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                 return NULL;
 332         indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
 333         indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
 334         grp_info = sbi_array_rcu_deref(EXT4_SB(sb), s_group_info, indexv);
 335         return grp_info[indexh];
 336 }
 337
 338 /*
 339  * Return the block number which was discovered to be invalid, or 0 if
 340  * the block bitmap is valid.
 341  */
 342 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
 343                                             struct ext4_group_desc *desc,
 344                                             ext4_group_t block_group,
 345                                             struct buffer_head *bh)
 346 {
 347         struct ext4_sb_info *sbi = EXT4_SB(sb);
 348         ext4_grpblk_t offset;
 349         ext4_grpblk_t next_zero_bit;
 350         ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
 351         ext4_fsblk_t blk;
 352         ext4_fsblk_t group_first_block;
 353
 354         if (ext4_has_feature_flex_bg(sb)) {
 355                 /* with FLEX_BG, the inode/block bitmaps and itable
 356                  * blocks may not be in the group at all
 357                  * so the bitmap validation will be skipped for those groups
 358                  * or it has to also read the block group where the bitmaps
 359                  * are located to verify they are set.
 360                  */
 361                 return 0;
 362         }
 363         group_first_block = ext4_group_first_block_no(sb, block_group);
 364
 365         /* check whether block bitmap block number is set */
 366         blk = ext4_block_bitmap(sb, desc);
 367         offset = blk - group_first_block;
 368         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 369             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 370                 /* bad block bitmap */
 371                 return blk;
 372
 373         /* check whether the inode bitmap block number is set */
 374         blk = ext4_inode_bitmap(sb, desc);
 375         offset = blk - group_first_block;
 376         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 377             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
 378                 /* bad block bitmap */
 379                 return blk;
 380
 381         /* check whether the inode table block number is set */
 382         blk = ext4_inode_table(sb, desc);
 383         offset = blk - group_first_block;
 384         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
 385             EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) >= max_bit)
 386                 return blk;
 387         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 388                         EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) + 1,
 389                         EXT4_B2C(sbi, offset));
 390         if (next_zero_bit <
 391             EXT4_B2C(sbi, offset + sbi->s_itb_per_group - 1) + 1)
 392                 /* bad bitmap for inode tables */
 393                 return blk;
 394         return 0;
 395 }
 396
 397 static int ext4_validate_block_bitmap(struct super_block *sb,
 398                                       struct ext4_group_desc *desc,
 399                                       ext4_group_t block_group,
 400                                       struct buffer_head *bh)
 401 {
 402         ext4_fsblk_t    blk;
 403         struct ext4_group_info *grp;
 404
 405         if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)
 406                 return 0;
 407
 408         grp = ext4_get_group_info(sb, block_group);
 409
 410         if (buffer_verified(bh))
 411                 return 0;
 412         if (!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 413                 return -EFSCORRUPTED;
 414
 415         ext4_lock_group(sb, block_group);
 416         if (buffer_verified(bh))
 417                 goto verified;
 418         if (unlikely(!ext4_block_bitmap_csum_verify(sb, desc, bh) ||
 419                      ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {
 420                 ext4_unlock_group(sb, block_group);
 421                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
 422                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 423                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 424                 return -EFSBADCRC;
 425         }
 426         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
 427         if (unlikely(blk != 0)) {
 428                 ext4_unlock_group(sb, block_group);
 429                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
 430                            block_group, blk);
 431                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 432                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 433                 return -EFSCORRUPTED;
 434         }
 435         blk = ext4_valid_block_bitmap_padding(sb, block_group, bh);
 436         if (unlikely(blk != 0)) {
 437                 ext4_unlock_group(sb, block_group);
 438                 ext4_error(sb, "bg %u: block %llu: padding at end of block bitmap is not set",
 439                            block_group, blk);
 440                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 441                                                  EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 442                 return -EFSCORRUPTED;
 443         }
 444         set_buffer_verified(bh);
 445 verified:
 446         ext4_unlock_group(sb, block_group);
 447         return 0;
 448 }
 449
 450 /**
 451  * ext4_read_block_bitmap_nowait()
 452  * @sb:                 super block
 453  * @block_group:        given block group
 454  * @ignore_locked:      ignore locked buffers
 455  *
 456  * Read the bitmap for a given block_group,and validate the
 457  * bits for block/inode/inode tables are set in the bitmaps
 458  *
 459  * Return buffer_head on success or an ERR_PTR in case of failure.
