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 (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  11  *  Big-endian to little-endian byte-swapping/bitmaps by
  12  *        David S. Miller (davem@caip.rutgers.edu), 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 /*
  84  * Return the number of clusters used for file system metadata; this
  85  * represents the overhead needed by the file system.
  86  */
  87 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
  88                                            ext4_group_t block_group,
  89                                            struct ext4_group_desc *gdp)
  90 {
  91         unsigned base_clusters, num_clusters;
  92         int block_cluster = -1, inode_cluster;
  93         int itbl_cluster_start = -1, itbl_cluster_end = -1;
  94         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  95         ext4_fsblk_t end = start + EXT4_BLOCKS_PER_GROUP(sb) - 1;
  96         ext4_fsblk_t itbl_blk_start, itbl_blk_end;
  97         struct ext4_sb_info *sbi = EXT4_SB(sb);
  98
  99         /* This is the number of clusters used by the superblock,
 100          * block group descriptors, and reserved block group
 101          * descriptor blocks */
 102         base_clusters = ext4_num_base_meta_clusters(sb, block_group);
 103         num_clusters = base_clusters;
 104
 105         /*
 106          * Account and record inode table clusters if any cluster
 107          * is in the block group, or inode table cluster range is
 108          * [-1, -1] and won't overlap with block/inode bitmap cluster
 109          * accounted below.
 110          */
 111         itbl_blk_start = ext4_inode_table(sb, gdp);
 112         itbl_blk_end = itbl_blk_start + sbi->s_itb_per_group - 1;
 113         if (itbl_blk_start <= end && itbl_blk_end >= start) {
 114                 itbl_blk_start = itbl_blk_start >= start ?
 115                         itbl_blk_start : start;
 116                 itbl_blk_end = itbl_blk_end <= end ?
 117                         itbl_blk_end : end;
 118
 119                 itbl_cluster_start = EXT4_B2C(sbi, itbl_blk_start - start);
 120                 itbl_cluster_end = EXT4_B2C(sbi, itbl_blk_end - start);
 121
 122                 num_clusters += itbl_cluster_end - itbl_cluster_start + 1;
 123                 /* check if border cluster is overlapped */
 124                 if (itbl_cluster_start == base_clusters - 1)
 125                         num_clusters--;
 126         }
 127
 128         /*
 129          * For the allocation bitmaps, we first need to check to see
 130          * if the block is in the block group.  If it is, then check
 131          * to see if the cluster is already accounted for in the clusters
 132          * used for the base metadata cluster and inode tables cluster.
 133          * Normally all of these blocks are contiguous, so the special
 134          * case handling shouldn't be necessary except for *very*
 135          * unusual file system layouts.
 136          */
 137         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 138                 block_cluster = EXT4_B2C(sbi,
 139                                          ext4_block_bitmap(sb, gdp) - start);
 140                 if (block_cluster >= base_clusters &&
 141                     (block_cluster < itbl_cluster_start ||
 142                     block_cluster > itbl_cluster_end))
 143                         num_clusters++;
 144         }
 145
 146         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 147                 inode_cluster = EXT4_B2C(sbi,
 148                                          ext4_inode_bitmap(sb, gdp) - start);
 149                 /*
 150                  * Additional check if inode bitmap is in just accounted
 151                  * block_cluster
 152                  */
 153                 if (inode_cluster != block_cluster &&
 154                     inode_cluster >= base_clusters &&
 155                     (inode_cluster < itbl_cluster_start ||
 156                     inode_cluster > itbl_cluster_end))
 157                         num_clusters++;
 158         }
 159
 160         return num_clusters;
 161 }
 162
 163 static unsigned int num_clusters_in_group(struct super_block *sb,
 164                                           ext4_group_t block_group)
 165 {
 166         unsigned int blocks;
 167
 168         if (block_group == ext4_get_groups_count(sb) - 1) {
 169                 /*
 170                  * Even though mke2fs always initializes the first and
 171                  * last group, just in case some other tool was used,
 172                  * we need to make sure we calculate the right free
 173                  * blocks.
