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 #include <kunit/static_stub.h>
  26
  27 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
  28                                             ext4_group_t block_group);
  29 /*
  30  * balloc.c contains the blocks allocation and deallocation routines
  31  */
  32
  33 /*
  34  * Calculate block group number for a given block number
  35  */
  36 ext4_group_t ext4_get_group_number(struct super_block *sb,
  37                                    ext4_fsblk_t block)
  38 {
  39         ext4_group_t group;
  40
  41         if (test_opt2(sb, STD_GROUP_SIZE))
  42                 group = (block -
  43                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
  44                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
  45         else
  46                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
  47         return group;
  48 }
  49
  50 /*
  51  * Calculate the block group number and offset into the block/cluster
  52  * allocation bitmap, given a block number
  53  */
  54 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  55                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  56 {
  57         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  58         ext4_grpblk_t offset;
  59
  60         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  61         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
  62                 EXT4_SB(sb)->s_cluster_bits;
  63         if (offsetp)
  64                 *offsetp = offset;
  65         if (blockgrpp)
  66                 *blockgrpp = blocknr;
  67
  68 }
  69
  70 /*
  71  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
  72  * and 0 otherwise.
  73  */
  74 static inline int ext4_block_in_group(struct super_block *sb,
  75                                       ext4_fsblk_t block,
  76                                       ext4_group_t block_group)
  77 {
  78         ext4_group_t actual_group;
  79
  80         actual_group = ext4_get_group_number(sb, block);
  81         return (actual_group == block_group) ? 1 : 0;
  82 }
  83
  84 /*
  85  * Return the number of clusters used for file system metadata; this
  86  * represents the overhead needed by the file system.
  87  */
  88 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
  89                                            ext4_group_t block_group,
  90                                            struct ext4_group_desc *gdp)
  91 {
  92         unsigned base_clusters, num_clusters;
  93         int block_cluster = -1, inode_cluster;
  94         int itbl_cluster_start = -1, itbl_cluster_end = -1;
  95         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
  96         ext4_fsblk_t end = start + EXT4_BLOCKS_PER_GROUP(sb) - 1;
  97         ext4_fsblk_t itbl_blk_start, itbl_blk_end;
  98         struct ext4_sb_info *sbi = EXT4_SB(sb);
  99
 100         /* This is the number of clusters used by the superblock,
 101          * block group descriptors, and reserved block group
 102          * descriptor blocks */
 103         base_clusters = ext4_num_base_meta_clusters(sb, block_group);
 104         num_clusters = base_clusters;
 105
 106         /*
 107          * Account and record inode table clusters if any cluster
 108          * is in the block group, or inode table cluster range is
 109          * [-1, -1] and won't overlap with block/inode bitmap cluster
 110          * accounted below.
 111          */
 112         itbl_blk_start = ext4_inode_table(sb, gdp);
 113         itbl_blk_end = itbl_blk_start + sbi->s_itb_per_group - 1;
 114         if (itbl_blk_start <= end && itbl_blk_end >= start) {
 115                 itbl_blk_start = max(itbl_blk_start, start);
 116                 itbl_blk_end = min(itbl_blk_end, end);
 117
 118                 itbl_cluster_start = EXT4_B2C(sbi, itbl_blk_start - start);
 119                 itbl_cluster_end = EXT4_B2C(sbi, itbl_blk_end - start);
 120
 121                 num_clusters += itbl_cluster_end - itbl_cluster_start + 1;
 122                 /* check if border cluster is overlapped */
 123                 if (itbl_cluster_start == base_clusters - 1)
 124                         num_clusters--;
 125         }
 126
 127         /*
 128          * For the allocation bitmaps, we first need to check to see
 129          * if the block is in the block group.  If it is, then check
 130          * to see if the cluster is already accounted for in the clusters
 131          * used for the base metadata cluster and inode tables cluster.
 132          * Normally all of these blocks are contiguous, so the special
 133          * case handling shouldn't be necessary except for *very*
 134          * unusual file system layouts.
