kernel/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/quotaops.h>
  18 #include <linux/buffer_head.h>
  19 #include "ext4.h"
  20 #include "ext4_jbd2.h"
  21 #include "mballoc.h"
  22
  23 #include <trace/events/ext4.h>
  24
  25 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
  26                                             ext4_group_t block_group);
  27 /*
  28  * balloc.c contains the blocks allocation and deallocation routines
  29  */
  30
  31 /*
  32  * Calculate block group number for a given block number
  33  */
  34 ext4_group_t ext4_get_group_number(struct super_block *sb,
  35                                    ext4_fsblk_t block)
  36 {
  37         ext4_group_t group;
  38
  39         if (test_opt2(sb, STD_GROUP_SIZE))
  40                 group = (block -
  41                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
  42                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
  43         else
  44                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
  45         return group;
  46 }
  47
  48 /*
  49  * Calculate the block group number and offset into the block/cluster
  50  * allocation bitmap, given a block number
  51  */
  52 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  53                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  54 {
  55         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  56         ext4_grpblk_t offset;
  57
  58         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  59         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
  60                 EXT4_SB(sb)->s_cluster_bits;
  61         if (offsetp)
  62                 *offsetp = offset;
  63         if (blockgrpp)
  64                 *blockgrpp = blocknr;
  65
  66 }
  67
  68 /*
  69  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
  70  * and 0 otherwise.
  71  */
  72 static inline int ext4_block_in_group(struct super_block *sb,
  73                                       ext4_fsblk_t block,
  74                                       ext4_group_t block_group)
  75 {
  76         ext4_group_t actual_group;
  77
  78         actual_group = ext4_get_group_number(sb, block);
  79         return (actual_group == block_group) ? 1 : 0;
  80 }
  81
  82 /* Return the number of clusters used for file system metadata; this
  83  * represents the overhead needed by the file system.
  84  */
  85 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
  86                                            ext4_group_t block_group,
  87                                            struct ext4_group_desc *gdp)
  88 {
  89         unsigned num_clusters;
  90         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
  91         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  92         ext4_fsblk_t itbl_blk;
  93         struct ext4_sb_info *sbi = EXT4_SB(sb);
  94
  95         /* This is the number of clusters used by the superblock,
  96          * block group descriptors, and reserved block group
  97          * descriptor blocks */
  98         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
  99
 100         /*
 101          * For the allocation bitmaps and inode table, we first need
 102          * to check to see if the block is in the block group.  If it
 103          * is, then check to see if the cluster is already accounted
 104          * for in the clusters used for the base metadata cluster, or
 105          * if we can increment the base metadata cluster to include
 106          * that block.  Otherwise, we will have to track the cluster
 107          * used for the allocation bitmap or inode table explicitly.
 108          * Normally all of these blocks are contiguous, so the special
 109          * case handling shouldn't be necessary except for *very*
 110          * unusual file system layouts.
 111          */
 112         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 113                 block_cluster = EXT4_B2C(sbi,
 114                                          ext4_block_bitmap(sb, gdp) - start);
 115                 if (block_cluster < num_clusters)
 116                         block_cluster = -1;
 117                 else if (block_cluster == num_clusters) {
 118                         num_clusters++;
 119                         block_cluster = -1;
 120                 }
 121         }
 122
 123         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 124                 inode_cluster = EXT4_B2C(sbi,
 125                                          ext4_inode_bitmap(sb, gdp) - start);
 126                 if (inode_cluster < num_clusters)
 127                         inode_cluster = -1;
 128                 else if (inode_cluster == num_clusters) {
 129                         num_clusters++;
 130                         inode_cluster = -1;
 131                 }
 132         }
 133
 134         itbl_blk = ext4_inode_table(sb, gdp);
 135         for (i = 0; i < sbi->s_itb_per_group; i++) {
 136                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
 137                         c = EXT4_B2C(sbi, itbl_blk + i - start);
 138                         if ((c < num_clusters) || (c == inode_cluster) ||
 139                             (c == block_cluster) || (c == itbl_cluster))
 140                                 continue;
 141                         if (c == num_clusters) {
 142                                 num_clusters++;
 143                                 continue;
 144                         }
 145                         num_clusters++;
 146                         itbl_cluster = c;
 147                 }
 148         }
 149
 150         if (block_cluster != -1)
 151                 num_clusters++;
 152         if (inode_cluster != -1)
 153                 num_clusters++;
 154
 155         return num_clusters;
 156 }
 157
 158 static unsigned int num_clusters_in_group(struct super_block *sb,
 159                                           ext4_group_t block_group)
 160 {
 161         unsigned int blocks;
 162
 163         if (block_group == ext4_get_groups_count(sb) - 1) {
 164                 /*
 165                  * Even though mke2fs always initializes the first and
 166                  * last group, just in case some other tool was used,
 167                  * we need to make sure we calculate the right free
 168                  * blocks.
