block_group);
 807         }
 808         return EXT4_NUM_B2C(sbi, num);
 809 }
 810 /**
 811  *      ext4_inode_to_goal_block - return a hint for block allocation
 812  *      @inode: inode for block allocation
 813  *
 814  *      Return the ideal location to start allocating blocks for a
 815  *      newly created inode.
 816  */
 817 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 818 {
 819         struct ext4_inode_info *ei = EXT4_I(inode);
 820         ext4_group_t block_group;
 821         ext4_grpblk_t colour;
 822         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 823         ext4_fsblk_t bg_start;
 824         ext4_fsblk_t last_block;
 825
 826         block_group = ei->i_block_group;
 827         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 828                 /*
 829                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 830                  * block groups per flexgroup, reserve the first block
 831                  * group for directories and special files.  Regular
 832                  * files will start at the second block group.  This
 833                  * tends to speed up directory access and improves
 834                  * fsck times.
 835                  */
 836                 block_group &= ~(flex_size-1);
 837                 if (S_ISREG(inode->i_mode))
 838                         block_group++;
 839         }
 840         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 841         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 842
 843         /*
 844          * If we are doing delayed allocation, we don't need take
 845          * colour into account.
 846          */
 847         if (test_opt(inode->i_sb, DELALLOC))
 848                 return bg_start;
 849
 850         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 851                 colour = (current->pid % 16) *
 852                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 853         else
 854                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 855         return bg_start + colour;
 856 }
 857