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 -EFSBADCRC;
 207         }
 208         memset(bh->b_data, 0, sb->s_blocksize);
 209
 210         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 211         if ((bit_max >> 3) >= bh->b_size)
 212                 return -EFSCORRUPTED;
 213
 214         for (bit = 0; bit < bit_max; bit++)
 215                 ext4_set_bit(bit, bh->b_data);
 216
 217         start = ext4_group_first_block_no(sb, block_group);
 218
 219         if (ext4_has_feature_flex_bg(sb))
 220                 flex_bg = 1;
 221
 222         /* Set bits for block and inode bitmaps, and inode table */
 223         tmp = ext4_block_bitmap(sb, gdp);
 224         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 225                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 226
 227         tmp = ext4_inode_bitmap(sb, gdp);
 228         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 229                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 230
 231         tmp = ext4_inode_table(sb, gdp);
 232         for (; tmp < ext4_inode_table(sb, gdp) +
 233                      sbi->s_itb_per_group; tmp++) {
 234                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 235                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 236         }
 237
 238         /*
 239          * Also if the number of blocks within the group is less than
 240          * the blocksize * 8 ( which is the size of bitmap ), set rest
 241          * of the block bitmap to 1
 242          */
 243         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 244                              sb->s_blocksize * 8, bh->b_data);
 245         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 246         ext4_group_desc_csum_set(sb, block_group, gdp);
 247         return 0;
 248 }
 249
 250 /* Return the number of free blocks in a block group.  It is used when
 251  * the block bitmap is uninitialized, so we can't just count the bits
 252  * in the bitmap. */
 253 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 254                                        ext4_group_t block_group,
 255                                        struct ext4_group_desc *gdp)
 256 {
 257         return num_clusters_in_group(sb, block_group) -
 258                 ext4_num_overhead_clusters(sb, block_group, gdp);
 259 }
 260
 261 /*
 262  * The free blocks are managed by bitmaps.  A file system contains several
 263  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 264  * block for inodes, N blocks for the inode table and data blocks.
 265  *
 266  * The file system contains group descriptors which are located after the
 267  * super block.  Each descriptor contains the number of the bitmap block and
 268  * the free blocks count in the block.  The descriptors are loaded in memory
 269  * when a file system is mounted (see ext4_fill_super).
 270  */
 271
 272 /**
 273  * ext4_get_group_desc() -- load group descriptor from disk
 274  * @sb:                 super block
 275  * @block_group:        given block group
 276  * @bh:                 pointer to the buffer head to store the block
 277  *                      group descriptor
 278  */
 279 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 280                                              ext4_group_t block_group,
 281                                              struct buffer_head **bh)
 282 {
 283         unsigned int group_desc;
 284         unsigned int offset;
 285         ext4_group_t ngroups = ext4_get_groups_count(sb);
 286         struct ext4_group_desc *desc;
 287         struct ext4_sb_info *sbi = EXT4_SB(sb);
 288
 289         if (block_group >= ngroups) {
 290                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 291                            " groups_count = %u", block_group, ngroups);
 292
 293                 return NULL;
 294         }
 295
 296         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 297         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 298         if (!sbi->s_group_desc[group_desc]) {
 299                 ext4_error(sb, "Group descriptor not loaded - "
 300                            "block_group = %u, group_desc = %u, desc = %u",
 301                            block_group, group_desc, offset);
 302                 return NULL;
 303         }
 304
 305         desc = (struct ext4_group_desc *)(
 306                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 307                 offset * EXT4_DESC_SIZE(sb));
 308         if (bh)
 309                 *bh = sbi->s_group_desc[group_desc];
 310         return desc;
 311 }
 312
 313 /*
 314  * Return the block number which was discovered to be invalid, or 0 if
 315  * the block bitmap is valid.
 316  */
 317 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 318                                             struct ext4_group_desc *desc,
 319                                             ext4_group_t block_group,
 320                                             struct buffer_head *bh)
 321 {
 322         struct ext4_sb_info *sbi = EXT4_SB(sb);
 323         ext4_grpblk_t offset;
 324         ext4_grpblk_t next_zero_bit;
 325         ext4_fsblk_t blk;
 326         ext4_fsblk_t group_first_block;
 327
 328         if (ext4_has_feature_flex_bg(sb)) {
 329                 /* with FLEX_BG, the inode/block bitmaps and itable
 330                  * blocks may not be in the group at all
 331                  * so the bitmap validation will be skipped for those groups
 332                  * or it has to also read the block group where the bitmaps
 333                  * are located to verify they are set.
