fs/ext4/balloc.c

   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
  24 /*
  25  * balloc.c contains the blocks allocation and deallocation routines
  26  */
  27
  28 /*
  29  * Calculate the block group number and offset, given a block number
  30  */
  31 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  32                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
  33 {
  34         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  35         ext4_grpblk_t offset;
  36
  37         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
  38         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
  39         if (offsetp)
  40                 *offsetp = offset;
  41         if (blockgrpp)
  42                 *blockgrpp = blocknr;
  43
  44 }
  45
  46 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
  47                         ext4_group_t block_group)
  48 {
  49         ext4_group_t actual_group;
  50         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
  51         if (actual_group == block_group)
  52                 return 1;
  53         return 0;
  54 }
  55
  56 static int ext4_group_used_meta_blocks(struct super_block *sb,
  57                                 ext4_group_t block_group)
  58 {
  59         ext4_fsblk_t tmp;
  60         struct ext4_sb_info *sbi = EXT4_SB(sb);
  61         /* block bitmap, inode bitmap, and inode table blocks */
  62         int used_blocks = sbi->s_itb_per_group + 2;
  63
  64         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
  65                 struct ext4_group_desc *gdp;
  66                 struct buffer_head *bh;
  67
  68                 gdp = ext4_get_group_desc(sb, block_group, &bh);
  69                 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
  70                                         block_group))
  71                         used_blocks--;
  72
  73                 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
  74                                         block_group))
  75                         used_blocks--;
  76
  77                 tmp = ext4_inode_table(sb, gdp);
  78                 for (; tmp < ext4_inode_table(sb, gdp) +
  79                                 sbi->s_itb_per_group; tmp++) {
  80                         if (!ext4_block_in_group(sb, tmp, block_group))
  81                                 used_blocks -= 1;
  82                 }
  83         }
  84         return used_blocks;
  85 }
  86
  87 /* Initializes an uninitialized block bitmap if given, and returns the
  88  * number of blocks free in the group. */
  89 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
  90                  ext4_group_t block_group, struct ext4_group_desc *gdp)
  91 {
  92         int bit, bit_max;
  93         unsigned free_blocks, group_blocks;
  94         struct ext4_sb_info *sbi = EXT4_SB(sb);
  95
  96         if (bh) {
  97                 J_ASSERT_BH(bh, buffer_locked(bh));
  98
  99                 /* If checksum is bad mark all blocks used to prevent allocation
 100                  * essentially implementing a per-group read-only flag. */
 101                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
 102                         ext4_error(sb, __func__,
 103                                   "Checksum bad for group %lu\n", block_group);
 104                         gdp->bg_free_blocks_count = 0;
 105                         gdp->bg_free_inodes_count = 0;
 106                         gdp->bg_itable_unused = 0;
 107                         memset(bh->b_data, 0xff, sb->s_blocksize);
 108                         return 0;
 109                 }
 110                 memset(bh->b_data, 0, sb->s_blocksize);
 111         }
 112
 113         /* Check for superblock and gdt backups in this group */
 114         bit_max = ext4_bg_has_super(sb, block_group);
 115
 116         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
 117             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
 118                           sbi->s_desc_per_block) {
 119                 if (bit_max) {
 120                         bit_max += ext4_bg_num_gdb(sb, block_group);
 121                         bit_max +=
 122                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
 123                 }
 124         } else { /* For META_BG_BLOCK_GROUPS */
 125                 bit_max += ext4_bg_num_gdb(sb, block_group);
 126         }
 127
 128         if (block_group == sbi->s_groups_count - 1) {
 129                 /*
 130                  * Even though mke2fs always initialize first and last group
 131                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
 132                  * to make sure we calculate the right free blocks
 133                  */
 134                 group_blocks = ext4_blocks_count(sbi->s_es) -
 135                         le32_to_cpu(sbi->s_es->s_first_data_block) -
 136                         (EXT4_BLOCKS_PER_GROUP(sb) * (sbi->s_groups_count - 1));
 137         } else {
 138                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
 139         }
 140
 141         free_blocks = group_blocks - bit_max;
 142
 143         if (bh) {
