[linux-2.6-block.git] / lib / raid6 / recov.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright 2002 H. Peter Anvin - All Rights Reserved
 *
 * ----------------------------------------------------------------------- */

/*
 * 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
Commit	Line	Data
dd165a65	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/* -- linux-c -- ------------------------------------------------------- *
	3	*
	4	* Copyright 2002 H. Peter Anvin - All Rights Reserved
	5	*
1da177e4 LT	6	* ----------------------------------------------------------------------- */
	7
	8	/*
a8e026c7	9	* raid6/recov.c
1da177e4 LT	10	*
	11	* RAID-6 data recovery in dual failure mode. In single failure mode,
	12	* use the RAID-5 algorithm (or, in the case of Q failure, just reconstruct
	13	* the syndrome.)
	14	*/
	15
daaa5f7c	16	#include <linux/export.h>
f701d589	17	#include <linux/raid/pq.h>
1da177e4 LT	18
1da177e4 LT	19	/* Recover two failed data blocks. */
2aa4ee2a JK	20	static void raid6_2data_recov_intx1(int disks, size_t bytes, int faila,
2aa4ee2a JK	21	int failb, void **ptrs)
1da177e4 LT	22	{
	23	u8 p, q, dp, dq;
	24	u8 px, qx, db;
	25	const u8 pbmul; / P multiplier table for B data */
	26	const u8 qmul; / Q multiplier table (for both) */
	27
	28	p = (u8 *)ptrs[disks-2];
	29	q = (u8 *)ptrs[disks-1];
	30
	31	/* Compute syndrome with zero for the missing data pages
	32	Use the dead data pages as temporary storage for
	33	delta p and delta q */
	34	dp = (u8 *)ptrs[faila];
	35	ptrs[faila] = (void *)raid6_empty_zero_page;
	36	ptrs[disks-2] = dp;
	37	dq = (u8 *)ptrs[failb];
	38	ptrs[failb] = (void *)raid6_empty_zero_page;
	39	ptrs[disks-1] = dq;
	40
	41	raid6_call.gen_syndrome(disks, bytes, ptrs);
	42
	43	/* Restore pointer table */
	44	ptrs[faila] = dp;
	45	ptrs[failb] = dq;
	46	ptrs[disks-2] = p;
	47	ptrs[disks-1] = q;
	48
	49	/* Now, pick the proper data tables */
	50	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
	51	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
	52
	53	/* Now do it... */
	54	while ( bytes-- ) {
	55	px = p ^ dp;
	56	qx = qmul[q ^ dq];
	57	dq++ = db = pbmul[px] ^ qx; / Reconstructed B */
	58	dp++ = db ^ px; / Reconstructed A */
	59	p++; q++;
	60	}
	61	}
1da177e4 LT	62
1da177e4 LT	63	/* Recover failure of one data block plus the P block */
2aa4ee2a JK	64	static void raid6_datap_recov_intx1(int disks, size_t bytes, int faila,
2aa4ee2a JK	65	void **ptrs)
1da177e4 LT	66	{
	67	u8 p, q, *dq;
	68	const u8 qmul; / Q multiplier table */
	69
	70	p = (u8 *)ptrs[disks-2];
	71	q = (u8 *)ptrs[disks-1];
	72
	73	/* Compute syndrome with zero for the missing data page
	74	Use the dead data page as temporary storage for delta q */
	75	dq = (u8 *)ptrs[faila];
	76	ptrs[faila] = (void *)raid6_empty_zero_page;
	77	ptrs[disks-1] = dq;
	78
	79	raid6_call.gen_syndrome(disks, bytes, ptrs);
	80
	81	/* Restore pointer table */
	82	ptrs[faila] = dq;
	83	ptrs[disks-1] = q;
	84
	85	/* Now, pick the proper data tables */
	86	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
	87
	88	/* Now do it... */
	89	while ( bytes-- ) {
	90	p++ ^= dq = qmul[q ^ dq];
	91	q++; dq++;
	92	}
	93	}
048a8b8c JK	94
	95
	96	const struct raid6_recov_calls raid6_recov_intx1 = {
	97	.data2 = raid6_2data_recov_intx1,
	98	.datap = raid6_datap_recov_intx1,
	99	.valid = NULL,
	100	.name = "intx1",
	101	.priority = 0,
	102	};
1da177e4	103
f701d589 DW	104	#ifndef __KERNEL__
f701d589 DW	105	/* Testing only */
1da177e4 LT	106
	107	/* Recover two failed blocks. */
	108	void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs)
	109	{
	110	if ( faila > failb ) {
	111	int tmp = faila;
	112	faila = failb;
	113	failb = tmp;
	114	}
	115
	116	if ( failb == disks-1 ) {
	117	if ( faila == disks-2 ) {
	118	/* P+Q failure. Just rebuild the syndrome. */
	119	raid6_call.gen_syndrome(disks, bytes, ptrs);
	120	} else {
	121	/* data+Q failure. Reconstruct data from P,
	122	then rebuild syndrome. */
	123	/* NOT IMPLEMENTED - equivalent to RAID-5 */
	124	}
	125	} else {
	126	if ( failb == disks-2 ) {
	127	/* data+P failure. */
	128	raid6_datap_recov(disks, bytes, faila, ptrs);
	129	} else {
	130	/* data+data failure. */
	131	raid6_2data_recov(disks, bytes, faila, failb, ptrs);
	132	}
	133	}
	134	}
	135
	136	#endif