 334                  */
 335                 return 0;
 336         }
 337         group_first_block = ext4_group_first_block_no(sb, block_group);
 338
 339         /* check whether block bitmap block number is set */
 340         blk = ext4_block_bitmap(sb, desc);
 341         offset = blk - group_first_block;
 342         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 343                 /* bad block bitmap */
 344                 return blk;
 345
 346         /* check whether the inode bitmap block number is set */
 347         blk = ext4_inode_bitmap(sb, desc);
 348         offset = blk - group_first_block;
 349         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 350                 /* bad block bitmap */
 351                 return blk;
 352
 353         /* check whether the inode table block number is set */
 354         blk = ext4_inode_table(sb, desc);
 355         offset = blk - group_first_block;
 356         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 357                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
 358                         EXT4_B2C(sbi, offset));
 359         if (next_zero_bit <
 360             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
 361                 /* bad bitmap for inode tables */
 362                 return blk;
 363         return 0;
 364 }
 365
 366 static int ext4_validate_block_bitmap(struct super_block *sb,
 367                                       struct ext4_group_desc *desc,
 368                                       ext4_group_t block_group,
 369                                       struct buffer_head *bh)
 370 {
 371         ext4_fsblk_t    blk;
 372         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
 373         struct ext4_sb_info *sbi = EXT4_SB(sb);
 374
 375         if (buffer_verified(bh))
 376                 return 0;
 377         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 378                 return -EFSCORRUPTED;
 379
 380         ext4_lock_group(sb, block_group);
 381         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 382                         desc, bh))) {
 383                 ext4_unlock_group(sb, block_group);
 384                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 385                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 386                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 387                                            grp->bb_free);
 388                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 389                 return -EFSBADCRC;
 390         }
 391         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 392         if (unlikely(blk != 0)) {
 393                 ext4_unlock_group(sb, block_group);
 394                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 395                            block_group, blk);
 396                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 397                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 398                                            grp->bb_free);
 399                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 400                 return -EFSCORRUPTED;
 401         }
 402         set_buffer_verified(bh);
 403         ext4_unlock_group(sb, block_group);
 404         return 0;
 405 }
 406
 407 /**
 408  * ext4_read_block_bitmap_nowait()
 409  * @sb:                 super block
 410  * @block_group:        given block group
 411  *
 412  * Read the bitmap for a given block_group,and validate the
 413  * bits for block/inode/inode tables are set in the bitmaps
 414  *
 415  * Return buffer_head on success or NULL in case of failure.
 416  */
 417 struct buffer_head *
 418 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 419 {
 420         struct ext4_group_desc *desc;
 421         struct buffer_head *bh;
 422         ext4_fsblk_t bitmap_blk;
 423         int err;
 424
 425         desc = ext4_get_group_desc(sb, block_group, NULL);
 426         if (!desc)
 427                 return ERR_PTR(-EFSCORRUPTED);
 428         bitmap_blk = ext4_block_bitmap(sb, desc);
 429         bh = sb_getblk(sb, bitmap_blk);
 430         if (unlikely(!bh)) {
 431                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 432                            "block_group = %u, block_bitmap = %llu",
 433                            block_group, bitmap_blk);
 434                 return ERR_PTR(-ENOMEM);
 435         }
 436
 437         if (bitmap_uptodate(bh))
 438                 goto verify;
 439
 440         lock_buffer(bh);
 441         if (bitmap_uptodate(bh)) {
 442                 unlock_buffer(bh);
 443                 goto verify;
 444         }
 445         ext4_lock_group(sb, block_group);
 446         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 447                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 448                 set_bitmap_uptodate(bh);
 449                 set_buffer_uptodate(bh);
 450                 ext4_unlock_group(sb, block_group);
 451                 unlock_buffer(bh);
 452                 if (err) {
 453                         ext4_error(sb, "Failed to init block bitmap for group "
 454                                    "%u: %d", block_group, err);
 455                         goto out;
 456                 }
 457                 goto verify;
 458         }
 459         ext4_unlock_group(sb, block_group);
 460         if (buffer_uptodate(bh)) {
 461                 /*