 169                  */
 170                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 171                         ext4_group_first_block_no(sb, block_group);
 172         } else
 173                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 174         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 175 }
 176
 177 /* Initializes an uninitialized block bitmap */
 178 static int ext4_init_block_bitmap(struct super_block *sb,
 179                                    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                 grp = ext4_get_group_info(sb, block_group);
 195                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 196                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 197                                            grp->bb_free);
 198                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 199                 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
 200                         int count;
 201                         count = ext4_free_inodes_count(sb, gdp);
 202                         percpu_counter_sub(&sbi->s_freeinodes_counter,
 203                                            count);
 204                 }
 205                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 206                 return -EIO;
 207         }
 208         memset(bh->b_data, 0, sb->s_blocksize);
 209
 210         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 211         for (bit = 0; bit < bit_max; bit++)
 212                 ext4_set_bit(bit, bh->b_data);
 213
 214         start = ext4_group_first_block_no(sb, block_group);
 215
 216         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
 217                 flex_bg = 1;
 218
 219         /* Set bits for block and inode bitmaps, and inode table */
 220         tmp = ext4_block_bitmap(sb, gdp);
 221         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 222                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 223
 224         tmp = ext4_inode_bitmap(sb, gdp);
 225         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 226                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 227
 228         tmp = ext4_inode_table(sb, gdp);
 229         for (; tmp < ext4_inode_table(sb, gdp) +
 230                      sbi->s_itb_per_group; tmp++) {
 231                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 232                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 233         }
 234
 235         /*
 236          * Also if the number of blocks within the group is less than
 237          * the blocksize * 8 ( which is the size of bitmap ), set rest
 238          * of the block bitmap to 1
 239          */
 240         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 241                              sb->s_blocksize * 8, bh->b_data);
 242         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 243         ext4_group_desc_csum_set(sb, block_group, gdp);
 244         return 0;
 245 }
 246
 247 /* Return the number of free blocks in a block group.  It is used when
 248  * the block bitmap is uninitialized, so we can't just count the bits
 249  * in the bitmap. */
 250 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 251                                        ext4_group_t block_group,
 252                                        struct ext4_group_desc *gdp)
 253 {
 254         return num_clusters_in_group(sb, block_group) -
 255                 ext4_num_overhead_clusters(sb, block_group, gdp);
 256 }
 257
 258 /*
 259  * The free blocks are managed by bitmaps.  A file system contains several
 260  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 261  * block for inodes, N blocks for the inode table and data blocks.
 262  *
 263  * The file system contains group descriptors which are located after the
 264  * super block.  Each descriptor contains the number of the bitmap block and
 265  * the free blocks count in the block.  The descriptors are loaded in memory
 266  * when a file system is mounted (see ext4_fill_super).
 267  */
 268
 269 /**
 270  * ext4_get_group_desc() -- load group descriptor from disk
 271  * @sb:                 super block
 272  * @block_group:        given block group
 273  * @bh:                 pointer to the buffer head to store the block
 274  *                      group descriptor
 275  */
 276 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 277                                              ext4_group_t block_group,
 278                                              struct buffer_head **bh)
 279 {
 280         unsigned int group_desc;
 281         unsigned int offset;
 282         ext4_group_t ngroups = ext4_get_groups_count(sb);
 283         struct ext4_group_desc *desc;
 284         struct ext4_sb_info *sbi = EXT4_SB(sb);
 285
 286         if (block_group >= ngroups) {
 287                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 288                            " groups_count = %u", block_group, ngroups);
 289
 290                 return NULL;
 291         }
 292
 293         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 294         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 295         if (!sbi->s_group_desc[group_desc]) {
 296                 ext4_error(sb, "Group descriptor not loaded - "
 297                            "block_group = %u, group_desc = %u, desc = %u",
 298                            block_group, group_desc, offset);
 299                 return NULL;
 300         }
 301
 302         desc = (struct ext4_group_desc *)(
 303                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 304                 offset * EXT4_DESC_SIZE(sb));
 305         if (bh)
 306                 *bh = sbi->s_group_desc[group_desc];
 307         return desc;
 308 }
 309
 310 /*
 311  * Return the block number which was discovered to be invalid, or 0 if
 312  * the block bitmap is valid.
