fs/ext4/balloc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/balloc.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card ([email protected])
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  Enhanced block allocation by Stephen Tweedie ([email protected]), 1993
  11  *  Big-endian to little-endian byte-swapping/bitmaps by
  12  *        David S. Miller ([email protected]), 1995
  13  */
  14
  15 #include <linux/time.h>
  16 #include <linux/capability.h>
  17 #include <linux/fs.h>
  18 #include <linux/quotaops.h>
  19 #include <linux/buffer_head.h>
  20 #include "ext4.h"
  21 #include "ext4_jbd2.h"
  22 #include "mballoc.h"
  23
  24 #include <trace/events/ext4.h>
  25
  26 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
  27                                             ext4_group_t block_group);
  28 /*
  29  * balloc.c contains the blocks allocation and deallocation routines
  30  */
  31
  32 /*
  33  * Calculate block group number for a given block number
  34  */
  35 ext4_group_t ext4_get_group_number(struct super_block *sb,
  36                                    ext4_fsblk_t block)
  37 {
  38         ext4_group_t group;
  39
  40         if (test_opt2(sb, STD_GROUP_SIZE))
  41                 group = (block -
  42                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
  43                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
  44         else
  45                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
  46         return group;
  47 }
  48
  49 /*
  50  * Calculate the block group number and offset into the block/cluster
  51  * allocation bitmap, given a block number
  52  */
  53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  54                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  55 {
  56         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  57         ext4_grpblk_t offset;
  58
  59         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  60         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
  61                 EXT4_SB(sb)->s_cluster_bits;
  62         if (offsetp)
  63                 *offsetp = offset;
  64         if (blockgrpp)
  65                 *blockgrpp = blocknr;
  66
  67 }
  68
  69 /*
  70  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
  71  * and 0 otherwise.
  72  */
  73 static inline int ext4_block_in_group(struct super_block *sb,
  74                                       ext4_fsblk_t block,
  75                                       ext4_group_t block_group)
  76 {
  77         ext4_group_t actual_group;
  78
  79         actual_group = ext4_get_group_number(sb, block);
  80         return (actual_group == block_group) ? 1 : 0;
  81 }
  82
  83 /* Return the number of clusters used for file system metadata; this
  84  * represents the overhead needed by the file system.
  85  */
  86 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
  87                                            ext4_group_t block_group,
  88                                            struct ext4_group_desc *gdp)
  89 {
  90         unsigned num_clusters;
  91         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
  92         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  93         ext4_fsblk_t itbl_blk;
  94         struct ext4_sb_info *sbi = EXT4_SB(sb);
  95
  96         /* This is the number of clusters used by the superblock,
  97          * block group descriptors, and reserved block group
  98          * descriptor blocks */
  99         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
 100
 101         /*
 102          * For the allocation bitmaps and inode table, we first need
 103          * to check to see if the block is in the block group.  If it
 104          * is, then check to see if the cluster is already accounted
 105          * for in the clusters used for the base metadata cluster, or
 106          * if we can increment the base metadata cluster to include
 107          * that block.  Otherwise, we will have to track the cluster
 108          * used for the allocation bitmap or inode table explicitly.
 109          * Normally all of these blocks are contiguous, so the special
 110          * case handling shouldn't be necessary except for *very*
 111          * unusual file system layouts.
 112          */
 113         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 114                 block_cluster = EXT4_B2C(sbi,
 115                                          ext4_block_bitmap(sb, gdp) - start);
 116                 if (block_cluster < num_clusters)
 117                         block_cluster = -1;
 118                 else if (block_cluster == num_clusters) {
 119                         num_clusters++;
 120                         block_cluster = -1;
 121                 }
 122         }
 123
 124         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 125                 inode_cluster = EXT4_B2C(sbi,
 126                                          ext4_inode_bitmap(sb, gdp) - start);
 127                 if (inode_cluster < num_clusters)
 128                         inode_cluster = -1;
 129                 else if (inode_cluster == num_clusters) {
 130                         num_clusters++;
 131                         inode_cluster = -1;
 132                 }
 133         }
 134
 135         itbl_blk = ext4_inode_table(sb, gdp);
 136         for (i = 0; i < sbi->s_itb_per_group; i++) {
 137                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
 138                         c = EXT4_B2C(sbi, itbl_blk + i - start);
 139                         if ((c < num_clusters) || (c == inode_cluster) ||
 140                             (c == block_cluster) || (c == itbl_cluster))
 141                                 continue;
 142                         if (c == num_clusters) {
 143                                 num_clusters++;
 144                                 continue;
 145                         }
 146                         num_clusters++;
 147                         itbl_cluster = c;
 148                 }
 149         }
 150
 151         if (block_cluster != -1)
 152                 num_clusters++;
 153         if (inode_cluster != -1)
 154                 num_clusters++;
 155
 156         return num_clusters;
 157 }
 158
 159 static unsigned int num_clusters_in_group(struct super_block *sb,
 160                                           ext4_group_t block_group)
 161 {
 162         unsigned int blocks;
 163
 164         if (block_group == ext4_get_groups_count(sb) - 1) {
 165                 /*
 166                  * Even though mke2fs always initializes the first and
 167                  * last group, just in case some other tool was used,
 168                  * we need to make sure we calculate the right free
 169                  * blocks.