 144                 ext4_fsblk_t start, tmp;
 145                 int flex_bg = 0;
 146
 147                 for (bit = 0; bit < bit_max; bit++)
 148                         ext4_set_bit(bit, bh->b_data);
 149
 150                 start = ext4_group_first_block_no(sb, block_group);
 151
 152                 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
 153                                               EXT4_FEATURE_INCOMPAT_FLEX_BG))
 154                         flex_bg = 1;
 155
 156                 /* Set bits for block and inode bitmaps, and inode table */
 157                 tmp = ext4_block_bitmap(sb, gdp);
 158                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 159                         ext4_set_bit(tmp - start, bh->b_data);
 160
 161                 tmp = ext4_inode_bitmap(sb, gdp);
 162                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
 163                         ext4_set_bit(tmp - start, bh->b_data);
 164
 165                 tmp = ext4_inode_table(sb, gdp);
 166                 for (; tmp < ext4_inode_table(sb, gdp) +
 167                                 sbi->s_itb_per_group; tmp++) {
 168                         if (!flex_bg ||
 169                                 ext4_block_in_group(sb, tmp, block_group))
 170                                 ext4_set_bit(tmp - start, bh->b_data);
 171                 }
 172                 /*
 173                  * Also if the number of blocks within the group is
 174                  * less than the blocksize * 8 ( which is the size
 175                  * of bitmap ), set rest of the block bitmap to 1
 176                  */
 177                 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
 178         }
 179         return free_blocks - ext4_group_used_meta_blocks(sb, block_group);
 180 }
 181
 182
 183 /*
 184  * The free blocks are managed by bitmaps.  A file system contains several
 185  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 186  * block for inodes, N blocks for the inode table and data blocks.
 187  *
 188  * The file system contains group descriptors which are located after the
 189  * super block.  Each descriptor contains the number of the bitmap block and
 190  * the free blocks count in the block.  The descriptors are loaded in memory
 191  * when a file system is mounted (see ext4_fill_super).
 192  */
 193
 194
 195 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
 196
 197 /**
 198  * ext4_get_group_desc() -- load group descriptor from disk
 199  * @sb:                 super block
 200  * @block_group:        given block group
 201  * @bh:                 pointer to the buffer head to store the block
 202  *                      group descriptor
 203  */
 204 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
 205                                              ext4_group_t block_group,
 206                                              struct buffer_head **bh)
 207 {
 208         unsigned long group_desc;
 209         unsigned long offset;
 210         struct ext4_group_desc *desc;
 211         struct ext4_sb_info *sbi = EXT4_SB(sb);
 212
 213         if (block_group >= sbi->s_groups_count) {
 214                 ext4_error(sb, "ext4_get_group_desc",
 215                            "block_group >= groups_count - "
 216                            "block_group = %lu, groups_count = %lu",
 217                            block_group, sbi->s_groups_count);
 218
 219                 return NULL;
 220         }
 221         smp_rmb();
 222
 223         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
 224         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
 225         if (!sbi->s_group_desc[group_desc]) {
 226                 ext4_error(sb, "ext4_get_group_desc",
 227                            "Group descriptor not loaded - "
 228                            "block_group = %lu, group_desc = %lu, desc = %lu",
 229                            block_group, group_desc, offset);
 230                 return NULL;
 231         }
 232
 233         desc = (struct ext4_group_desc *)(
 234                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
 235                 offset * EXT4_DESC_SIZE(sb));
 236         if (bh)
 237                 *bh = sbi->s_group_desc[group_desc];
 238         return desc;
 239 }
 240
 241 static int ext4_valid_block_bitmap(struct super_block *sb,
 242                                         struct ext4_group_desc *desc,
 243                                         unsigned int block_group,
 244                                         struct buffer_head *bh)
 245 {
 246         ext4_grpblk_t offset;
 247         ext4_grpblk_t next_zero_bit;
 248         ext4_fsblk_t bitmap_blk;
 249         ext4_fsblk_t group_first_block;
 250
 251         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
 252                 /* with FLEX_BG, the inode/block bitmaps and itable
 253                  * blocks may not be in the group at all
 254                  * so the bitmap validation will be skipped for those groups
 255                  * or it has to also read the block group where the bitmaps
 256                  * are located to verify they are set.
