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- /* -*- 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
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