2 * linux/fs/ext4/bitmap.c
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)
10 #include <linux/buffer_head.h>
11 #include <linux/jbd2.h>
16 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
18 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
20 unsigned int i, sum = 0;
22 for (i = 0; i < numchars; i++)
23 sum += nibblemap[bitmap[i] & 0xf] +
24 nibblemap[(bitmap[i] >> 4) & 0xf];
28 #endif /* EXT4FS_DEBUG */
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)
35 __u32 provided, calculated;
36 struct ext4_sb_info *sbi = EXT4_SB(sb);
38 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
39 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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);
50 return provided == calculated;
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)
58 struct ext4_sb_info *sbi = EXT4_SB(sb);
60 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
61 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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);
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)
75 __u32 provided, calculated;
76 struct ext4_sb_info *sbi = EXT4_SB(sb);
78 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
79 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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);
90 if (provided == calculated)
93 ext4_error(sb, "Bad block bitmap checksum: block_group = %u", group);
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)
102 struct ext4_sb_info *sbi = EXT4_SB(sb);
104 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
105 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
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);