Root/fs/ocfs2/blockcheck.h

1/* -*- 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/* Count errors and error correction from blockcheck.c */
25struct ocfs2_blockcheck_stats {
26    spinlock_t b_lock;
27    u64 b_check_count; /* Number of blocks we've checked */
28    u64 b_failure_count; /* Number of failed checksums */
29    u64 b_recover_count; /* Number of blocks fixed by ecc */
30
31    /*
32     * debugfs entries, used if this is passed to
33     * ocfs2_blockcheck_stats_debugfs_install()
34     */
35    struct dentry *b_debug_dir; /* Parent of the debugfs files */
36    struct dentry *b_debug_check; /* Exposes b_check_count */
37    struct dentry *b_debug_failure; /* Exposes b_failure_count */
38    struct dentry *b_debug_recover; /* Exposes b_recover_count */
39};
40
41
42/* High level block API */
43void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
44                struct ocfs2_block_check *bc);
45int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
46                struct ocfs2_block_check *bc);
47void ocfs2_compute_meta_ecc_bhs(struct super_block *sb,
48                struct buffer_head **bhs, int nr,
49                struct ocfs2_block_check *bc);
50int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
51                struct buffer_head **bhs, int nr,
52                struct ocfs2_block_check *bc);
53
54/* Lower level API */
55void ocfs2_block_check_compute(void *data, size_t blocksize,
56                   struct ocfs2_block_check *bc);
57int ocfs2_block_check_validate(void *data, size_t blocksize,
58                   struct ocfs2_block_check *bc,
59                   struct ocfs2_blockcheck_stats *stats);
60void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
61                   struct ocfs2_block_check *bc);
62int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
63                   struct ocfs2_block_check *bc,
64                   struct ocfs2_blockcheck_stats *stats);
65
66/* Debug Initialization */
67int ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats,
68                       struct dentry *parent);
69void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats);
70
71/*
72 * Hamming code functions
73 */
74
75/*
76 * Encoding hamming code parity bits for a buffer.
77 *
78 * This is the low level encoder function. It can be called across
79 * multiple hunks just like the crc32 code. 'd' is the number of bits
80 * _in_this_hunk_. nr is the bit offset of this hunk. So, if you had
81 * two 512B buffers, you would do it like so:
82 *
83 * parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0);
84 * parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8);
85 *
86 * If you just have one buffer, use ocfs2_hamming_encode_block().
87 */
88u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d,
89             unsigned int nr);
90/*
91 * Fix a buffer with a bit error. The 'fix' is the original parity
92 * xor'd with the parity calculated now.
93 *
94 * Like ocfs2_hamming_encode(), this can handle hunks. nr is the bit
95 * offset of the current hunk. If bit to be fixed is not part of the
96 * current hunk, this does nothing.
97 *
98 * If you only have one buffer, use ocfs2_hamming_fix_block().
99 */
100void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr,
101               unsigned int fix);
102
103/* Convenience wrappers for a single buffer of data */
104extern u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize);
105extern void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
106                    unsigned int fix);
107#endif
108

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