 257                  */
 258                 return 1;
 259         }
 260         group_first_block = ext4_group_first_block_no(sb, block_group);
 261
 262         /* check whether block bitmap block number is set */
 263         bitmap_blk = ext4_block_bitmap(sb, desc);
 264         offset = bitmap_blk - group_first_block;
 265         if (!ext4_test_bit(offset, bh->b_data))
 266                 /* bad block bitmap */
 267                 goto err_out;
 268
 269         /* check whether the inode bitmap block number is set */
 270         bitmap_blk = ext4_inode_bitmap(sb, desc);
 271         offset = bitmap_blk - group_first_block;
 272         if (!ext4_test_bit(offset, bh->b_data))
 273                 /* bad block bitmap */
 274                 goto err_out;
 275
 276         /* check whether the inode table block number is set */
 277         bitmap_blk = ext4_inode_table(sb, desc);
 278         offset = bitmap_blk - group_first_block;
 279         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
 280                                 offset + EXT4_SB(sb)->s_itb_per_group,
 281                                 offset);
 282         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
 283                 /* good bitmap for inode tables */
 284                 return 1;
 285
 286 err_out:
 287         ext4_error(sb, __func__,
 288                         "Invalid block bitmap - "
 289                         "block_group = %d, block = %llu",
 290                         block_group, bitmap_blk);
 291         return 0;
 292 }
 293 /**
 294  * ext4_read_block_bitmap()
 295  * @sb:                 super block
 296  * @block_group:        given block group
 297  *
 298  * Read the bitmap for a given block_group,and validate the
 299  * bits for block/inode/inode tables are set in the bitmaps
 300  *
 301  * Return buffer_head on success or NULL in case of failure.
 302  */
 303 struct buffer_head *
 304 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 305 {
 306         struct ext4_group_desc *desc;
 307         struct buffer_head *bh = NULL;
 308         ext4_fsblk_t bitmap_blk;
 309
 310         desc = ext4_get_group_desc(sb, block_group, NULL);
 311         if (!desc)
 312                 return NULL;
 313         bitmap_blk = ext4_block_bitmap(sb, desc);
 314         bh = sb_getblk(sb, bitmap_blk);
 315         if (unlikely(!bh)) {
 316                 ext4_error(sb, __func__,
 317                             "Cannot read block bitmap - "
 318                             "block_group = %lu, block_bitmap = %llu",
 319                             block_group, bitmap_blk);
 320                 return NULL;
 321         }
 322         if (buffer_uptodate(bh) &&
 323             !(desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)))
 324                 return bh;
 325
 326         lock_buffer(bh);
 327         spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
 328         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
 329                 ext4_init_block_bitmap(sb, bh, block_group, desc);
 330                 set_buffer_uptodate(bh);
 331                 unlock_buffer(bh);
 332                 spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 333                 return bh;
 334         }
 335         spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
 336         if (bh_submit_read(bh) < 0) {
 337                 put_bh(bh);
 338                 ext4_error(sb, __func__,
 339                             "Cannot read block bitmap - "
 340                             "block_group = %lu, block_bitmap = %llu",
 341                             block_group, bitmap_blk);
 342                 return NULL;
 343         }
 344         ext4_valid_block_bitmap(sb, desc, block_group, bh);
 345         /*
 346          * file system mounted not to panic on error,
 347          * continue with corrupt bitmap
 348          */
 349         return bh;
 350 }
 351
 352 /**
 353  * ext4_free_blocks_sb() -- Free given blocks and update quota
 354  * @handle:                     handle to this transaction
 355  * @sb:                         super block
 356  * @block:                      start physcial block to free
 357  * @count:                      number of blocks to free
 358  * @pdquot_freed_blocks:        pointer to quota
 359  *
 360  * XXX This function is only used by the on-line resizing code, which
 361  * should probably be fixed up to call the mballoc variant.  There
 362  * this needs to be cleaned up later; in fact, I'm not convinced this
 363  * is 100% correct in the face of the mballoc code.  The online resizing
 364  * code needs to be fixed up to more tightly (and correctly) interlock
 365  * with the mballoc code.
