LCOV - code coverage report
Current view: top level - fs/ext4 - balloc.c (source / functions) Hit Total Coverage
Test: Real Lines: 138 290 47.6 %
Date: 2020-10-17 15:46:43 Functions: 0 22 0.0 %
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0
       2                 :            : /*
       3                 :            :  *  linux/fs/ext4/balloc.c
       4                 :            :  *
       5                 :            :  * Copyright (C) 1992, 1993, 1994, 1995
       6                 :            :  * Remy Card (card@masi.ibp.fr)
       7                 :            :  * Laboratoire MASI - Institut Blaise Pascal
       8                 :            :  * Universite Pierre et Marie Curie (Paris VI)
       9                 :            :  *
      10                 :            :  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
      11                 :            :  *  Big-endian to little-endian byte-swapping/bitmaps by
      12                 :            :  *        David S. Miller (davem@caip.rutgers.edu), 1995
      13                 :            :  */
      14                 :            : 
      15                 :            : #include <linux/time.h>
      16                 :            : #include <linux/capability.h>
      17                 :            : #include <linux/fs.h>
      18                 :            : #include <linux/quotaops.h>
      19                 :            : #include <linux/buffer_head.h>
      20                 :            : #include "ext4.h"
      21                 :            : #include "ext4_jbd2.h"
      22                 :            : #include "mballoc.h"
      23                 :            : 
      24                 :            : #include <trace/events/ext4.h>
      25                 :            : 
      26                 :            : static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
      27                 :            :                                             ext4_group_t block_group);
      28                 :            : /*
      29                 :            :  * balloc.c contains the blocks allocation and deallocation routines
      30                 :            :  */
      31                 :            : 
      32                 :            : /*
      33                 :            :  * Calculate block group number for a given block number
      34                 :            :  */
      35                 :          3 : ext4_group_t ext4_get_group_number(struct super_block *sb,
      36                 :            :                                    ext4_fsblk_t block)
      37                 :            : {
      38                 :            :         ext4_group_t group;
      39                 :            : 
      40                 :          3 :         if (test_opt2(sb, STD_GROUP_SIZE))
      41                 :          3 :                 group = (block -
      42                 :          3 :                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
      43                 :          3 :                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
      44                 :            :         else
      45                 :          0 :                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
      46                 :          3 :         return group;
      47                 :            : }
      48                 :            : 
      49                 :            : /*
      50                 :            :  * Calculate the block group number and offset into the block/cluster
      51                 :            :  * allocation bitmap, given a block number
      52                 :            :  */
      53                 :          3 : void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
      54                 :            :                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
      55                 :            : {
      56                 :          3 :         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
      57                 :            :         ext4_grpblk_t offset;
      58                 :            : 
      59                 :          3 :         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
      60                 :          3 :         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
      61                 :          3 :                 EXT4_SB(sb)->s_cluster_bits;
      62                 :          3 :         if (offsetp)
      63                 :          3 :                 *offsetp = offset;
      64                 :          3 :         if (blockgrpp)
      65                 :          3 :                 *blockgrpp = blocknr;
      66                 :            : 
      67                 :          3 : }
      68                 :            : 
      69                 :            : /*
      70                 :            :  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
      71                 :            :  * and 0 otherwise.
      72                 :            :  */
      73                 :            : static inline int ext4_block_in_group(struct super_block *sb,
      74                 :            :                                       ext4_fsblk_t block,
      75                 :            :                                       ext4_group_t block_group)
      76                 :            : {
      77                 :            :         ext4_group_t actual_group;
      78                 :            : 
      79                 :          0 :         actual_group = ext4_get_group_number(sb, block);
      80                 :            :         return (actual_group == block_group) ? 1 : 0;
      81                 :            : }
      82                 :            : 
      83                 :            : /* Return the number of clusters used for file system metadata; this
      84                 :            :  * represents the overhead needed by the file system.
      85                 :            :  */
      86                 :          0 : static unsigned ext4_num_overhead_clusters(struct super_block *sb,
      87                 :            :                                            ext4_group_t block_group,
      88                 :            :                                            struct ext4_group_desc *gdp)
      89                 :            : {
      90                 :            :         unsigned num_clusters;
      91                 :            :         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
      92                 :            :         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
      93                 :            :         ext4_fsblk_t itbl_blk;
      94                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
      95                 :            : 
      96                 :            :         /* This is the number of clusters used by the superblock,
      97                 :            :          * block group descriptors, and reserved block group
      98                 :            :          * descriptor blocks */
      99                 :          0 :         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
     100                 :            : 
     101                 :            :         /*
     102                 :            :          * For the allocation bitmaps and inode table, we first need
     103                 :            :          * to check to see if the block is in the block group.  If it
     104                 :            :          * is, then check to see if the cluster is already accounted
     105                 :            :          * for in the clusters used for the base metadata cluster, or
     106                 :            :          * if we can increment the base metadata cluster to include
     107                 :            :          * that block.  Otherwise, we will have to track the cluster
     108                 :            :          * used for the allocation bitmap or inode table explicitly.
     109                 :            :          * Normally all of these blocks are contiguous, so the special
     110                 :            :          * case handling shouldn't be necessary except for *very*
     111                 :            :          * unusual file system layouts.
