[net-next-2.6.git] / lib / raid6 / raid6recov.c

/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright 2002 H. Peter Anvin - 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 as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * raid6recov.c
 *
 * RAID-6 data recovery in dual failure mode.  In single failure mode,
 * use the RAID-5 algorithm (or, in the case of Q failure, just reconstruct
 * the syndrome.)
 */

#include <linux/raid/pq.h>

/* Recover two failed data blocks. */
void raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
		       void **ptrs)
{
	u8 *p, *q, *dp, *dq;
	u8 px, qx, db;
	const u8 *pbmul;	/* P multiplier table for B data */
	const u8 *qmul;		/* Q multiplier table (for both) */

	p = (u8 *)ptrs[disks-2];
	q = (u8 *)ptrs[disks-1];

	/* Compute syndrome with zero for the missing data pages
	   Use the dead data pages as temporary storage for
	   delta p and delta q */
	dp = (u8 *)ptrs[faila];
	ptrs[faila] = (void *)raid6_empty_zero_page;
	ptrs[disks-2] = dp;
	dq = (u8 *)ptrs[failb];
	ptrs[failb] = (void *)raid6_empty_zero_page;
	ptrs[disks-1] = dq;

	raid6_call.gen_syndrome(disks, bytes, ptrs);

	/* Restore pointer table */
	ptrs[faila]   = dp;
	ptrs[failb]   = dq;
	ptrs[disks-2] = p;
	ptrs[disks-1] = q;

	/* Now, pick the proper data tables */
	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
	qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];

	/* Now do it... */
	while ( bytes-- ) {
		px    = *p ^ *dp;
		qx    = qmul[*q ^ *dq];
		*dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */
		*dp++ = db ^ px; /* Reconstructed A */
		p++; q++;
	}
}
EXPORT_SYMBOL_GPL(raid6_2data_recov);

/* Recover failure of one data block plus the P block */
void raid6_datap_recov(int disks, size_t bytes, int faila, void **ptrs)
{
	u8 *p, *q, *dq;
	const u8 *qmul;		/* Q multiplier table */

	p = (u8 *)ptrs[disks-2];
	q = (u8 *)ptrs[disks-1];

	/* Compute syndrome with zero for the missing data page
	   Use the dead data page as temporary storage for delta q */
	dq = (u8 *)ptrs[faila];
	ptrs[faila] = (void *)raid6_empty_zero_page;
	ptrs[disks-1] = dq;

	raid6_call.gen_syndrome(disks, bytes, ptrs);

	/* Restore pointer table */
	ptrs[faila]   = dq;
	ptrs[disks-1] = q;

	/* Now, pick the proper data tables */
	qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];

	/* Now do it... */
	while ( bytes-- ) {
		*p++ ^= *dq = qmul[*q ^ *dq];
		q++; dq++;
	}
}
EXPORT_SYMBOL_GPL(raid6_datap_recov);

#ifndef __KERNEL__
/* Testing only */

/* Recover two failed blocks. */
void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs)
{
	if ( faila > failb ) {
		int tmp = faila;
		faila = failb;
		failb = tmp;
	}

	if ( failb == disks-1 ) {
		if ( faila == disks-2 ) {
			/* P+Q failure.  Just rebuild the syndrome. */
			raid6_call.gen_syndrome(disks, bytes, ptrs);
		} else {
			/* data+Q failure.  Reconstruct data from P,
			   then rebuild syndrome. */
			/* NOT IMPLEMENTED - equivalent to RAID-5 */
		}
	} else {
		if ( failb == disks-2 ) {
			/* data+P failure. */
			raid6_datap_recov(disks, bytes, faila, ptrs);
		} else {
			/* data+data failure. */
			raid6_2data_recov(disks, bytes, faila, failb, ptrs);
		}
	}
}

