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 /* High level block API */
  25 void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
  26                             struct ocfs2_block_check *bc);
  27 int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
  28                             struct ocfs2_block_check *bc);
  29 void ocfs2_compute_meta_ecc_bhs(struct super_block *sb,
  30                                 struct buffer_head **bhs, int nr,
  31                                 struct ocfs2_block_check *bc);
  32 int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
  33                                 struct buffer_head **bhs, int nr,
  34                                 struct ocfs2_block_check *bc);
  35
  36 /* Lower level API */
  37 void ocfs2_block_check_compute(void *data, size_t blocksize,
  38                                struct ocfs2_block_check *bc);
  39 int ocfs2_block_check_validate(void *data, size_t blocksize,
  40                                struct ocfs2_block_check *bc);
  41 void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
  42                                    struct ocfs2_block_check *bc);
  43 int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,
  44                                    struct ocfs2_block_check *bc);
  45
  46 /*
  47  * Hamming code functions
  48  */
  49
  50 /*
  51  * Encoding hamming code parity bits for a buffer.
  52  *
  53  * This is the low level encoder function.  It can be called across
  54  * multiple hunks just like the crc32 code.  'd' is the number of bits
  55  * _in_this_hunk_.  nr is the bit offset of this hunk.  So, if you had
  56  * two 512B buffers, you would do it like so:
  57  *
  58  * parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0);
  59  * parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8);
  60  *
  61  * If you just have one buffer, use ocfs2_hamming_encode_block().
  62  */
  63 u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d,
  64                          unsigned int nr);
  65 /*
  66  * Fix a buffer with a bit error.  The 'fix' is the original parity
  67  * xor'd with the parity calculated now.
  68  *
  69  * Like ocfs2_hamming_encode(), this can handle hunks.  nr is the bit
  70  * offset of the current hunk.  If bit to be fixed is not part of the
  71  * current hunk, this does nothing.
  72  *
  73  * If you only have one buffer, use ocfs2_hamming_fix_block().
  74  */
  75 void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr,
  76                        unsigned int fix);
  77
  78 /* Convenience wrappers for a single buffer of data */
  79 extern u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize);
  80 extern void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
  81                                     unsigned int fix);
  82 #endif