 174                  */
 175                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 176                         ext4_group_first_block_no(sb, block_group);
 177         } else
 178                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 179         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 180 }
 181
 182 /* Initializes an uninitialized block bitmap */
 183 static int ext4_init_block_bitmap(struct super_block *sb,
 184                                    struct buffer_head *bh,
 185                                    ext4_group_t block_group,
 186                                    struct ext4_group_desc *gdp)
 187 {
 188         unsigned int bit, bit_max;
 189         struct ext4_sb_info *sbi = EXT4_SB(sb);
 190         ext4_fsblk_t start, tmp;
 191
 192         ASSERT(buffer_locked(bh));
 193
 194         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 195                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 196                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT |
 197                                         EXT4_GROUP_INFO_IBITMAP_CORRUPT);
 198                 return -EFSBADCRC;
 199         }
 200         memset(bh->b_data, 0, sb->s_blocksize);
 201
 202         bit_max = ext4_num_base_meta_clusters(sb, block_group);
 203         if ((bit_max >> 3) >= bh->b_size)
 204                 return -EFSCORRUPTED;
 205
 206         for (bit = 0; bit < bit_max; bit++)
 207                 ext4_set_bit(bit, bh->b_data);
 208
 209         start = ext4_group_first_block_no(sb, block_group);
 210
 211         /* Set bits for block and inode bitmaps, and inode table */
 212         tmp = ext4_block_bitmap(sb, gdp);
 213         if (ext4_block_in_group(sb, tmp, block_group))
 214                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 215
 216         tmp = ext4_inode_bitmap(sb, gdp);
 217         if (ext4_block_in_group(sb, tmp, block_group))
 218                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 219
 220         tmp = ext4_inode_table(sb, gdp);
 221         for (; tmp < ext4_inode_table(sb, gdp) +
 222                      sbi->s_itb_per_group; tmp++) {
 223                 if (ext4_block_in_group(sb, tmp, block_group))
 224                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 225         }
 226
 227         /*
 228          * Also if the number of blocks within the group is less than
 229          * the blocksize * 8 ( which is the size of bitmap ), set rest
 230          * of the block bitmap to 1
 231          */
 232         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 233                              sb->s_blocksize * 8, bh->b_data);
 234         return 0;
 235 }
 236
 237 /* Return the number of free blocks in a block group.  It is used when
 238  * the block bitmap is uninitialized, so we can't just count the bits
 239  * in the bitmap. */
 240 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 241                                        ext4_group_t block_group,
 242                                        struct ext4_group_desc *gdp)
 243 {
 244         return num_clusters_in_group(sb, block_group) -
 245                 ext4_num_overhead_clusters(sb, block_group, gdp);
 246 }
 247
 248 /*
 249  * The free blocks are managed by bitmaps.  A file system contains several
 250  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 251  * block for inodes, N blocks for the inode table and data blocks.
 252  *
 253  * The file system contains group descriptors which are located after the
 254  * super block.  Each descriptor contains the number of the bitmap block and
 255  * the free blocks count in the block.  The descriptors are loaded in memory
 256  * when a file system is mounted (see ext4_fill_super).
 257  */
 258
 259 /**
 260  * ext4_get_group_desc() -- load group descriptor from disk
 261  * @sb:                 super block
 262  * @block_group:        given block group
 263  * @bh:                 pointer to the buffer head to store the block
 264  *                      group descriptor
 265  */
 266 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 267                                              ext4_group_t block_group,
 268                                              struct buffer_head **bh)
 269 {
 270         unsigned int group_desc;
 271         unsigned int offset;
 272         ext4_group_t ngroups = ext4_get_groups_count(sb);
 273         struct ext4_group_desc *desc;
 274         struct ext4_sb_info *sbi = EXT4_SB(sb);
 275         struct buffer_head *bh_p;
 276
 277         if (block_group >= ngroups) {
 278                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 279                            " groups_count = %u", block_group, ngroups);
 280
 281                 return NULL;
 282         }
 283
 284         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 285         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 286         bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc);
 287         /*
 288          * sbi_array_rcu_deref returns with rcu unlocked, this is ok since
 289          * the pointer being dereferenced won't be dereferenced again. By
 290          * looking at the usage in add_new_gdb() the value isn't modified,
 291          * just the pointer, and so it remains valid.
