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                 ext4_error(sb, "Checksum bad for group %u", block_group);
 195                 grp = ext4_get_group_info(sb, block_group);
 196                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 197                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 198                                            grp->bb_free);
 199                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 200                 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
 201                         int count;
 202                         count = ext4_free_inodes_count(sb, gdp);
 203                         percpu_counter_sub(&sbi->s_freeinodes_counter,
 204                                            count);
 205                 }
 206                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 207                 return -EFSBADCRC;
 208         }
 209         memset(bh->b_data, 0, sb->s_blocksize);
 210
 211         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 212         for (bit = 0; bit < bit_max; bit++)
 213                 ext4_set_bit(bit, bh->b_data);
 214
 215         start = ext4_group_first_block_no(sb, block_group);
 216
 217         if (ext4_has_feature_flex_bg(sb))
 218                 flex_bg = 1;
 219
 220         /* Set bits for block and inode bitmaps, and inode table */
 221         tmp = ext4_block_bitmap(sb, gdp);
 222         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 223                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 224
 225         tmp = ext4_inode_bitmap(sb, gdp);
 226         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 227                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 228
 229         tmp = ext4_inode_table(sb, gdp);
 230         for (; tmp < ext4_inode_table(sb, gdp) +
 231                      sbi->s_itb_per_group; tmp++) {
 232                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 233                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 234         }
 235
 236         /*
 237          * Also if the number of blocks within the group is less than
 238          * the blocksize * 8 ( which is the size of bitmap ), set rest
 239          * of the block bitmap to 1
 240          */
 241         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 242                              sb->s_blocksize * 8, bh->b_data);
 243         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
 244         ext4_group_desc_csum_set(sb, block_group, gdp);
 245         return 0;
 246 }
 247
 248 /* Return the number of free blocks in a block group.  It is used when
 249  * the block bitmap is uninitialized, so we can't just count the bits
 250  * in the bitmap. */
 251 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 252                                        ext4_group_t block_group,
 253                                        struct ext4_group_desc *gdp)
 254 {
 255         return num_clusters_in_group(sb, block_group) -
 256                 ext4_num_overhead_clusters(sb, block_group, gdp);
 257 }
 258
 259 /*
 260  * The free blocks are managed by bitmaps.  A file system contains several
 261  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 262  * block for inodes, N blocks for the inode table and data blocks.
 263  *
 264  * The file system contains group descriptors which are located after the
 265  * super block.  Each descriptor contains the number of the bitmap block and
 266  * the free blocks count in the block.  The descriptors are loaded in memory
 267  * when a file system is mounted (see ext4_fill_super).
 268  */
 269
 270 /**
 271  * ext4_get_group_desc() -- load group descriptor from disk
 272  * @sb:                 super block
 273  * @block_group:        given block group
 274  * @bh:                 pointer to the buffer head to store the block
 275  *                      group descriptor
 276  */
 277 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 278                                              ext4_group_t block_group,
 279                                              struct buffer_head **bh)
 280 {
 281         unsigned int group_desc;
 282         unsigned int offset;
 283         ext4_group_t ngroups = ext4_get_groups_count(sb);
 284         struct ext4_group_desc *desc;
 285         struct ext4_sb_info *sbi = EXT4_SB(sb);
 286
 287         if (block_group >= ngroups) {
 288                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 289                            " groups_count = %u", block_group, ngroups);
 290
 291                 return NULL;
 292         }
 293
 294         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 295         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 296         if (!sbi->s_group_desc[group_desc]) {
 297                 ext4_error(sb, "Group descriptor not loaded - "
 298                            "block_group = %u, group_desc = %u, desc = %u",
 299                            block_group, group_desc, offset);
 300                 return NULL;
 301         }
 302
 303         desc = (struct ext4_group_desc *)(
 304                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 305                 offset * EXT4_DESC_SIZE(sb));
 306         if (bh)
 307                 *bh = sbi->s_group_desc[group_desc];
 308         return desc;
 309 }
 310
 311 /*
 312  * Return the block number which was discovered to be invalid, or 0 if
 313  * the block bitmap is valid.