 313  */
 314 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 315                                             struct ext4_group_desc *desc,
 316                                             ext4_group_t block_group,
 317                                             struct buffer_head *bh)
 318 {
 319         struct ext4_sb_info *sbi = EXT4_SB(sb);
 320         ext4_grpblk_t offset;
 321         ext4_grpblk_t next_zero_bit;
 322         ext4_fsblk_t blk;
 323         ext4_fsblk_t group_first_block;
 324
 325         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 326                 /* with FLEX_BG, the inode/block bitmaps and itable
 327                  * blocks may not be in the group at all
 328                  * so the bitmap validation will be skipped for those groups
 329                  * or it has to also read the block group where the bitmaps
 330                  * are located to verify they are set.
 331                  */
 332                 return 0;
 333         }
 334         group_first_block = ext4_group_first_block_no(sb, block_group);
 335
 336         /* check whether block bitmap block number is set */
 337         blk = ext4_block_bitmap(sb, desc);
 338         offset = blk - group_first_block;
 339         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 340                 /* bad block bitmap */
 341                 return blk;
 342
 343         /* check whether the inode bitmap block number is set */
 344         blk = ext4_inode_bitmap(sb, desc);
 345         offset = blk - group_first_block;
 346         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 347                 /* bad block bitmap */
 348                 return blk;
 349
 350         /* check whether the inode table block number is set */
 351         blk = ext4_inode_table(sb, desc);
 352         offset = blk - group_first_block;
 353         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 354                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
 355                         EXT4_B2C(sbi, offset));
 356         if (next_zero_bit <
 357             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
 358                 /* bad bitmap for inode tables */
 359                 return blk;
 360         return 0;
 361 }
 362
 363 static void ext4_validate_block_bitmap(struct super_block *sb,
 364                                        struct ext4_group_desc *desc,
 365                                        ext4_group_t block_group,
 366                                        struct buffer_head *bh)
 367 {
 368         ext4_fsblk_t    blk;
 369         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
 370         struct ext4_sb_info *sbi = EXT4_SB(sb);
 371
 372         if (buffer_verified(bh))
 373                 return;
 374
 375         ext4_lock_group(sb, block_group);
 376         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 377         if (unlikely(blk != 0)) {
 378                 ext4_unlock_group(sb, block_group);
 379                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 380                            block_group, blk);
 381                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 382                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 383                                            grp->bb_free);
 384                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 385                 return;
 386         }
 387         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 388                         desc, bh))) {
 389                 ext4_unlock_group(sb, block_group);
 390                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 391                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 392                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 393                                            grp->bb_free);
 394                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 395                 return;
 396         }
 397         set_buffer_verified(bh);
 398         ext4_unlock_group(sb, block_group);
 399 }
 400
 401 /**
 402  * ext4_read_block_bitmap_nowait()
 403  * @sb:                 super block
 404  * @block_group:        given block group
 405  *
 406  * Read the bitmap for a given block_group,and validate the
 407  * bits for block/inode/inode tables are set in the bitmaps
 408  *
 409  * Return buffer_head on success or NULL in case of failure.