 292          */
 293         if (!bh_p) {
 294                 ext4_error(sb, "Group descriptor not loaded - "
 295                            "block_group = %u, group_desc = %u, desc = %u",
 296                            block_group, group_desc, offset);
 297                 return NULL;
 298         }
 299
 300         desc = (struct ext4_group_desc *)(
 301                 (__u8 *)bh_p->b_data +
 302                 offset * EXT4_DESC_SIZE(sb));
 303         if (bh)
 304                 *bh = bh_p;
 305         return desc;
 306 }
 307
 308 static ext4_fsblk_t ext4_valid_block_bitmap_padding(struct super_block *sb,
 309                                                     ext4_group_t block_group,
 310                                                     struct buffer_head *bh)
 311 {
 312         ext4_grpblk_t next_zero_bit;
 313         unsigned long bitmap_size = sb->s_blocksize * 8;
 314         unsigned int offset = num_clusters_in_group(sb, block_group);
 315
 316         if (bitmap_size <= offset)
 317                 return 0;
 318
 319         next_zero_bit = ext4_find_next_zero_bit(bh->b_data, bitmap_size, offset);
 320
 321         return (next_zero_bit < bitmap_size ? next_zero_bit : 0);
 322 }
 323
 324 struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
 325                                             ext4_group_t group)
 326 {
 327          struct ext4_group_info **grp_info;
 328          long indexv, indexh;
 329
 330          if (unlikely(group >= EXT4_SB(sb)->s_groups_count)) {
 331                  ext4_error(sb, "invalid group %u", group);
 332                  return NULL;
 333          }
 334          indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
 335          indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
 336          grp_info = sbi_array_rcu_deref(EXT4_SB(sb), s_group_info, indexv);
 337          return grp_info[indexh];
 338 }
 339
 340 /*
 341  * Return the block number which was discovered to be invalid, or 0 if
 342  * the block bitmap is valid.
 343  */
 344 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 345                                             struct ext4_group_desc *desc,
 346                                             ext4_group_t block_group,
 347                                             struct buffer_head *bh)
 348 {
 349         struct ext4_sb_info *sbi = EXT4_SB(sb);
 350         ext4_grpblk_t offset;
 351         ext4_grpblk_t next_zero_bit;
 352         ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
 353         ext4_fsblk_t blk;
 354         ext4_fsblk_t group_first_block;
 355
 356         if (ext4_has_feature_flex_bg(sb)) {
 357                 /* with FLEX_BG, the inode/block bitmaps and itable
 358                  * blocks may not be in the group at all
 359                  * so the bitmap validation will be skipped for those groups
 360                  * or it has to also read the block group where the bitmaps
 361                  * are located to verify they are set.
