fs/ext4/bitmap.c

   1 /*
   2  *  linux/fs/ext4/bitmap.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
  10 #include <linux/buffer_head.h>
  11 #include <linux/jbd2.h>
  12 #include "ext4.h"
  13
  14 #ifdef EXT4FS_DEBUG
  15
  16 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
  17
  18 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  19 {
  20         unsigned int i, sum = 0;
  21
  22         for (i = 0; i < numchars; i++)
  23                 sum += nibblemap[bitmap[i] & 0xf] +
  24                         nibblemap[(bitmap[i] >> 4) & 0xf];
  25         return sum;
  26 }
  27
  28 #endif  /*  EXT4FS_DEBUG  */
  29
  30 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  31                                   struct ext4_group_desc *gdp,
  32                                   struct buffer_head *bh, int sz)
  33 {
  34         __u32 hi;
  35         __u32 provided, calculated;
  36         struct ext4_sb_info *sbi = EXT4_SB(sb);
  37
  38         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  39                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  40                 return 1;
  41
  42         provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  43         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  44         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  45                 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  46                 provided |= (hi << 16);
  47         } else
  48                 calculated &= 0xFFFF;
  49
  50         return provided == calculated;
  51 }
  52
  53 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  54                                 struct ext4_group_desc *gdp,
  55                                 struct buffer_head *bh, int sz)
  56 {
  57         __u32 csum;
  58         struct ext4_sb_info *sbi = EXT4_SB(sb);
  59
  60         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  61                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  62                 return;
  63
  64         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  65         gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  66         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  67                 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  68 }
  69
  70 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  71                                   struct ext4_group_desc *gdp,
  72                                   struct buffer_head *bh, int sz)
  73 {
  74         __u32 hi;
  75         __u32 provided, calculated;
  76         struct ext4_sb_info *sbi = EXT4_SB(sb);
  77
  78         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  79                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  80                 return 1;
  81
  82         provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  83         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  84         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  85                 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  86                 provided |= (hi << 16);
  87         } else
  88                 calculated &= 0xFFFF;
  89
  90         if (provided == calculated)
  91                 return 1;
  92
  93         ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
  94         return 0;
  95 }
  96
  97 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  98                                 struct ext4_group_desc *gdp,
  99                                 struct buffer_head *bh, int sz)
 100 {
 101         __u32 csum;
 102         struct ext4_sb_info *sbi = EXT4_SB(sb);
 103
 104         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
 105                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
 106                 return;
 107
 108         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
 109         gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
 110         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
 111                 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
 112 }