[linux.git] / lib / raid6 / recov.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.
 *
 * ----------------------------------------------------------------------- */

/*
 * raid6/recov.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/export.h>
#include <linux/raid/pq.h>

/* Recover two failed data blocks. */
void raid6_2data_recov_intx1(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++;
	}
}

/* Recover failure of one data block plus the P block */
void raid6_datap_recov_intx1(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++;
	}
}


const struct raid6_recov_calls raid6_recov_intx1 = {
	.data2 = raid6_2data_recov_intx1,
	.datap = raid6_datap_recov_intx1,
	.valid = NULL,
	.name = "intx1",
	.priority = 0,
};

#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	/*
a8e026c7	14	* raid6/recov.c
1da177e4 LT	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
daaa5f7c	21	#include <linux/export.h>
f701d589	22	#include <linux/raid/pq.h>
1da177e4 LT	23
1da177e4 LT	24	/* Recover two failed data blocks. */
048a8b8c	25	void raid6_2data_recov_intx1(int disks, size_t bytes, int faila, int failb,
1da177e4 LT	26	void **ptrs)
	27	{
	28	u8 p, q, dp, dq;
	29	u8 px, qx, db;
	30	const u8 pbmul; / P multiplier table for B data */
	31	const u8 qmul; / Q multiplier table (for both) */
	32
	33	p = (u8 *)ptrs[disks-2];
	34	q = (u8 *)ptrs[disks-1];
	35
	36	/* Compute syndrome with zero for the missing data pages
	37	Use the dead data pages as temporary storage for
	38	delta p and delta q */
	39	dp = (u8 *)ptrs[faila];
	40	ptrs[faila] = (void *)raid6_empty_zero_page;
	41	ptrs[disks-2] = dp;
	42	dq = (u8 *)ptrs[failb];
	43	ptrs[failb] = (void *)raid6_empty_zero_page;
	44	ptrs[disks-1] = dq;
	45
	46	raid6_call.gen_syndrome(disks, bytes, ptrs);
	47
	48	/* Restore pointer table */
	49	ptrs[faila] = dp;
	50	ptrs[failb] = dq;
	51	ptrs[disks-2] = p;
	52	ptrs[disks-1] = q;
	53
	54	/* Now, pick the proper data tables */
	55	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
	56	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
	57
	58	/* Now do it... */
	59	while ( bytes-- ) {
	60	px = p ^ dp;
	61	qx = qmul[q ^ dq];
	62	dq++ = db = pbmul[px] ^ qx; / Reconstructed B */
	63	dp++ = db ^ px; / Reconstructed A */
	64	p++; q++;
	65	}
	66	}
1da177e4 LT	67
1da177e4 LT	68	/* Recover failure of one data block plus the P block */
048a8b8c	69	void raid6_datap_recov_intx1(int disks, size_t bytes, int faila, void **ptrs)
1da177e4 LT	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	}
048a8b8c JK	98
	99
	100	const struct raid6_recov_calls raid6_recov_intx1 = {
	101	.data2 = raid6_2data_recov_intx1,
	102	.datap = raid6_datap_recov_intx1,
	103	.valid = NULL,
	104	.name = "intx1",
	105	.priority = 0,
	106	};
1da177e4	107
f701d589 DW	108	#ifndef __KERNEL__
f701d589 DW	109	/* Testing only */
1da177e4 LT	110
	111	/* Recover two failed blocks. */
	112	void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs)
	113	{
	114	if ( faila > failb ) {
	115	int tmp = faila;
	116	faila = failb;
	117	failb = tmp;
	118	}
	119
	120	if ( failb == disks-1 ) {
	121	if ( faila == disks-2 ) {
	122	/* P+Q failure. Just rebuild the syndrome. */
	123	raid6_call.gen_syndrome(disks, bytes, ptrs);
	124	} else {
	125	/* data+Q failure. Reconstruct data from P,
	126	then rebuild syndrome. */
	127	/* NOT IMPLEMENTED - equivalent to RAID-5 */
	128	}
	129	} else {
	130	if ( failb == disks-2 ) {
	131	/* data+P failure. */
	132	raid6_datap_recov(disks, bytes, faila, ptrs);
	133	} else {
	134	/* data+data failure. */
	135	raid6_2data_recov(disks, bytes, faila, failb, ptrs);
	136	}
	137	}
	138	}
	139
	140	#endif