 314  */
 315 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 316                                             struct ext4_group_desc *desc,
 317                                             ext4_group_t block_group,
 318                                             struct buffer_head *bh)
 319 {
 320         struct ext4_sb_info *sbi = EXT4_SB(sb);
 321         ext4_grpblk_t offset;
 322         ext4_grpblk_t next_zero_bit;
 323         ext4_fsblk_t blk;
 324         ext4_fsblk_t group_first_block;
 325
 326         if (ext4_has_feature_flex_bg(sb)) {
 327                 /* with FLEX_BG, the inode/block bitmaps and itable
 328                  * blocks may not be in the group at all
 329                  * so the bitmap validation will be skipped for those groups
 330                  * or it has to also read the block group where the bitmaps
 331                  * are located to verify they are set.
 332                  */
 333                 return 0;
 334         }
 335         group_first_block = ext4_group_first_block_no(sb, block_group);
 336
 337         /* check whether block bitmap block number is set */
 338         blk = ext4_block_bitmap(sb, desc);
 339         offset = blk - group_first_block;
 340         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 341                 /* bad block bitmap */
 342                 return blk;
 343
 344         /* check whether the inode bitmap block number is set */
 345         blk = ext4_inode_bitmap(sb, desc);
 346         offset = blk - group_first_block;
 347         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 348                 /* bad block bitmap */
 349                 return blk;
 350
 351         /* check whether the inode table block number is set */
 352         blk = ext4_inode_table(sb, desc);
 353         offset = blk - group_first_block;
 354         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 355                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
 356                         EXT4_B2C(sbi, offset));
 357         if (next_zero_bit <
 358             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
 359                 /* bad bitmap for inode tables */
 360                 return blk;
 361         return 0;
 362 }
 363
 364 static int ext4_validate_block_bitmap(struct super_block *sb,
 365                                       struct ext4_group_desc *desc,
 366                                       ext4_group_t block_group,
 367                                       struct buffer_head *bh)
 368 {
 369         ext4_fsblk_t    blk;
 370         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
 371         struct ext4_sb_info *sbi = EXT4_SB(sb);
 372
 373         if (buffer_verified(bh))
 374                 return 0;
 375         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 376                 return -EFSCORRUPTED;
 377
 378         ext4_lock_group(sb, block_group);
 379         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 380                         desc, bh))) {
 381                 ext4_unlock_group(sb, block_group);
 382                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 383                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 384                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 385                                            grp->bb_free);
 386                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 387                 return -EFSBADCRC;
 388         }
 389         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 390         if (unlikely(blk != 0)) {
 391                 ext4_unlock_group(sb, block_group);
 392                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 393                            block_group, blk);
 394                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 395                         percpu_counter_sub(&sbi->s_freeclusters_counter,
 396                                            grp->bb_free);
 397                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 398                 return -EFSCORRUPTED;
 399         }
 400         set_buffer_verified(bh);
 401         ext4_unlock_group(sb, block_group);
 402         return 0;
 403 }
 404
 405 /**
 406  * ext4_read_block_bitmap_nowait()
 407  * @sb:                 super block
 408  * @block_group:        given block group
 409  *
 410  * Read the bitmap for a given block_group,and validate the
 411  * bits for block/inode/inode tables are set in the bitmaps
 412  *
 413  * Return buffer_head on success or NULL in case of failure.