     112                 :            :          */
     113                 :          0 :         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
     114                 :          0 :                 block_cluster = EXT4_B2C(sbi,
     115                 :            :                                          ext4_block_bitmap(sb, gdp) - start);
     116                 :          0 :                 if (block_cluster < num_clusters)
     117                 :            :                         block_cluster = -1;
     118                 :          0 :                 else if (block_cluster == num_clusters) {
     119                 :          0 :                         num_clusters++;
     120                 :            :                         block_cluster = -1;
     121                 :            :                 }
     122                 :            :         }
     123                 :            : 
     124                 :          0 :         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
     125                 :          0 :                 inode_cluster = EXT4_B2C(sbi,
     126                 :            :                                          ext4_inode_bitmap(sb, gdp) - start);
     127                 :          0 :                 if (inode_cluster < num_clusters)
     128                 :            :                         inode_cluster = -1;
     129                 :          0 :                 else if (inode_cluster == num_clusters) {
     130                 :          0 :                         num_clusters++;
     131                 :            :                         inode_cluster = -1;
     132                 :            :                 }
     133                 :            :         }
     134                 :            : 
     135                 :          0 :         itbl_blk = ext4_inode_table(sb, gdp);
     136                 :          0 :         for (i = 0; i < sbi->s_itb_per_group; i++) {
     137                 :          0 :                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
     138                 :          0 :                         c = EXT4_B2C(sbi, itbl_blk + i - start);
     139                 :          0 :                         if ((c < num_clusters) || (c == inode_cluster) ||
     140                 :          0 :                             (c == block_cluster) || (c == itbl_cluster))
     141                 :          0 :                                 continue;
     142                 :          0 :                         if (c == num_clusters) {
     143                 :          0 :                                 num_clusters++;
     144                 :          0 :                                 continue;
     145                 :            :                         }
     146                 :          0 :                         num_clusters++;
     147                 :            :                         itbl_cluster = c;
     148                 :            :                 }
     149                 :            :         }
     150                 :            : 
     151                 :          0 :         if (block_cluster != -1)
     152                 :          0 :                 num_clusters++;
     153                 :          0 :         if (inode_cluster != -1)
     154                 :          0 :                 num_clusters++;
     155                 :            : 
     156                 :          0 :         return num_clusters;
     157                 :            : }
     158                 :            : 
     159                 :          0 : static unsigned int num_clusters_in_group(struct super_block *sb,
     160                 :            :                                           ext4_group_t block_group)
     161                 :            : {
     162                 :            :         unsigned int blocks;
     163                 :            : 
     164                 :          0 :         if (block_group == ext4_get_groups_count(sb) - 1) {
     165                 :            :                 /*
     166                 :            :                  * Even though mke2fs always initializes the first and
     167                 :            :                  * last group, just in case some other tool was used,
     168                 :            :                  * we need to make sure we calculate the right free
     169                 :            :                  * blocks.
     170                 :            :                  */
     171                 :          0 :                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
     172                 :            :                         ext4_group_first_block_no(sb, block_group);
     173                 :            :         } else
     174                 :          0 :                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
     175                 :          0 :         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
     176                 :            : }
     177                 :            : 
     178                 :            : /* Initializes an uninitialized block bitmap */
     179                 :          0 : static int ext4_init_block_bitmap(struct super_block *sb,
     180                 :            :                                    struct buffer_head *bh,
     181                 :            :                                    ext4_group_t block_group,
     182                 :            :                                    struct ext4_group_desc *gdp)
     183                 :            : {
     184                 :            :         unsigned int bit, bit_max;
     185                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
     186                 :            :         ext4_fsblk_t start, tmp;
     187                 :            : 
     188                 :          0 :         J_ASSERT_BH(bh, buffer_locked(bh));
     189                 :            : 
     190                 :            :         /* If checksum is bad mark all blocks used to prevent allocation
     191                 :            :          * essentially implementing a per-group read-only flag. */
     192                 :          0 :         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
     193                 :          0 :                 ext4_mark_group_bitmap_corrupted(sb, block_group,
     194                 :            :                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT |
     195                 :            :                                         EXT4_GROUP_INFO_IBITMAP_CORRUPT);
     196                 :          0 :                 return -EFSBADCRC;
     197                 :            :         }
     198                 :          0 :         memset(bh->b_data, 0, sb->s_blocksize);
     199                 :            : 
     200                 :          0 :         bit_max = ext4_num_base_meta_clusters(sb, block_group);
     201                 :          0 :         if ((bit_max >> 3) >= bh->b_size)
     202                 :            :                 return -EFSCORRUPTED;
     203                 :            : 
     204                 :          0 :         for (bit = 0; bit < bit_max; bit++)
     205                 :          0 :                 ext4_set_bit(bit, bh->b_data);
     206                 :            : 
     207                 :            :         start = ext4_group_first_block_no(sb, block_group);
     208                 :            : 
     209                 :            :         /* Set bits for block and inode bitmaps, and inode table */
     210                 :          0 :         tmp = ext4_block_bitmap(sb, gdp);
     211                 :          0 :         if (ext4_block_in_group(sb, tmp, block_group))
     212                 :          0 :                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
     213                 :            : 
     214                 :          0 :         tmp = ext4_inode_bitmap(sb, gdp);
     215                 :          0 :         if (ext4_block_in_group(sb, tmp, block_group))
     216                 :          0 :                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
     217                 :            : 
     218                 :          0 :         tmp = ext4_inode_table(sb, gdp);
     219                 :          0 :         for (; tmp < ext4_inode_table(sb, gdp) +
     220                 :          0 :                      sbi->s_itb_per_group; tmp++) {
     221                 :          0 :                 if (ext4_block_in_group(sb, tmp, block_group))
     222                 :          0 :                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
     223                 :            :         }
     224                 :            : 
     225                 :            :         /*
     226                 :            :          * Also if the number of blocks within the group is less than
     227                 :            :          * the blocksize * 8 ( which is the size of bitmap ), set rest
     228                 :            :          * of the block bitmap to 1
     229                 :            :          */
     230                 :          0 :         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
     231                 :          0 :                              sb->s_blocksize * 8, bh->b_data);
     232                 :          0 :         return 0;
     233                 :            : }
     234                 :            : 
     235                 :            : /* Return the number of free blocks in a block group.  It is used when
     236                 :            :  * the block bitmap is uninitialized, so we can't just count the bits
     237                 :            :  * in the bitmap. */
     238                 :          0 : unsigned ext4_free_clusters_after_init(struct super_block *sb,
     239                 :            :                                        ext4_group_t block_group,
     240                 :            :                                        struct ext4_group_desc *gdp)
     241                 :            : {
     242                 :          0 :         return num_clusters_in_group(sb, block_group) - 
     243                 :          0 :                 ext4_num_overhead_clusters(sb, block_group, gdp);
     244                 :            : }
     245                 :            : 
     246                 :            : /*
     247                 :            :  * The free blocks are managed by bitmaps.  A file system contains several
     248                 :            :  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
     249                 :            :  * block for inodes, N blocks for the inode table and data blocks.
