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 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  15 {
  16         return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
  17 }
  18
  19 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  20                                   struct ext4_group_desc *gdp,
  21                                   struct buffer_head *bh, int sz)
  22 {
  23         __u32 hi;
  24         __u32 provided, calculated;
  25         struct ext4_sb_info *sbi = EXT4_SB(sb);
  26
  27         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  28                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  29                 return 1;
  30
  31         provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  32         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  33         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  34                 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  35                 provided |= (hi << 16);
  36         } else
  37                 calculated &= 0xFFFF;
  38
  39         return provided == calculated;
  40 }
  41
  42 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  43                                 struct ext4_group_desc *gdp,
  44                                 struct buffer_head *bh, int sz)
  45 {
  46         __u32 csum;
  47         struct ext4_sb_info *sbi = EXT4_SB(sb);
  48
  49         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  50                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  51                 return;
  52
  53         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  54         gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  55         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  56                 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  57 }
  58
  59 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  60                                   struct ext4_group_desc *gdp,
  61                                   struct buffer_head *bh, int sz)
  62 {
  63         __u32 hi;
  64         __u32 provided, calculated;
  65         struct ext4_sb_info *sbi = EXT4_SB(sb);
  66
  67         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  68                                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  69                 return 1;
  70
  71         provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  72         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  73         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  74                 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  75                 provided |= (hi << 16);
  76         } else
  77                 calculated &= 0xFFFF;
  78
  79         if (provided == calculated)
  80                 return 1;
  81
  82         ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
  83         return 0;
  84 }
  85
  86 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  87                                 struct ext4_group_desc *gdp,
  88                                 struct buffer_head *bh, int sz)
  89 {
  90         __u32 csum;
  91         struct ext4_sb_info *sbi = EXT4_SB(sb);
  92
  93         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
  94                         EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
  95                 return;
  96
  97         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  98         gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  99         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
 100                 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
 101 }