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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 | ||
f701d589 | 16 | #include <linux/raid/pq.h> |
1da177e4 LT |
17 | |
18 | /* Recover two failed data blocks. */ | |
2aa4ee2a JK |
19 | static void raid6_2data_recov_intx1(int disks, size_t bytes, int faila, |
20 | int failb, void **ptrs) | |
1da177e4 LT |
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 | } | |
1da177e4 LT |
61 | |
62 | /* Recover failure of one data block plus the P block */ | |
2aa4ee2a JK |
63 | static void raid6_datap_recov_intx1(int disks, size_t bytes, int faila, |
64 | void **ptrs) | |
1da177e4 LT |
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 | } | |
048a8b8c JK |
93 | |
94 | ||
95 | const 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 | }; | |
1da177e4 | 102 | |
f701d589 DW |
103 | #ifndef __KERNEL__ |
104 | /* Testing only */ | |
1da177e4 LT |
105 | |
106 | /* Recover two failed blocks. */ | |
107 | void 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 |