linux/fs/ocfs2/blockcheck.h
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   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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