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         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_feature_flex_bg(sb))
 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_feature_flex_bg(sb)) {
 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 int 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 0;
 374         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 375                 return -EFSCORRUPTED;
 376
 377         ext4_lock_group(sb, block_group);
 378         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 379                         desc, bh))) {
 380                 ext4_unlock_group(sb, block_group);
 381                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 382                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 383                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 384                                            grp->bb_free);
 385                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 386                 return -EFSBADCRC;
 387         }
 388         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 389         if (unlikely(blk != 0)) {
 390                 ext4_unlock_group(sb, block_group);
 391                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 392                            block_group, blk);
 393                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 394                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 395                                            grp->bb_free);
 396                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 397                 return -EFSCORRUPTED;
 398         }
 399         set_buffer_verified(bh);
 400         ext4_unlock_group(sb, block_group);
 401         return 0;
 402 }
 403
 404 /**
 405  * ext4_read_block_bitmap_nowait()
 406  * @sb:                 super block
 407  * @block_group:        given block group
 408  *
 409  * Read the bitmap for a given block_group,and validate the
 410  * bits for block/inode/inode tables are set in the bitmaps
 411  *
 412  * Return buffer_head on success or NULL in case of failure.
 413  */
 414 struct buffer_head *
 415 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 416 {
 417         struct ext4_group_desc *desc;
 418         struct buffer_head *bh;
 419         ext4_fsblk_t bitmap_blk;
 420         int err;
 421
 422         desc = ext4_get_group_desc(sb, block_group, NULL);
 423         if (!desc)
 424                 return ERR_PTR(-EFSCORRUPTED);
 425         bitmap_blk = ext4_block_bitmap(sb, desc);
 426         bh = sb_getblk(sb, bitmap_blk);
 427         if (unlikely(!bh)) {
 428                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 429                            "block_group = %u, block_bitmap = %llu",
 430                            block_group, bitmap_blk);
 431                 return ERR_PTR(-ENOMEM);
 432         }
 433
 434         if (bitmap_uptodate(bh))
 435                 goto verify;
 436
 437         lock_buffer(bh);
 438         if (bitmap_uptodate(bh)) {
 439                 unlock_buffer(bh);
 440                 goto verify;
 441         }
 442         ext4_lock_group(sb, block_group);
 443         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 444                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 445                 set_bitmap_uptodate(bh);
 446                 set_buffer_uptodate(bh);
 447                 ext4_unlock_group(sb, block_group);
 448                 unlock_buffer(bh);
 449                 if (err) {
 450                         ext4_error(sb, "Failed to init block bitmap for group "
 451                                    "%u: %d", block_group, err);
 452                         goto out;
 453                 }
 454                 goto verify;
 455         }
 456         ext4_unlock_group(sb, block_group);
 457         if (buffer_uptodate(bh)) {
 458                 /*
 459                  * if not uninit if bh is uptodate,
 460                  * bitmap is also uptodate
 461                  */
 462                 set_bitmap_uptodate(bh);
 463                 unlock_buffer(bh);
 464                 goto verify;
 465         }
 466         /*
 467          * submit the buffer_head for reading
 468          */
 469         set_buffer_new(bh);
 470         trace_ext4_read_block_bitmap_load(sb, block_group);
 471         bh->b_end_io = ext4_end_bitmap_read;
 472         get_bh(bh);
 473         submit_bh(READ | REQ_META | REQ_PRIO, bh);
 474         return bh;
 475 verify:
 476         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 477         if (err)
 478                 goto out;
 479         return bh;
 480 out:
 481         put_bh(bh);
 482         return ERR_PTR(err);
 483 }
 484
 485 /* Returns 0 on success, 1 on error */
 486 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 487                            struct buffer_head *bh)
 488 {
 489         struct ext4_group_desc *desc;
 490
 491         if (!buffer_new(bh))
 492                 return 0;
 493         desc = ext4_get_group_desc(sb, block_group, NULL);
 494         if (!desc)
 495                 return -EFSCORRUPTED;
 496         wait_on_buffer(bh);
 497         if (!buffer_uptodate(bh)) {
 498                 ext4_error(sb, "Cannot read block bitmap - "
 499                            "block_group = %u, block_bitmap = %llu",
 500                            block_group, (unsigned long long) bh->b_blocknr);
 501                 return -EIO;
 502         }
 503         clear_buffer_new(bh);
 504         /* Panic or remount fs read-only if block bitmap is invalid */
 505         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 506 }
 507
 508 struct buffer_head *
 509 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 510 {
 511         struct buffer_head *bh;
 512         int err;
 513
 514         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 515         if (IS_ERR(bh))
 516                 return bh;
 517         err = ext4_wait_block_bitmap(sb, block_group, bh);
 518         if (err) {
 519                 put_bh(bh);
 520                 return ERR_PTR(err);
 521         }
 522         return bh;
 523 }
 524
 525 /**
 526  * ext4_has_free_clusters()
 527  * @sbi:        in-core super block structure.
