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136 lines
3.3 KiB
136 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* -*- linux-c -*- ------------------------------------------------------- * |
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* |
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* Copyright 2002 H. Peter Anvin - All Rights Reserved |
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* |
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* ----------------------------------------------------------------------- */ |
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/* |
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* raid6/recov.c |
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* |
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* RAID-6 data recovery in dual failure mode. In single failure mode, |
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* use the RAID-5 algorithm (or, in the case of Q failure, just reconstruct |
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* the syndrome.) |
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*/ |
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#include <linux/export.h> |
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#include <linux/raid/pq.h> |
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/* Recover two failed data blocks. */ |
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static void raid6_2data_recov_intx1(int disks, size_t bytes, int faila, |
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int failb, void **ptrs) |
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{ |
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u8 *p, *q, *dp, *dq; |
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u8 px, qx, db; |
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const u8 *pbmul; /* P multiplier table for B data */ |
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const u8 *qmul; /* Q multiplier table (for both) */ |
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p = (u8 *)ptrs[disks-2]; |
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q = (u8 *)ptrs[disks-1]; |
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/* Compute syndrome with zero for the missing data pages |
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Use the dead data pages as temporary storage for |
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delta p and delta q */ |
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dp = (u8 *)ptrs[faila]; |
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ptrs[faila] = (void *)raid6_empty_zero_page; |
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ptrs[disks-2] = dp; |
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dq = (u8 *)ptrs[failb]; |
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ptrs[failb] = (void *)raid6_empty_zero_page; |
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ptrs[disks-1] = dq; |
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raid6_call.gen_syndrome(disks, bytes, ptrs); |
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/* Restore pointer table */ |
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ptrs[faila] = dp; |
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ptrs[failb] = dq; |
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ptrs[disks-2] = p; |
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ptrs[disks-1] = q; |
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/* Now, pick the proper data tables */ |
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pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; |
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; |
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/* Now do it... */ |
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while ( bytes-- ) { |
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px = *p ^ *dp; |
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qx = qmul[*q ^ *dq]; |
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*dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */ |
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*dp++ = db ^ px; /* Reconstructed A */ |
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p++; q++; |
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} |
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} |
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/* Recover failure of one data block plus the P block */ |
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static void raid6_datap_recov_intx1(int disks, size_t bytes, int faila, |
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void **ptrs) |
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{ |
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u8 *p, *q, *dq; |
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const u8 *qmul; /* Q multiplier table */ |
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p = (u8 *)ptrs[disks-2]; |
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q = (u8 *)ptrs[disks-1]; |
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/* Compute syndrome with zero for the missing data page |
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Use the dead data page as temporary storage for delta q */ |
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dq = (u8 *)ptrs[faila]; |
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ptrs[faila] = (void *)raid6_empty_zero_page; |
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ptrs[disks-1] = dq; |
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raid6_call.gen_syndrome(disks, bytes, ptrs); |
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/* Restore pointer table */ |
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ptrs[faila] = dq; |
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ptrs[disks-1] = q; |
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/* Now, pick the proper data tables */ |
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; |
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/* Now do it... */ |
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while ( bytes-- ) { |
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*p++ ^= *dq = qmul[*q ^ *dq]; |
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q++; dq++; |
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} |
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} |
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const struct raid6_recov_calls raid6_recov_intx1 = { |
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.data2 = raid6_2data_recov_intx1, |
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.datap = raid6_datap_recov_intx1, |
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.valid = NULL, |
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.name = "intx1", |
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.priority = 0, |
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}; |
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#ifndef __KERNEL__ |
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/* Testing only */ |
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/* Recover two failed blocks. */ |
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void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs) |
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{ |
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if ( faila > failb ) { |
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int tmp = faila; |
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faila = failb; |
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failb = tmp; |
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} |
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if ( failb == disks-1 ) { |
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if ( faila == disks-2 ) { |
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/* P+Q failure. Just rebuild the syndrome. */ |
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raid6_call.gen_syndrome(disks, bytes, ptrs); |
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} else { |
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/* data+Q failure. Reconstruct data from P, |
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then rebuild syndrome. */ |
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/* NOT IMPLEMENTED - equivalent to RAID-5 */ |
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} |
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} else { |
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if ( failb == disks-2 ) { |
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/* data+P failure. */ |
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raid6_datap_recov(disks, bytes, faila, ptrs); |
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} else { |
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/* data+data failure. */ |
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raid6_2data_recov(disks, bytes, faila, failb, ptrs); |
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} |
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} |
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} |
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#endif
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