 135          */
 136         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
 137                 block_cluster = EXT4_B2C(sbi,
 138                                          ext4_block_bitmap(sb, gdp) - start);
 139                 if (block_cluster >= base_clusters &&
 140                     (block_cluster < itbl_cluster_start ||
 141                     block_cluster > itbl_cluster_end))
 142                         num_clusters++;
 143         }
 144
 145         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
 146                 inode_cluster = EXT4_B2C(sbi,
 147                                          ext4_inode_bitmap(sb, gdp) - start);
 148                 /*
 149                  * Additional check if inode bitmap is in just accounted
 150                  * block_cluster
 151                  */
 152                 if (inode_cluster != block_cluster &&
 153                     inode_cluster >= base_clusters &&
 154                     (inode_cluster < itbl_cluster_start ||
 155                     inode_cluster > itbl_cluster_end))
 156                         num_clusters++;
 157         }
 158
 159         return num_clusters;
 160 }
 161
 162 static unsigned int num_clusters_in_group(struct super_block *sb,
 163                                           ext4_group_t block_group)
 164 {
 165         unsigned int blocks;
 166
 167         if (block_group == ext4_get_groups_count(sb) - 1) {
 168                 /*
 169                  * Even though mke2fs always initializes the first and
 170                  * last group, just in case some other tool was used,
 171                  * we need to make sure we calculate the right free
 172                  * blocks.
 173                  */
 174                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
 175                         ext4_group_first_block_no(sb, block_group);
 176         } else
 177                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
 178         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
 179 }
 180
 181 /* Initializes an uninitialized block bitmap */
 182 static int ext4_init_block_bitmap(struct super_block *sb,
 183                                    struct buffer_head *bh,
 184                                    ext4_group_t block_group,
 185                                    struct ext4_group_desc *gdp)
 186 {
 187         unsigned int bit, bit_max;
 188         struct ext4_sb_info *sbi = EXT4_SB(sb);
 189         ext4_fsblk_t start, tmp;
 190
 191         ASSERT(buffer_locked(bh));
 192
 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         /* Set bits for block and inode bitmaps, and inode table */
 211         tmp = ext4_block_bitmap(sb, gdp);
 212         if (ext4_block_in_group(sb, tmp, block_group))
 213                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 214
 215         tmp = ext4_inode_bitmap(sb, gdp);
 216         if (ext4_block_in_group(sb, tmp, block_group))
 217                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 218
 219         tmp = ext4_inode_table(sb, gdp);
 220         for (; tmp < ext4_inode_table(sb, gdp) +
 221                      sbi->s_itb_per_group; tmp++) {
 222                 if (ext4_block_in_group(sb, tmp, block_group))
 223                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
 224         }
 225
 226         /*
 227          * Also if the number of blocks within the group is less than
 228          * the blocksize * 8 ( which is the size of bitmap ), set rest
 229          * of the block bitmap to 1
 230          */
 231         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
 232                              sb->s_blocksize * 8, bh->b_data);
 233         return 0;
 234 }
 235
 236 /* Return the number of free blocks in a block group.  It is used when
 237  * the block bitmap is uninitialized, so we can't just count the bits
 238  * in the bitmap. */
 239 unsigned ext4_free_clusters_after_init(struct super_block *sb,
 240                                        ext4_group_t block_group,
 241                                        struct ext4_group_desc *gdp)
 242 {
 243         return num_clusters_in_group(sb, block_group) -
 244                 ext4_num_overhead_clusters(sb, block_group, gdp);
 245 }
 246
 247 /*
 248  * The free blocks are managed by bitmaps.  A file system contains several
 249  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 250  * block for inodes, N blocks for the inode table and data blocks.
 251  *
 252  * The file system contains group descriptors which are located after the
 253  * super block.  Each descriptor contains the number of the bitmap block and
 254  * the free blocks count in the block.  The descriptors are loaded in memory
 255  * when a file system is mounted (see ext4_fill_super).
