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   1 /*
   2  *  linux/fs/ext4/balloc.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
  10  *  Big-endian to little-endian byte-swapping/bitmaps by
  11  *        David S. Miller (davem@caip.rutgers.edu), 1995
  12  */
  13
  14 #include <linux/time.h>
  15 #include <linux/capability.h>
  16 #include <linux/fs.h>
  17 #include <linux/jbd2.h>
  18 #include <linux/quotaops.h>
  19 #include <linux/buffer_head.h>
  20 #include "ext4.h"
  21 #include "ext4_jbd2.h"
  22 #include "group.h"
  23 #include "mballoc.h"
  24
  25 /*
  26  * balloc.c contains the blocks allocation and deallocation routines
  27  */
  28
  29 /*
  30  * Calculate the block group number and offset, given a block number
  31  */
  32 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  33                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  34 {
  35         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  36         ext4_grpblk_t offset;
  37
  38         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  39         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
  40         if (offsetp)
  41                 *offsetp = offset;
  42         if (blockgrpp)
  43                 *blockgrpp = blocknr;
  44
  45 }
  46
  47 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
  48                         ext4_group_t block_group)
  49 {
  50         ext4_group_t actual_group;
  51         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
  52         if (actual_group == block_group)
  53                 return 1;
  54         return 0;
  55 }
  56
  57 static int ext4_group_used_meta_blocks(struct super_block *sb,
  58                                        ext4_group_t block_group,
  59                                        struct ext4_group_desc *gdp)
  60 {
  61         ext4_fsblk_t tmp;
  62         struct ext4_sb_info *sbi = EXT4_SB(sb);
  63         /* block bitmap, inode bitmap, and inode table blocks */
  64         int used_blocks = sbi->s_itb_per_group + 2;
  65
  66         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
  67                 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
  68                                         block_group))
  69                         used_blocks--;
  70
  71                 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
  72                                         block_group))
  73                         used_blocks--;
  74
  75                 tmp = ext4_inode_table(sb, gdp);
  76                 for (; tmp < ext4_inode_table(sb, gdp) +
  77                                 sbi->s_itb_per_group; tmp++) {
  78                         if (!ext4_block_in_group(sb, tmp, block_group))
  79                                 used_blocks -= 1;
  80                 }
  81         }
  82         return used_blocks;
  83 }
  84
  85 /* Initializes an uninitialized block bitmap if given, and returns the
  86  * number of blocks free in the group. */
  87 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
  88                  ext4_group_t block_group, struct ext4_group_desc *gdp)
  89 {
  90         int bit, bit_max;
  91         ext4_group_t ngroups = ext4_get_groups_count(sb);
  92         unsigned free_blocks, group_blocks;
  93         struct ext4_sb_info *sbi = EXT4_SB(sb);
  94
  95         if (bh) {
  96                 J_ASSERT_BH(bh, buffer_locked(bh));
  97
  98                 /* If checksum is bad mark all blocks used to prevent allocation
  99                  * essentially implementing a per-group read-only flag. */
 100                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
 101                         ext4_error(sb, __func__,
 102                                   "Checksum bad for group %u", block_group);
 103                         ext4_free_blks_set(sb, gdp, 0);
 104                         ext4_free_inodes_set(sb, gdp, 0);
 105                         ext4_itable_unused_set(sb, gdp, 0);
 106                         memset(bh->b_data, 0xff, sb->s_blocksize);
 107                         return 0;
 108                 }
 109                 memset(bh->b_data, 0, sb->s_blocksize);
 110         }
 111
 112         /* Check for superblock and gdt backups in this group */
 113         bit_max = ext4_bg_has_super(sb, block_group);
 114
 115         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 116             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 117                           sbi->s_desc_per_block) {
 118                 if (bit_max) {
 119                         bit_max += ext4_bg_num_gdb(sb, block_group);
 120                         bit_max +=
 121                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 122                 }
 123         } else { /* For META_BG_BLOCK_GROUPS */
 124                 bit_max += ext4_bg_num_gdb(sb, block_group);
 125         }
 126
 127         if (block_group == ngroups - 1) {
 128                 /*
 129                  * Even though mke2fs always initialize first and last group
 130                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
 131                  * to make sure we calculate the right free blocks
 132                  */
 133                 group_blocks = ext4_blocks_count(sbi->s_es) -
 134                         le32_to_cpu(sbi->s_es->s_first_data_block) -