 528  * @nclusters:  number of needed blocks
 529  * @flags:      flags from ext4_mb_new_blocks()
 530  *
 531  * Check if filesystem has nclusters free & available for allocation.
 532  * On success return 1, return 0 on failure.
 533  */
 534 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 535                                   s64 nclusters, unsigned int flags)
 536 {
 537         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 538         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 539         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 540
 541         free_clusters  = percpu_counter_read_positive(fcc);
 542         dirty_clusters = percpu_counter_read_positive(dcc);
 543         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 544
 545         /*
 546          * r_blocks_count should always be multiple of the cluster ratio so
 547          * we are safe to do a plane bit shift only.
 548          */
 549         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 550               resv_clusters;
 551
 552         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 553                                         EXT4_FREECLUSTERS_WATERMARK) {
 554                 free_clusters  = percpu_counter_sum_positive(fcc);
 555                 dirty_clusters = percpu_counter_sum_positive(dcc);
 556         }
 557         /* Check whether we have space after accounting for current
 558          * dirty clusters & root reserved clusters.
 559          */
 560         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 561                 return 1;
 562
 563         /* Hm, nope.  Are (enough) root reserved clusters available? */
 564         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 565             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 566             capable(CAP_SYS_RESOURCE) ||
 567             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 568
 569                 if (free_clusters >= (nclusters + dirty_clusters +
 570                                       resv_clusters))
 571                         return 1;
 572         }
 573         /* No free blocks. Let's see if we can dip into reserved pool */
 574         if (flags & EXT4_MB_USE_RESERVED) {
 575                 if (free_clusters >= (nclusters + dirty_clusters))
 576                         return 1;
 577         }
 578
 579         return 0;
 580 }
 581
 582 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 583                              s64 nclusters, unsigned int flags)
 584 {
 585         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 586                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 587                 return 0;
 588         } else
 589                 return -ENOSPC;
 590 }
 591
 592 /**
 593  * ext4_should_retry_alloc()
 594  * @sb:                 super block
 595  * @retries             number of attemps has been made
 596  *
 597  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 598  * it is profitable to retry the operation, this function will wait
 599  * for the current or committing transaction to complete, and then
 600  * return TRUE.
 601  *
 602  * if the total number of retries exceed three times, return FALSE.