 170                  */
 171                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 172                         ext4_group_first_block_no(sb, block_group);
 173         } else
 174                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 175         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 176 }
 177
 178 /* Initializes an uninitialized block bitmap */
 179 static int ext4_init_block_bitmap(struct super_block *sb,
 180                                    struct buffer_head *bh,
 181                                    ext4_group_t block_group,
 182                                    struct ext4_group_desc *gdp)
 183 {
 184         unsigned int bit, bit_max;
 185         struct ext4_sb_info *sbi = EXT4_SB(sb);
 186         ext4_fsblk_t start, tmp;
 187         int flex_bg = 0;
 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_mark_group_bitmap_corrupted(sb, block_group,
 195                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT |
 196                                         EXT4_GROUP_INFO_IBITMAP_CORRUPT);
 197                 return -EFSBADCRC;
 198         }
 199         memset(bh->b_data, 0, sb->s_blocksize);
 200
 201         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 202         if ((bit_max >> 3) >= bh->b_size)
 203                 return -EFSCORRUPTED;
 204
 205         for (bit = 0; bit < bit_max; bit++)
 206                 ext4_set_bit(bit, bh->b_data);
 207
 208         start = ext4_group_first_block_no(sb, block_group);
 209
 210         if (ext4_has_feature_flex_bg(sb))
 211                 flex_bg = 1;
 212
 213         /* Set bits for block and inode bitmaps, and inode table */
 214         tmp = ext4_block_bitmap(sb, gdp);
 215         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 216                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 217
 218         tmp = ext4_inode_bitmap(sb, gdp);
 219         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 220                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 221
 222         tmp = ext4_inode_table(sb, gdp);
 223         for (; tmp < ext4_inode_table(sb, gdp) +
 224                      sbi->s_itb_per_group; tmp++) {
 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
 229         /*
 230          * Also if the number of blocks within the group is less than
 231          * the blocksize * 8 ( which is the size of bitmap ), set rest
 232          * of the block bitmap to 1
 233          */
 234         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 235                              sb->s_blocksize * 8, bh->b_data);
 236         return 0;
 237 }
 238
 239 /* Return the number of free blocks in a block group.  It is used when
 240  * the block bitmap is uninitialized, so we can't just count the bits
 241  * in the bitmap. */
 242 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 243                                        ext4_group_t block_group,
 244                                        struct ext4_group_desc *gdp)
 245 {
 246         return num_clusters_in_group(sb, block_group) -
 247                 ext4_num_overhead_clusters(sb, block_group, gdp);
 248 }
 249
 250 /*
 251  * The free blocks are managed by bitmaps.  A file system contains several
 252  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 253  * block for inodes, N blocks for the inode table and data blocks.
 254  *
 255  * The file system contains group descriptors which are located after the
 256  * super block.  Each descriptor contains the number of the bitmap block and
 257  * the free blocks count in the block.  The descriptors are loaded in memory
 258  * when a file system is mounted (see ext4_fill_super).