 135                         (EXT4_BLOCKS_PER_GROUP(sb) * (ngroups - 1));
 136         } else {
 137                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
 138         }
 139
 140         free_blocks = group_blocks - bit_max;
 141
 142         if (bh) {
 143                 ext4_fsblk_t start, tmp;
 144                 int flex_bg = 0;
 145
 146                 for (bit = 0; bit < bit_max; bit++)
 147                         ext4_set_bit(bit, bh->b_data);
 148
 149                 start = ext4_group_first_block_no(sb, block_group);
 150
 151                 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
 152                                               EXT4_FEATURE_INCOMPAT_FLEX_BG))
 153                         flex_bg = 1;
 154
 155                 /* Set bits for block and inode bitmaps, and inode table */
 156                 tmp = ext4_block_bitmap(sb, gdp);
 157                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 158                         ext4_set_bit(tmp - start, bh->b_data);
 159
 160                 tmp = ext4_inode_bitmap(sb, gdp);
 161                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 162                         ext4_set_bit(tmp - start, bh->b_data);
 163
 164                 tmp = ext4_inode_table(sb, gdp);
 165                 for (; tmp < ext4_inode_table(sb, gdp) +
 166                                 sbi->s_itb_per_group; tmp++) {
 167                         if (!flex_bg ||
 168                                 ext4_block_in_group(sb, tmp, block_group))
 169                                 ext4_set_bit(tmp - start, bh->b_data);
 170                 }
 171                 /*
 172                  * Also if the number of blocks within the group is
 173                  * less than the blocksize * 8 ( which is the size
 174                  * of bitmap ), set rest of the block bitmap to 1
 175                  */
 176                 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
 177         }
 178         return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
 179 }
 180
 181
 182 /*
 183  * The free blocks are managed by bitmaps.  A file system contains several
 184  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 185  * block for inodes, N blocks for the inode table and data blocks.
 186  *
 187  * The file system contains group descriptors which are located after the
 188  * super block.  Each descriptor contains the number of the bitmap block and
 189  * the free blocks count in the block.  The descriptors are loaded in memory
 190  * when a file system is mounted (see ext4_fill_super).
 191  */
 192
 193
 194 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 195
 196 /**
 197  * ext4_get_group_desc() -- load group descriptor from disk
 198  * @sb:                 super block
 199  * @block_group:        given block group
 200  * @bh:                 pointer to the buffer head to store the block
 201  *                      group descriptor
 202  */
 203 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 204                                              ext4_group_t block_group,
 205                                              struct buffer_head **bh)
 206 {
 207         unsigned int group_desc;
 208         unsigned int offset;
 209         ext4_group_t ngroups = ext4_get_groups_count(sb);
 210         struct ext4_group_desc *desc;
 211         struct ext4_sb_info *sbi = EXT4_SB(sb);
 212
 213         if (block_group >= ngroups) {
 214                 ext4_error(sb, "ext4_get_group_desc",
 215                            "block_group >= groups_count - "
 216                            "block_group = %u, groups_count = %u",
 217                            block_group, ngroups);
 218
 219                 return NULL;
 220         }
 221
 222         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 223         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 224         if (!sbi->s_group_desc[group_desc]) {
 225                 ext4_error(sb, "ext4_get_group_desc",
 226                            "Group descriptor not loaded - "
 227                            "block_group = %u, group_desc = %u, desc = %u",
 228                            block_group, group_desc, offset);
 229                 return NULL;
 230         }
 231
 232         desc = (struct ext4_group_desc *)(
 233                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 234                 offset * EXT4_DESC_SIZE(sb));
 235         if (bh)
 236                 *bh = sbi->s_group_desc[group_desc];
 237         return desc;
 238 }
 239
 240 static int ext4_valid_block_bitmap(struct super_block *sb,
 241                                         struct ext4_group_desc *desc,
 242                                         unsigned int block_group,
 243                                         struct buffer_head *bh)
 244 {
 245         ext4_grpblk_t offset;
 246         ext4_grpblk_t next_zero_bit;
 247         ext4_fsblk_t bitmap_blk;
 248         ext4_fsblk_t group_first_block;
 249
 250         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 251                 /* with FLEX_BG, the inode/block bitmaps and itable
 252                  * blocks may not be in the group at all
 253                  * so the bitmap validation will be skipped for those groups
 254                  * or it has to also read the block group where the bitmaps
 255                  * are located to verify they are set.