 366  */
 367 void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
 368                          ext4_fsblk_t block, unsigned long count,
 369                          unsigned long *pdquot_freed_blocks)
 370 {
 371         struct buffer_head *bitmap_bh = NULL;
 372         struct buffer_head *gd_bh;
 373         ext4_group_t block_group;
 374         ext4_grpblk_t bit;
 375         unsigned long i;
 376         unsigned long overflow;
 377         struct ext4_group_desc *desc;
 378         struct ext4_super_block *es;
 379         struct ext4_sb_info *sbi;
 380         int err = 0, ret;
 381         ext4_grpblk_t group_freed;
 382
 383         *pdquot_freed_blocks = 0;
 384         sbi = EXT4_SB(sb);
 385         es = sbi->s_es;
 386         if (block < le32_to_cpu(es->s_first_data_block) ||
 387             block + count < block ||
 388             block + count > ext4_blocks_count(es)) {
 389                 ext4_error(sb, "ext4_free_blocks",
 390                            "Freeing blocks not in datazone - "
 391                            "block = %llu, count = %lu", block, count);
 392                 goto error_return;
 393         }
 394
 395         ext4_debug("freeing block(s) %llu-%llu\n", block, block + count - 1);
 396
 397 do_more:
 398         overflow = 0;
 399         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
 400         /*
 401          * Check to see if we are freeing blocks across a group
 402          * boundary.
 403          */
 404         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
 405                 overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
 406                 count -= overflow;
 407         }
 408         brelse(bitmap_bh);
 409         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
 410         if (!bitmap_bh)
 411                 goto error_return;
 412         desc = ext4_get_group_desc(sb, block_group, &gd_bh);
 413         if (!desc)
 414                 goto error_return;
 415
 416         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
 417             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
 418             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
 419             in_range(block + count - 1, ext4_inode_table(sb, desc),
 420                      sbi->s_itb_per_group)) {
 421                 ext4_error(sb, "ext4_free_blocks",
 422                            "Freeing blocks in system zones - "
 423                            "Block = %llu, count = %lu",
 424                            block, count);
 425                 goto error_return;
 426         }
 427
 428         /*
 429          * We are about to start releasing blocks in the bitmap,
 430          * so we need undo access.
 431          */
 432         /* @@@ check errors */
 433         BUFFER_TRACE(bitmap_bh, "getting undo access");
 434         err = ext4_journal_get_undo_access(handle, bitmap_bh);
 435         if (err)
 436                 goto error_return;
 437
 438         /*
 439          * We are about to modify some metadata.  Call the journal APIs
 440          * to unshare ->b_data if a currently-committing transaction is
 441          * using it
 442          */
 443         BUFFER_TRACE(gd_bh, "get_write_access");
 444         err = ext4_journal_get_write_access(handle, gd_bh);
 445         if (err)
 446                 goto error_return;
 447
 448         jbd_lock_bh_state(bitmap_bh);
 449
 450         for (i = 0, group_freed = 0; i < count; i++) {
 451                 /*
 452                  * An HJ special.  This is expensive...
 453                  */
 454 #ifdef CONFIG_JBD2_DEBUG
 455                 jbd_unlock_bh_state(bitmap_bh);
 456                 {
 457                         struct buffer_head *debug_bh;
 458                         debug_bh = sb_find_get_block(sb, block + i);
 459                         if (debug_bh) {
 460                                 BUFFER_TRACE(debug_bh, "Deleted!");
 461                                 if (!bh2jh(bitmap_bh)->b_committed_data)
 462                                         BUFFER_TRACE(debug_bh,
 463                                                 "No commited data in bitmap");
 464                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
 465                                 __brelse(debug_bh);
 466                         }
 467                 }
 468                 jbd_lock_bh_state(bitmap_bh);
 469 #endif
 470                 if (need_resched()) {
 471                         jbd_unlock_bh_state(bitmap_bh);
 472                         cond_resched();
 473                         jbd_lock_bh_state(bitmap_bh);
 474                 }
 475                 /* @@@ This prevents newly-allocated data from being
 476                  * freed and then reallocated within the same
 477                  * transaction.