 259  */
 260
 261 /**
 262  * ext4_get_group_desc() -- load group descriptor from disk
 263  * @sb:                 super block
 264  * @block_group:        given block group
 265  * @bh:                 pointer to the buffer head to store the block
 266  *                      group descriptor
 267  */
 268 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 269                                              ext4_group_t block_group,
 270                                              struct buffer_head **bh)
 271 {
 272         unsigned int group_desc;
 273         unsigned int offset;
 274         ext4_group_t ngroups = ext4_get_groups_count(sb);
 275         struct ext4_group_desc *desc;
 276         struct ext4_sb_info *sbi = EXT4_SB(sb);
 277
 278         if (block_group >= ngroups) {
 279                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 280                            " groups_count = %u", block_group, ngroups);
 281
 282                 return NULL;
 283         }
 284
 285         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 286         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 287         if (!sbi->s_group_desc[group_desc]) {
 288                 ext4_error(sb, "Group descriptor not loaded - "
 289                            "block_group = %u, group_desc = %u, desc = %u",
 290                            block_group, group_desc, offset);
 291                 return NULL;
 292         }
 293
 294         desc = (struct ext4_group_desc *)(
 295                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 296                 offset * EXT4_DESC_SIZE(sb));
 297         if (bh)
 298                 *bh = sbi->s_group_desc[group_desc];
 299         return desc;
 300 }
 301
 302 /*
 303  * Return the block number which was discovered to be invalid, or 0 if
 304  * the block bitmap is valid.
 305  */
 306 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 307                                             struct ext4_group_desc *desc,
 308                                             ext4_group_t block_group,
 309                                             struct buffer_head *bh)
 310 {
 311         struct ext4_sb_info *sbi = EXT4_SB(sb);
 312         ext4_grpblk_t offset;
 313         ext4_grpblk_t next_zero_bit;
 314         ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
 315         ext4_fsblk_t blk;
 316         ext4_fsblk_t group_first_block;
 317
 318         if (ext4_has_feature_flex_bg(sb)) {
 319                 /* with FLEX_BG, the inode/block bitmaps and itable
 320                  * blocks may not be in the group at all
 321                  * so the bitmap validation will be skipped for those groups
 322                  * or it has to also read the block group where the bitmaps
 323                  * are located to verify they are set.
 324                  */
 325                 return 0;
 326         }
 327         group_first_block = ext4_group_first_block_no(sb, block_group);
 328
 329         /* check whether block bitmap block number is set */
 330         blk = ext4_block_bitmap(sb, desc);
 331         offset = blk - group_first_block;
 332         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 333             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 334                 /* bad block bitmap */
 335                 return blk;
 336
 337         /* check whether the inode bitmap block number is set */
 338         blk = ext4_inode_bitmap(sb, desc);
 339         offset = blk - group_first_block;
 340         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 341             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 342                 /* bad block bitmap */
 343                 return blk;
 344
 345         /* check whether the inode table block number is set */
 346         blk = ext4_inode_table(sb, desc);
 347         offset = blk - group_first_block;
 348         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 349             EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
 350                 return blk;
 351         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 352                         EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
 353                         EXT4_B2C(sbi, offset));
 354         if (next_zero_bit <
 355             EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
 356                 /* bad bitmap for inode tables */
 357                 return blk;
 358         return 0;
 359 }
 360
 361 static int ext4_validate_block_bitmap(struct super_block *sb,
 362                                       struct ext4_group_desc *desc,
 363                                       ext4_group_t block_group,
 364                                       struct buffer_head *bh)
 365 {
 366         ext4_fsblk_t    blk;
 367         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
 368
 369         if (buffer_verified(bh))
 370                 return 0;
 371         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 372                 return -EFSCORRUPTED;
 373
 374         ext4_lock_group(sb, block_group);
 375         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
 376                         desc, bh))) {
 377                 ext4_unlock_group(sb, block_group);
 378                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 379                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 380                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 381                 return -EFSBADCRC;
 382         }
 383         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 384         if (unlikely(blk != 0)) {
 385                 ext4_unlock_group(sb, block_group);
 386                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 387                            block_group, blk);
 388                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 389                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 390                 return -EFSCORRUPTED;
 391         }
 392         set_buffer_verified(bh);
 393         ext4_unlock_group(sb, block_group);
 394         return 0;
 395 }
 396
 397 /**
 398  * ext4_read_block_bitmap_nowait()
 399  * @sb:                 super block
 400  * @block_group:        given block group
 401  *
 402  * Read the bitmap for a given block_group,and validate the
 403  * bits for block/inode/inode tables are set in the bitmaps
 404  *
 405  * Return buffer_head on success or NULL in case of failure.