 256                  */
 257                 return 1;
 258         }
 259         group_first_block = ext4_group_first_block_no(sb, block_group);
 260
 261         /* check whether block bitmap block number is set */
 262         bitmap_blk = ext4_block_bitmap(sb, desc);
 263         offset = bitmap_blk - group_first_block;
 264         if (!ext4_test_bit(offset, bh->b_data))
 265                 /* bad block bitmap */
 266                 goto err_out;
 267
 268         /* check whether the inode bitmap block number is set */
 269         bitmap_blk = ext4_inode_bitmap(sb, desc);
 270         offset = bitmap_blk - group_first_block;
 271         if (!ext4_test_bit(offset, bh->b_data))
 272                 /* bad block bitmap */
 273                 goto err_out;
 274
 275         /* check whether the inode table block number is set */
 276         bitmap_blk = ext4_inode_table(sb, desc);
 277         offset = bitmap_blk - group_first_block;
 278         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 279                                 offset + EXT4_SB(sb)->s_itb_per_group,
 280                                 offset);
 281         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
 282                 /* good bitmap for inode tables */
 283                 return 1;
 284
 285 err_out:
 286         ext4_error(sb, __func__,
 287                         "Invalid block bitmap - "
 288                         "block_group = %d, block = %llu",
 289                         block_group, bitmap_blk);
 290         return 0;
 291 }
 292 /**
 293  * ext4_read_block_bitmap()
 294  * @sb:                 super block
 295  * @block_group:        given block group
 296  *
 297  * Read the bitmap for a given block_group,and validate the
 298  * bits for block/inode/inode tables are set in the bitmaps
 299  *
 300  * Return buffer_head on success or NULL in case of failure.
 301  */
 302 struct buffer_head *
 303 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 304 {
 305         struct ext4_group_desc *desc;
 306         struct buffer_head *bh = NULL;
 307         ext4_fsblk_t bitmap_blk;
 308
 309         desc = ext4_get_group_desc(sb, block_group, NULL);
 310         if (!desc)
 311                 return NULL;
 312         bitmap_blk = ext4_block_bitmap(sb, desc);
 313         bh = sb_getblk(sb, bitmap_blk);
 314         if (unlikely(!bh)) {
 315                 ext4_error(sb, __func__,
 316                             "Cannot read block bitmap - "
 317                             "block_group = %u, block_bitmap = %llu",
 318                             block_group, bitmap_blk);
 319                 return NULL;
 320         }
 321
 322         if (bitmap_uptodate(bh))
 323                 return bh;
 324
 325         lock_buffer(bh);
 326         if (bitmap_uptodate(bh)) {
 327                 unlock_buffer(bh);
 328                 return bh;
 329         }
 330         spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
 331         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 332                 ext4_init_block_bitmap(sb, bh, block_group, desc);
 333                 set_bitmap_uptodate(bh);
 334                 set_buffer_uptodate(bh);
 335                 spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 336                 unlock_buffer(bh);
 337                 return bh;
 338         }
 339         spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 340         if (buffer_uptodate(bh)) {
 341                 /*
 342                  * if not uninit if bh is uptodate,
 343                  * bitmap is also uptodate
 344                  */
 345                 set_bitmap_uptodate(bh);
 346                 unlock_buffer(bh);
 347                 return bh;
 348         }
 349         /*
 350          * submit the buffer_head for read. We can
 351          * safely mark the bitmap as uptodate now.
 352          * We do it here so the bitmap uptodate bit
 353          * get set with buffer lock held.