 460  */
 461 struct buffer_head *
 462 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
 463                               bool ignore_locked)
 464 {
 465         struct ext4_group_desc *desc;
 466         struct ext4_sb_info *sbi = EXT4_SB(sb);
 467         struct buffer_head *bh;
 468         ext4_fsblk_t bitmap_blk;
 469         int err;
 470
 471         desc = ext4_get_group_desc(sb, block_group, NULL);
 472         if (!desc)
 473                 return ERR_PTR(-EFSCORRUPTED);
 474         bitmap_blk = ext4_block_bitmap(sb, desc);
 475         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 476             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
 477                 ext4_error(sb, "Invalid block bitmap block %llu in "
 478                            "block_group %u", bitmap_blk, block_group);
 479                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 480                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 481                 return ERR_PTR(-EFSCORRUPTED);
 482         }
 483         bh = sb_getblk(sb, bitmap_blk);
 484         if (unlikely(!bh)) {
 485                 ext4_warning(sb, "Cannot get buffer for block bitmap - "
 486                              "block_group = %u, block_bitmap = %llu",
 487                              block_group, bitmap_blk);
 488                 return ERR_PTR(-ENOMEM);
 489         }
 490
 491         if (ignore_locked && buffer_locked(bh)) {
 492                 /* buffer under IO already, return if called for prefetching */
 493                 put_bh(bh);
 494                 return NULL;
 495         }
 496
 497         if (bitmap_uptodate(bh))
 498                 goto verify;
 499
 500         lock_buffer(bh);
 501         if (bitmap_uptodate(bh)) {
 502                 unlock_buffer(bh);
 503                 goto verify;
 504         }
 505         ext4_lock_group(sb, block_group);
 506         if (ext4_has_group_desc_csum(sb) &&
 507             (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 508                 if (block_group == 0) {
 509                         ext4_unlock_group(sb, block_group);
 510                         unlock_buffer(bh);
 511                         ext4_error(sb, "Block bitmap for bg 0 marked "
 512                                    "uninitialized");
 513                         err = -EFSCORRUPTED;
 514                         goto out;
 515                 }
 516                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 517                 if (err) {
 518                         ext4_unlock_group(sb, block_group);
 519                         unlock_buffer(bh);
 520                         ext4_error(sb, "Failed to init block bitmap for group "
 521                                    "%u: %d", block_group, err);
 522                         goto out;
 523                 }
 524                 set_bitmap_uptodate(bh);
 525                 set_buffer_uptodate(bh);
 526                 set_buffer_verified(bh);
 527                 ext4_unlock_group(sb, block_group);
 528                 unlock_buffer(bh);
 529                 return bh;
 530         }
 531         ext4_unlock_group(sb, block_group);
 532         if (buffer_uptodate(bh)) {
 533                 /*
 534                  * if not uninit if bh is uptodate,
 535                  * bitmap is also uptodate
 536                  */
 537                 set_bitmap_uptodate(bh);
 538                 unlock_buffer(bh);
 539                 goto verify;
 540         }
 541         /*
 542          * submit the buffer_head for reading
 543          */
 544         set_buffer_new(bh);
 545         trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
 546         ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
 547                             (ignore_locked ? REQ_RAHEAD : 0),
 548                             ext4_end_bitmap_read);
 549         return bh;
 550 verify:
 551         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 552         if (err)
 553                 goto out;
 554         return bh;
 555 out:
 556         put_bh(bh);
 557         return ERR_PTR(err);
 558 }
 559
 560 /* Returns 0 on success, -errno on error */
 561 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 562                            struct buffer_head *bh)
 563 {
 564         struct ext4_group_desc *desc;
 565
 566         if (!buffer_new(bh))
 567                 return 0;
 568         desc = ext4_get_group_desc(sb, block_group, NULL);
 569         if (!desc)
 570                 return -EFSCORRUPTED;
 571         wait_on_buffer(bh);
 572         ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
 573         if (!buffer_uptodate(bh)) {
 574                 ext4_error_err(sb, EIO, "Cannot read block bitmap - "
 575                                "block_group = %u, block_bitmap = %llu",
 576                                block_group, (unsigned long long) bh->b_blocknr);
 577                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 578                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 579                 return -EIO;
 580         }
 581         clear_buffer_new(bh);
 582         /* Panic or remount fs read-only if block bitmap is invalid */
 583         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 584 }
 585
 586 struct buffer_head *
 587 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 588 {
 589         struct buffer_head *bh;
 590         int err;
 591
 592         bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
 593         if (IS_ERR(bh))
 594                 return bh;
 595         err = ext4_wait_block_bitmap(sb, block_group, bh);
 596         if (err) {
 597                 put_bh(bh);
 598                 return ERR_PTR(err);
 599         }
 600         return bh;
 601 }
 602
 603 /**
 604  * ext4_has_free_clusters()
 605  * @sbi:        in-core super block structure.
