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(bitmap, 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, 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
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, 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
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, 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
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, 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