 354          */
 355         set_bitmap_uptodate(bh);
 356         if (bh_submit_read(bh) < 0) {
 357                 put_bh(bh);
 358                 ext4_error(sb, __func__,
 359                             "Cannot read block bitmap - "
 360                             "block_group = %u, block_bitmap = %llu",
 361                             block_group, bitmap_blk);
 362                 return NULL;
 363         }
 364         ext4_valid_block_bitmap(sb, desc, block_group, bh);
 365         /*
 366          * file system mounted not to panic on error,
 367          * continue with corrupt bitmap
 368          */
 369         return bh;
 370 }
 371
 372 /**
 373  * ext4_add_groupblocks() -- Add given blocks to an existing group
 374  * @handle:                     handle to this transaction
 375  * @sb:                         super block
 376  * @block:                      start physcial block to add to the block group
 377  * @count:                      number of blocks to free
 378  *
 379  * This marks the blocks as free in the bitmap. We ask the
 380  * mballoc to reload the buddy after this by setting group
 381  * EXT4_GROUP_INFO_NEED_INIT_BIT flag
 382  */
 383 void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
 384                          ext4_fsblk_t block, unsigned long count)
 385 {
 386         struct buffer_head *bitmap_bh = NULL;
 387         struct buffer_head *gd_bh;
 388         ext4_group_t block_group;
 389         ext4_grpblk_t bit;
 390         unsigned int i;
 391         struct ext4_group_desc *desc;
 392         struct ext4_super_block *es;
 393         struct ext4_sb_info *sbi;
 394         int err = 0, ret, blk_free_count;
 395         ext4_grpblk_t blocks_freed;
 396         struct ext4_group_info *grp;
 397
 398         sbi = EXT4_SB(sb);
 399         es = sbi->s_es;
 400         ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
 401
 402         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
 403         grp = ext4_get_group_info(sb, block_group);
 404         /*
 405          * Check to see if we are freeing blocks across a group
 406          * boundary.
 407          */
 408         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
 409                 goto error_return;
 410         }
 411         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
 412         if (!bitmap_bh)
 413                 goto error_return;
 414         desc = ext4_get_group_desc(sb, block_group, &gd_bh);
 415         if (!desc)
 416                 goto error_return;
 417
 418         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
 419             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
 420             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
 421             in_range(block + count - 1, ext4_inode_table(sb, desc),
 422                      sbi->s_itb_per_group)) {
 423                 ext4_error(sb, __func__,
 424                            "Adding blocks in system zones - "
 425                            "Block = %llu, count = %lu",
 426                            block, count);
 427                 goto error_return;
 428         }
 429
 430         /*
 431          * We are about to add blocks to the bitmap,
 432          * so we need undo access.
 433          */
 434         BUFFER_TRACE(bitmap_bh, "getting undo access");
 435         err = ext4_journal_get_undo_access(handle, bitmap_bh);
 436         if (err)
 437                 goto error_return;
 438
 439         /*
 440          * We are about to modify some metadata.  Call the journal APIs
 441          * to unshare ->b_data if a currently-committing transaction is
 442          * using it
 443          */
 444         BUFFER_TRACE(gd_bh, "get_write_access");
 445         err = ext4_journal_get_write_access(handle, gd_bh);
 446         if (err)
 447                 goto error_return;
 448         /*
 449          * make sure we don't allow a parallel init on other groups in the
 450          * same buddy cache
 451          */
 452         down_write(&grp->alloc_sem);
 453         for (i = 0, blocks_freed = 0; i < count; i++) {
 454                 BUFFER_TRACE(bitmap_bh, "clear bit");
 455                 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 456                                                 bit + i, bitmap_bh->b_data)) {
 457                         ext4_error(sb, __func__,
 458                                    "bit already cleared for block %llu",
 459                                    (ext4_fsblk_t)(block + i));
 460                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 461                 } else {
 462                         blocks_freed++;
 463                 }
 464         }
 465         spin_lock(sb_bgl_lock(sbi, block_group));
 466         blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
 467         ext4_free_blks_set(sb, desc, blk_free_count);
 468         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
 469         spin_unlock(sb_bgl_lock(sbi, block_group));
 470         percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
 471
 472         if (sbi->s_log_groups_per_flex) {
 473                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
 474                 atomic_add(blocks_freed,
 475                            &sbi->s_flex_groups[flex_group].free_blocks);
 476         }
 477         /*
 478          * request to reload the buddy with the
 479          * new bitmap information
 480          */
 481         set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
 482         ext4_mb_update_group_info(grp, blocks_freed);
 483         up_write(&grp->alloc_sem);
 484
 485         /* We dirtied the bitmap block */
 486         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 487         err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
 488
 489         /* And the group descriptor block */
 490         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 491         ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
 492         if (!err)
 493                 err = ret;
 494         sb->s_dirt = 1;
 495
 496 error_return:
 497         brelse(bitmap_bh);
 498         ext4_std_error(sb, err);
 499         return;
 500 }
 501
 502 /**
 503  * ext4_free_blocks() -- Free given blocks and update quota
 504  * @handle:             handle for this transaction
 505  * @inode:              inode
 506  * @block:              start physical block to free
 507  * @count:              number of blocks to count
 508  * @metadata:           Are these metadata blocks
 509  */
 510 void ext4_free_blocks(handle_t *handle, struct inode *inode,
 511                         ext4_fsblk_t block, unsigned long count,
 512                         int metadata)
 513 {
 514         struct super_block *sb;
 515         unsigned long dquot_freed_blocks;
 516
 517         /* this isn't the right place to decide whether block is metadata
 518          * inode.c/extents.c knows better, but for safety ... */
 519         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
 520                 metadata = 1;
 521
 522         /* We need to make sure we don't reuse
 523          * block released untill the transaction commit.
