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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /lib/raid6/recov.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/raid6/recov.c')
-rw-r--r--lib/raid6/recov.c136
1 files changed, 136 insertions, 0 deletions
diff --git a/lib/raid6/recov.c b/lib/raid6/recov.c
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+// 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