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
14 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
15 {
16 return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
17 }
18
19 int 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, sbi->s_csum_seed, (__u8 *)bh->b_data, 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
41 void 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, sbi->s_csum_seed, (__u8 *)bh->b_data, 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
57 int 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, sbi->s_csum_seed, (__u8 *)bh->b_data, 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
80 void 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, sbi->s_csum_seed, (__u8 *)bh->b_data, 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
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