 410  */
 411 struct buffer_head *
 412 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 413 {
 414         struct ext4_group_desc *desc;
 415         struct buffer_head *bh;
 416         ext4_fsblk_t bitmap_blk;
 417
 418         desc = ext4_get_group_desc(sb, block_group, NULL);
 419         if (!desc)
 420                 return NULL;
 421         bitmap_blk = ext4_block_bitmap(sb, desc);
 422         bh = sb_getblk(sb, bitmap_blk);
 423         if (unlikely(!bh)) {
 424                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 425                            "block_group = %u, block_bitmap = %llu",
 426                            block_group, bitmap_blk);
 427                 return NULL;
 428         }
 429
 430         if (bitmap_uptodate(bh))
 431                 goto verify;
 432
 433         lock_buffer(bh);
 434         if (bitmap_uptodate(bh)) {
 435                 unlock_buffer(bh);
 436                 goto verify;
 437         }
 438         ext4_lock_group(sb, block_group);
 439         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 440                 int err;
 441
 442                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 443                 set_bitmap_uptodate(bh);
 444                 set_buffer_uptodate(bh);
 445                 ext4_unlock_group(sb, block_group);
 446                 unlock_buffer(bh);
 447                 if (err)
 448                         ext4_error(sb, "Checksum bad for grp %u", block_group);
 449                 return bh;
 450         }
 451         ext4_unlock_group(sb, block_group);
 452         if (buffer_uptodate(bh)) {
 453                 /*
 454                  * if not uninit if bh is uptodate,
 455                  * bitmap is also uptodate
 456                  */
 457                 set_bitmap_uptodate(bh);
 458                 unlock_buffer(bh);
 459                 goto verify;
 460         }
 461         /*
 462          * submit the buffer_head for reading
 463          */
 464         set_buffer_new(bh);
 465         trace_ext4_read_block_bitmap_load(sb, block_group);
 466         bh->b_end_io = ext4_end_bitmap_read;
 467         get_bh(bh);
 468         submit_bh(READ | REQ_META | REQ_PRIO, bh);
 469         return bh;
 470 verify:
 471         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 472         if (buffer_verified(bh))
 473                 return bh;
 474         put_bh(bh);
 475         return NULL;
 476 }
 477
 478 /* Returns 0 on success, 1 on error */
 479 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 480                            struct buffer_head *bh)
 481 {
 482         struct ext4_group_desc *desc;
 483
 484         if (!buffer_new(bh))
 485                 return 0;
 486         desc = ext4_get_group_desc(sb, block_group, NULL);
 487         if (!desc)
 488                 return 1;
 489         wait_on_buffer(bh);
 490         if (!buffer_uptodate(bh)) {
 491                 ext4_error(sb, "Cannot read block bitmap - "
 492                            "block_group = %u, block_bitmap = %llu",
 493                            block_group, (unsigned long long) bh->b_blocknr);
 494                 return 1;
 495         }
 496         clear_buffer_new(bh);
 497         /* Panic or remount fs read-only if block bitmap is invalid */
 498         ext4_validate_block_bitmap(sb, desc, block_group, bh);
 499         /* ...but check for error just in case errors=continue. */
 500         return !buffer_verified(bh);
 501 }
 502
 503 struct buffer_head *
 504 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 505 {
 506         struct buffer_head *bh;
 507
 508         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 509         if (!bh)
 510                 return NULL;
 511         if (ext4_wait_block_bitmap(sb, block_group, bh)) {
 512                 put_bh(bh);
 513                 return NULL;
 514         }
 515         return bh;
 516 }
 517
 518 /**
 519  * ext4_has_free_clusters()
 520  * @sbi:        in-core super block structure.
 521  * @nclusters:  number of needed blocks
 522  * @flags:      flags from ext4_mb_new_blocks()
 523  *
 524  * Check if filesystem has nclusters free & available for allocation.
 525  * On success return 1, return 0 on failure.
 526  */
 527 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 528                                   s64 nclusters, unsigned int flags)
 529 {
 530         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 531         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 532         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 533
 534         free_clusters  = percpu_counter_read_positive(fcc);
 535         dirty_clusters = percpu_counter_read_positive(dcc);
 536         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 537
 538         /*
 539          * r_blocks_count should always be multiple of the cluster ratio so
 540          * we are safe to do a plane bit shift only.
 541          */
 542         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 543               resv_clusters;
 544
 545         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 546                                         EXT4_FREECLUSTERS_WATERMARK) {
 547                 free_clusters  = percpu_counter_sum_positive(fcc);
 548                 dirty_clusters = percpu_counter_sum_positive(dcc);
 549         }
 550         /* Check whether we have space after accounting for current
 551          * dirty clusters & root reserved clusters.
 552          */
 553         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 554                 return 1;
 555
 556         /* Hm, nope.  Are (enough) root reserved clusters available? */
 557         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 558             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 559             capable(CAP_SYS_RESOURCE) ||
 560             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 561
 562                 if (free_clusters >= (nclusters + dirty_clusters +
 563                                       resv_clusters))
 564                         return 1;
 565         }
 566         /* No free blocks. Let's see if we can dip into reserved pool */
 567         if (flags & EXT4_MB_USE_RESERVED) {
 568                 if (free_clusters >= (nclusters + dirty_clusters))
 569                         return 1;
 570         }
 571
 572         return 0;
 573 }
 574
 575 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 576                              s64 nclusters, unsigned int flags)
 577 {
 578         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 579                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 580                 return 0;
 581         } else
 582                 return -ENOSPC;
 583 }
 584
 585 /**
 586  * ext4_should_retry_alloc()
 587  * @sb:                 super block
 588  * @retries             number of attemps has been made
 589  *
 590  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 591  * it is profitable to retry the operation, this function will wait
 592  * for the current or committing transaction to complete, and then
 593  * return TRUE.