 256  */
 257
 258 /**
 259  * ext4_get_group_desc() -- load group descriptor from disk
 260  * @sb:                 super block
 261  * @block_group:        given block group
 262  * @bh:                 pointer to the buffer head to store the block
 263  *                      group descriptor
 264  */
 265 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 266                                              ext4_group_t block_group,
 267                                              struct buffer_head **bh)
 268 {
 269         unsigned int group_desc;
 270         unsigned int offset;
 271         ext4_group_t ngroups = ext4_get_groups_count(sb);
 272         struct ext4_group_desc *desc;
 273         struct ext4_sb_info *sbi = EXT4_SB(sb);
 274         struct buffer_head *bh_p;
 275
 276         KUNIT_STATIC_STUB_REDIRECT(ext4_get_group_desc,
 277                                    sb, block_group, bh);
 278
 279         if (block_group >= ngroups) {
 280                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
 281                            " groups_count = %u", block_group, ngroups);
 282
 283                 return NULL;
 284         }
 285
 286         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 287         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 288         bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc);
 289         /*
 290          * sbi_array_rcu_deref returns with rcu unlocked, this is ok since
 291          * the pointer being dereferenced won't be dereferenced again. By
 292          * looking at the usage in add_new_gdb() the value isn't modified,
 293          * just the pointer, and so it remains valid.
 294          */
 295         if (!bh_p) {
 296                 ext4_error(sb, "Group descriptor not loaded - "
 297                            "block_group = %u, group_desc = %u, desc = %u",
 298                            block_group, group_desc, offset);
 299                 return NULL;
 300         }
 301
 302         desc = (struct ext4_group_desc *)(
 303                 (__u8 *)bh_p->b_data +
 304                 offset * EXT4_DESC_SIZE(sb));
 305         if (bh)
 306                 *bh = bh_p;
 307         return desc;
 308 }
 309
 310 static ext4_fsblk_t ext4_valid_block_bitmap_padding(struct super_block *sb,
 311                                                     ext4_group_t block_group,
 312                                                     struct buffer_head *bh)
 313 {
 314         ext4_grpblk_t next_zero_bit;
 315         unsigned long bitmap_size = sb->s_blocksize * 8;
 316         unsigned int offset = num_clusters_in_group(sb, block_group);
 317
 318         if (bitmap_size <= offset)
 319                 return 0;
 320
 321         next_zero_bit = ext4_find_next_zero_bit(bh->b_data, bitmap_size, offset);
 322
 323         return (next_zero_bit < bitmap_size ? next_zero_bit : 0);
 324 }
 325
 326 struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
 327                                             ext4_group_t group)
 328 {
 329         struct ext4_group_info **grp_info;
 330         long indexv, indexh;
 331
 332         if (unlikely(group >= EXT4_SB(sb)->s_groups_count))
 333                 return NULL;
 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         KUNIT_STATIC_STUB_REDIRECT(ext4_read_block_bitmap_nowait,
 474                                    sb, block_group, ignore_locked);
 475
 476         desc = ext4_get_group_desc(sb, block_group, NULL);
 477         if (!desc)
 478                 return ERR_PTR(-EFSCORRUPTED);
 479         bitmap_blk = ext4_block_bitmap(sb, desc);
 480         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
 481             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
 482                 ext4_error(sb, "Invalid block bitmap block %llu in "
 483                            "block_group %u", bitmap_blk, block_group);
 484                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 485                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 486                 return ERR_PTR(-EFSCORRUPTED);
 487         }
 488         bh = sb_getblk(sb, bitmap_blk);
 489         if (unlikely(!bh)) {
 490                 ext4_warning(sb, "Cannot get buffer for block bitmap - "
 491                              "block_group = %u, block_bitmap = %llu",
 492                              block_group, bitmap_blk);
 493                 return ERR_PTR(-ENOMEM);
 494         }
 495
 496         if (ignore_locked && buffer_locked(bh)) {
 497                 /* buffer under IO already, return if called for prefetching */
 498                 put_bh(bh);
 499                 return NULL;