 462                  * if not uninit if bh is uptodate,
 463                  * bitmap is also uptodate
 464                  */
 465                 set_bitmap_uptodate(bh);
 466                 unlock_buffer(bh);
 467                 goto verify;
 468         }
 469         /*
 470          * submit the buffer_head for reading
 471          */
 472         set_buffer_new(bh);
 473         trace_ext4_read_block_bitmap_load(sb, block_group);
 474         bh->b_end_io = ext4_end_bitmap_read;
 475         get_bh(bh);
 476         submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
 477         return bh;
 478 verify:
 479         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 480         if (err)
 481                 goto out;
 482         return bh;
 483 out:
 484         put_bh(bh);
 485         return ERR_PTR(err);
 486 }
 487
 488 /* Returns 0 on success, 1 on error */
 489 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 490                            struct buffer_head *bh)
 491 {
 492         struct ext4_group_desc *desc;
 493
 494         if (!buffer_new(bh))
 495                 return 0;
 496         desc = ext4_get_group_desc(sb, block_group, NULL);
 497         if (!desc)
 498                 return -EFSCORRUPTED;
 499         wait_on_buffer(bh);
 500         if (!buffer_uptodate(bh)) {
 501                 ext4_error(sb, "Cannot read block bitmap - "
 502                            "block_group = %u, block_bitmap = %llu",
 503                            block_group, (unsigned long long) bh->b_blocknr);
 504                 return -EIO;
 505         }
 506         clear_buffer_new(bh);
 507         /* Panic or remount fs read-only if block bitmap is invalid */
 508         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 509 }
 510
 511 struct buffer_head *
 512 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 513 {
 514         struct buffer_head *bh;
 515         int err;
 516
 517         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 518         if (IS_ERR(bh))
 519                 return bh;
 520         err = ext4_wait_block_bitmap(sb, block_group, bh);
 521         if (err) {
 522                 put_bh(bh);
 523                 return ERR_PTR(err);
 524         }
 525         return bh;
 526 }
 527
 528 /**
 529  * ext4_has_free_clusters()
 530  * @sbi:        in-core super block structure.
 531  * @nclusters:  number of needed blocks
 532  * @flags:      flags from ext4_mb_new_blocks()
 533  *
 534  * Check if filesystem has nclusters free & available for allocation.
 535  * On success return 1, return 0 on failure.
 536  */
 537 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 538                                   s64 nclusters, unsigned int flags)
 539 {
 540         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 541         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 542         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 543
 544         free_clusters  = percpu_counter_read_positive(fcc);
 545         dirty_clusters = percpu_counter_read_positive(dcc);
 546         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 547
 548         /*
 549          * r_blocks_count should always be multiple of the cluster ratio so
 550          * we are safe to do a plane bit shift only.
 551          */
 552         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 553               resv_clusters;
 554
 555         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 556                                         EXT4_FREECLUSTERS_WATERMARK) {
 557                 free_clusters  = percpu_counter_sum_positive(fcc);
 558                 dirty_clusters = percpu_counter_sum_positive(dcc);
 559         }
 560         /* Check whether we have space after accounting for current
 561          * dirty clusters & root reserved clusters.
 562          */
 563         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 564                 return 1;
 565
 566         /* Hm, nope.  Are (enough) root reserved clusters available? */
 567         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 568             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 569             capable(CAP_SYS_RESOURCE) ||
 570             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 571
 572                 if (free_clusters >= (nclusters + dirty_clusters +
 573                                       resv_clusters))
 574                         return 1;
 575         }
 576         /* No free blocks. Let's see if we can dip into reserved pool */
 577         if (flags & EXT4_MB_USE_RESERVED) {
 578                 if (free_clusters >= (nclusters + dirty_clusters))
 579                         return 1;
 580         }
 581
 582         return 0;
 583 }
 584
 585 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 586                              s64 nclusters, unsigned int flags)
 587 {
 588         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 589                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 590                 return 0;
 591         } else
 592                 return -ENOSPC;
 593 }
 594
 595 /**
 596  * ext4_should_retry_alloc()
 597  * @sb:                 super block
 598  * @retries             number of attemps has been made
 599  *
 600  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 601  * it is profitable to retry the operation, this function will wait
 602  * for the current or committing transaction to complete, and then
 603  * return TRUE.