 362                  */
 363                 return 0;
 364         }
 365         group_first_block = ext4_group_first_block_no(sb, block_group);
 366
 367         /* check whether block bitmap block number is set */
 368         blk = ext4_block_bitmap(sb, desc);
 369         offset = blk - group_first_block;
 370         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 371             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 372                 /* bad block bitmap */
 373                 return blk;
 374
 375         /* check whether the inode bitmap block number is set */
 376         blk = ext4_inode_bitmap(sb, desc);
 377         offset = blk - group_first_block;
 378         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 379             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 380                 /* bad block bitmap */
 381                 return blk;
 382
 383         /* check whether the inode table block number is set */
 384         blk = ext4_inode_table(sb, desc);
 385         offset = blk - group_first_block;
 386         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 387             EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) >= max_bit)
 388                 return blk;
 389         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 390                         EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) + 1,
 391                         EXT4_B2C(sbi, offset));
 392         if (next_zero_bit <
 393             EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) + 1)
 394                 /* bad bitmap for inode tables */
 395                 return blk;
 396         return 0;
 397 }
 398
 399 static int ext4_validate_block_bitmap(struct super_block *sb,
 400                                       struct ext4_group_desc *desc,
 401                                       ext4_group_t block_group,
 402                                       struct buffer_head *bh)
 403 {
 404         ext4_fsblk_t    blk;
 405         struct ext4_group_info *grp;
 406
 407         if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)
 408                 return 0;
 409
 410         grp = ext4_get_group_info(sb, block_group);
 411
 412         if (buffer_verified(bh))
 413                 return 0;
 414         if (!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 415                 return -EFSCORRUPTED;
 416
 417         ext4_lock_group(sb, block_group);
 418         if (buffer_verified(bh))
 419                 goto verified;
 420         if (unlikely(!ext4_block_bitmap_csum_verify(sb, desc, bh) ||
 421                      ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {
 422                 ext4_unlock_group(sb, block_group);
 423                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 424                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 425                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 426                 return -EFSBADCRC;
 427         }
 428         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 429         if (unlikely(blk != 0)) {
 430                 ext4_unlock_group(sb, block_group);
 431                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 432                            block_group, blk);
 433                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 434                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 435                 return -EFSCORRUPTED;
 436         }
 437         blk = ext4_valid_block_bitmap_padding(sb, block_group, bh);
 438         if (unlikely(blk != 0)) {
 439                 ext4_unlock_group(sb, block_group);
 440                 ext4_error(sb, "bg %u: block %llu: padding at end of block bitmap is not set",
 441                            block_group, blk);
 442                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 443                                                  EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 444                 return -EFSCORRUPTED;
 445         }
 446         set_buffer_verified(bh);
 447 verified:
 448         ext4_unlock_group(sb, block_group);
 449         return 0;
 450 }
 451
 452 /**
 453  * ext4_read_block_bitmap_nowait()
 454  * @sb:                 super block
 455  * @block_group:        given block group
 456  * @ignore_locked:      ignore locked buffers
 457  *
 458  * Read the bitmap for a given block_group,and validate the
 459  * bits for block/inode/inode tables are set in the bitmaps
 460  *
 461  * Return buffer_head on success or an ERR_PTR in case of failure.
 462  */
 463 struct buffer_head *
 464 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
 465                               bool ignore_locked)
 466 {
 467         struct ext4_group_desc *desc;
 468         struct ext4_sb_info *sbi = EXT4_SB(sb);
 469         struct buffer_head *bh;
 470         ext4_fsblk_t bitmap_blk;
 471         int err;
 472
 473         desc = ext4_get_group_desc(sb, block_group, NULL);
 474         if (!desc)
 475                 return ERR_PTR(-EFSCORRUPTED);
 476         bitmap_blk = ext4_block_bitmap(sb, desc);
 477         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 478             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
 479                 ext4_error(sb, "Invalid block bitmap block %llu in "