 478                  *
 479                  * Ideally we would want to allow that to happen, but to
 480                  * do so requires making jbd2_journal_forget() capable of
 481                  * revoking the queued write of a data block, which
 482                  * implies blocking on the journal lock.  *forget()
 483                  * cannot block due to truncate races.
 484                  *
 485                  * Eventually we can fix this by making jbd2_journal_forget()
 486                  * return a status indicating whether or not it was able
 487                  * to revoke the buffer.  On successful revoke, it is
 488                  * safe not to set the allocation bit in the committed
 489                  * bitmap, because we know that there is no outstanding
 490                  * activity on the buffer any more and so it is safe to
 491                  * reallocate it.
 492                  */
 493                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
 494                 J_ASSERT_BH(bitmap_bh,
 495                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
 496                 ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
 497                                 bh2jh(bitmap_bh)->b_committed_data);
 498
 499                 /*
 500                  * We clear the bit in the bitmap after setting the committed
 501                  * data bit, because this is the reverse order to that which
 502                  * the allocator uses.
 503                  */
 504                 BUFFER_TRACE(bitmap_bh, "clear bit");
 505                 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
 506                                                 bit + i, bitmap_bh->b_data)) {
 507                         jbd_unlock_bh_state(bitmap_bh);
 508                         ext4_error(sb, __func__,
 509                                    "bit already cleared for block %llu",
 510                                    (ext4_fsblk_t)(block + i));
 511                         jbd_lock_bh_state(bitmap_bh);
 512                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
 513                 } else {
 514                         group_freed++;
 515                 }
 516         }
 517         jbd_unlock_bh_state(bitmap_bh);
 518
 519         spin_lock(sb_bgl_lock(sbi, block_group));
 520         le16_add_cpu(&desc->bg_free_blocks_count, group_freed);
 521         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
 522         spin_unlock(sb_bgl_lock(sbi, block_group));
 523         percpu_counter_add(&sbi->s_freeblocks_counter, count);
 524
 525         if (sbi->s_log_groups_per_flex) {
 526                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
 527                 spin_lock(sb_bgl_lock(sbi, flex_group));
 528                 sbi->s_flex_groups[flex_group].free_blocks += count;
 529                 spin_unlock(sb_bgl_lock(sbi, flex_group));
 530         }
 531
 532         /* We dirtied the bitmap block */
 533         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
 534         err = ext4_journal_dirty_metadata(handle, bitmap_bh);
 535
 536         /* And the group descriptor block */
 537         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
 538         ret = ext4_journal_dirty_metadata(handle, gd_bh);
 539         if (!err) err = ret;
 540         *pdquot_freed_blocks += group_freed;
 541
 542         if (overflow && !err) {
 543                 block += count;
 544                 count = overflow;
 545                 goto do_more;
 546         }
 547         sb->s_dirt = 1;
 548 error_return:
 549         brelse(bitmap_bh);
 550         ext4_std_error(sb, err);
 551         return;
 552 }
 553
 554 /**
 555  * ext4_free_blocks() -- Free given blocks and update quota
 556  * @handle:             handle for this transaction
 557  * @inode:              inode
 558  * @block:              start physical block to free
 559  * @count:              number of blocks to count
 560  * @metadata:           Are these metadata blocks
 561  */
 562 void ext4_free_blocks(handle_t *handle, struct inode *inode,
 563                         ext4_fsblk_t block, unsigned long count,
 564                         int metadata)
 565 {
 566         struct super_block *sb;
 567         unsigned long dquot_freed_blocks;
 568
 569         /* this isn't the right place to decide whether block is metadata
 570          * inode.c/extents.c knows better, but for safety ... */
 571         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
 572                 metadata = 1;
 573
 574         /* We need to make sure we don't reuse
 575          * block released untill the transaction commit.