 524          * writeback mode have weak data consistency so
 525          * don't force data as metadata when freeing block
 526          * for writeback mode.
 527          */
 528         if (metadata == 0 && !ext4_should_writeback_data(inode))
 529                 metadata = 1;
 530
 531         sb = inode->i_sb;
 532
 533         ext4_mb_free_blocks(handle, inode, block, count,
 534                             metadata, &dquot_freed_blocks);
 535         if (dquot_freed_blocks)
 536                 vfs_dq_free_block(inode, dquot_freed_blocks);
 537         return;
 538 }
 539
 540 /**
 541  * ext4_has_free_blocks()
 542  * @sbi:        in-core super block structure.
 543  * @nblocks:    number of needed blocks
 544  *
 545  * Check if filesystem has nblocks free & available for allocation.
 546  * On success return 1, return 0 on failure.
 547  */
 548 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
 549 {
 550         s64 free_blocks, dirty_blocks, root_blocks;
 551         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
 552         struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
 553
 554         free_blocks  = percpu_counter_read_positive(fbc);
 555         dirty_blocks = percpu_counter_read_positive(dbc);
 556         root_blocks = ext4_r_blocks_count(sbi->s_es);
 557
 558         if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
 559                                                 EXT4_FREEBLOCKS_WATERMARK) {
 560                 free_blocks  = percpu_counter_sum_positive(fbc);
 561                 dirty_blocks = percpu_counter_sum_positive(dbc);
 562                 if (dirty_blocks < 0) {
 563                         printk(KERN_CRIT "Dirty block accounting "
 564                                         "went wrong %lld\n",
 565                                         (long long)dirty_blocks);
 566                 }
 567         }
 568         /* Check whether we have space after
 569          * accounting for current dirty blocks & root reserved blocks.
 570          */
 571         if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
 572                 return 1;
 573
 574         /* Hm, nope.  Are (enough) root reserved blocks available? */
 575         if (sbi->s_resuid == current_fsuid() ||
 576             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
 577             capable(CAP_SYS_RESOURCE)) {
 578                 if (free_blocks >= (nblocks + dirty_blocks))
 579                         return 1;
 580         }
 581
 582         return 0;
 583 }
 584
 585 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
 586                                                 s64 nblocks)
 587 {
 588         if (ext4_has_free_blocks(sbi, nblocks)) {
 589                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
 590                 return 0;
 591         } else
 592                 return -ENOSPC;
 593 }
 594
 595 /**
 596  * ext4_should_retry_alloc()
 597  * @sb:                 super block
 598  * @retries             number of attemps has been made
 599  *
 600  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 601  * it is profitable to retry the operation, this function will wait
 602  * for the current or commiting transaction to complete, and then
 603  * return TRUE.
 604  *
 605  * if the total number of retries exceed three times, return FALSE.
 606  */
 607 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 608 {
 609         if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
 610             (*retries)++ > 3 ||
 611             !EXT4_SB(sb)->s_journal)
 612                 return 0;
 613
 614         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 615
 616         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 617 }
 618
 619 /*
 620  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 621  *
 622  * @handle:             handle to this transaction
 623  * @inode:              file inode
 624  * @goal:               given target block(filesystem wide)
 625  * @count:              pointer to total number of blocks needed
 626  * @errp:               error code
 627  *
 628  * Return 1st allocated block number on success, *count stores total account
 629  * error stores in errp pointer
 630  */
 631 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 632                 ext4_fsblk_t goal, unsigned long *count, int *errp)
 633 {
 634         struct ext4_allocation_request ar;
 635         ext4_fsblk_t ret;
 636
 637         memset(&ar, 0, sizeof(ar));
 638         /* Fill with neighbour allocated blocks */
 639         ar.inode = inode;
 640         ar.goal = goal;
 641         ar.len = count ? *count : 1;
 642
 643         ret = ext4_mb_new_blocks(handle, &ar, errp);
 644         if (count)
 645                 *count = ar.len;
 646
 647         /*
 648          * Account for the allocated meta blocks
 649          */
 650         if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
 651                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 652                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 653                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 654         }
 655         return ret;
 656 }
 657
 658 /**
 659  * ext4_count_free_blocks() -- count filesystem free blocks
 660  * @sb:         superblock
 661  *
 662  * Adds up the number of free blocks from each block group.