 480                            "block_group %u", bitmap_blk, block_group);
 481                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 482                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 483                 return ERR_PTR(-EFSCORRUPTED);
 484         }
 485         bh = sb_getblk(sb, bitmap_blk);
 486         if (unlikely(!bh)) {
 487                 ext4_warning(sb, "Cannot get buffer for block bitmap - "
 488                              "block_group = %u, block_bitmap = %llu",
 489                              block_group, bitmap_blk);
 490                 return ERR_PTR(-ENOMEM);
 491         }
 492
 493         if (ignore_locked && buffer_locked(bh)) {
 494                 /* buffer under IO already, return if called for prefetching */
 495                 put_bh(bh);
 496                 return NULL;
 497         }
 498
 499         if (bitmap_uptodate(bh))
 500                 goto verify;
 501
 502         lock_buffer(bh);
 503         if (bitmap_uptodate(bh)) {
 504                 unlock_buffer(bh);
 505                 goto verify;
 506         }
 507         ext4_lock_group(sb, block_group);
 508         if (ext4_has_group_desc_csum(sb) &&
 509             (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 510                 if (block_group == 0) {
 511                         ext4_unlock_group(sb, block_group);
 512                         unlock_buffer(bh);
 513                         ext4_error(sb, "Block bitmap for bg 0 marked "
 514                                    "uninitialized");
 515                         err = -EFSCORRUPTED;
 516                         goto out;
 517                 }
 518                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 519                 if (err) {
 520                         ext4_unlock_group(sb, block_group);
 521                         unlock_buffer(bh);
 522                         ext4_error(sb, "Failed to init block bitmap for group "
 523                                    "%u: %d", block_group, err);
 524                         goto out;
 525                 }
 526                 set_bitmap_uptodate(bh);
 527                 set_buffer_uptodate(bh);
 528                 set_buffer_verified(bh);
 529                 ext4_unlock_group(sb, block_group);
 530                 unlock_buffer(bh);
 531                 return bh;
 532         }
 533         ext4_unlock_group(sb, block_group);
 534         if (buffer_uptodate(bh)) {
 535                 /*
 536                  * if not uninit if bh is uptodate,
 537                  * bitmap is also uptodate
 538                  */
 539                 set_bitmap_uptodate(bh);
 540                 unlock_buffer(bh);
 541                 goto verify;
 542         }
 543         /*
 544          * submit the buffer_head for reading
 545          */
 546         set_buffer_new(bh);
 547         trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
 548         ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
 549                             (ignore_locked ? REQ_RAHEAD : 0),
 550                             ext4_end_bitmap_read);
 551         return bh;
 552 verify:
 553         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 554         if (err)
 555                 goto out;
 556         return bh;
 557 out:
 558         put_bh(bh);
 559         return ERR_PTR(err);
 560 }
 561
 562 /* Returns 0 on success, -errno on error */
 563 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 564                            struct buffer_head *bh)
 565 {
 566         struct ext4_group_desc *desc;
 567
 568         if (!buffer_new(bh))
 569                 return 0;
 570         desc = ext4_get_group_desc(sb, block_group, NULL);
 571         if (!desc)
 572                 return -EFSCORRUPTED;
 573         wait_on_buffer(bh);
 574         ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
 575         if (!buffer_uptodate(bh)) {
 576                 ext4_error_err(sb, EIO, "Cannot read block bitmap - "
 577                                "block_group = %u, block_bitmap = %llu",
 578                                block_group, (unsigned long long) bh->b_blocknr);
 579                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 580                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 581                 return -EIO;
 582         }
 583         clear_buffer_new(bh);
 584         /* Panic or remount fs read-only if block bitmap is invalid */
 585         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 586 }
 587
 588 struct buffer_head *
 589 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 590 {
 591         struct buffer_head *bh;
 592         int err;
 593
 594         bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
 595         if (IS_ERR(bh))
 596                 return bh;
 597         err = ext4_wait_block_bitmap(sb, block_group, bh);
 598         if (err) {
 599                 put_bh(bh);
 600                 return ERR_PTR(err);
 601         }
 602         return bh;
 603 }
 604
 605 /**
 606  * ext4_has_free_clusters()
 607  * @sbi:        in-core super block structure.
 608  * @nclusters:  number of needed blocks
 609  * @flags:      flags from ext4_mb_new_blocks()
 610  *
 611  * Check if filesystem has nclusters free & available for allocation.
 612  * On success return 1, return 0 on failure.