 594  *
 595  * if the total number of retries exceed three times, return FALSE.
 596  */
 597 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 598 {
 599         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 600             (*retries)++ > 3 ||
 601             !EXT4_SB(sb)->s_journal)
 602                 return 0;
 603
 604         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 605
 606         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 607 }
 608
 609 /*
 610  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 611  *
 612  * @handle:             handle to this transaction
 613  * @inode:              file inode
 614  * @goal:               given target block(filesystem wide)
 615  * @count:              pointer to total number of clusters needed
 616  * @errp:               error code
 617  *
 618  * Return 1st allocated block number on success, *count stores total account
 619  * error stores in errp pointer
 620  */
 621 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 622                                   ext4_fsblk_t goal, unsigned int flags,
 623                                   unsigned long *count, int *errp)
 624 {
 625         struct ext4_allocation_request ar;
 626         ext4_fsblk_t ret;
 627
 628         memset(&ar, 0, sizeof(ar));
 629         /* Fill with neighbour allocated blocks */
 630         ar.inode = inode;
 631         ar.goal = goal;
 632         ar.len = count ? *count : 1;
 633         ar.flags = flags;
 634
 635         ret = ext4_mb_new_blocks(handle, &ar, errp);
 636         if (count)
 637                 *count = ar.len;
 638         /*
 639          * Account for the allocated meta blocks.  We will never
 640          * fail EDQUOT for metdata, but we do account for it.
 641          */
 642         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 643                 dquot_alloc_block_nofail(inode,
 644                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 645         }
 646         return ret;
 647 }
 648
 649 /**
 650  * ext4_count_free_clusters() -- count filesystem free clusters
 651  * @sb:         superblock
 652  *
 653  * Adds up the number of free clusters from each block group.
 654  */
 655 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 656 {
 657         ext4_fsblk_t desc_count;
 658         struct ext4_group_desc *gdp;
 659         ext4_group_t i;
 660         ext4_group_t ngroups = ext4_get_groups_count(sb);
 661         struct ext4_group_info *grp;
 662 #ifdef EXT4FS_DEBUG
 663         struct ext4_super_block *es;
 664         ext4_fsblk_t bitmap_count;
 665         unsigned int x;
 666         struct buffer_head *bitmap_bh = NULL;
 667
 668         es = EXT4_SB(sb)->s_es;
 669         desc_count = 0;
 670         bitmap_count = 0;
 671         gdp = NULL;
 672
 673         for (i = 0; i < ngroups; i++) {
 674                 gdp = ext4_get_group_desc(sb, i, NULL);
 675                 if (!gdp)
 676                         continue;
 677                 grp = NULL;
 678                 if (EXT4_SB(sb)->s_group_info)
 679                         grp = ext4_get_group_info(sb, i);
 680                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 681                         desc_count += ext4_free_group_clusters(sb, gdp);
 682                 brelse(bitmap_bh);
 683                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 684                 if (bitmap_bh == NULL)
 685                         continue;
 686
 687                 x = ext4_count_free(bitmap_bh->b_data,
 688                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 689                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 690                         i, ext4_free_group_clusters(sb, gdp), x);
 691                 bitmap_count += x;
 692         }
 693         brelse(bitmap_bh);
 694         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 695                ", computed = %llu, %llu\n",
 696                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 697                desc_count, bitmap_count);
 698         return bitmap_count;
 699 #else
 700         desc_count = 0;
 701         for (i = 0; i < ngroups; i++) {
 702                 gdp = ext4_get_group_desc(sb, i, NULL);
 703                 if (!gdp)
 704                         continue;
 705                 grp = NULL;
 706                 if (EXT4_SB(sb)->s_group_info)
 707                         grp = ext4_get_group_info(sb, i);
 708                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 709                         desc_count += ext4_free_group_clusters(sb, gdp);
 710         }
 711
 712         return desc_count;
 713 #endif
 714 }
 715
 716 static inline int test_root(ext4_group_t a, int b)
 717 {
 718         while (1) {
 719                 if (a < b)
 720                         return 0;
 721                 if (a == b)
 722                         return 1;
 723                 if ((a % b) != 0)
 724                         return 0;
 725                 a = a / b;
 726         }
 727 }
 728
 729 /**
 730  *      ext4_bg_has_super - number of blocks used by the superblock in group
 731  *      @sb: superblock for filesystem
 732  *      @group: group number to check
 733  *
 734  *      Return the number of blocks used by the superblock (primary or backup)
 735  *      in this group.  Currently this will be only 0 or 1.