     250                 :            :  *
     251                 :            :  * The file system contains group descriptors which are located after the
     252                 :            :  * super block.  Each descriptor contains the number of the bitmap block and
     253                 :            :  * the free blocks count in the block.  The descriptors are loaded in memory
     254                 :            :  * when a file system is mounted (see ext4_fill_super).
     255                 :            :  */
     256                 :            : 
     257                 :            : /**
     258                 :            :  * ext4_get_group_desc() -- load group descriptor from disk
     259                 :            :  * @sb:                 super block
     260                 :            :  * @block_group:        given block group
     261                 :            :  * @bh:                 pointer to the buffer head to store the block
     262                 :            :  *                      group descriptor
     263                 :            :  */
     264                 :          3 : struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
     265                 :            :                                              ext4_group_t block_group,
     266                 :            :                                              struct buffer_head **bh)
     267                 :            : {
     268                 :            :         unsigned int group_desc;
     269                 :            :         unsigned int offset;
     270                 :            :         ext4_group_t ngroups = ext4_get_groups_count(sb);
     271                 :            :         struct ext4_group_desc *desc;
     272                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
     273                 :            :         struct buffer_head *bh_p;
     274                 :            : 
     275                 :          3 :         if (block_group >= ngroups) {
     276                 :          0 :                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
     277                 :            :                            " groups_count = %u", block_group, ngroups);
     278                 :            : 
     279                 :          0 :                 return NULL;
     280                 :            :         }
     281                 :            : 
     282                 :          3 :         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
     283                 :          3 :         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
     284                 :          3 :         bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc);
     285                 :            :         /*
     286                 :            :          * sbi_array_rcu_deref returns with rcu unlocked, this is ok since
     287                 :            :          * the pointer being dereferenced won't be dereferenced again. By
     288                 :            :          * looking at the usage in add_new_gdb() the value isn't modified,
     289                 :            :          * just the pointer, and so it remains valid.
     290                 :            :          */
     291                 :          3 :         if (!bh_p) {
     292                 :          0 :                 ext4_error(sb, "Group descriptor not loaded - "
     293                 :            :                            "block_group = %u, group_desc = %u, desc = %u",
     294                 :            :                            block_group, group_desc, offset);
     295                 :          0 :                 return NULL;
     296                 :            :         }
     297                 :            : 
     298                 :          3 :         desc = (struct ext4_group_desc *)(
     299                 :          3 :                 (__u8 *)bh_p->b_data +
     300                 :          3 :                 offset * EXT4_DESC_SIZE(sb));
     301                 :          3 :         if (bh)
     302                 :          3 :                 *bh = bh_p;
     303                 :          3 :         return desc;
     304                 :            : }
     305                 :            : 
     306                 :            : /*
     307                 :            :  * Return the block number which was discovered to be invalid, or 0 if
     308                 :            :  * the block bitmap is valid.
     309                 :            :  */
     310                 :          3 : static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
     311                 :            :                                             struct ext4_group_desc *desc,
     312                 :            :                                             ext4_group_t block_group,
     313                 :            :                                             struct buffer_head *bh)
     314                 :            : {
     315                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
     316                 :            :         ext4_grpblk_t offset;
     317                 :            :         ext4_grpblk_t next_zero_bit;
     318                 :          3 :         ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
     319                 :            :         ext4_fsblk_t blk;
     320                 :            :         ext4_fsblk_t group_first_block;
     321                 :            : 
     322                 :          3 :         if (ext4_has_feature_flex_bg(sb)) {
     323                 :            :                 /* with FLEX_BG, the inode/block bitmaps and itable
     324                 :            :                  * blocks may not be in the group at all
     325                 :            :                  * so the bitmap validation will be skipped for those groups
     326                 :            :                  * or it has to also read the block group where the bitmaps
     327                 :            :                  * are located to verify they are set.
