/* -*- 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. */static 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 */static 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