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)
22{
23 __u32 hi;
24 __u32 provided, calculated;
25 struct ext4_sb_info *sbi = EXT4_SB(sb);
26 int sz;
27
28 if (!ext4_has_feature_metadata_csum(sb))
29 return 1;
30
31 sz = EXT4_INODES_PER_GROUP(sb) >> 3;
32 provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
33 calculated = ext4_chksum(crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
34 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
35 hi = le16_to_cpu(gdp->bg_inode_bitmap_csum_hi);
36 provided |= (hi << 16);
37 } else
38 calculated &= 0xFFFF;
39
40 return provided == calculated;
41}
42
43void ext4_inode_bitmap_csum_set(struct super_block *sb,
44 struct ext4_group_desc *gdp,
45 struct buffer_head *bh)
46{
47 __u32 csum;
48 struct ext4_sb_info *sbi = EXT4_SB(sb);
49 int sz;
50
51 if (!ext4_has_feature_metadata_csum(sb))
52 return;
53
54 sz = EXT4_INODES_PER_GROUP(sb) >> 3;
55 csum = ext4_chksum(crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
56 gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
57 if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
58 gdp->bg_inode_bitmap_csum_hi = cpu_to_le16(csum >> 16);
59}
60
61int ext4_block_bitmap_csum_verify(struct super_block *sb,
62 struct ext4_group_desc *gdp,
63 struct buffer_head *bh)
64{
65 __u32 hi;
66 __u32 provided, calculated;
67 struct ext4_sb_info *sbi = EXT4_SB(sb);
68 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
69
70 if (!ext4_has_feature_metadata_csum(sb))
71 return 1;
72
73 provided = le16_to_cpu(gdp->bg_block_bitmap_csum_lo);
74 calculated = ext4_chksum(crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
75 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END) {
76 hi = le16_to_cpu(gdp->bg_block_bitmap_csum_hi);
77 provided |= (hi << 16);
78 } else
79 calculated &= 0xFFFF;
80
81 return provided == calculated;
82}
83
84void ext4_block_bitmap_csum_set(struct super_block *sb,
85 struct ext4_group_desc *gdp,
86 struct buffer_head *bh)
87{
88 int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
89 __u32 csum;
90 struct ext4_sb_info *sbi = EXT4_SB(sb);
91
92 if (!ext4_has_feature_metadata_csum(sb))
93 return;
94
95 csum = ext4_chksum(crc: sbi->s_csum_seed, address: (__u8 *)bh->b_data, length: sz);
96 gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
97 if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
98 gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
99}
100

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