 500         }
 501
 502         if (bitmap_uptodate(bh))
 503                 goto verify;
 504
 505         lock_buffer(bh);
 506         if (bitmap_uptodate(bh)) {
 507                 unlock_buffer(bh);
 508                 goto verify;
 509         }
 510         ext4_lock_group(sb, block_group);
 511         if (ext4_has_group_desc_csum(sb) &&
 512             (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
 513                 if (block_group == 0) {
 514                         ext4_unlock_group(sb, block_group);
 515                         unlock_buffer(bh);
 516                         ext4_error(sb, "Block bitmap for bg 0 marked "
 517                                    "uninitialized");
 518                         err = -EFSCORRUPTED;
 519                         goto out;
 520                 }
 521                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
 522                 if (err) {
 523                         ext4_unlock_group(sb, block_group);
 524                         unlock_buffer(bh);
 525                         ext4_error(sb, "Failed to init block bitmap for group "
 526                                    "%u: %d", block_group, err);
 527                         goto out;
 528                 }
 529                 set_bitmap_uptodate(bh);
 530                 set_buffer_uptodate(bh);
 531                 set_buffer_verified(bh);
 532                 ext4_unlock_group(sb, block_group);
 533                 unlock_buffer(bh);
 534                 return bh;
 535         }
 536         ext4_unlock_group(sb, block_group);
 537         if (buffer_uptodate(bh)) {
 538                 /*
 539                  * if not uninit if bh is uptodate,
 540                  * bitmap is also uptodate
 541                  */
 542                 set_bitmap_uptodate(bh);
 543                 unlock_buffer(bh);
 544                 goto verify;
 545         }
 546         /*
 547          * submit the buffer_head for reading
 548          */
 549         set_buffer_new(bh);
 550         trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
 551         ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
 552                             (ignore_locked ? REQ_RAHEAD : 0),
 553                             ext4_end_bitmap_read);
 554         return bh;
 555 verify:
 556         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
 557         if (err)
 558                 goto out;
 559         return bh;
 560 out:
 561         put_bh(bh);
 562         return ERR_PTR(err);
 563 }
 564
 565 /* Returns 0 on success, -errno on error */
 566 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
 567                            struct buffer_head *bh)
 568 {
 569         struct ext4_group_desc *desc;
 570
 571         KUNIT_STATIC_STUB_REDIRECT(ext4_wait_block_bitmap,
 572                                    sb, block_group, bh);
 573
 574         if (!buffer_new(bh))
 575                 return 0;
 576         desc = ext4_get_group_desc(sb, block_group, NULL);
 577         if (!desc)
 578                 return -EFSCORRUPTED;
 579         wait_on_buffer(bh);
 580         ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
 581         if (!buffer_uptodate(bh)) {
 582                 ext4_error_err(sb, EIO, "Cannot read block bitmap - "
 583                                "block_group = %u, block_bitmap = %llu",
 584                                block_group, (unsigned long long) bh->b_blocknr);
 585                 ext4_mark_group_bitmap_corrupted(sb, block_group,
 586                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
 587                 return -EIO;
 588         }
 589         clear_buffer_new(bh);
 590         /* Panic or remount fs read-only if block bitmap is invalid */
 591         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
 592 }
 593
 594 struct buffer_head *
 595 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 596 {
 597         struct buffer_head *bh;
 598         int err;
 599
 600         bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
 601         if (IS_ERR(bh))
 602                 return bh;
 603         err = ext4_wait_block_bitmap(sb, block_group, bh);
 604         if (err) {
 605                 put_bh(bh);
 606                 return ERR_PTR(err);
 607         }
 608         return bh;
 609 }
 610
 611 /**
 612  * ext4_has_free_clusters()
 613  * @sbi:        in-core super block structure.
 614  * @nclusters:  number of needed blocks
 615  * @flags:      flags from ext4_mb_new_blocks()
 616  *
 617  * Check if filesystem has nclusters free & available for allocation.
 618  * On success return 1, return 0 on failure.