 606  * @nclusters:  number of needed blocks
 607  * @flags:      flags from ext4_mb_new_blocks()
 608  *
 609  * Check if filesystem has nclusters free & available for allocation.
 610  * On success return 1, return 0 on failure.
 611  */
 612 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 613                                   s64 nclusters, unsigned int flags)
 614 {
 615         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 616         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 617         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 618
 619         free_clusters  = percpu_counter_read_positive(fcc);
 620         dirty_clusters = percpu_counter_read_positive(dcc);
 621         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 622
 623         /*
 624          * r_blocks_count should always be multiple of the cluster ratio so
 625          * we are safe to do a plane bit shift only.
 626          */
 627         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 628               resv_clusters;
 629
 630         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 631                                         EXT4_FREECLUSTERS_WATERMARK) {
 632                 free_clusters  = percpu_counter_sum_positive(fcc);
 633                 dirty_clusters = percpu_counter_sum_positive(dcc);
 634         }
 635         /* Check whether we have space after accounting for current
 636          * dirty clusters & root reserved clusters.
 637          */
 638         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 639                 return 1;
 640
 641         /* Hm, nope.  Are (enough) root reserved clusters available? */
 642         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 643             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 644             capable(CAP_SYS_RESOURCE) ||
 645             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 646
 647                 if (free_clusters >= (nclusters + dirty_clusters +
 648                                       resv_clusters))
 649                         return 1;
 650         }
 651         /* No free blocks. Let's see if we can dip into reserved pool */
 652         if (flags & EXT4_MB_USE_RESERVED) {
 653                 if (free_clusters >= (nclusters + dirty_clusters))
 654                         return 1;
 655         }
 656
 657         return 0;
 658 }
 659
 660 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 661                              s64 nclusters, unsigned int flags)
 662 {
 663         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 664                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 665                 return 0;
 666         } else
 667                 return -ENOSPC;
 668 }
 669
 670 /**
 671  * ext4_should_retry_alloc() - check if a block allocation should be retried
 672  * @sb:                 superblock
 673  * @retries:            number of retry attempts made so far
 674  *
 675  * ext4_should_retry_alloc() is called when ENOSPC is returned while
 676  * attempting to allocate blocks.  If there's an indication that a pending
 677  * journal transaction might free some space and allow another attempt to
 678  * succeed, this function will wait for the current or committing transaction
 679  * to complete and then return TRUE.
 680  */
 681 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 682 {
 683         struct ext4_sb_info *sbi = EXT4_SB(sb);
 684
 685         if (!sbi->s_journal)
 686                 return 0;
 687
 688         if (++(*retries) > 3) {
 689                 percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
 690                 return 0;
 691         }
 692
 693         /*
 694          * if there's no indication that blocks are about to be freed it's
 695          * possible we just missed a transaction commit that did so
 696          */
 697         smp_mb();
 698         if (sbi->s_mb_free_pending == 0) {
 699                 if (test_opt(sb, DISCARD)) {
 700                         atomic_inc(&sbi->s_retry_alloc_pending);
 701                         flush_work(&sbi->s_discard_work);
 702                         atomic_dec(&sbi->s_retry_alloc_pending);
 703                 }
 704                 return ext4_has_free_clusters(sbi, 1, 0);
 705         }
 706
 707         /*
 708          * it's possible we've just missed a transaction commit here,
 709          * so ignore the returned status
 710          */
 711         ext4_debug("%s: retrying operation after ENOSPC\n", sb->s_id);
 712         (void) jbd2_journal_force_commit_nested(sbi->s_journal);
 713         return 1;
 714 }
 715
 716 /*
 717  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 718  *
 719  * @handle:             handle to this transaction
 720  * @inode:              file inode
 721  * @goal:               given target block(filesystem wide)
 722  * @count:              pointer to total number of clusters needed
 723  * @errp:               error code
 724  *
 725  * Return 1st allocated block number on success, *count stores total account
 726  * error stores in errp pointer
 727  */
 728 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 729                                   ext4_fsblk_t goal, unsigned int flags,
 730                                   unsigned long *count, int *errp)
 731 {
 732         struct ext4_allocation_request ar;
 733         ext4_fsblk_t ret;
 734
 735         memset(&ar, 0, sizeof(ar));
 736         /* Fill with neighbour allocated blocks */
 737         ar.inode = inode;
 738         ar.goal = goal;
 739         ar.len = count ? *count : 1;
 740         ar.flags = flags;
 741
 742         ret = ext4_mb_new_blocks(handle, &ar, errp);
 743         if (count)
 744                 *count = ar.len;
 745         /*
 746          * Account for the allocated meta blocks.  We will never
 747          * fail EDQUOT for metdata, but we do account for it.