 406  */
 407 struct buffer_head *
 408 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
 409 {
 410         struct ext4_group_desc *desc;
 411         struct ext4_sb_info *sbi = EXT4_SB(sb);
 412         struct buffer_head *bh;
 413         ext4_fsblk_t bitmap_blk;
 414         int err;
 415
 416         desc = ext4_get_group_desc(sb, block_group, NULL);
 417         if (!desc)
 418                 return ERR_PTR(-EFSCORRUPTED);
 419         bitmap_blk = ext4_block_bitmap(sb, desc);
 420         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 421             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
 422                 ext4_error(sb, "Invalid block bitmap block %llu in "
 423                            "block_group %u", bitmap_blk, block_group);
 424                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 425                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 426                 return ERR_PTR(-EFSCORRUPTED);
 427         }
 428         bh = sb_getblk(sb, bitmap_blk);
 429         if (unlikely(!bh)) {
 430                 ext4_error(sb, "Cannot get buffer for block bitmap - "
 431                            "block_group = %u, block_bitmap = %llu",
 432                            block_group, bitmap_blk);
 433                 return ERR_PTR(-ENOMEM);
 434         }
 435
 436         if (bitmap_uptodate(bh))
 437                 goto verify;
 438
 439         lock_buffer(bh);
 440         if (bitmap_uptodate(bh)) {
 441                 unlock_buffer(bh);
 442                 goto verify;
 443         }
 444         ext4_lock_group(sb, block_group);
 445         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 446                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 447                 set_bitmap_uptodate(bh);
 448                 set_buffer_uptodate(bh);
 449                 set_buffer_verified(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                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 505                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 506                 return -EIO;
 507         }
 508         clear_buffer_new(bh);
 509         /* Panic or remount fs read-only if block bitmap is invalid */
 510         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 511 }
 512
 513 struct buffer_head *
 514 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 515 {
 516         struct buffer_head *bh;
 517         int err;
 518
 519         bh = ext4_read_block_bitmap_nowait(sb, block_group);
 520         if (IS_ERR(bh))
 521                 return bh;
 522         err = ext4_wait_block_bitmap(sb, block_group, bh);
 523         if (err) {
 524                 put_bh(bh);
 525                 return ERR_PTR(err);
 526         }
 527         return bh;
 528 }
 529
 530 /**
 531  * ext4_has_free_clusters()
 532  * @sbi:        in-core super block structure.
 533  * @nclusters:  number of needed blocks
 534  * @flags:      flags from ext4_mb_new_blocks()
 535  *
 536  * Check if filesystem has nclusters free & available for allocation.
 537  * On success return 1, return 0 on failure.
 538  */
 539 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 540                                   s64 nclusters, unsigned int flags)
 541 {
 542         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 543         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 544         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 545
 546         free_clusters  = percpu_counter_read_positive(fcc);
 547         dirty_clusters = percpu_counter_read_positive(dcc);
 548         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 549
 550         /*
 551          * r_blocks_count should always be multiple of the cluster ratio so
 552          * we are safe to do a plane bit shift only.
 553          */
 554         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 555               resv_clusters;
 556
 557         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 558                                         EXT4_FREECLUSTERS_WATERMARK) {
 559                 free_clusters  = percpu_counter_sum_positive(fcc);
 560                 dirty_clusters = percpu_counter_sum_positive(dcc);
 561         }
 562         /* Check whether we have space after accounting for current
 563          * dirty clusters & root reserved clusters.
 564          */
 565         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 566                 return 1;
 567
 568         /* Hm, nope.  Are (enough) root reserved clusters available? */
 569         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 570             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 571             capable(CAP_SYS_RESOURCE) ||
 572             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 573
 574                 if (free_clusters >= (nclusters + dirty_clusters +
 575                                       resv_clusters))
 576                         return 1;
 577         }
 578         /* No free blocks. Let's see if we can dip into reserved pool */
 579         if (flags & EXT4_MB_USE_RESERVED) {
 580                 if (free_clusters >= (nclusters + dirty_clusters))
 581                         return 1;
 582         }
 583
 584         return 0;
 585 }
 586
 587 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 588                              s64 nclusters, unsigned int flags)
 589 {
 590         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 591                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 592                 return 0;
 593         } else
 594                 return -ENOSPC;
 595 }
 596
 597 /**
 598  * ext4_should_retry_alloc()
 599  * @sb:                 super block
 600  * @retries             number of attemps has been made
 601  *
 602  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 603  * it is profitable to retry the operation, this function will wait
 604  * for the current or committing transaction to complete, and then
 605  * return TRUE.  We will only retry once.