 414  */
 415 struct buffer_head *
 416 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 417 {
 418         struct ext4_group_desc *desc;
 419         struct buffer_head *bh;
 420         ext4_fsblk_t bitmap_blk;
 421         int err;
 422
 423         desc = ext4_get_group_desc(sb, block_group, NULL);
 424         if (!desc)
 425                 return ERR_PTR(-EFSCORRUPTED);
 426         bitmap_blk = ext4_block_bitmap(sb, desc);
 427         bh = sb_getblk(sb, bitmap_blk);
 428         if (unlikely(!bh)) {
 429                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 430                            "block_group = %u, block_bitmap = %llu",
 431                            block_group, bitmap_blk);
 432                 return ERR_PTR(-ENOMEM);
 433         }
 434
 435         if (bitmap_uptodate(bh))
 436                 goto verify;
 437
 438         lock_buffer(bh);
 439         if (bitmap_uptodate(bh)) {
 440                 unlock_buffer(bh);
 441                 goto verify;
 442         }
 443         ext4_lock_group(sb, block_group);
 444         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 445
 446                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 447                 set_bitmap_uptodate(bh);
 448                 set_buffer_uptodate(bh);
 449                 ext4_unlock_group(sb, block_group);
 450                 unlock_buffer(bh);
 451                 if (err)
 452                         goto out;
 453                 goto verify;
 454         }
 455         ext4_unlock_group(sb, block_group);
 456         if (buffer_uptodate(bh)) {
 457                 /*
 458                  * if not uninit if bh is uptodate,
 459                  * bitmap is also uptodate
 460                  */
 461                 set_bitmap_uptodate(bh);
 462                 unlock_buffer(bh);
 463                 goto verify;
 464         }
 465         /*
 466          * submit the buffer_head for reading
 467          */
 468         set_buffer_new(bh);
 469         trace_ext4_read_block_bitmap_load(sb, block_group);
 470         bh->b_end_io = ext4_end_bitmap_read;
 471         get_bh(bh);
 472         submit_bh(READ | REQ_META | REQ_PRIO, bh);
 473         return bh;
 474 verify:
 475         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 476         if (err)
 477                 goto out;
 478         return bh;
 479 out:
 480         put_bh(bh);
 481         return ERR_PTR(err);
 482 }
 483
 484 /* Returns 0 on success, 1 on error */
 485 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 486                            struct buffer_head *bh)
 487 {
 488         struct ext4_group_desc *desc;
 489
 490         if (!buffer_new(bh))
 491                 return 0;
 492         desc = ext4_get_group_desc(sb, block_group, NULL);
 493         if (!desc)
 494                 return -EFSCORRUPTED;
 495         wait_on_buffer(bh);
 496         if (!buffer_uptodate(bh)) {
 497                 ext4_error(sb, "Cannot read block bitmap - "
 498                            "block_group = %u, block_bitmap = %llu",
 499                            block_group, (unsigned long long) bh->b_blocknr);
 500                 return -EIO;
 501         }
 502         clear_buffer_new(bh);
 503         /* Panic or remount fs read-only if block bitmap is invalid */
 504         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 505 }
 506
 507 struct buffer_head *
 508 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 509 {
 510         struct buffer_head *bh;
 511         int err;
 512
 513         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 514         if (IS_ERR(bh))
 515                 return bh;
 516         err = ext4_wait_block_bitmap(sb, block_group, bh);
 517         if (err) {
 518                 put_bh(bh);
 519                 return ERR_PTR(err);
 520         }
 521         return bh;
 522 }
 523
 524 /**
 525  * ext4_has_free_clusters()
 526  * @sbi:        in-core super block structure.
 527  * @nclusters:  number of needed blocks
 528  * @flags:      flags from ext4_mb_new_blocks()
 529  *
 530  * Check if filesystem has nclusters free & available for allocation.
 531  * On success return 1, return 0 on failure.
 532  */
 533 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 534                                   s64 nclusters, unsigned int flags)
 535 {
 536         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 537         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 538         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 539
 540         free_clusters  = percpu_counter_read_positive(fcc);
 541         dirty_clusters = percpu_counter_read_positive(dcc);
 542         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 543
 544         /*
 545          * r_blocks_count should always be multiple of the cluster ratio so
 546          * we are safe to do a plane bit shift only.
 547          */
 548         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 549               resv_clusters;
 550
 551         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 552                                         EXT4_FREECLUSTERS_WATERMARK) {
 553                 free_clusters  = percpu_counter_sum_positive(fcc);
 554                 dirty_clusters = percpu_counter_sum_positive(dcc);
 555         }
 556         /* Check whether we have space after accounting for current
 557          * dirty clusters & root reserved clusters.
 558          */
 559         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 560                 return 1;
 561
 562         /* Hm, nope.  Are (enough) root reserved clusters available? */
 563         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 564             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 565             capable(CAP_SYS_RESOURCE) ||
 566             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 567
 568                 if (free_clusters >= (nclusters + dirty_clusters +
 569                                       resv_clusters))
 570                         return 1;
 571         }
 572         /* No free blocks. Let's see if we can dip into reserved pool */
 573         if (flags & EXT4_MB_USE_RESERVED) {
 574                 if (free_clusters >= (nclusters + dirty_clusters))
 575                         return 1;
 576         }
 577
 578         return 0;
 579 }
 580
 581 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 582                              s64 nclusters, unsigned int flags)
 583 {
 584         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 585                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 586                 return 0;
 587         } else
 588                 return -ENOSPC;
 589 }
 590
 591 /**
 592  * ext4_should_retry_alloc()
 593  * @sb:                 super block
 594  * @retries             number of attemps has been made
 595  *
 596  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 597  * it is profitable to retry the operation, this function will wait
 598  * for the current or committing transaction to complete, and then
 599  * return TRUE.
