1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/bitmap.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 */
10
11#include <linux/buffer_head.h>
12#include "ext4.h"
13
14unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
15{
16 return numchars * BITS_PER_BYTE - memweight(ptr: bitmap, bytes: numchars);
17}
18
19int ext4_inode_bitmap_csum_verify(struct super_block *sb,
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_metadata_csum(sb))
28 return 1;
29
30 provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
31 calculated = ext4_chksum(sbi, crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
32 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
33 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
34 provided |= (hi << 16);
35 } else
36 calculated &= 0xFFFF;
37
38 return provided == calculated;
39}
40
41void ext4_inode_bitmap_csum_set(struct super_block *sb,
42 struct ext4_group_desc *gdp,
43 struct buffer_head *bh, int sz)
44{
45 __u32 csum;
46 struct ext4_sb_info *sbi = EXT4_SB(sb);
47
48 if (!ext4_has_metadata_csum(sb))
49 return;
50
51 csum = ext4_chksum(sbi, crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
52 gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
53 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
54 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
55}
56
57int ext4_block_bitmap_csum_verify(struct super_block *sb,
58 struct ext4_group_desc *gdp,
59 struct buffer_head *bh)
60{
61 __u32 hi;
62 __u32 provided, calculated;
63 struct ext4_sb_info *sbi = EXT4_SB(sb);
64 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
65
66 if (!ext4_has_metadata_csum(sb))
67 return 1;
68
69 provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
70 calculated = ext4_chksum(sbi, crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
71 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
72 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
73 provided |= (hi << 16);
74 } else
75 calculated &= 0xFFFF;
76
77 return provided == calculated;
78}
79
80void ext4_block_bitmap_csum_set(struct super_block *sb,
81 struct ext4_group_desc *gdp,
82 struct buffer_head *bh)
83{
84 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
85 __u32 csum;
86 struct ext4_sb_info *sbi = EXT4_SB(sb);
87
88 if (!ext4_has_metadata_csum(sb))
89 return;
90
91 csum = ext4_chksum(sbi, crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
92 gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
93 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
94 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
95}
96

source code of linux/fs/ext4/bitmap.c