 613  */
 614 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 615                                   s64 nclusters, unsigned int flags)
 616 {
 617         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 618         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 619         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 620
 621         free_clusters  = percpu_counter_read_positive(fcc);
 622         dirty_clusters = percpu_counter_read_positive(dcc);
 623         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 624
 625         /*
 626          * r_blocks_count should always be multiple of the cluster ratio so
 627          * we are safe to do a plane bit shift only.
 628          */
 629         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 630               resv_clusters;
 631
 632         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 633                                         EXT4_FREECLUSTERS_WATERMARK) {
 634                 free_clusters  = percpu_counter_sum_positive(fcc);
 635                 dirty_clusters = percpu_counter_sum_positive(dcc);
 636         }
 637         /* Check whether we have space after accounting for current
 638          * dirty clusters & root reserved clusters.
 639          */
 640         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 641                 return 1;
 642
 643         /* Hm, nope.  Are (enough) root reserved clusters available? */
 644         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 645             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 646             capable(CAP_SYS_RESOURCE) ||
 647             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 648
 649                 if (free_clusters >= (nclusters + dirty_clusters +
 650                                       resv_clusters))
 651                         return 1;
 652         }
 653         /* No free blocks. Let's see if we can dip into reserved pool */
 654         if (flags & EXT4_MB_USE_RESERVED) {
 655                 if (free_clusters >= (nclusters + dirty_clusters))
 656                         return 1;
 657         }
 658
 659         return 0;
 660 }
 661
 662 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 663                              s64 nclusters, unsigned int flags)
 664 {
 665         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 666                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 667                 return 0;
 668         } else
 669                 return -ENOSPC;
 670 }
 671
 672 /**
 673  * ext4_should_retry_alloc() - check if a block allocation should be retried
 674  * @sb:                 superblock
 675  * @retries:            number of retry attempts made so far
 676  *
 677  * ext4_should_retry_alloc() is called when ENOSPC is returned while
 678  * attempting to allocate blocks.  If there's an indication that a pending
 679  * journal transaction might free some space and allow another attempt to
 680  * succeed, this function will wait for the current or committing transaction
 681  * to complete and then return TRUE.
 682  */
 683 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 684 {
 685         struct ext4_sb_info *sbi = EXT4_SB(sb);
 686
 687         if (!sbi->s_journal)
 688                 return 0;
 689
 690         if (++(*retries) > 3) {
 691                 percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
 692                 return 0;
 693         }
 694
 695         /*
 696          * if there's no indication that blocks are about to be freed it's
 697          * possible we just missed a transaction commit that did so
 698          */
 699         smp_mb();
 700         if (sbi->s_mb_free_pending == 0) {
 701                 if (test_opt(sb, DISCARD)) {
 702                         atomic_inc(&sbi->s_retry_alloc_pending);
 703                         flush_work(&sbi->s_discard_work);
 704                         atomic_dec(&sbi->s_retry_alloc_pending);
 705                 }
 706                 return ext4_has_free_clusters(sbi, 1, 0);
 707         }
 708
 709         /*
 710          * it's possible we've just missed a transaction commit here,
 711          * so ignore the returned status
 712          */
 713         ext4_debug("%s: retrying operation after ENOSPC\n", sb->s_id);
 714         (void) jbd2_journal_force_commit_nested(sbi->s_journal);
 715         return 1;
 716 }
 717
 718 /*
 719  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 720  *
 721  * @handle:             handle to this transaction
 722  * @inode:              file inode
 723  * @goal:               given target block(filesystem wide)
 724  * @count:              pointer to total number of clusters needed
 725  * @errp:               error code
 726  *
 727  * Return 1st allocated block number on success, *count stores total account
 728  * error stores in errp pointer
 729  */
 730 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 731                                   ext4_fsblk_t goal, unsigned int flags,
 732                                   unsigned long *count, int *errp)
 733 {
 734         struct ext4_allocation_request ar;
 735         ext4_fsblk_t ret;
 736
 737         memset(&ar, 0, sizeof(ar));
 738         /* Fill with neighbour allocated blocks */
 739         ar.inode = inode;
 740         ar.goal = goal;
 741         ar.len = count ? *count : 1;
 742         ar.flags = flags;
 743
 744         ret = ext4_mb_new_blocks(handle, &ar, errp);
 745         if (count)
 746                 *count = ar.len;
 747         /*
 748          * Account for the allocated meta blocks.  We will never
 749          * fail EDQUOT for metdata, but we do account for it.
