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161 lines
5 KiB
C
161 lines
5 KiB
C
/*
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* Copyright (C) 2013 Andrea Mazzoleni
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __RAID_H
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#define __RAID_H
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/**
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* RAID mode supporting up to 6 parities.
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*
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* It requires SSSE3 to get good performance with triple or more
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* parities.
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*
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* This is the default mode set after calling raid_init().
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*/
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#define RAID_MODE_CAUCHY 0
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/**
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* RAID mode supporting up to 3 parities,
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*
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* It has a fast triple parity implementation even without SSSE3, but it
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* cannot go beyond triple parity.
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* This is mostly intended for low end CPUs like ARM and AMD Athlon.
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*/
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#define RAID_MODE_VANDERMONDE 1
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/**
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* Max level of parity disks supported.
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*/
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#define RAID_PARITY_MAX 6
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/**
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* Maximum number of data disks supported.
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*/
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#define RAID_DATA_MAX 251
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/**
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* Initializes the RAID system.
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*/
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void raid_init(void);
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/**
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* Runs a basic functionality self test.
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*
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* It returns 0 on success.
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*/
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int raid_selftest(void);
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/**
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* Sets the mode to use. One of RAID_MODE_*.
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*
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* You can change mode at any time, and it will affect next calls to raid_par(),
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* raid_rec() and raid_recpar().
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*
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* The two modes are compatible for the first two levels of parity.
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* The third one is different.
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*/
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void raid_mode(int mode);
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/**
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* Sets the zero buffer to use in recovering.
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*
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* Before calling raid_rec_dataonly() and raid_recpar() you must provide a memory
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* buffer filled with zero with the same size of the blocks to recover.
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*/
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void raid_zero(void *zero);
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/**
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* Sets an additional buffer used by raid_rec_dataonly() to avoid to overwrite
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* unused parities.
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*/
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void raid_waste(void *zero);
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/**
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* Computes the parity.
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*
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* @nd Number of data blocks.
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* @np Number of parities blocks to compute.
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* @size Size of the blocks pointed by @v. It must be a multipler of 64.
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* @v Vector of pointers to the blocks of data and parity.
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* It has (@nd + @np) elements. The starting elements are the blocks for
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* data, following with the parity blocks.
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* Each blocks has @size bytes.
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*/
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void raid_par(int nd, int np, size_t size, void **v);
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/**
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* Recovers failures in data and parity blocks.
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*
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* All the data and parity blocks marked as bad in the @id and @ip vector
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* are recovered and recomputed.
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*
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* The parities blocks to use for recovering are automatically selected from
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* the ones NOT present in the @ip vector.
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*
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* Ensure to have @nrd + @nrp <= @np, otherwise recovering is not possible.
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*
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* @nrd Number of failed data blocks to recover.
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* @id[] Vector of @nrd indexes of the data blocks to recover.
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* The indexes start from 0. They must be in order.
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* @nrp Number of failed parity blocks to recover.
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* @ip[] Vector of @nrp indexes of the parity blocks to recover.
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* The indexes start from 0. They must be in order.
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* All the parities not specified here are assumed correct, and they are
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* not recomputed.
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* @nd Number of data blocks.
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* @np Number of parity blocks.
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* @size Size of the blocks pointed by @v. It must be a multipler of 64.
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* @v Vector of pointers to the blocks of data and parity.
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* It has (@nd + @np) elements. The starting elements are the blocks
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* for data, following with the parity blocks.
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* Each blocks has @size bytes.
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*/
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void raid_rec(int nrd, int *id, int nrp, int *ip, int nd, int np, size_t size, void **v);
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/**
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* Recovers failures of data blocks using the specified parities.
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*
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* The data blocks marked as bad in the @id vector are recovered.
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*
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* If you have provided an additional buffer with raid_waste(), the
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* parity blocks are not modified. Without this buffer, the content of
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* parities blocks not specified in the @ip vector will be destroyed.
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*
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* @nr Number of failed data blocks to recover.
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* @id[] Vector of @nr indexes of the data blocksto recover.
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* The indexes start from 0. They must be in order.
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* @ip[] Vector of @nr indexes of the parity blocks to use for recovering.
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* The indexes start from 0. They must be in order.
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* @nd Number of data blocks.
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* @size Size of the blocks pointed by @v. It must be a multipler of 64.
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* @v Vector of pointers to the blocks of data and parity.
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* It has (@nd + @ip[@nr - 1] + 1) elements. The starting elements are the
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* blocks for data, following with the parity blocks.
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* Each blocks has @size bytes.
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*/
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void raid_rec_dataonly(int nr, int *id, int *ip, int nd, size_t size, void **v);
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/**
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* Sorts a small vector of integers.
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*
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* If you have block indexes not in order, you can use this function to sort
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* them before callign raid_rec().
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*
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* @n Number of integers. No more than RAID_PARITY_MAX.
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* \paran v Vector of integers.
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*/
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void raid_sort(int n, int *v);
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#endif
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