 576          * writeback mode have weak data consistency so
 577          * don't force data as metadata when freeing block
 578          * for writeback mode.
 579          */
 580         if (metadata == 0 && !ext4_should_writeback_data(inode))
 581                 metadata = 1;
 582
 583         sb = inode->i_sb;
 584
 585         ext4_mb_free_blocks(handle, inode, block, count,
 586                             metadata, &dquot_freed_blocks);
 587         if (dquot_freed_blocks)
 588                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 589         return;
 590 }
 591
 592 /**
 593  * ext4_has_free_blocks()
 594  * @sbi:        in-core super block structure.
 595  * @nblocks:    number of needed blocks
 596  *
 597  * Check if filesystem has nblocks free & available for allocation.
 598  * On success return 1, return 0 on failure.
 599  */
 600 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
 601 {
 602         s64 free_blocks, dirty_blocks, root_blocks;
 603         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
 604         struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
 605
 606         free_blocks  = percpu_counter_read_positive(fbc);
 607         dirty_blocks = percpu_counter_read_positive(dbc);
 608         root_blocks = ext4_r_blocks_count(sbi->s_es);
 609
 610         if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
 611                                                 EXT4_FREEBLOCKS_WATERMARK) {
 612                 free_blocks  = percpu_counter_sum_positive(fbc);
 613                 dirty_blocks = percpu_counter_sum_positive(dbc);
 614                 if (dirty_blocks < 0) {
 615                         printk(KERN_CRIT "Dirty block accounting "
 616                                         "went wrong %lld\n",
 617                                         (long long)dirty_blocks);
 618                 }
 619         }
 620         /* Check whether we have space after
 621          * accounting for current dirty blocks & root reserved blocks.
 622          */
 623         if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
 624                 return 1;
 625
 626         /* Hm, nope.  Are (enough) root reserved blocks available? */
 627         if (sbi->s_resuid == current_fsuid() ||
 628             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
 629             capable(CAP_SYS_RESOURCE)) {
 630                 if (free_blocks >= (nblocks + dirty_blocks))
 631                         return 1;
 632         }
 633
 634         return 0;
 635 }
 636
 637 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
 638                                                 s64 nblocks)
 639 {
 640         if (ext4_has_free_blocks(sbi, nblocks)) {
 641                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
 642                 return 0;
 643         } else
 644                 return -ENOSPC;
 645 }
 646
 647 /**
 648  * ext4_should_retry_alloc()
 649  * @sb:                 super block
 650  * @retries             number of attemps has been made
 651  *
 652  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
 653  * it is profitable to retry the operation, this function will wait
 654  * for the current or commiting transaction to complete, and then
 655  * return TRUE.
 656  *
 657  * if the total number of retries exceed three times, return FALSE.
 658  */
 659 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 660 {
 661         if (!ext4_has_free_blocks(EXT4_SB(sb), 1) || (*retries)++ > 3)
 662                 return 0;
 663
 664         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
 665
 666         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
 667 }
 668
 669 /*
 670  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
 671  *
 672  * @handle:             handle to this transaction
 673  * @inode:              file inode
 674  * @goal:               given target block(filesystem wide)
 675  * @count:              pointer to total number of blocks needed
 676  * @errp:               error code
 677  *
 678  * Return 1st allocated block number on success, *count stores total account
 679  * error stores in errp pointer
 680  */
 681 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
 682                 ext4_fsblk_t goal, unsigned long *count, int *errp)
 683 {
 684         struct ext4_allocation_request ar;
 685         ext4_fsblk_t ret;
 686
 687         memset(&ar, 0, sizeof(ar));
 688         /* Fill with neighbour allocated blocks */
 689         ar.inode = inode;
 690         ar.goal = goal;
 691         ar.len = count ? *count : 1;
 692
 693         ret = ext4_mb_new_blocks(handle, &ar, errp);
 694         if (count)
 695                 *count = ar.len;
 696
 697         /*
 698          * Account for the allocated meta blocks
 699          */
 700         if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
 701                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 702                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
 703                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 704         }
 705         return ret;
 706 }
 707
 708 /**
 709  * ext4_count_free_blocks() -- count filesystem free blocks
 710  * @sb:         superblock
 711  *
 712  * Adds up the number of free blocks from each block group.