 750          */
 751         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 752                 dquot_alloc_block_nofail(inode,
 753                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 754         }
 755         return ret;
 756 }
 757
 758 /**
 759  * ext4_count_free_clusters() -- count filesystem free clusters
 760  * @sb:         superblock
 761  *
 762  * Adds up the number of free clusters from each block group.
 763  */
 764 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 765 {
 766         ext4_fsblk_t desc_count;
 767         struct ext4_group_desc *gdp;
 768         ext4_group_t i;
 769         ext4_group_t ngroups = ext4_get_groups_count(sb);
 770         struct ext4_group_info *grp;
 771 #ifdef EXT4FS_DEBUG
 772         struct ext4_super_block *es;
 773         ext4_fsblk_t bitmap_count;
 774         unsigned int x;
 775         struct buffer_head *bitmap_bh = NULL;
 776
 777         es = EXT4_SB(sb)->s_es;
 778         desc_count = 0;
 779         bitmap_count = 0;
 780         gdp = NULL;
 781
 782         for (i = 0; i < ngroups; i++) {
 783                 gdp = ext4_get_group_desc(sb, i, NULL);
 784                 if (!gdp)
 785                         continue;
 786                 grp = NULL;
 787                 if (EXT4_SB(sb)->s_group_info)
 788                         grp = ext4_get_group_info(sb, i);
 789                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 790                         desc_count += ext4_free_group_clusters(sb, gdp);
 791                 brelse(bitmap_bh);
 792                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 793                 if (IS_ERR(bitmap_bh)) {
 794                         bitmap_bh = NULL;
 795                         continue;
 796                 }
 797
 798                 x = ext4_count_free(bitmap_bh->b_data,
 799                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 800                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 801                         i, ext4_free_group_clusters(sb, gdp), x);
 802                 bitmap_count += x;
 803         }
 804         brelse(bitmap_bh);
 805         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 806                ", computed = %llu, %llu\n",
 807                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 808                desc_count, bitmap_count);
 809         return bitmap_count;
 810 #else
 811         desc_count = 0;
 812         for (i = 0; i < ngroups; i++) {
 813                 gdp = ext4_get_group_desc(sb, i, NULL);
 814                 if (!gdp)
 815                         continue;
 816                 grp = NULL;
 817                 if (EXT4_SB(sb)->s_group_info)
 818                         grp = ext4_get_group_info(sb, i);
 819                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 820                         desc_count += ext4_free_group_clusters(sb, gdp);
 821         }
 822
 823         return desc_count;
 824 #endif
 825 }
 826
 827 static inline int test_root(ext4_group_t a, int b)
 828 {
 829         while (1) {
 830                 if (a < b)
 831                         return 0;
 832                 if (a == b)
 833                         return 1;
 834                 if ((a % b) != 0)
 835                         return 0;
 836                 a = a / b;
 837         }
 838 }
 839
 840 /**
 841  *      ext4_bg_has_super - number of blocks used by the superblock in group
 842  *      @sb: superblock for filesystem
 843  *      @group: group number to check
 844  *
 845  *      Return the number of blocks used by the superblock (primary or backup)
 846  *      in this group.  Currently this will be only 0 or 1.