#endif
Commit	Line	Data
1da177e4 LT	1	/* -- linux-c -- ------------------------------------------------------- *
	2	*
	3	* Copyright 2002 H. Peter Anvin - All Rights Reserved
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
93ed05e2	8	* Boston MA 02111-1307, USA; either version 2 of the License, or
1da177e4 LT	9	* (at your option) any later version; incorporated herein by reference.
	10	*
	11	* ----------------------------------------------------------------------- */
	12
	13	/*
	14	* raid6recov.c
	15	*
	16	* RAID-6 data recovery in dual failure mode. In single failure mode,
	17	* use the RAID-5 algorithm (or, in the case of Q failure, just reconstruct
	18	* the syndrome.)
	19	*/
	20
f701d589	21	#include <linux/raid/pq.h>
1da177e4 LT	22
	23	/* Recover two failed data blocks. */
	24	void raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
	25	void **ptrs)
	26	{
	27	u8 p, q, dp, dq;
	28	u8 px, qx, db;
	29	const u8 pbmul; / P multiplier table for B data */
	30	const u8 qmul; / Q multiplier table (for both) */
	31
	32	p = (u8 *)ptrs[disks-2];
	33	q = (u8 *)ptrs[disks-1];
	34
	35	/* Compute syndrome with zero for the missing data pages
	36	Use the dead data pages as temporary storage for
	37	delta p and delta q */
	38	dp = (u8 *)ptrs[faila];
	39	ptrs[faila] = (void *)raid6_empty_zero_page;
	40	ptrs[disks-2] = dp;
	41	dq = (u8 *)ptrs[failb];
	42	ptrs[failb] = (void *)raid6_empty_zero_page;
	43	ptrs[disks-1] = dq;
	44
	45	raid6_call.gen_syndrome(disks, bytes, ptrs);
	46
	47	/* Restore pointer table */
	48	ptrs[faila] = dp;
	49	ptrs[failb] = dq;
	50	ptrs[disks-2] = p;
	51	ptrs[disks-1] = q;
	52
	53	/* Now, pick the proper data tables */
	54	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
	55	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
	56
	57	/* Now do it... */
	58	while ( bytes-- ) {
	59	px = p ^ dp;
	60	qx = qmul[q ^ dq];
	61	dq++ = db = pbmul[px] ^ qx; / Reconstructed B */
	62	dp++ = db ^ px; / Reconstructed A */
	63	p++; q++;
	64	}
	65	}
f701d589	66	EXPORT_SYMBOL_GPL(raid6_2data_recov);
1da177e4 LT	67
	68	/* Recover failure of one data block plus the P block */
	69	void raid6_datap_recov(int disks, size_t bytes, int faila, void **ptrs)
	70	{
	71	u8 p, q, *dq;
	72	const u8 qmul; / Q multiplier table */
	73
	74	p = (u8 *)ptrs[disks-2];
	75	q = (u8 *)ptrs[disks-1];
	76
	77	/* Compute syndrome with zero for the missing data page
	78	Use the dead data page as temporary storage for delta q */
	79	dq = (u8 *)ptrs[faila];
	80	ptrs[faila] = (void *)raid6_empty_zero_page;
	81	ptrs[disks-1] = dq;
	82
	83	raid6_call.gen_syndrome(disks, bytes, ptrs);
	84
	85	/* Restore pointer table */
	86	ptrs[faila] = dq;
	87	ptrs[disks-1] = q;
	88
	89	/* Now, pick the proper data tables */
	90	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
	91
	92	/* Now do it... */
	93	while ( bytes-- ) {
	94	p++ ^= dq = qmul[q ^ dq];
	95	q++; dq++;
	96	}
	97	}
f701d589	98	EXPORT_SYMBOL_GPL(raid6_datap_recov);
1da177e4	99
f701d589 DW	100	#ifndef __KERNEL__
f701d589 DW	101	/* Testing only */
1da177e4 LT	102
	103	/* Recover two failed blocks. */
	104	void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs)
	105	{
	106	if ( faila > failb ) {
	107	int tmp = faila;
	108	faila = failb;
	109	failb = tmp;
	110	}
	111
	112	if ( failb == disks-1 ) {
	113	if ( faila == disks-2 ) {
	114	/* P+Q failure. Just rebuild the syndrome. */
	115	raid6_call.gen_syndrome(disks, bytes, ptrs);
	116	} else {
	117	/* data+Q failure. Reconstruct data from P,
	118	then rebuild syndrome. */
	119	/* NOT IMPLEMENTED - equivalent to RAID-5 */
	120	}
	121	} else {
	122	if ( failb == disks-2 ) {
	123	/* data+P failure. */
	124	raid6_datap_recov(disks, bytes, faila, ptrs);
	125	} else {
	126	/* data+data failure. */
	127	raid6_2data_recov(disks, bytes, faila, failb, ptrs);
	128	}
	129	}
	130	}
	131
	132	#endif