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