 847  */
 848 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 849 {
 850         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 851
 852         if (group == 0)
 853                 return 1;
 854         if (ext4_has_feature_sparse_super2(sb)) {
 855                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 856                     group == le32_to_cpu(es->s_backup_bgs[1]))
 857                         return 1;
 858                 return 0;
 859         }
 860         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 861                 return 1;
 862         if (!(group & 1))
 863                 return 0;
 864         if (test_root(group, 3) || (test_root(group, 5)) ||
 865             test_root(group, 7))
 866                 return 1;
 867
 868         return 0;
 869 }
 870
 871 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 872                                         ext4_group_t group)
 873 {
 874         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 875         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 876         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 877
 878         if (group == first || group == first + 1 || group == last)
 879                 return 1;
 880         return 0;
 881 }
 882
 883 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 884                                         ext4_group_t group)
 885 {
 886         if (!ext4_bg_has_super(sb, group))
 887                 return 0;
 888
 889         return EXT4_SB(sb)->s_gdb_count;
 890 }
 891
 892 /**
 893  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 894  *      @sb: superblock for filesystem
 895  *      @group: group number to check
 896  *
 897  *      Return the number of blocks used by the group descriptor table
 898  *      (primary or backup) in this group.  In the future there may be a
 899  *      different number of descriptor blocks in each group.
 900  */
 901 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 902 {
 903         unsigned long first_meta_bg =
 904                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 905         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 906
 907         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 908                 return ext4_bg_num_gdb_nometa(sb, group);
 909
 910         return ext4_bg_num_gdb_meta(sb,group);
 911
 912 }
 913
 914 /*
 915  * This function returns the number of file system metadata clusters at
 916  * the beginning of a block group, including the reserved gdt blocks.
 917  */
 918 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 919                                      ext4_group_t block_group)
 920 {
 921         struct ext4_sb_info *sbi = EXT4_SB(sb);
 922         unsigned num;
 923
 924         /* Check for superblock and gdt backups in this group */
 925         num = ext4_bg_has_super(sb, block_group);
 926
 927         if (!ext4_has_feature_meta_bg(sb) ||
 928             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 929                           sbi->s_desc_per_block) {
 930                 if (num) {
 931                         num += ext4_bg_num_gdb_nometa(sb, block_group);
 932                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 933                 }
 934         } else { /* For META_BG_BLOCK_GROUPS */
 935                 num += ext4_bg_num_gdb_meta(sb, block_group);
 936         }
 937         return EXT4_NUM_B2C(sbi, num);
 938 }
 939 /**
 940  *      ext4_inode_to_goal_block - return a hint for block allocation
 941  *      @inode: inode for block allocation
 942  *
 943  *      Return the ideal location to start allocating blocks for a
 944  *      newly created inode.
 945  */
 946 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 947 {
 948         struct ext4_inode_info *ei = EXT4_I(inode);
 949         ext4_group_t block_group;
 950         ext4_grpblk_t colour;
 951         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 952         ext4_fsblk_t bg_start;
 953         ext4_fsblk_t last_block;
 954
 955         block_group = ei->i_block_group;
 956         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 957                 /*
 958                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 959                  * block groups per flexgroup, reserve the first block
 960                  * group for directories and special files.  Regular
 961                  * files will start at the second block group.  This
 962                  * tends to speed up directory access and improves
 963                  * fsck times.
 964                  */
 965                 block_group &= ~(flex_size-1);
 966                 if (S_ISREG(inode->i_mode))
 967                         block_group++;
 968         }
 969         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 970         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 971
 972         /*
 973          * If we are doing delayed allocation, we don't need take
 974          * colour into account.
 975          */
 976         if (test_opt(inode->i_sb, DELALLOC))
 977                 return bg_start;
 978
 979         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 980                 colour = (task_pid_nr(current) % 16) *
 981                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 982         else
 983                 colour = (task_pid_nr(current) % 16) *
 984                         ((last_block - bg_start) / 16);
 985         return bg_start + colour;
 986 }
 987