     328                 :            :                  */
     329                 :            :                 return 0;
     330                 :            :         }
     331                 :            :         group_first_block = ext4_group_first_block_no(sb, block_group);
     332                 :            : 
     333                 :            :         /* check whether block bitmap block number is set */
     334                 :          0 :         blk = ext4_block_bitmap(sb, desc);
     335                 :          0 :         offset = blk - group_first_block;
     336                 :          0 :         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
     337                 :          0 :             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
     338                 :            :                 /* bad block bitmap */
     339                 :            :                 return blk;
     340                 :            : 
     341                 :            :         /* check whether the inode bitmap block number is set */
     342                 :          0 :         blk = ext4_inode_bitmap(sb, desc);
     343                 :          0 :         offset = blk - group_first_block;
     344                 :          0 :         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
     345                 :          0 :             !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
     346                 :            :                 /* bad block bitmap */
     347                 :            :                 return blk;
     348                 :            : 
     349                 :            :         /* check whether the inode table block number is set */
     350                 :          0 :         blk = ext4_inode_table(sb, desc);
     351                 :          0 :         offset = blk - group_first_block;
     352                 :          0 :         if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
     353                 :          0 :             EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
     354                 :            :                 return blk;
     355                 :          0 :         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
     356                 :            :                         EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
     357                 :            :                         EXT4_B2C(sbi, offset));
     358                 :          0 :         if (next_zero_bit <
     359                 :          0 :             EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
     360                 :            :                 /* bad bitmap for inode tables */
     361                 :          0 :                 return blk;
     362                 :            :         return 0;
     363                 :            : }
     364                 :            : 
     365                 :          3 : static int ext4_validate_block_bitmap(struct super_block *sb,
     366                 :            :                                       struct ext4_group_desc *desc,
     367                 :            :                                       ext4_group_t block_group,
     368                 :            :                                       struct buffer_head *bh)
     369                 :            : {
     370                 :            :         ext4_fsblk_t    blk;
     371                 :          3 :         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
     372                 :            : 
     373                 :          3 :         if (buffer_verified(bh))
     374                 :            :                 return 0;
     375                 :          3 :         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
     376                 :            :                 return -EFSCORRUPTED;
     377                 :            : 
     378                 :          3 :         ext4_lock_group(sb, block_group);
     379                 :          3 :         if (buffer_verified(bh))
     380                 :            :                 goto verified;
     381                 :          3 :         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
     382                 :            :                         desc, bh))) {
     383                 :            :                 ext4_unlock_group(sb, block_group);
     384                 :          0 :                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
     385                 :          0 :                 ext4_mark_group_bitmap_corrupted(sb, block_group,
     386                 :            :                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
     387                 :          0 :                 return -EFSBADCRC;
     388                 :            :         }
     389                 :          3 :         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
     390                 :          3 :         if (unlikely(blk != 0)) {
     391                 :            :                 ext4_unlock_group(sb, block_group);
     392                 :          0 :                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
     393                 :            :                            block_group, blk);
     394                 :          0 :                 ext4_mark_group_bitmap_corrupted(sb, block_group,
     395                 :            :                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
     396                 :          0 :                 return -EFSCORRUPTED;
     397                 :            :         }
     398                 :            :         set_buffer_verified(bh);
     399                 :            : verified:
     400                 :            :         ext4_unlock_group(sb, block_group);
     401                 :          3 :         return 0;
     402                 :            : }
     403                 :            : 
     404                 :            : /**
     405                 :            :  * ext4_read_block_bitmap_nowait()
     406                 :            :  * @sb:                 super block
     407                 :            :  * @block_group:        given block group
     408                 :            :  *
     409                 :            :  * Read the bitmap for a given block_group,and validate the
     410                 :            :  * bits for block/inode/inode tables are set in the bitmaps
     411                 :            :  *
     412                 :            :  * Return buffer_head on success or NULL in case of failure.