 619  */
 620 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 621                                   s64 nclusters, unsigned int flags)
 622 {
 623         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
 624         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
 625         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 626
 627         free_clusters  = percpu_counter_read_positive(fcc);
 628         dirty_clusters = percpu_counter_read_positive(dcc);
 629         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
 630
 631         /*
 632          * r_blocks_count should always be multiple of the cluster ratio so
 633          * we are safe to do a plane bit shift only.
 634          */
 635         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
 636               resv_clusters;
 637
 638         if (free_clusters - (nclusters + rsv + dirty_clusters) <
 639                                         EXT4_FREECLUSTERS_WATERMARK) {
 640                 free_clusters  = percpu_counter_sum_positive(fcc);
 641                 dirty_clusters = percpu_counter_sum_positive(dcc);
 642         }
 643         /* Check whether we have space after accounting for current
 644          * dirty clusters & root reserved clusters.
 645          */
 646         if (free_clusters >= (rsv + nclusters + dirty_clusters))
 647                 return 1;
 648
 649         /* Hm, nope.  Are (enough) root reserved clusters available? */
 650         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
 651             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
 652             capable(CAP_SYS_RESOURCE) ||
 653             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 654
 655                 if (free_clusters >= (nclusters + dirty_clusters +
 656                                       resv_clusters))
 657                         return 1;
 658         }
 659         /* No free blocks. Let's see if we can dip into reserved pool */
 660         if (flags & EXT4_MB_USE_RESERVED) {
 661                 if (free_clusters >= (nclusters + dirty_clusters))
 662                         return 1;
 663         }
 664
 665         return 0;
 666 }
 667
 668 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 669                              s64 nclusters, unsigned int flags)
 670 {
 671         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 672                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 673                 return 0;
 674         } else
 675                 return -ENOSPC;
 676 }
 677
 678 /**
 679  * ext4_should_retry_alloc() - check if a block allocation should be retried
 680  * @sb:                 superblock
 681  * @retries:            number of retry attempts made so far
 682  *
 683  * ext4_should_retry_alloc() is called when ENOSPC is returned while
 684  * attempting to allocate blocks.  If there's an indication that a pending
 685  * journal transaction might free some space and allow another attempt to
 686  * succeed, this function will wait for the current or committing transaction
 687  * to complete and then return TRUE.
 688  */
 689 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 690 {
 691         struct ext4_sb_info *sbi = EXT4_SB(sb);
 692
 693         if (!sbi->s_journal)
 694                 return 0;
 695
 696         if (++(*retries) > 3) {
 697                 percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
 698                 return 0;
 699         }
 700
 701         /*
 702          * if there's no indication that blocks are about to be freed it's
 703          * possible we just missed a transaction commit that did so
 704          */
 705         smp_mb();
 706         if (sbi->s_mb_free_pending == 0) {
 707                 if (test_opt(sb, DISCARD)) {
 708                         atomic_inc(&sbi->s_retry_alloc_pending);
 709                         flush_work(&sbi->s_discard_work);
 710                         atomic_dec(&sbi->s_retry_alloc_pending);
 711                 }
 712                 return ext4_has_free_clusters(sbi, 1, 0);
 713         }
 714
 715         /*
 716          * it's possible we've just missed a transaction commit here,
 717          * so ignore the returned status
 718          */
 719         ext4_debug("%s: retrying operation after ENOSPC\n", sb->s_id);
 720         (void) jbd2_journal_force_commit_nested(sbi->s_journal);
 721         return 1;
 722 }
 723
 724 /*
 725  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 726  *
 727  * @handle:             handle to this transaction
 728  * @inode:              file inode
 729  * @goal:               given target block(filesystem wide)
 730  * @count:              pointer to total number of clusters needed
 731  * @errp:               error code
 732  *
 733  * Return 1st allocated block number on success, *count stores total account
 734  * error stores in errp pointer
 735  */
 736 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 737                                   ext4_fsblk_t goal, unsigned int flags,
 738                                   unsigned long *count, int *errp)
 739 {
 740         struct ext4_allocation_request ar;
 741         ext4_fsblk_t ret;
 742
 743         memset(&ar, 0, sizeof(ar));
 744         /* Fill with neighbour allocated blocks */
 745         ar.inode = inode;
 746         ar.goal = goal;
 747         ar.len = count ? *count : 1;
 748         ar.flags = flags;
 749
 750         ret = ext4_mb_new_blocks(handle, &ar, errp);
 751         if (count)
 752                 *count = ar.len;
 753         /*
 754          * Account for the allocated meta blocks.  We will never
 755          * fail EDQUOT for metdata, but we do account for it.