 604  *
 605  * if the total number of retries exceed three times, return FALSE.
 606  */
 607 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 608 {
 609         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 610             (*retries)++ > 3 ||
 611             !EXT4_SB(sb)->s_journal)
 612                 return 0;
 613
 614         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 615
 616         smp_mb();
 617         if (EXT4_SB(sb)->s_mb_free_pending)
 618                 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 619         return 1;
 620 }
 621
 622 /*
 623  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 624  *
 625  * @handle:             handle to this transaction
 626  * @inode:              file inode
 627  * @goal:               given target block(filesystem wide)
 628  * @count:              pointer to total number of clusters needed
 629  * @errp:               error code
 630  *
 631  * Return 1st allocated block number on success, *count stores total account
 632  * error stores in errp pointer
 633  */
 634 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 635                                   ext4_fsblk_t goal, unsigned int flags,
 636                                   unsigned long *count, int *errp)
 637 {
 638         struct ext4_allocation_request ar;
 639         ext4_fsblk_t ret;
 640
 641         memset(&ar, 0, sizeof(ar));
 642         /* Fill with neighbour allocated blocks */
 643         ar.inode = inode;
 644         ar.goal = goal;
 645         ar.len = count ? *count : 1;
 646         ar.flags = flags;
 647
 648         ret = ext4_mb_new_blocks(handle, &ar, errp);
 649         if (count)
 650                 *count = ar.len;
 651         /*
 652          * Account for the allocated meta blocks.  We will never
 653          * fail EDQUOT for metdata, but we do account for it.
 654          */
 655         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 656                 dquot_alloc_block_nofail(inode,
 657                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 658         }
 659         return ret;
 660 }
 661
 662 /**
 663  * ext4_count_free_clusters() -- count filesystem free clusters
 664  * @sb:         superblock
 665  *
 666  * Adds up the number of free clusters from each block group.
 667  */
 668 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 669 {
 670         ext4_fsblk_t desc_count;
 671         struct ext4_group_desc *gdp;
 672         ext4_group_t i;
 673         ext4_group_t ngroups = ext4_get_groups_count(sb);
 674         struct ext4_group_info *grp;
 675 #ifdef EXT4FS_DEBUG
 676         struct ext4_super_block *es;
 677         ext4_fsblk_t bitmap_count;
 678         unsigned int x;
 679         struct buffer_head *bitmap_bh = NULL;
 680
 681         es = EXT4_SB(sb)->s_es;
 682         desc_count = 0;
 683         bitmap_count = 0;
 684         gdp = NULL;
 685
 686         for (i = 0; i < ngroups; i++) {
 687                 gdp = ext4_get_group_desc(sb, i, NULL);
 688                 if (!gdp)
 689                         continue;
 690                 grp = NULL;
 691                 if (EXT4_SB(sb)->s_group_info)
 692                         grp = ext4_get_group_info(sb, i);
 693                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 694                         desc_count += ext4_free_group_clusters(sb, gdp);
 695                 brelse(bitmap_bh);
 696                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 697                 if (IS_ERR(bitmap_bh)) {
 698                         bitmap_bh = NULL;
 699                         continue;
 700                 }
 701
 702                 x = ext4_count_free(bitmap_bh->b_data,
 703                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 704                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 705                         i, ext4_free_group_clusters(sb, gdp), x);
 706                 bitmap_count += x;
 707         }
 708         brelse(bitmap_bh);
 709         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 710                ", computed = %llu, %llu\n",
 711                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 712                desc_count, bitmap_count);
 713         return bitmap_count;
 714 #else
 715         desc_count = 0;
 716         for (i = 0; i < ngroups; i++) {
 717                 gdp = ext4_get_group_desc(sb, i, NULL);
 718                 if (!gdp)
 719                         continue;
 720                 grp = NULL;
 721                 if (EXT4_SB(sb)->s_group_info)
 722                         grp = ext4_get_group_info(sb, i);
 723                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 724                         desc_count += ext4_free_group_clusters(sb, gdp);
 725         }
 726
 727         return desc_count;
 728 #endif
 729 }
 730
 731 static inline int test_root(ext4_group_t a, int b)
 732 {
 733         while (1) {
 734                 if (a < b)
 735                         return 0;
 736                 if (a == b)
 737                         return 1;
 738                 if ((a % b) != 0)
 739                         return 0;
 740                 a = a / b;
 741         }
 742 }
 743
 744 /**
 745  *      ext4_bg_has_super - number of blocks used by the superblock in group
 746  *      @sb: superblock for filesystem
 747  *      @group: group number to check
 748  *
 749  *      Return the number of blocks used by the superblock (primary or backup)
 750  *      in this group.  Currently this will be only 0 or 1.