 603  */
 604 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 605 {
 606         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 607             (*retries)++ > 3 ||
 608             !EXT4_SB(sb)->s_journal)
 609                 return 0;
 610
 611         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 612
 613         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 614 }
 615
 616 /*
 617  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 618  *
 619  * @handle:             handle to this transaction
 620  * @inode:              file inode
 621  * @goal:               given target block(filesystem wide)
 622  * @count:              pointer to total number of clusters needed
 623  * @errp:               error code
 624  *
 625  * Return 1st allocated block number on success, *count stores total account
 626  * error stores in errp pointer
 627  */
 628 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 629                                   ext4_fsblk_t goal, unsigned int flags,
 630                                   unsigned long *count, int *errp)
 631 {
 632         struct ext4_allocation_request ar;
 633         ext4_fsblk_t ret;
 634
 635         memset(&ar, 0, sizeof(ar));
 636         /* Fill with neighbour allocated blocks */
 637         ar.inode = inode;
 638         ar.goal = goal;
 639         ar.len = count ? *count : 1;
 640         ar.flags = flags;
 641
 642         ret = ext4_mb_new_blocks(handle, &ar, errp);
 643         if (count)
 644                 *count = ar.len;
 645         /*
 646          * Account for the allocated meta blocks.  We will never
 647          * fail EDQUOT for metdata, but we do account for it.
 648          */
 649         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 650                 dquot_alloc_block_nofail(inode,
 651                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 652         }
 653         return ret;
 654 }
 655
 656 /**
 657  * ext4_count_free_clusters() -- count filesystem free clusters
 658  * @sb:         superblock
 659  *
 660  * Adds up the number of free clusters from each block group.
 661  */
 662 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 663 {
 664         ext4_fsblk_t desc_count;
 665         struct ext4_group_desc *gdp;
 666         ext4_group_t i;
 667         ext4_group_t ngroups = ext4_get_groups_count(sb);
 668         struct ext4_group_info *grp;
 669 #ifdef EXT4FS_DEBUG
 670         struct ext4_super_block *es;
 671         ext4_fsblk_t bitmap_count;
 672         unsigned int x;
 673         struct buffer_head *bitmap_bh = NULL;
 674
 675         es = EXT4_SB(sb)->s_es;
 676         desc_count = 0;
 677         bitmap_count = 0;
 678         gdp = NULL;
 679
 680         for (i = 0; i < ngroups; i++) {
 681                 gdp = ext4_get_group_desc(sb, i, NULL);
 682                 if (!gdp)
 683                         continue;
 684                 grp = NULL;
 685                 if (EXT4_SB(sb)->s_group_info)
 686                         grp = ext4_get_group_info(sb, i);
 687                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 688                         desc_count += ext4_free_group_clusters(sb, gdp);
 689                 brelse(bitmap_bh);
 690                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 691                 if (IS_ERR(bitmap_bh)) {
 692                         bitmap_bh = NULL;
 693                         continue;
 694                 }
 695
 696                 x = ext4_count_free(bitmap_bh->b_data,
 697                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 698                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 699                         i, ext4_free_group_clusters(sb, gdp), x);
 700                 bitmap_count += x;
 701         }
 702         brelse(bitmap_bh);
 703         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 704                ", computed = %llu, %llu\n",
 705                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 706                desc_count, bitmap_count);
 707         return bitmap_count;
 708 #else
 709         desc_count = 0;
 710         for (i = 0; i < ngroups; i++) {
 711                 gdp = ext4_get_group_desc(sb, i, NULL);
 712                 if (!gdp)
 713                         continue;
 714                 grp = NULL;
 715                 if (EXT4_SB(sb)->s_group_info)
 716                         grp = ext4_get_group_info(sb, i);
 717                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 718                         desc_count += ext4_free_group_clusters(sb, gdp);
 719         }
 720
 721         return desc_count;
 722 #endif
 723 }
 724
 725 static inline int test_root(ext4_group_t a, int b)
 726 {
 727         while (1) {
 728                 if (a < b)
 729                         return 0;
 730                 if (a == b)
 731                         return 1;
 732                 if ((a % b) != 0)
 733                         return 0;
 734                 a = a / b;
 735         }
 736 }
 737
 738 /**
 739  *      ext4_bg_has_super - number of blocks used by the superblock in group
 740  *      @sb: superblock for filesystem
 741  *      @group: group number to check
 742  *
 743  *      Return the number of blocks used by the superblock (primary or backup)
 744  *      in this group.  Currently this will be only 0 or 1.