 748          */
 749         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 750                 dquot_alloc_block_nofail(inode,
 751                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 752         }
 753         return ret;
 754 }
 755
 756 /**
 757  * ext4_count_free_clusters() -- count filesystem free clusters
 758  * @sb:         superblock
 759  *
 760  * Adds up the number of free clusters from each block group.
 761  */
 762 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 763 {
 764         ext4_fsblk_t desc_count;
 765         struct ext4_group_desc *gdp;
 766         ext4_group_t i;
 767         ext4_group_t ngroups = ext4_get_groups_count(sb);
 768         struct ext4_group_info *grp;
 769 #ifdef EXT4FS_DEBUG
 770         struct ext4_super_block *es;
 771         ext4_fsblk_t bitmap_count;
 772         unsigned int x;
 773         struct buffer_head *bitmap_bh = NULL;
 774
 775         es = EXT4_SB(sb)->s_es;
 776         desc_count = 0;
 777         bitmap_count = 0;
 778         gdp = NULL;
 779
 780         for (i = 0; i < ngroups; i++) {
 781                 gdp = ext4_get_group_desc(sb, i, NULL);
 782                 if (!gdp)
 783                         continue;
 784                 grp = NULL;
 785                 if (EXT4_SB(sb)->s_group_info)
 786                         grp = ext4_get_group_info(sb, i);
 787                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 788                         desc_count += ext4_free_group_clusters(sb, gdp);
 789                 brelse(bitmap_bh);
 790                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 791                 if (IS_ERR(bitmap_bh)) {
 792                         bitmap_bh = NULL;
 793                         continue;
 794                 }
 795
 796                 x = ext4_count_free(bitmap_bh->b_data,
 797                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 798                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 799                         i, ext4_free_group_clusters(sb, gdp), x);
 800                 bitmap_count += x;
 801         }
 802         brelse(bitmap_bh);
 803         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 804                ", computed = %llu, %llu\n",
 805                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 806                desc_count, bitmap_count);
 807         return bitmap_count;
 808 #else
 809         desc_count = 0;
 810         for (i = 0; i < ngroups; i++) {
 811                 gdp = ext4_get_group_desc(sb, i, NULL);
 812                 if (!gdp)
 813                         continue;
 814                 grp = NULL;
 815                 if (EXT4_SB(sb)->s_group_info)
 816                         grp = ext4_get_group_info(sb, i);
 817                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 818                         desc_count += ext4_free_group_clusters(sb, gdp);
 819         }
 820
 821         return desc_count;
 822 #endif
 823 }
 824
 825 static inline int test_root(ext4_group_t a, int b)
 826 {
 827         while (1) {
 828                 if (a < b)
 829                         return 0;
 830                 if (a == b)
 831                         return 1;
 832                 if ((a % b) != 0)
 833                         return 0;
 834                 a = a / b;
 835         }
 836 }
 837
 838 /**
 839  *      ext4_bg_has_super - number of blocks used by the superblock in group
 840  *      @sb: superblock for filesystem
 841  *      @group: group number to check
 842  *
 843  *      Return the number of blocks used by the superblock (primary or backup)
 844  *      in this group.  Currently this will be only 0 or 1.