 600  *
 601  * if the total number of retries exceed three times, return FALSE.
 602  */
 603 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 604 {
 605         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 606             (*retries)++ > 3 ||
 607             !EXT4_SB(sb)->s_journal)
 608                 return 0;
 609
 610         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 611
 612         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 613 }
 614
 615 /*
 616  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 617  *
 618  * @handle:             handle to this transaction
 619  * @inode:              file inode
 620  * @goal:               given target block(filesystem wide)
 621  * @count:              pointer to total number of clusters needed
 622  * @errp:               error code
 623  *
 624  * Return 1st allocated block number on success, *count stores total account
 625  * error stores in errp pointer
 626  */
 627 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 628                                   ext4_fsblk_t goal, unsigned int flags,
 629                                   unsigned long *count, int *errp)
 630 {
 631         struct ext4_allocation_request ar;
 632         ext4_fsblk_t ret;
 633
 634         memset(&ar, 0, sizeof(ar));
 635         /* Fill with neighbour allocated blocks */
 636         ar.inode = inode;
 637         ar.goal = goal;
 638         ar.len = count ? *count : 1;
 639         ar.flags = flags;
 640
 641         ret = ext4_mb_new_blocks(handle, &ar, errp);
 642         if (count)
 643                 *count = ar.len;
 644         /*
 645          * Account for the allocated meta blocks.  We will never
 646          * fail EDQUOT for metdata, but we do account for it.
 647          */
 648         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 649                 dquot_alloc_block_nofail(inode,
 650                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 651         }
 652         return ret;
 653 }
 654
 655 /**
 656  * ext4_count_free_clusters() -- count filesystem free clusters
 657  * @sb:         superblock
 658  *
 659  * Adds up the number of free clusters from each block group.
 660  */
 661 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 662 {
 663         ext4_fsblk_t desc_count;
 664         struct ext4_group_desc *gdp;
 665         ext4_group_t i;
 666         ext4_group_t ngroups = ext4_get_groups_count(sb);
 667         struct ext4_group_info *grp;
 668 #ifdef EXT4FS_DEBUG
 669         struct ext4_super_block *es;
 670         ext4_fsblk_t bitmap_count;
 671         unsigned int x;
 672         struct buffer_head *bitmap_bh = NULL;
 673
 674         es = EXT4_SB(sb)->s_es;
 675         desc_count = 0;
 676         bitmap_count = 0;
 677         gdp = NULL;
 678
 679         for (i = 0; i < ngroups; i++) {
 680                 gdp = ext4_get_group_desc(sb, i, NULL);
 681                 if (!gdp)
 682                         continue;
 683                 grp = NULL;
 684                 if (EXT4_SB(sb)->s_group_info)
 685                         grp = ext4_get_group_info(sb, i);
 686                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 687                         desc_count += ext4_free_group_clusters(sb, gdp);
 688                 brelse(bitmap_bh);
 689                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 690                 if (IS_ERR(bitmap_bh)) {
 691                         bitmap_bh = NULL;
 692                         continue;
 693                 }
 694
 695                 x = ext4_count_free(bitmap_bh->b_data,
 696                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 697                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 698                         i, ext4_free_group_clusters(sb, gdp), x);
 699                 bitmap_count += x;
 700         }
 701         brelse(bitmap_bh);
 702         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 703                ", computed = %llu, %llu\n",
 704                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 705                desc_count, bitmap_count);
 706         return bitmap_count;
 707 #else
 708         desc_count = 0;
 709         for (i = 0; i < ngroups; i++) {
 710                 gdp = ext4_get_group_desc(sb, i, NULL);
 711                 if (!gdp)
 712                         continue;
 713                 grp = NULL;
 714                 if (EXT4_SB(sb)->s_group_info)
 715                         grp = ext4_get_group_info(sb, i);
 716                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 717                         desc_count += ext4_free_group_clusters(sb, gdp);
 718         }
 719
 720         return desc_count;
 721 #endif
 722 }
 723
 724 static inline int test_root(ext4_group_t a, int b)
 725 {
 726         while (1) {
 727                 if (a < b)
 728                         return 0;
 729                 if (a == b)
 730                         return 1;
 731                 if ((a % b) != 0)
 732                         return 0;
 733                 a = a / b;
 734         }
 735 }
 736
 737 /**
 738  *      ext4_bg_has_super - number of blocks used by the superblock in group
 739  *      @sb: superblock for filesystem
 740  *      @group: group number to check
 741  *
 742  *      Return the number of blocks used by the superblock (primary or backup)
 743  *      in this group.  Currently this will be only 0 or 1.
