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Joel Becker70ad1ba2008-10-16 17:54:25 -07001/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * blockcheck.h
5 *
6 * Checksum and ECC codes for the OCFS2 userspace library.
7 *
8 * Copyright (C) 2004, 2008 Oracle. All rights reserved.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public
12 * License, version 2, as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 */
19
20#ifndef OCFS2_BLOCKCHECK_H
21#define OCFS2_BLOCKCHECK_H
22
23
24/* High level block API */
25void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
26 struct ocfs2_block_check *bc);
27int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
28 struct ocfs2_block_check *bc);
29void ocfs2_compute_meta_ecc_bhs(struct super_block *sb,
30 struct buffer_head **bhs, int nr,
31 struct ocfs2_block_check *bc);
32int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
33 struct buffer_head **bhs, int nr,
34 struct ocfs2_block_check *bc);
35
36/* Lower level API */
37void ocfs2_block_check_compute(void *data, size_t blocksize,
38 struct ocfs2_block_check *bc);
39int ocfs2_block_check_validate(void *data, size_t blocksize,
40 struct ocfs2_block_check *bc);
41void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
42 struct ocfs2_block_check *bc);
43int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
44 struct ocfs2_block_check *bc);
45
46/*
47 * Hamming code functions
48 */
49
50/*
51 * Encoding hamming code parity bits for a buffer.
52 *
53 * This is the low level encoder function. It can be called across
54 * multiple hunks just like the crc32 code. 'd' is the number of bits
55 * _in_this_hunk_. nr is the bit offset of this hunk. So, if you had
56 * two 512B buffers, you would do it like so:
57 *
58 * parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0);
59 * parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8);
60 *
61 * If you just have one buffer, use ocfs2_hamming_encode_block().
62 */
63u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d,
64 unsigned int nr);
65/*
66 * Fix a buffer with a bit error. The 'fix' is the original parity
67 * xor'd with the parity calculated now.
68 *
69 * Like ocfs2_hamming_encode(), this can handle hunks. nr is the bit
70 * offset of the current hunk. If bit to be fixed is not part of the
71 * current hunk, this does nothing.
72 *
73 * If you only have one buffer, use ocfs2_hamming_fix_block().
74 */
75void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr,
76 unsigned int fix);
77
78/* Convenience wrappers for a single buffer of data */
79extern u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize);
80extern void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
81 unsigned int fix);
82#endif