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 */
  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