 745  */
 746 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 747 {
 748         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 749
 750         if (group == 0)
 751                 return 1;
 752         if (ext4_has_feature_sparse_super2(sb)) {
 753                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 754                     group == le32_to_cpu(es->s_backup_bgs[1]))
 755                         return 1;
 756                 return 0;
 757         }
 758         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 759                 return 1;
 760         if (!(group & 1))
 761                 return 0;
 762         if (test_root(group, 3) || (test_root(group, 5)) ||
 763             test_root(group, 7))
 764                 return 1;
 765
 766         return 0;
 767 }
 768
 769 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 770                                         ext4_group_t group)
 771 {
 772         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 773         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 774         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 775
 776         if (group == first || group == first + 1 || group == last)
 777                 return 1;
 778         return 0;
 779 }
 780
 781 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 782                                         ext4_group_t group)
 783 {
 784         if (!ext4_bg_has_super(sb, group))
 785                 return 0;
 786
 787         if (ext4_has_feature_meta_bg(sb))
 788                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 789         else
 790                 return EXT4_SB(sb)->s_gdb_count;
 791 }
 792
 793 /**
 794  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 795  *      @sb: superblock for filesystem
 796  *      @group: group number to check
 797  *
 798  *      Return the number of blocks used by the group descriptor table
 799  *      (primary or backup) in this group.  In the future there may be a
 800  *      different number of descriptor blocks in each group.
 801  */
 802 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 803 {
 804         unsigned long first_meta_bg =
 805                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 806         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 807
 808         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 809                 return ext4_bg_num_gdb_nometa(sb, group);
 810
 811         return ext4_bg_num_gdb_meta(sb,group);
 812
 813 }
 814
 815 /*
 816  * This function returns the number of file system metadata clusters at
 817  * the beginning of a block group, including the reserved gdt blocks.
 818  */
 819 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 820                                      ext4_group_t block_group)
 821 {
 822         struct ext4_sb_info *sbi = EXT4_SB(sb);
 823         unsigned num;
 824
 825         /* Check for superblock and gdt backups in this group */
 826         num = ext4_bg_has_super(sb, block_group);
 827
 828         if (!ext4_has_feature_meta_bg(sb) ||
 829             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 830                           sbi->s_desc_per_block) {
 831                 if (num) {
 832                         num += ext4_bg_num_gdb(sb, block_group);
 833                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 834                 }
 835         } else { /* For META_BG_BLOCK_GROUPS */
 836                 num += ext4_bg_num_gdb(sb, block_group);
 837         }
 838         return EXT4_NUM_B2C(sbi, num);
 839 }
 840 /**
 841  *      ext4_inode_to_goal_block - return a hint for block allocation
 842  *      @inode: inode for block allocation
 843  *
 844  *      Return the ideal location to start allocating blocks for a
 845  *      newly created inode.
 846  */
 847 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 848 {
 849         struct ext4_inode_info *ei = EXT4_I(inode);
 850         ext4_group_t block_group;
 851         ext4_grpblk_t colour;
 852         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 853         ext4_fsblk_t bg_start;
 854         ext4_fsblk_t last_block;
 855
 856         block_group = ei->i_block_group;
 857         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 858                 /*
 859                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 860                  * block groups per flexgroup, reserve the first block
 861                  * group for directories and special files.  Regular
 862                  * files will start at the second block group.  This
 863                  * tends to speed up directory access and improves
 864                  * fsck times.
 865                  */
 866                 block_group &= ~(flex_size-1);
 867                 if (S_ISREG(inode->i_mode))
 868                         block_group++;
 869         }
 870         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 871         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 872
 873         /*
 874          * If we are doing delayed allocation, we don't need take
 875          * colour into account.
 876          */
 877         if (test_opt(inode->i_sb, DELALLOC))
 878                 return bg_start;
 879
 880         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 881                 colour = (current->pid % 16) *
 882                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 883         else
 884                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 885         return bg_start + colour;
 886 }
 887