     413                 :            :  */
     414                 :            : struct buffer_head *
     415                 :          3 : ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
     416                 :            : {
     417                 :            :         struct ext4_group_desc *desc;
     418                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
     419                 :            :         struct buffer_head *bh;
     420                 :            :         ext4_fsblk_t bitmap_blk;
     421                 :            :         int err;
     422                 :            : 
     423                 :          3 :         desc = ext4_get_group_desc(sb, block_group, NULL);
     424                 :          3 :         if (!desc)
     425                 :            :                 return ERR_PTR(-EFSCORRUPTED);
     426                 :          3 :         bitmap_blk = ext4_block_bitmap(sb, desc);
     427                 :          3 :         if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
     428                 :            :             (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
     429                 :          2 :                 ext4_error(sb, "Invalid block bitmap block %llu in "
     430                 :            :                            "block_group %u", bitmap_blk, block_group);
     431                 :          0 :                 ext4_mark_group_bitmap_corrupted(sb, block_group,
     432                 :            :                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
     433                 :          0 :                 return ERR_PTR(-EFSCORRUPTED);
     434                 :            :         }
     435                 :            :         bh = sb_getblk(sb, bitmap_blk);
     436                 :          3 :         if (unlikely(!bh)) {
     437                 :          0 :                 ext4_warning(sb, "Cannot get buffer for block bitmap - "
     438                 :            :                              "block_group = %u, block_bitmap = %llu",
     439                 :            :                              block_group, bitmap_blk);
     440                 :          0 :                 return ERR_PTR(-ENOMEM);
     441                 :            :         }
     442                 :            : 
     443                 :          3 :         if (bitmap_uptodate(bh))
     444                 :            :                 goto verify;
     445                 :            : 
     446                 :          3 :         lock_buffer(bh);
     447                 :          3 :         if (bitmap_uptodate(bh)) {
     448                 :          0 :                 unlock_buffer(bh);
     449                 :          0 :                 goto verify;
     450                 :            :         }
     451                 :          3 :         ext4_lock_group(sb, block_group);
     452                 :          3 :         if (ext4_has_group_desc_csum(sb) &&
     453                 :          0 :             (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
     454                 :          0 :                 if (block_group == 0) {
     455                 :            :                         ext4_unlock_group(sb, block_group);
     456                 :          0 :                         unlock_buffer(bh);
     457                 :          0 :                         ext4_error(sb, "Block bitmap for bg 0 marked "
     458                 :            :                                    "uninitialized");
     459                 :            :                         err = -EFSCORRUPTED;
     460                 :          0 :                         goto out;
     461                 :            :                 }
     462                 :          0 :                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
     463                 :            :                 set_bitmap_uptodate(bh);
     464                 :            :                 set_buffer_uptodate(bh);
     465                 :            :                 set_buffer_verified(bh);
     466                 :            :                 ext4_unlock_group(sb, block_group);
     467                 :          0 :                 unlock_buffer(bh);
     468                 :          0 :                 if (err) {
     469                 :          0 :                         ext4_error(sb, "Failed to init block bitmap for group "
     470                 :            :                                    "%u: %d", block_group, err);
     471                 :          0 :                         goto out;
     472                 :            :                 }
     473                 :            :                 goto verify;
     474                 :            :         }
     475                 :            :         ext4_unlock_group(sb, block_group);
     476                 :          3 :         if (buffer_uptodate(bh)) {
     477                 :            :                 /*
     478                 :            :                  * if not uninit if bh is uptodate,
     479                 :            :                  * bitmap is also uptodate
     480                 :            :                  */
     481                 :            :                 set_bitmap_uptodate(bh);
     482                 :          1 :                 unlock_buffer(bh);
     483                 :          1 :                 goto verify;
     484                 :            :         }
     485                 :            :         /*
     486                 :            :          * submit the buffer_head for reading
     487                 :            :          */
     488                 :            :         set_buffer_new(bh);
     489                 :          3 :         trace_ext4_read_block_bitmap_load(sb, block_group);
     490                 :          3 :         bh->b_end_io = ext4_end_bitmap_read;
     491                 :            :         get_bh(bh);
     492                 :          3 :         submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
     493                 :          3 :         return bh;
     494                 :            : verify:
     495                 :          3 :         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
     496                 :          3 :         if (err)
     497                 :            :                 goto out;
     498                 :            :         return bh;
     499                 :            : out:
     500                 :          0 :         put_bh(bh);
     501                 :          0 :         return ERR_PTR(err);
     502                 :            : }
     503                 :            : 
     504                 :            : /* Returns 0 on success, 1 on error */
     505                 :          3 : int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
     506                 :            :                            struct buffer_head *bh)
     507                 :            : {
     508                 :            :         struct ext4_group_desc *desc;
     509                 :            : 
     510                 :          3 :         if (!buffer_new(bh))
     511                 :            :                 return 0;
     512                 :          3 :         desc = ext4_get_group_desc(sb, block_group, NULL);
     513                 :          3 :         if (!desc)
     514                 :            :                 return -EFSCORRUPTED;
     515                 :          3 :         wait_on_buffer(bh);
     516                 :          3 :         if (!buffer_uptodate(bh)) {
     517                 :          0 :                 ext4_error(sb, "Cannot read block bitmap - "
     518                 :            :                            "block_group = %u, block_bitmap = %llu",
     519                 :            :                            block_group, (unsigned long long) bh->b_blocknr);
     520                 :          0 :                 ext4_mark_group_bitmap_corrupted(sb, block_group,
     521                 :            :                                         EXT4_GROUP_INFO_BBITMAP_CORRUPT);
     522                 :          0 :                 return -EIO;
     523                 :            :         }
     524                 :            :         clear_buffer_new(bh);
     525                 :            :         /* Panic or remount fs read-only if block bitmap is invalid */
     526                 :          3 :         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
     527                 :            : }
     528                 :            : 
     529                 :            : struct buffer_head *
     530                 :          3 : ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
     531                 :            : {
     532                 :            :         struct buffer_head *bh;
     533                 :            :         int err;
     534                 :            : 
     535                 :          3 :         bh = ext4_read_block_bitmap_nowait(sb, block_group);
     536                 :          3 :         if (IS_ERR(bh))
     537                 :            :                 return bh;
     538                 :          3 :         err = ext4_wait_block_bitmap(sb, block_group, bh);
     539                 :          3 :         if (err) {
     540                 :          0 :                 put_bh(bh);
     541                 :          0 :                 return ERR_PTR(err);
     542                 :            :         }
     543                 :            :         return bh;
     544                 :            : }
     545                 :            : 
     546                 :            : /**
     547                 :            :  * ext4_has_free_clusters()
     548                 :            :  * @sbi:        in-core super block structure.
     549                 :            :  * @nclusters:  number of needed blocks
     550                 :            :  * @flags:      flags from ext4_mb_new_blocks()
     551                 :            :  *
     552                 :            :  * Check if filesystem has nclusters free & available for allocation.