 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)++ > 1 ||
 611             !EXT4_SB(sb)->s_journal)
 612                 return 0;
 613
 614         smp_mb();
 615         if (EXT4_SB(sb)->s_mb_free_pending == 0)
 616                 return 0;
 617
 618         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 619         jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 620         return 1;
 621 }
 622
 623 /*
 624  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 625  *
 626  * @handle:             handle to this transaction
 627  * @inode:              file inode
 628  * @goal:               given target block(filesystem wide)
 629  * @count:              pointer to total number of clusters needed
 630  * @errp:               error code
 631  *
 632  * Return 1st allocated block number on success, *count stores total account
 633  * error stores in errp pointer
 634  */
 635 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 636                                   ext4_fsblk_t goal, unsigned int flags,
 637                                   unsigned long *count, int *errp)
 638 {
 639         struct ext4_allocation_request ar;
 640         ext4_fsblk_t ret;
 641
 642         memset(&ar, 0, sizeof(ar));
 643         /* Fill with neighbour allocated blocks */
 644         ar.inode = inode;
 645         ar.goal = goal;
 646         ar.len = count ? *count : 1;
 647         ar.flags = flags;
 648
 649         ret = ext4_mb_new_blocks(handle, &ar, errp);
 650         if (count)
 651                 *count = ar.len;
 652         /*
 653          * Account for the allocated meta blocks.  We will never
 654          * fail EDQUOT for metdata, but we do account for it.
 655          */
 656         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 657                 dquot_alloc_block_nofail(inode,
 658                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 659         }
 660         return ret;
 661 }
 662
 663 /**
 664  * ext4_count_free_clusters() -- count filesystem free clusters
 665  * @sb:         superblock
 666  *
 667  * Adds up the number of free clusters from each block group.
 668  */
 669 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 670 {
 671         ext4_fsblk_t desc_count;
 672         struct ext4_group_desc *gdp;
 673         ext4_group_t i;
 674         ext4_group_t ngroups = ext4_get_groups_count(sb);
 675         struct ext4_group_info *grp;
 676 #ifdef EXT4FS_DEBUG
 677         struct ext4_super_block *es;
 678         ext4_fsblk_t bitmap_count;
 679         unsigned int x;
 680         struct buffer_head *bitmap_bh = NULL;
 681
 682         es = EXT4_SB(sb)->s_es;
 683         desc_count = 0;
 684         bitmap_count = 0;
 685         gdp = NULL;
 686
 687         for (i = 0; i < ngroups; i++) {
 688                 gdp = ext4_get_group_desc(sb, i, NULL);
 689                 if (!gdp)
 690                         continue;
 691                 grp = NULL;
 692                 if (EXT4_SB(sb)->s_group_info)
 693                         grp = ext4_get_group_info(sb, i);
 694                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 695                         desc_count += ext4_free_group_clusters(sb, gdp);
 696                 brelse(bitmap_bh);
 697                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 698                 if (IS_ERR(bitmap_bh)) {
 699                         bitmap_bh = NULL;
 700                         continue;
 701                 }
 702
 703                 x = ext4_count_free(bitmap_bh->b_data,
 704                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 705                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 706                         i, ext4_free_group_clusters(sb, gdp), x);
 707                 bitmap_count += x;
 708         }
 709         brelse(bitmap_bh);
 710         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 711                ", computed = %llu, %llu\n",
 712                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 713                desc_count, bitmap_count);
 714         return bitmap_count;
 715 #else
 716         desc_count = 0;
 717         for (i = 0; i < ngroups; i++) {
 718                 gdp = ext4_get_group_desc(sb, i, NULL);
 719                 if (!gdp)
 720                         continue;
 721                 grp = NULL;
 722                 if (EXT4_SB(sb)->s_group_info)
 723                         grp = ext4_get_group_info(sb, i);
 724                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 725                         desc_count += ext4_free_group_clusters(sb, gdp);
 726         }
 727
 728         return desc_count;
 729 #endif
 730 }
 731
 732 static inline int test_root(ext4_group_t a, int b)
 733 {
 734         while (1) {
 735                 if (a < b)
 736                         return 0;
 737                 if (a == b)
 738                         return 1;
 739                 if ((a % b) != 0)
 740                         return 0;
 741                 a = a / b;
 742         }
 743 }
 744
 745 /**
 746  *      ext4_bg_has_super - number of blocks used by the superblock in group
 747  *      @sb: superblock for filesystem
 748  *      @group: group number to check
 749  *
 750  *      Return the number of blocks used by the superblock (primary or backup)
 751  *      in this group.  Currently this will be only 0 or 1.