 756          */
 757         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
 758                 dquot_alloc_block_nofail(inode,
 759                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
 760         }
 761         return ret;
 762 }
 763
 764 /**
 765  * ext4_count_free_clusters() -- count filesystem free clusters
 766  * @sb:         superblock
 767  *
 768  * Adds up the number of free clusters from each block group.
 769  */
 770 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 771 {
 772         ext4_fsblk_t desc_count;
 773         struct ext4_group_desc *gdp;
 774         ext4_group_t i;
 775         ext4_group_t ngroups = ext4_get_groups_count(sb);
 776         struct ext4_group_info *grp;
 777 #ifdef EXT4FS_DEBUG
 778         struct ext4_super_block *es;
 779         ext4_fsblk_t bitmap_count;
 780         unsigned int x;
 781         struct buffer_head *bitmap_bh = NULL;
 782
 783         es = EXT4_SB(sb)->s_es;
 784         desc_count = 0;
 785         bitmap_count = 0;
 786         gdp = NULL;
 787
 788         for (i = 0; i < ngroups; i++) {
 789                 gdp = ext4_get_group_desc(sb, i, NULL);
 790                 if (!gdp)
 791                         continue;
 792                 grp = NULL;
 793                 if (EXT4_SB(sb)->s_group_info)
 794                         grp = ext4_get_group_info(sb, i);
 795                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 796                         desc_count += ext4_free_group_clusters(sb, gdp);
 797                 brelse(bitmap_bh);
 798                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 799                 if (IS_ERR(bitmap_bh)) {
 800                         bitmap_bh = NULL;
 801                         continue;
 802                 }
 803
 804                 x = ext4_count_free(bitmap_bh->b_data,
 805                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
 806                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 807                         i, ext4_free_group_clusters(sb, gdp), x);
 808                 bitmap_count += x;
 809         }
 810         brelse(bitmap_bh);
 811         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
 812                ", computed = %llu, %llu\n",
 813                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
 814                desc_count, bitmap_count);
 815         return bitmap_count;
 816 #else
 817         desc_count = 0;
 818         for (i = 0; i < ngroups; i++) {
 819                 gdp = ext4_get_group_desc(sb, i, NULL);
 820                 if (!gdp)
 821                         continue;
 822                 grp = NULL;
 823                 if (EXT4_SB(sb)->s_group_info)
 824                         grp = ext4_get_group_info(sb, i);
 825                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
 826                         desc_count += ext4_free_group_clusters(sb, gdp);
 827         }
 828
 829         return desc_count;
 830 #endif
 831 }
 832
 833 static inline int test_root(ext4_group_t a, int b)
 834 {
 835         while (1) {
 836                 if (a < b)
 837                         return 0;
 838                 if (a == b)
 839                         return 1;
 840                 if ((a % b) != 0)
 841                         return 0;
 842                 a = a / b;
 843         }
 844 }
 845
 846 /**
 847  *      ext4_bg_has_super - number of blocks used by the superblock in group
 848  *      @sb: superblock for filesystem
 849  *      @group: group number to check
 850  *
 851  *      Return the number of blocks used by the superblock (primary or backup)
 852  *      in this group.  Currently this will be only 0 or 1.