 663  */
 664 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
 665 {
 666         ext4_fsblk_t desc_count;
 667         struct ext4_group_desc *gdp;
 668         ext4_group_t i;
 669         ext4_group_t ngroups = ext4_get_groups_count(sb);
 670 #ifdef EXT4FS_DEBUG
 671         struct ext4_super_block *es;
 672         ext4_fsblk_t bitmap_count;
 673         unsigned int x;
 674         struct buffer_head *bitmap_bh = NULL;
 675
 676         es = EXT4_SB(sb)->s_es;
 677         desc_count = 0;
 678         bitmap_count = 0;
 679         gdp = NULL;
 680
 681         for (i = 0; i < ngroups; i++) {
 682                 gdp = ext4_get_group_desc(sb, i, NULL);
 683                 if (!gdp)
 684                         continue;
 685                 desc_count += ext4_free_blks_count(sb, gdp);
 686                 brelse(bitmap_bh);
 687                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 688                 if (bitmap_bh == NULL)
 689                         continue;
 690
 691                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
 692                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 693                         i, ext4_free_blks_count(sb, gdp), x);
 694                 bitmap_count += x;
 695         }
 696         brelse(bitmap_bh);
 697         printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
 698                 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
 699                desc_count, bitmap_count);
 700         return bitmap_count;
 701 #else
 702         desc_count = 0;
 703         for (i = 0; i < ngroups; i++) {
 704                 gdp = ext4_get_group_desc(sb, i, NULL);
 705                 if (!gdp)
 706                         continue;
 707                 desc_count += ext4_free_blks_count(sb, gdp);
 708         }
 709
 710         return desc_count;
 711 #endif
 712 }
 713
 714 static inline int test_root(ext4_group_t a, int b)
 715 {
 716         int num = b;
 717
 718         while (a > num)
 719                 num *= b;
 720         return num == a;
 721 }
 722
 723 static int ext4_group_sparse(ext4_group_t group)
 724 {
 725         if (group <= 1)
 726                 return 1;
 727         if (!(group & 1))
 728                 return 0;
 729         return (test_root(group, 7) || test_root(group, 5) ||
 730                 test_root(group, 3));
 731 }
 732
 733 /**
 734  *      ext4_bg_has_super - number of blocks used by the superblock in group
 735  *      @sb: superblock for filesystem
 736  *      @group: group number to check
 737  *
 738  *      Return the number of blocks used by the superblock (primary or backup)
 739  *      in this group.  Currently this will be only 0 or 1.
 740  */
 741 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 742 {
 743         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
 744                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
 745                         !ext4_group_sparse(group))
 746                 return 0;
 747         return 1;
 748 }
 749
 750 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 751                                         ext4_group_t group)
 752 {
 753         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 754         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 755         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 756
 757         if (group == first || group == first + 1 || group == last)
 758                 return 1;
 759         return 0;
 760 }
 761
 762 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 763                                         ext4_group_t group)
 764 {
 765         return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
 766 }
 767
 768 /**
 769  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 770  *      @sb: superblock for filesystem
 771  *      @group: group number to check
 772  *
 773  *      Return the number of blocks used by the group descriptor table
 774  *      (primary or backup) in this group.  In the future there may be a
 775  *      different number of descriptor blocks in each group.
 776  */
 777 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 778 {
 779         unsigned long first_meta_bg =
 780                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 781         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 782
 783         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 784                         metagroup < first_meta_bg)
 785                 return ext4_bg_num_gdb_nometa(sb, group);
 786
 787         return ext4_bg_num_gdb_meta(sb,group);
 788
 789 }
 790