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