 744  */
 745 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 746 {
 747         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 748
 749         if (group == 0)
 750                 return 1;
 751         if (ext4_has_feature_sparse_super2(sb)) {
 752                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 753                     group == le32_to_cpu(es->s_backup_bgs[1]))
 754                         return 1;
 755                 return 0;
 756         }
 757         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 758                 return 1;
 759         if (!(group & 1))
 760                 return 0;
 761         if (test_root(group, 3) || (test_root(group, 5)) ||
 762             test_root(group, 7))
 763                 return 1;
 764
 765         return 0;
 766 }
 767
 768 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 769                                         ext4_group_t group)
 770 {
 771         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 772         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 773         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 774
 775         if (group == first || group == first + 1 || group == last)
 776                 return 1;
 777         return 0;
 778 }
 779
 780 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 781                                         ext4_group_t group)
 782 {
 783         if (!ext4_bg_has_super(sb, group))
 784                 return 0;
 785
 786         if (ext4_has_feature_meta_bg(sb))
 787                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 788         else
 789                 return EXT4_SB(sb)->s_gdb_count;
 790 }
 791
 792 /**
 793  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 794  *      @sb: superblock for filesystem
 795  *      @group: group number to check
 796  *
 797  *      Return the number of blocks used by the group descriptor table
 798  *      (primary or backup) in this group.  In the future there may be a
 799  *      different number of descriptor blocks in each group.
 800  */
 801 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 802 {
 803         unsigned long first_meta_bg =
 804                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 805         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 806
 807         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 808                 return ext4_bg_num_gdb_nometa(sb, group);
 809
 810         return ext4_bg_num_gdb_meta(sb,group);
 811
 812 }
 813
 814 /*
 815  * This function returns the number of file system metadata clusters at
 816  * the beginning of a block group, including the reserved gdt blocks.
 817  */
 818 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 819                                      ext4_group_t block_group)
 820 {
 821         struct ext4_sb_info *sbi = EXT4_SB(sb);
 822         unsigned num;
 823
 824         /* Check for superblock and gdt backups in this group */
 825         num = ext4_bg_has_super(sb, block_group);
 826
 827         if (!ext4_has_feature_meta_bg(sb) ||
 828             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 829                           sbi->s_desc_per_block) {
 830                 if (num) {
 831                         num += ext4_bg_num_gdb(sb, block_group);
 832                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 833                 }
 834         } else { /* For META_BG_BLOCK_GROUPS */
 835                 num += ext4_bg_num_gdb(sb, block_group);
 836         }
 837         return EXT4_NUM_B2C(sbi, num);
 838 }
 839 /**
 840  *      ext4_inode_to_goal_block - return a hint for block allocation
 841  *      @inode: inode for block allocation
 842  *
 843  *      Return the ideal location to start allocating blocks for a
 844  *      newly created inode.
 845  */
 846 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 847 {
 848         struct ext4_inode_info *ei = EXT4_I(inode);
 849         ext4_group_t block_group;
 850         ext4_grpblk_t colour;
 851         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 852         ext4_fsblk_t bg_start;
 853         ext4_fsblk_t last_block;
 854
 855         block_group = ei->i_block_group;
 856         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 857                 /*
 858                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 859                  * block groups per flexgroup, reserve the first block
 860                  * group for directories and special files.  Regular
 861                  * files will start at the second block group.  This
 862                  * tends to speed up directory access and improves
 863                  * fsck times.
 864                  */
 865                 block_group &= ~(flex_size-1);
 866                 if (S_ISREG(inode->i_mode))
 867                         block_group++;
 868         }
 869         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 870         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 871
 872         /*
 873          * If we are doing delayed allocation, we don't need take
 874          * colour into account.
 875          */
 876         if (test_opt(inode->i_sb, DELALLOC))
 877                 return bg_start;
 878
 879         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 880                 colour = (current->pid % 16) *
 881                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 882         else
 883                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 884         return bg_start + colour;
 885 }
 886