     553                 :            :  * On success return 1, return 0 on failure.
     554                 :            :  */
     555                 :          3 : static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
     556                 :            :                                   s64 nclusters, unsigned int flags)
     557                 :            : {
     558                 :            :         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
     559                 :          3 :         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
     560                 :          3 :         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
     561                 :            : 
     562                 :            :         free_clusters  = percpu_counter_read_positive(fcc);
     563                 :            :         dirty_clusters = percpu_counter_read_positive(dcc);
     564                 :          3 :         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
     565                 :            : 
     566                 :            :         /*
     567                 :            :          * r_blocks_count should always be multiple of the cluster ratio so
     568                 :            :          * we are safe to do a plane bit shift only.
     569                 :            :          */
     570                 :          3 :         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
     571                 :            :               resv_clusters;
     572                 :            : 
     573                 :          3 :         if (free_clusters - (nclusters + rsv + dirty_clusters) <
     574                 :          3 :                                         EXT4_FREECLUSTERS_WATERMARK) {
     575                 :            :                 free_clusters  = percpu_counter_sum_positive(fcc);
     576                 :            :                 dirty_clusters = percpu_counter_sum_positive(dcc);
     577                 :            :         }
     578                 :            :         /* Check whether we have space after accounting for current
     579                 :            :          * dirty clusters & root reserved clusters.
     580                 :            :          */
     581                 :          3 :         if (free_clusters >= (rsv + nclusters + dirty_clusters))
     582                 :            :                 return 1;
     583                 :            : 
     584                 :            :         /* Hm, nope.  Are (enough) root reserved clusters available? */
     585                 :          0 :         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
     586                 :          0 :             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
     587                 :          0 :             capable(CAP_SYS_RESOURCE) ||
     588                 :          0 :             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
     589                 :            : 
     590                 :          0 :                 if (free_clusters >= (nclusters + dirty_clusters +
     591                 :            :                                       resv_clusters))
     592                 :            :                         return 1;
     593                 :            :         }
     594                 :            :         /* No free blocks. Let's see if we can dip into reserved pool */
     595                 :          0 :         if (flags & EXT4_MB_USE_RESERVED) {
     596                 :          0 :                 if (free_clusters >= (nclusters + dirty_clusters))
     597                 :            :                         return 1;
     598                 :            :         }
     599                 :            : 
     600                 :          0 :         return 0;
     601                 :            : }
     602                 :            : 
     603                 :          3 : int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
     604                 :            :                              s64 nclusters, unsigned int flags)
     605                 :            : {
     606                 :          3 :         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
     607                 :          3 :                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
     608                 :          3 :                 return 0;
     609                 :            :         } else
     610                 :            :                 return -ENOSPC;
     611                 :            : }
     612                 :            : 
     613                 :            : /**
     614                 :            :  * ext4_should_retry_alloc() - check if a block allocation should be retried
     615                 :            :  * @sb:                 super block
     616                 :            :  * @retries:            number of attemps has been made
     617                 :            :  *
     618                 :            :  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
     619                 :            :  * it is profitable to retry the operation, this function will wait
     620                 :            :  * for the current or committing transaction to complete, and then
     621                 :            :  * return TRUE.  We will only retry once.
     622                 :            :  */
     623                 :          0 : int ext4_should_retry_alloc(struct super_block *sb, int *retries)
     624                 :            : {
     625                 :          0 :         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
     626                 :          0 :             (*retries)++ > 1 ||
     627                 :          0 :             !EXT4_SB(sb)->s_journal)
     628                 :            :                 return 0;
     629                 :            : 
     630                 :          0 :         smp_mb();
     631                 :          0 :         if (EXT4_SB(sb)->s_mb_free_pending == 0)
     632                 :            :                 return 0;
     633                 :            : 
     634                 :            :         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
     635                 :          0 :         jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
     636                 :          0 :         return 1;
     637                 :            : }
     638                 :            : 
     639                 :            : /*
     640                 :            :  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
     641                 :            :  *
     642                 :            :  * @handle:             handle to this transaction
     643                 :            :  * @inode:              file inode
     644                 :            :  * @goal:               given target block(filesystem wide)
     645                 :            :  * @count:              pointer to total number of clusters needed
     646                 :            :  * @errp:               error code
     647                 :            :  *
     648                 :            :  * Return 1st allocated block number on success, *count stores total account
     649                 :            :  * error stores in errp pointer
     650                 :            :  */
     651                 :          3 : ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
     652                 :            :                                   ext4_fsblk_t goal, unsigned int flags,
     653                 :            :                                   unsigned long *count, int *errp)
     654                 :            : {
     655                 :            :         struct ext4_allocation_request ar;
     656                 :            :         ext4_fsblk_t ret;
     657                 :            : 
     658                 :          3 :         memset(&ar, 0, sizeof(ar));
     659                 :            :         /* Fill with neighbour allocated blocks */
     660                 :          3 :         ar.inode = inode;
     661                 :          3 :         ar.goal = goal;
     662                 :          3 :         ar.len = count ? *count : 1;
     663                 :          3 :         ar.flags = flags;
     664                 :            : 
     665                 :          3 :         ret = ext4_mb_new_blocks(handle, &ar, errp);
     666                 :          3 :         if (count)
     667                 :          0 :                 *count = ar.len;
     668                 :            :         /*
     669                 :            :          * Account for the allocated meta blocks.  We will never
     670                 :            :          * fail EDQUOT for metdata, but we do account for it.