 736  */
 737 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 738 {
 739         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 740
 741         if (group == 0)
 742                 return 1;
 743         if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_SPARSE_SUPER2)) {
 744                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 745                     group == le32_to_cpu(es->s_backup_bgs[1]))
 746                         return 1;
 747                 return 0;
 748         }
 749         if ((group <= 1) || !EXT4_HAS_RO_COMPAT_FEATURE(sb,
 750                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER))
 751                 return 1;
 752         if (!(group & 1))
 753                 return 0;
 754         if (test_root(group, 3) || (test_root(group, 5)) ||
 755             test_root(group, 7))
 756                 return 1;
 757
 758         return 0;
 759 }
 760
 761 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 762                                         ext4_group_t group)
 763 {
 764         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 765         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 766         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 767
 768         if (group == first || group == first + 1 || group == last)
 769                 return 1;
 770         return 0;
 771 }
 772
 773 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 774                                         ext4_group_t group)
 775 {
 776         if (!ext4_bg_has_super(sb, group))
 777                 return 0;
 778
 779         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
 780                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 781         else
 782                 return EXT4_SB(sb)->s_gdb_count;
 783 }
 784
 785 /**
 786  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 787  *      @sb: superblock for filesystem
 788  *      @group: group number to check
 789  *
 790  *      Return the number of blocks used by the group descriptor table
 791  *      (primary or backup) in this group.  In the future there may be a
 792  *      different number of descriptor blocks in each group.
 793  */
 794 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 795 {
 796         unsigned long first_meta_bg =
 797                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 798         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 799
 800         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 801                         metagroup < first_meta_bg)
 802                 return ext4_bg_num_gdb_nometa(sb, group);
 803
 804         return ext4_bg_num_gdb_meta(sb,group);
 805
 806 }
 807
 808 /*
 809  * This function returns the number of file system metadata clusters at
 810  * the beginning of a block group, including the reserved gdt blocks.
 811  */
 812 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 813                                      ext4_group_t block_group)
 814 {
 815         struct ext4_sb_info *sbi = EXT4_SB(sb);
 816         unsigned num;
 817
 818         /* Check for superblock and gdt backups in this group */
 819         num = ext4_bg_has_super(sb, block_group);
 820
 821         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 822             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 823                           sbi->s_desc_per_block) {
 824                 if (num) {
 825                         num += ext4_bg_num_gdb(sb, block_group);
 826                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 827                 }
 828         } else { /* For META_BG_BLOCK_GROUPS */
 829                 num += ext4_bg_num_gdb(sb, block_group);
 830         }
 831         return EXT4_NUM_B2C(sbi, num);
 832 }
 833 /**
 834  *      ext4_inode_to_goal_block - return a hint for block allocation
 835  *      @inode: inode for block allocation
 836  *
 837  *      Return the ideal location to start allocating blocks for a
 838  *      newly created inode.
 839  */
 840 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 841 {
 842         struct ext4_inode_info *ei = EXT4_I(inode);
 843         ext4_group_t block_group;
 844         ext4_grpblk_t colour;
 845         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 846         ext4_fsblk_t bg_start;
 847         ext4_fsblk_t last_block;
 848
 849         block_group = ei->i_block_group;
 850         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 851                 /*
 852                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 853                  * block groups per flexgroup, reserve the first block
 854                  * group for directories and special files.  Regular
 855                  * files will start at the second block group.  This
 856                  * tends to speed up directory access and improves
 857                  * fsck times.
 858                  */
 859                 block_group &= ~(flex_size-1);
 860                 if (S_ISREG(inode->i_mode))
 861                         block_group++;
 862         }
 863         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 864         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 865
 866         /*
 867          * If we are doing delayed allocation, we don't need take
 868          * colour into account.
 869          */
 870         if (test_opt(inode->i_sb, DELALLOC))
 871                 return bg_start;
 872
 873         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 874                 colour = (current->pid % 16) *
 875                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 876         else
 877                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 878         return bg_start + colour;
 879 }
 880