 751  */
 752 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 753 {
 754         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 755
 756         if (group == 0)
 757                 return 1;
 758         if (ext4_has_feature_sparse_super2(sb)) {
 759                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 760                     group == le32_to_cpu(es->s_backup_bgs[1]))
 761                         return 1;
 762                 return 0;
 763         }
 764         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 765                 return 1;
 766         if (!(group & 1))
 767                 return 0;
 768         if (test_root(group, 3) || (test_root(group, 5)) ||
 769             test_root(group, 7))
 770                 return 1;
 771
 772         return 0;
 773 }
 774
 775 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 776                                         ext4_group_t group)
 777 {
 778         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 779         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 780         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 781
 782         if (group == first || group == first + 1 || group == last)
 783                 return 1;
 784         return 0;
 785 }
 786
 787 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 788                                         ext4_group_t group)
 789 {
 790         if (!ext4_bg_has_super(sb, group))
 791                 return 0;
 792
 793         if (ext4_has_feature_meta_bg(sb))
 794                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 795         else
 796                 return EXT4_SB(sb)->s_gdb_count;
 797 }
 798
 799 /**
 800  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 801  *      @sb: superblock for filesystem
 802  *      @group: group number to check
 803  *
 804  *      Return the number of blocks used by the group descriptor table
 805  *      (primary or backup) in this group.  In the future there may be a
 806  *      different number of descriptor blocks in each group.
 807  */
 808 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 809 {
 810         unsigned long first_meta_bg =
 811                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 812         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 813
 814         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 815                 return ext4_bg_num_gdb_nometa(sb, group);
 816
 817         return ext4_bg_num_gdb_meta(sb,group);
 818
 819 }
 820
 821 /*
 822  * This function returns the number of file system metadata clusters at
 823  * the beginning of a block group, including the reserved gdt blocks.
 824  */
 825 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 826                                      ext4_group_t block_group)
 827 {
 828         struct ext4_sb_info *sbi = EXT4_SB(sb);
 829         unsigned num;
 830
 831         /* Check for superblock and gdt backups in this group */
 832         num = ext4_bg_has_super(sb, block_group);
 833
 834         if (!ext4_has_feature_meta_bg(sb) ||
 835             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 836                           sbi->s_desc_per_block) {
 837                 if (num) {
 838                         num += ext4_bg_num_gdb(sb, block_group);
 839                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 840                 }
 841         } else { /* For META_BG_BLOCK_GROUPS */
 842                 num += ext4_bg_num_gdb(sb, block_group);
 843         }
 844         return EXT4_NUM_B2C(sbi, num);
 845 }
 846 /**
 847  *      ext4_inode_to_goal_block - return a hint for block allocation
 848  *      @inode: inode for block allocation
 849  *
 850  *      Return the ideal location to start allocating blocks for a
 851  *      newly created inode.
 852  */
 853 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 854 {
 855         struct ext4_inode_info *ei = EXT4_I(inode);
 856         ext4_group_t block_group;
 857         ext4_grpblk_t colour;
 858         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 859         ext4_fsblk_t bg_start;
 860         ext4_fsblk_t last_block;
 861
 862         block_group = ei->i_block_group;
 863         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 864                 /*
 865                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 866                  * block groups per flexgroup, reserve the first block
 867                  * group for directories and special files.  Regular
 868                  * files will start at the second block group.  This
 869                  * tends to speed up directory access and improves
 870                  * fsck times.
 871                  */
 872                 block_group &= ~(flex_size-1);
 873                 if (S_ISREG(inode->i_mode))
 874                         block_group++;
 875         }
 876         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 877         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 878
 879         /*
 880          * If we are doing delayed allocation, we don't need take
 881          * colour into account.
 882          */
 883         if (test_opt(inode->i_sb, DELALLOC))
 884                 return bg_start;
 885
 886         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 887                 colour = (current->pid % 16) *
 888                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 889         else
 890                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 891         return bg_start + colour;
 892 }
 893