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 */
25 struct 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 */
43 void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
44 			    struct ocfs2_block_check *bc);
45 int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
46 			    struct ocfs2_block_check *bc);
47 void ocfs2_compute_meta_ecc_bhs(struct super_block *sb,
48 				struct buffer_head **bhs, int nr,
49 				struct ocfs2_block_check *bc);
50 int 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 */
55 void ocfs2_block_check_compute(void *data, size_t blocksize,
56 			       struct ocfs2_block_check *bc);
57 int ocfs2_block_check_validate(void *data, size_t blocksize,
58 			       struct ocfs2_block_check *bc,
59 			       struct ocfs2_blockcheck_stats *stats);
60 void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
61 				   struct ocfs2_block_check *bc);
62 int 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 */
67 int ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats,
68 					   struct dentry *parent);
69 void 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  */
88 u32 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  */
100 void 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 */
104 extern u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize);
105 extern void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
106 				    unsigned int fix);
107 #endif
108