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 
ext4_count_free(char * bitmap,unsigned int numchars)14 unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
15 {
16 	return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
17 }
18 
ext4_inode_bitmap_csum_verify(struct super_block * sb,ext4_group_t group,struct ext4_group_desc * gdp,struct buffer_head * bh,int sz)19 int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
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 
ext4_inode_bitmap_csum_set(struct super_block * sb,ext4_group_t group,struct ext4_group_desc * gdp,struct buffer_head * bh,int sz)41 void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
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 
ext4_block_bitmap_csum_verify(struct super_block * sb,ext4_group_t group,struct ext4_group_desc * gdp,struct buffer_head * bh)57 int ext4_block_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
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 	if (provided == calculated)
78 		return 1;
79 
80 	return 0;
81 }
82 
ext4_block_bitmap_csum_set(struct super_block * sb,ext4_group_t group,struct ext4_group_desc * gdp,struct buffer_head * bh)83 void ext4_block_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
84 				struct ext4_group_desc *gdp,
85 				struct buffer_head *bh)
86 {
87 	int sz = EXT4_CLUSTERS_PER_GROUP(sb) / 8;
88 	__u32 csum;
89 	struct ext4_sb_info *sbi = EXT4_SB(sb);
90 
91 	if (!ext4_has_metadata_csum(sb))
92 		return;
93 
94 	csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
95 	gdp->bg_block_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
96 	if (sbi->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_END)
97 		gdp->bg_block_bitmap_csum_hi = cpu_to_le16(csum >> 16);
98 }
99