     671                 :            :          */
     672                 :          3 :         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
     673                 :          3 :                 dquot_alloc_block_nofail(inode,
     674                 :          3 :                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
     675                 :            :         }
     676                 :          3 :         return ret;
     677                 :            : }
     678                 :            : 
     679                 :            : /**
     680                 :            :  * ext4_count_free_clusters() -- count filesystem free clusters
     681                 :            :  * @sb:         superblock
     682                 :            :  *
     683                 :            :  * Adds up the number of free clusters from each block group.
     684                 :            :  */
     685                 :          3 : ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
     686                 :            : {
     687                 :            :         ext4_fsblk_t desc_count;
     688                 :            :         struct ext4_group_desc *gdp;
     689                 :            :         ext4_group_t i;
     690                 :            :         ext4_group_t ngroups = ext4_get_groups_count(sb);
     691                 :            :         struct ext4_group_info *grp;
     692                 :            : #ifdef EXT4FS_DEBUG
     693                 :            :         struct ext4_super_block *es;
     694                 :            :         ext4_fsblk_t bitmap_count;
     695                 :            :         unsigned int x;
     696                 :            :         struct buffer_head *bitmap_bh = NULL;
     697                 :            : 
     698                 :            :         es = EXT4_SB(sb)->s_es;
     699                 :            :         desc_count = 0;
     700                 :            :         bitmap_count = 0;
     701                 :            :         gdp = NULL;
     702                 :            : 
     703                 :            :         for (i = 0; i < ngroups; i++) {
     704                 :            :                 gdp = ext4_get_group_desc(sb, i, NULL);
     705                 :            :                 if (!gdp)
     706                 :            :                         continue;
     707                 :            :                 grp = NULL;
     708                 :            :                 if (EXT4_SB(sb)->s_group_info)
     709                 :            :                         grp = ext4_get_group_info(sb, i);
     710                 :            :                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
     711                 :            :                         desc_count += ext4_free_group_clusters(sb, gdp);
     712                 :            :                 brelse(bitmap_bh);
     713                 :            :                 bitmap_bh = ext4_read_block_bitmap(sb, i);
     714                 :            :                 if (IS_ERR(bitmap_bh)) {
     715                 :            :                         bitmap_bh = NULL;
     716                 :            :                         continue;
     717                 :            :                 }
     718                 :            : 
     719                 :            :                 x = ext4_count_free(bitmap_bh->b_data,
     720                 :            :                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
     721                 :            :                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
     722                 :            :                         i, ext4_free_group_clusters(sb, gdp), x);
     723                 :            :                 bitmap_count += x;
     724                 :            :         }
     725                 :            :         brelse(bitmap_bh);
     726                 :            :         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
     727                 :            :                ", computed = %llu, %llu\n",
     728                 :            :                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
     729                 :            :                desc_count, bitmap_count);
     730                 :            :         return bitmap_count;
     731                 :            : #else
     732                 :            :         desc_count = 0;
     733                 :          3 :         for (i = 0; i < ngroups; i++) {
     734                 :          3 :                 gdp = ext4_get_group_desc(sb, i, NULL);
     735                 :          3 :                 if (!gdp)
     736                 :          0 :                         continue;
     737                 :            :                 grp = NULL;
     738                 :          3 :                 if (EXT4_SB(sb)->s_group_info)
     739                 :          3 :                         grp = ext4_get_group_info(sb, i);
     740                 :          3 :                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
     741                 :          3 :                         desc_count += ext4_free_group_clusters(sb, gdp);
     742                 :            :         }
     743                 :            : 
     744                 :          3 :         return desc_count;
     745                 :            : #endif
     746                 :            : }
     747                 :            : 
     748                 :            : static inline int test_root(ext4_group_t a, int b)
     749                 :            : {
     750                 :            :         while (1) {
     751                 :          3 :                 if (a < b)
     752                 :            :                         return 0;
     753                 :          3 :                 if (a == b)
     754                 :            :                         return 1;
     755                 :          3 :                 if ((a % b) != 0)
     756                 :            :                         return 0;
     757                 :          3 :                 a = a / b;
     758                 :            :         }
     759                 :            : }
     760                 :            : 
     761                 :            : /**
     762                 :            :  *      ext4_bg_has_super - number of blocks used by the superblock in group
     763                 :            :  *      @sb: superblock for filesystem
     764                 :            :  *      @group: group number to check
     765                 :            :  *
     766                 :            :  *      Return the number of blocks used by the superblock (primary or backup)
     767                 :            :  *      in this group.  Currently this will be only 0 or 1.