 845  */
 846 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 847 {
 848         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 849
 850         if (group == 0)
 851                 return 1;
 852         if (ext4_has_feature_sparse_super2(sb)) {
 853                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 854                     group == le32_to_cpu(es->s_backup_bgs[1]))
 855                         return 1;
 856                 return 0;
 857         }
 858         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 859                 return 1;
 860         if (!(group & 1))
 861                 return 0;
 862         if (test_root(group, 3) || (test_root(group, 5)) ||
 863             test_root(group, 7))
 864                 return 1;
 865
 866         return 0;
 867 }
 868
 869 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 870                                         ext4_group_t group)
 871 {
 872         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 873         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 874         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 875
 876         if (group == first || group == first + 1 || group == last)
 877                 return 1;
 878         return 0;
 879 }
 880
 881 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 882                                         ext4_group_t group)
 883 {
 884         if (!ext4_bg_has_super(sb, group))
 885                 return 0;
 886
 887         if (ext4_has_feature_meta_bg(sb))
 888                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 889         else
 890                 return EXT4_SB(sb)->s_gdb_count;
 891 }
 892
 893 /**
 894  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 895  *      @sb: superblock for filesystem
 896  *      @group: group number to check
 897  *
 898  *      Return the number of blocks used by the group descriptor table
 899  *      (primary or backup) in this group.  In the future there may be a
 900  *      different number of descriptor blocks in each group.
 901  */
 902 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 903 {
 904         unsigned long first_meta_bg =
 905                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 906         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 907
 908         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 909                 return ext4_bg_num_gdb_nometa(sb, group);
 910
 911         return ext4_bg_num_gdb_meta(sb,group);
 912
 913 }
 914
 915 /*
 916  * This function returns the number of file system metadata blocks at
 917  * the beginning of a block group, including the reserved gdt blocks.
 918  */
 919 unsigned int ext4_num_base_meta_blocks(struct super_block *sb,
 920                                        ext4_group_t block_group)
 921 {
 922         struct ext4_sb_info *sbi = EXT4_SB(sb);
 923         unsigned num;
 924
 925         /* Check for superblock and gdt backups in this group */
 926         num = ext4_bg_has_super(sb, block_group);
 927
 928         if (!ext4_has_feature_meta_bg(sb) ||
 929             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 930                           sbi->s_desc_per_block) {
 931                 if (num) {
 932                         num += ext4_bg_num_gdb_nometa(sb, block_group);
 933                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 934                 }
 935         } else { /* For META_BG_BLOCK_GROUPS */
 936                 num += ext4_bg_num_gdb_meta(sb, block_group);
 937         }
 938         return num;
 939 }
 940
 941 static unsigned int ext4_num_base_meta_clusters(struct super_block *sb,
 942                                                 ext4_group_t block_group)
 943 {
 944         return EXT4_NUM_B2C(EXT4_SB(sb), ext4_num_base_meta_blocks(sb, block_group));
 945 }
 946
 947 /**
 948  *      ext4_inode_to_goal_block - return a hint for block allocation
 949  *      @inode: inode for block allocation
 950  *
 951  *      Return the ideal location to start allocating blocks for a
 952  *      newly created inode.
 953  */
 954 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 955 {
 956         struct ext4_inode_info *ei = EXT4_I(inode);
 957         ext4_group_t block_group;
 958         ext4_grpblk_t colour;
 959         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 960         ext4_fsblk_t bg_start;
 961         ext4_fsblk_t last_block;
 962
 963         block_group = ei->i_block_group;
 964         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 965                 /*
 966                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 967                  * block groups per flexgroup, reserve the first block
 968                  * group for directories and special files.  Regular
 969                  * files will start at the second block group.  This
 970                  * tends to speed up directory access and improves
 971                  * fsck times.
 972                  */
 973                 block_group &= ~(flex_size-1);
 974                 if (S_ISREG(inode->i_mode))
 975                         block_group++;
 976         }
 977         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 978         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 979
 980         /*
 981          * If we are doing delayed allocation, we don't need take
 982          * colour into account.
 983          */
 984         if (test_opt(inode->i_sb, DELALLOC))
 985                 return bg_start;
 986
 987         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 988                 colour = (task_pid_nr(current) % 16) *
 989                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 990         else
 991                 colour = (task_pid_nr(current) % 16) *
 992                         ((last_block - bg_start) / 16);
 993         return bg_start + colour;
 994 }
 995