/* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * blockcheck.h
   *
   * Checksum and ECC codes for the OCFS2 userspace library.
   *
   * Copyright (C) 2004, 2008 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License, version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   */
  
  #ifndef OCFS2_BLOCKCHECK_H
  #define OCFS2_BLOCKCHECK_H

  /* Count errors and error correction from blockcheck.c */
  struct ocfs2_blockcheck_stats {
  	spinlock_t b_lock;
  	u64 b_check_count;	/* Number of blocks we've checked */
  	u64 b_failure_count;	/* Number of failed checksums */
  	u64 b_recover_count;	/* Number of blocks fixed by ecc */
  
  	/*
  	 * debugfs entries, used if this is passed to
  	 * ocfs2_blockcheck_stats_debugfs_install()
  	 */
  	struct dentry *b_debug_dir;	/* Parent of the debugfs  files */
  	struct dentry *b_debug_check;	/* Exposes b_check_count */
  	struct dentry *b_debug_failure;	/* Exposes b_failure_count */
  	struct dentry *b_debug_recover;	/* Exposes b_recover_count */
  };

  /* High level block API */
  void ocfs2_compute_meta_ecc(struct super_block *sb, void *data,
  			    struct ocfs2_block_check *bc);
  int ocfs2_validate_meta_ecc(struct super_block *sb, void *data,
  			    struct ocfs2_block_check *bc);
  void ocfs2_compute_meta_ecc_bhs(struct super_block *sb,
  				struct buffer_head **bhs, int nr,
  				struct ocfs2_block_check *bc);
  int ocfs2_validate_meta_ecc_bhs(struct super_block *sb,
  				struct buffer_head **bhs, int nr,
  				struct ocfs2_block_check *bc);
  
  /* Lower level API */
  void ocfs2_block_check_compute(void *data, size_t blocksize,
  			       struct ocfs2_block_check *bc);
  int ocfs2_block_check_validate(void *data, size_t blocksize,

  			       struct ocfs2_block_check *bc,
  			       struct ocfs2_blockcheck_stats *stats);

  void ocfs2_block_check_compute_bhs(struct buffer_head **bhs, int nr,
  				   struct ocfs2_block_check *bc);
  int ocfs2_block_check_validate_bhs(struct buffer_head **bhs, int nr,

  				   struct ocfs2_block_check *bc,
  				   struct ocfs2_blockcheck_stats *stats);
  
  /* Debug Initialization */
  int ocfs2_blockcheck_stats_debugfs_install(struct ocfs2_blockcheck_stats *stats,
  					   struct dentry *parent);
  void ocfs2_blockcheck_stats_debugfs_remove(struct ocfs2_blockcheck_stats *stats);

  
  /*
   * Hamming code functions
   */
  
  /*
   * Encoding hamming code parity bits for a buffer.
   *
   * This is the low level encoder function.  It can be called across
   * multiple hunks just like the crc32 code.  'd' is the number of bits
   * _in_this_hunk_.  nr is the bit offset of this hunk.  So, if you had
   * two 512B buffers, you would do it like so:
   *
   * parity = ocfs2_hamming_encode(0, buf1, 512 * 8, 0);
   * parity = ocfs2_hamming_encode(parity, buf2, 512 * 8, 512 * 8);
   *
   * If you just have one buffer, use ocfs2_hamming_encode_block().
   */
  u32 ocfs2_hamming_encode(u32 parity, void *data, unsigned int d,
  			 unsigned int nr);
  /*
   * Fix a buffer with a bit error.  The 'fix' is the original parity
   * xor'd with the parity calculated now.
   *
   * Like ocfs2_hamming_encode(), this can handle hunks.  nr is the bit
   * offset of the current hunk.  If bit to be fixed is not part of the
   * current hunk, this does nothing.
   *
   * If you only have one buffer, use ocfs2_hamming_fix_block().
   */
  void ocfs2_hamming_fix(void *data, unsigned int d, unsigned int nr,
  		       unsigned int fix);
  
  /* Convenience wrappers for a single buffer of data */
  extern u32 ocfs2_hamming_encode_block(void *data, unsigned int blocksize);
  extern void ocfs2_hamming_fix_block(void *data, unsigned int blocksize,
  				    unsigned int fix);
  #endif