 752  */
 753 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 754 {
 755         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 756
 757         if (group == 0)
 758                 return 1;
 759         if (ext4_has_feature_sparse_super2(sb)) {
 760                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 761                     group == le32_to_cpu(es->s_backup_bgs[1]))
 762                         return 1;
 763                 return 0;
 764         }
 765         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 766                 return 1;
 767         if (!(group & 1))
 768                 return 0;
 769         if (test_root(group, 3) || (test_root(group, 5)) ||
 770             test_root(group, 7))
 771                 return 1;
 772
 773         return 0;
 774 }
 775
 776 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 777                                         ext4_group_t group)
 778 {
 779         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 780         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 781         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 782
 783         if (group == first || group == first + 1 || group == last)
 784                 return 1;
 785         return 0;
 786 }
 787
 788 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 789                                         ext4_group_t group)
 790 {
 791         if (!ext4_bg_has_super(sb, group))
 792                 return 0;
 793
 794         if (ext4_has_feature_meta_bg(sb))
 795                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 796         else
 797                 return EXT4_SB(sb)->s_gdb_count;
 798 }
 799
 800 /**
 801  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 802  *      @sb: superblock for filesystem
 803  *      @group: group number to check
 804  *
 805  *      Return the number of blocks used by the group descriptor table
 806  *      (primary or backup) in this group.  In the future there may be a
 807  *      different number of descriptor blocks in each group.
 808  */
 809 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 810 {
 811         unsigned long first_meta_bg =
 812                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 813         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 814
 815         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 816                 return ext4_bg_num_gdb_nometa(sb, group);
 817
 818         return ext4_bg_num_gdb_meta(sb,group);
 819
 820 }
 821
 822 /*
 823  * This function returns the number of file system metadata clusters at
 824  * the beginning of a block group, including the reserved gdt blocks.
 825  */
 826 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 827                                      ext4_group_t block_group)
 828 {
 829         struct ext4_sb_info *sbi = EXT4_SB(sb);
 830         unsigned num;
 831
 832         /* Check for superblock and gdt backups in this group */
 833         num = ext4_bg_has_super(sb, block_group);
 834
 835         if (!ext4_has_feature_meta_bg(sb) ||
 836             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 837                           sbi->s_desc_per_block) {
 838                 if (num) {
 839                         num += ext4_bg_num_gdb(sb, block_group);
 840                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 841                 }
 842         } else { /* For META_BG_BLOCK_GROUPS */
 843                 num += ext4_bg_num_gdb(sb, block_group);
 844         }
 845         return EXT4_NUM_B2C(sbi, num);
 846 }
 847 /**
 848  *      ext4_inode_to_goal_block - return a hint for block allocation
 849  *      @inode: inode for block allocation
 850  *
 851  *      Return the ideal location to start allocating blocks for a
 852  *      newly created inode.
 853  */
 854 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 855 {
 856         struct ext4_inode_info *ei = EXT4_I(inode);
 857         ext4_group_t block_group;
 858         ext4_grpblk_t colour;
 859         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 860         ext4_fsblk_t bg_start;
 861         ext4_fsblk_t last_block;
 862
 863         block_group = ei->i_block_group;
 864         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 865                 /*
 866                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 867                  * block groups per flexgroup, reserve the first block
 868                  * group for directories and special files.  Regular
 869                  * files will start at the second block group.  This
 870                  * tends to speed up directory access and improves
 871                  * fsck times.
 872                  */
 873                 block_group &= ~(flex_size-1);
 874                 if (S_ISREG(inode->i_mode))
 875                         block_group++;
 876         }
 877         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 878         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 879
 880         /*
 881          * If we are doing delayed allocation, we don't need take
 882          * colour into account.
 883          */
 884         if (test_opt(inode->i_sb, DELALLOC))
 885                 return bg_start;
 886
 887         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 888                 colour = (current->pid % 16) *
 889                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 890         else
 891                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
 892         return bg_start + colour;
 893 }
 894