 713  */
 714 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
 715 {
 716         ext4_fsblk_t desc_count;
 717         struct ext4_group_desc *gdp;
 718         ext4_group_t i;
 719         ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
 720 #ifdef EXT4FS_DEBUG
 721         struct ext4_super_block *es;
 722         ext4_fsblk_t bitmap_count;
 723         unsigned long x;
 724         struct buffer_head *bitmap_bh = NULL;
 725
 726         es = EXT4_SB(sb)->s_es;
 727         desc_count = 0;
 728         bitmap_count = 0;
 729         gdp = NULL;
 730
 731         smp_rmb();
 732         for (i = 0; i < ngroups; i++) {
 733                 gdp = ext4_get_group_desc(sb, i, NULL);
 734                 if (!gdp)
 735                         continue;
 736                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
 737                 brelse(bitmap_bh);
 738                 bitmap_bh = ext4_read_block_bitmap(sb, i);
 739                 if (bitmap_bh == NULL)
 740                         continue;
 741
 742                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
 743                 printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
 744                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
 745                 bitmap_count += x;
 746         }
 747         brelse(bitmap_bh);
 748         printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
 749                 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
 750                desc_count, bitmap_count);
 751         return bitmap_count;
 752 #else
 753         desc_count = 0;
 754         smp_rmb();
 755         for (i = 0; i < ngroups; i++) {
 756                 gdp = ext4_get_group_desc(sb, i, NULL);
 757                 if (!gdp)
 758                         continue;
 759                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
 760         }
 761
 762         return desc_count;
 763 #endif
 764 }
 765
 766 static inline int test_root(ext4_group_t a, int b)
 767 {
 768         int num = b;
 769
 770         while (a > num)
 771                 num *= b;
 772         return num == a;
 773 }
 774
 775 static int ext4_group_sparse(ext4_group_t group)
 776 {
 777         if (group <= 1)
 778                 return 1;
 779         if (!(group & 1))
 780                 return 0;
 781         return (test_root(group, 7) || test_root(group, 5) ||
 782                 test_root(group, 3));
 783 }
 784
 785 /**
 786  *      ext4_bg_has_super - number of blocks used by the superblock in group
 787  *      @sb: superblock for filesystem
 788  *      @group: group number to check
 789  *
 790  *      Return the number of blocks used by the superblock (primary or backup)
 791  *      in this group.  Currently this will be only 0 or 1.
 792  */
 793 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
 794 {
 795         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
 796                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
 797                         !ext4_group_sparse(group))
 798                 return 0;
 799         return 1;
 800 }
 801
 802 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
 803                                         ext4_group_t group)
 804 {
 805         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 806         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
 807         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
 808
 809         if (group == first || group == first + 1 || group == last)
 810                 return 1;
 811         return 0;
 812 }
 813
 814 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
 815                                         ext4_group_t group)
 816 {
 817         return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
 818 }
 819
 820 /**
 821  *      ext4_bg_num_gdb - number of blocks used by the group table in group
 822  *      @sb: superblock for filesystem
 823  *      @group: group number to check
 824  *
 825  *      Return the number of blocks used by the group descriptor table
 826  *      (primary or backup) in this group.  In the future there may be a
 827  *      different number of descriptor blocks in each group.
 828  */
 829 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 830 {
 831         unsigned long first_meta_bg =
 832                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
 833         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
 834
 835         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
 836                         metagroup < first_meta_bg)
 837                 return ext4_bg_num_gdb_nometa(sb, group);
 838
 839         return ext4_bg_num_gdb_meta(sb,group);
 840
 841 }
 842