 853  */
 854 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 855 {
 856         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 857
 858         if (group == 0)
 859                 return 1;
 860         if (ext4_has_feature_sparse_super2(sb)) {
 861                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
 862                     group == le32_to_cpu(es->s_backup_bgs[1]))
 863                         return 1;
 864                 return 0;
 865         }
 866         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
 867                 return 1;
 868         if (!(group & 1))
 869                 return 0;
 870         if (test_root(group, 3) || (test_root(group, 5)) ||
 871             test_root(group, 7))
 872                 return 1;
 873
 874         return 0;
 875 }
 876
 877 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 878                                         ext4_group_t group)
 879 {
 880         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 881         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 882         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 883
 884         if (group == first || group == first + 1 || group == last)
 885                 return 1;
 886         return 0;
 887 }
 888
 889 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 890                                         ext4_group_t group)
 891 {
 892         if (!ext4_bg_has_super(sb, group))
 893                 return 0;
 894
 895         if (ext4_has_feature_meta_bg(sb))
 896                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 897         else
 898                 return EXT4_SB(sb)->s_gdb_count;
 899 }
 900
 901 /**
 902  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 903  *      @sb: superblock for filesystem
 904  *      @group: group number to check
 905  *
 906  *      Return the number of blocks used by the group descriptor table
 907  *      (primary or backup) in this group.  In the future there may be a
 908  *      different number of descriptor blocks in each group.
 909  */
 910 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 911 {
 912         unsigned long first_meta_bg =
 913                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 914         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 915
 916         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
 917                 return ext4_bg_num_gdb_nometa(sb, group);
 918
 919         return ext4_bg_num_gdb_meta(sb,group);
 920
 921 }
 922
 923 /*
 924  * This function returns the number of file system metadata blocks at
 925  * the beginning of a block group, including the reserved gdt blocks.
 926  */
 927 unsigned int ext4_num_base_meta_blocks(struct super_block *sb,
 928                                        ext4_group_t block_group)
 929 {
 930         struct ext4_sb_info *sbi = EXT4_SB(sb);
 931         unsigned num;
 932
 933         /* Check for superblock and gdt backups in this group */
 934         num = ext4_bg_has_super(sb, block_group);
 935
 936         if (!ext4_has_feature_meta_bg(sb) ||
 937             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 938                           sbi->s_desc_per_block) {
 939                 if (num) {
 940                         num += ext4_bg_num_gdb_nometa(sb, block_group);
 941                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 942                 }
 943         } else { /* For META_BG_BLOCK_GROUPS */
 944                 num += ext4_bg_num_gdb_meta(sb, block_group);
 945         }
 946         return num;
 947 }
 948
 949 static unsigned int ext4_num_base_meta_clusters(struct super_block *sb,
 950                                                 ext4_group_t block_group)
 951 {
 952         return EXT4_NUM_B2C(EXT4_SB(sb), ext4_num_base_meta_blocks(sb, block_group));
 953 }
 954
 955 /**
 956  *      ext4_inode_to_goal_block - return a hint for block allocation
 957  *      @inode: inode for block allocation
 958  *
 959  *      Return the ideal location to start allocating blocks for a
 960  *      newly created inode.
 961  */
 962 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
 963 {
 964         struct ext4_inode_info *ei = EXT4_I(inode);
 965         ext4_group_t block_group;
 966         ext4_grpblk_t colour;
 967         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
 968         ext4_fsblk_t bg_start;
 969         ext4_fsblk_t last_block;
 970
 971         block_group = ei->i_block_group;
 972         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
 973                 /*
 974                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
 975                  * block groups per flexgroup, reserve the first block
 976                  * group for directories and special files.  Regular
 977                  * files will start at the second block group.  This
 978                  * tends to speed up directory access and improves
 979                  * fsck times.
 980                  */
 981                 block_group &= ~(flex_size-1);
 982                 if (S_ISREG(inode->i_mode))
 983                         block_group++;
 984         }
 985         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
 986         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
 987
 988         /*
 989          * If we are doing delayed allocation, we don't need take
 990          * colour into account.
 991          */
 992         if (test_opt(inode->i_sb, DELALLOC))
 993                 return bg_start;
 994
 995         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
 996                 colour = (task_pid_nr(current) % 16) *
 997                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
 998         else
 999                 colour = (task_pid_nr(current) % 16) *
1000                         ((last_block - bg_start) / 16);
1001         return bg_start + colour;
1002 }
1003