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 "ext4.h"
  12
  13 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
  14 {
  15         return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
  16 }
  17
  18 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  19                                   struct ext4_group_desc *gdp,
  20                                   struct buffer_head *bh, int sz)
  21 {
  22         __u32 hi;
  23         __u32 provided, calculated;
  24         struct ext4_sb_info *sbi = EXT4_SB(sb);
  25
  26         if (!ext4_has_metadata_csum(sb))
  27                 return 1;
  28
  29         provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
  30         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  31         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
  32                 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
  33                 provided |= (hi << 16);
  34         } else
  35                 calculated &= 0xFFFF;
  36
  37         return provided == calculated;
  38 }
  39
  40 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  41                                 struct ext4_group_desc *gdp,
  42                                 struct buffer_head *bh, int sz)
  43 {
  44         __u32 csum;
  45         struct ext4_sb_info *sbi = EXT4_SB(sb);
  46
  47         if (!ext4_has_metadata_csum(sb))
  48                 return;
  49
  50         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  51         gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  52         if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  53                 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  54 }
  55
  56 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
  57                                   struct ext4_group_desc *gdp,
  58                                   struct buffer_head *bh)
  59 {
  60         __u32 hi;
  61         __u32 provided, calculated;
  62         struct ext4_sb_info *sbi = EXT4_SB(sb);
  63         int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  64
  65         if (!ext4_has_metadata_csum(sb))
  66                 return 1;
  67
  68         provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
  69         calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  70         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
  71                 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
  72                 provided |= (hi << 16);
  73         } else
  74                 calculated &= 0xFFFF;
  75
  76         if (provided == calculated)
  77                 return 1;
  78
  79         return 0;
  80 }
  81
  82 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
  83                                 struct ext4_group_desc *gdp,
  84                                 struct buffer_head *bh)
  85 {
  86         int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
  87         __u32 csum;
  88         struct ext4_sb_info *sbi = EXT4_SB(sb);
  89
  90         if (!ext4_has_metadata_csum(sb))
  91                 return;
  92
  93         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
  94         gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
  95         if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
  96                 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
  97 }