     768                 :            :  */
     769                 :          3 : int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
     770                 :            : {
     771                 :          3 :         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
     772                 :            : 
     773                 :          3 :         if (group == 0)
     774                 :            :                 return 1;
     775                 :          3 :         if (ext4_has_feature_sparse_super2(sb)) {
     776                 :          0 :                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
     777                 :          0 :                     group == le32_to_cpu(es->s_backup_bgs[1]))
     778                 :            :                         return 1;
     779                 :          0 :                 return 0;
     780                 :            :         }
     781                 :          3 :         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
     782                 :            :                 return 1;
     783                 :          3 :         if (!(group & 1))
     784                 :            :                 return 0;
     785                 :          3 :         if (test_root(group, 3) || (test_root(group, 5)) ||
     786                 :            :             test_root(group, 7))
     787                 :            :                 return 1;
     788                 :            : 
     789                 :          3 :         return 0;
     790                 :            : }
     791                 :            : 
     792                 :            : static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
     793                 :            :                                         ext4_group_t group)
     794                 :            : {
     795                 :            :         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
     796                 :          0 :         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
     797                 :          0 :         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
     798                 :            : 
     799                 :          0 :         if (group == first || group == first + 1 || group == last)
     800                 :            :                 return 1;
     801                 :            :         return 0;
     802                 :            : }
     803                 :            : 
     804                 :          3 : static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
     805                 :            :                                         ext4_group_t group)
     806                 :            : {
     807                 :          3 :         if (!ext4_bg_has_super(sb, group))
     808                 :            :                 return 0;
     809                 :            : 
     810                 :          3 :         if (ext4_has_feature_meta_bg(sb))
     811                 :          0 :                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
     812                 :            :         else
     813                 :          3 :                 return EXT4_SB(sb)->s_gdb_count;
     814                 :            : }
     815                 :            : 
     816                 :            : /**
     817                 :            :  *      ext4_bg_num_gdb - number of blocks used by the group table in group
     818                 :            :  *      @sb: superblock for filesystem
     819                 :            :  *      @group: group number to check
     820                 :            :  *
     821                 :            :  *      Return the number of blocks used by the group descriptor table
     822                 :            :  *      (primary or backup) in this group.  In the future there may be a
     823                 :            :  *      different number of descriptor blocks in each group.
     824                 :            :  */
     825                 :          3 : unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
     826                 :            : {
     827                 :          3 :         unsigned long first_meta_bg =
     828                 :          3 :                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
     829                 :          3 :         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
     830                 :            : 
     831                 :          3 :         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
     832                 :          3 :                 return ext4_bg_num_gdb_nometa(sb, group);
     833                 :            : 
     834                 :          0 :         return ext4_bg_num_gdb_meta(sb,group);
     835                 :            : 
     836                 :            : }
     837                 :            : 
     838                 :            : /*
     839                 :            :  * This function returns the number of file system metadata clusters at
     840                 :            :  * the beginning of a block group, including the reserved gdt blocks.
     841                 :            :  */
     842                 :          0 : static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
     843                 :            :                                      ext4_group_t block_group)
     844                 :            : {
     845                 :            :         struct ext4_sb_info *sbi = EXT4_SB(sb);
     846                 :            :         unsigned num;
     847                 :            : 
     848                 :            :         /* Check for superblock and gdt backups in this group */
     849                 :          0 :         num = ext4_bg_has_super(sb, block_group);
     850                 :            : 
     851                 :          0 :         if (!ext4_has_feature_meta_bg(sb) ||
     852                 :          0 :             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
     853                 :          0 :                           sbi->s_desc_per_block) {
     854                 :          0 :                 if (num) {
     855                 :          0 :                         num += ext4_bg_num_gdb(sb, block_group);
     856                 :          0 :                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
     857                 :            :                 }
     858                 :            :         } else { /* For META_BG_BLOCK_GROUPS */
     859                 :          0 :                 num += ext4_bg_num_gdb(sb, block_group);
     860                 :            :         }
     861                 :          0 :         return EXT4_NUM_B2C(sbi, num);
     862                 :            : }
     863                 :            : /**
     864                 :            :  *      ext4_inode_to_goal_block - return a hint for block allocation
     865                 :            :  *      @inode: inode for block allocation
     866                 :            :  *
     867                 :            :  *      Return the ideal location to start allocating blocks for a
     868                 :            :  *      newly created inode.
     869                 :            :  */
     870                 :          3 : ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
     871                 :            : {
     872                 :            :         struct ext4_inode_info *ei = EXT4_I(inode);
     873                 :            :         ext4_group_t block_group;
     874                 :            :         ext4_grpblk_t colour;
     875                 :          3 :         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
     876                 :            :         ext4_fsblk_t bg_start;
     877                 :            :         ext4_fsblk_t last_block;
     878                 :            : 
     879                 :          3 :         block_group = ei->i_block_group;
     880                 :          3 :         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
     881                 :            :                 /*
     882                 :            :                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
     883                 :            :                  * block groups per flexgroup, reserve the first block
     884                 :            :                  * group for directories and special files.  Regular
     885                 :            :                  * files will start at the second block group.  This
     886                 :            :                  * tends to speed up directory access and improves
     887                 :            :                  * fsck times.
     888                 :            :                  */
     889                 :          3 :                 block_group &= ~(flex_size-1);
     890                 :          3 :                 if (S_ISREG(inode->i_mode))
     891                 :          3 :                         block_group++;
     892                 :            :         }
     893                 :            :         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
     894                 :          3 :         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
     895                 :            : 
     896                 :            :         /*
     897                 :            :          * If we are doing delayed allocation, we don't need take
     898                 :            :          * colour into account.
     899                 :            :          */
     900                 :          3 :         if (test_opt(inode->i_sb, DELALLOC))
     901                 :            :                 return bg_start;
     902                 :            : 
     903                 :          0 :         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
     904                 :          0 :                 colour = (current->pid % 16) *
     905                 :          0 :                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
     906                 :            :         else
     907                 :          0 :                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
     908                 :          0 :         return bg_start + colour;
     909                 :            : }
     910                 :            : 
    

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