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/*
* linux/fs/ext4/bitmap.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*/
#include <linux/buffer_head.h>
#include <linux/jbd2.h>
#include "ext4.h"
#ifdef EXT4FS_DEBUG
static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
{
unsigned int i, sum = 0;
if (!map)
return 0;
for (i = 0; i < numchars; i++)
sum += nibblemap[map->b_data[i] & 0xf] +
nibblemap[(map->b_data[i] >> 4) & 0xf];
return sum;
}
#endif /* EXT4FS_DEBUG */
int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz)
{
__u32 hi;
__u32 provided, calculated;
struct ext4_sb_info *sbi = EXT4_SB(sb);
if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
return 1;
provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
provided |= (hi << 16);
} else
calculated &= 0xFFFF;
return provided == calculated;
}
void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz)
{
__u32 csum;
struct ext4_sb_info *sbi = EXT4_SB(sb);
if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
return;
csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
}
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