bitmap.c

 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)
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(sbi->s_csum_seed, (__u8 *)bh->b_data, 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(sbi->s_csum_seed, (__u8 *)bh->b_data, 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(sbi->s_csum_seed, (__u8 *)bh->b_data, 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(sbi->s_csum_seed, (__u8 *)bh->b_data, 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}