Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-or-later
2 : // Copyright (C) 2015 Andrea Mazzoleni
3 :
4 : #include "internal.h"
5 : #include "combo.h"
6 : #include "gf.h"
7 :
8 : /**
9 : * Validate the provided failed blocks.
10 : *
11 : * This function checks if the specified failed blocks satisfy the redundancy
12 : * information using the data from the known valid parity blocks.
13 : *
14 : * It's similar to raid_check(), just with a different format for arguments.
15 : *
16 : * The number of failed blocks @nr must be strictly less than the number of
17 : * parities @nv, because you need one more parity to validate the recovering.
18 : *
19 : * No data or parity blocks are modified.
20 : *
21 : * @nr Number of failed data blocks.
22 : * @id[] Vector of @nr indexes of the failed data blocks.
23 : * The indexes start from 0. They must be in order.
24 : * @nv Number of valid parity blocks.
25 : * @ip[] Vector of @nv indexes of the valid parity blocks.
26 : * The indexes start from 0. They must be in order.
27 : * @nd Number of data blocks.
28 : * @size Size of the blocks pointed by @v. It must be a multiple of 64.
29 : * @v Vector of pointers to the blocks of data and parity.
30 : * It has (@nd + @ip[@nv - 1] + 1) elements. The starting elements are the
31 : * blocks for data, following with the parity blocks.
32 : * Each block has @size bytes.
33 : * @return 0 if the check is satisfied. -1 otherwise.
34 : */
35 11255 : static int raid_validate(int nr, int *id, int nv, int *ip, int nd, size_t size, void **vv)
36 : {
37 11255 : uint8_t **v = (uint8_t **)vv;
38 : const uint8_t *T[RAID_PARITY_MAX][RAID_PARITY_MAX];
39 : uint8_t G[RAID_PARITY_MAX * RAID_PARITY_MAX];
40 : uint8_t V[RAID_PARITY_MAX * RAID_PARITY_MAX];
41 : size_t i;
42 : int j, k, l;
43 :
44 11255 : BUG_ON(nr >= nv);
45 :
46 : /* setup the coefficients matrix */
47 41316 : for (j = 0; j < nr; ++j)
48 119934 : for (k = 0; k < nr; ++k)
49 179746 : G[j * nr + k] = A(ip[j], id[k]);
50 :
51 : /* invert it to solve the system of linear equations */
52 11255 : raid_invert(G, V, nr);
53 :
54 : /* get multiplication tables */
55 41316 : for (j = 0; j < nr; ++j)
56 119934 : for (k = 0; k < nr; ++k)
57 179746 : T[j][k] = table(V[j * nr + k]);
58 :
59 : /* check all positions */
60 35831 : for (i = 0; i < size; ++i) {
61 : uint8_t p[RAID_PARITY_MAX];
62 :
63 : /* get parity */
64 151819 : for (j = 0; j < nv; ++j)
65 115994 : p[j] = v[nd + ip[j]][i];
66 :
67 : /* compute delta parity, skipping broken disks */
68 609025 : for (j = 0, k = 0; j < nd; ++j) {
69 : uint8_t b;
70 :
71 : /* skip broken disks */
72 573200 : if (k < nr && id[k] == j) {
73 66916 : ++k;
74 66916 : continue;
75 : }
76 :
77 506284 : b = v[j][i];
78 2094442 : for (l = 0; l < nv; ++l)
79 1588158 : p[l] ^= gfmul[b][gfgen[ip[l]][j]];
80 : }
81 :
82 : /* reconstruct data */
83 102741 : for (j = 0; j < nr; ++j) {
84 66916 : uint8_t b = 0;
85 66916 : int idj = id[j];
86 :
87 : /* recompute the data */
88 234594 : for (k = 0; k < nr; ++k)
89 167678 : b ^= T[j][k][p[k]];
90 :
91 : /* add the parity contribution of the reconstructed data */
92 166984 : for (l = nr; l < nv; ++l)
93 100068 : p[l] ^= gfmul[b][gfgen[ip[l]][idj]];
94 : }
95 :
96 : /* check that the final parity is 0 */
97 60482 : for (l = nr; l < nv; ++l)
98 35906 : if (p[l] != 0)
99 11249 : return -1;
100 : }
101 :
102 6 : return 0;
103 : }
104 :
105 11255 : int raid_check(int nr, int *ir, int nd, int np, size_t size, void **v)
106 : {
107 : /* valid parity index */
108 : int ip[RAID_PARITY_MAX];
109 : int vp;
110 : int rd;
111 : int i, j;
112 :
113 : /* enforce limit on size */
114 11255 : BUG_ON(size % 64 != 0);
115 :
116 : /* enforce limit on number of failures */
117 11255 : BUG_ON(nr >= np); /* >= because we check with extra parity */
118 11255 : BUG_ON(np > RAID_PARITY_MAX);
119 :
120 : /* enforce order in index vector */
121 11255 : BUG_ON(nr >= 2 && ir[0] >= ir[1]);
122 11255 : BUG_ON(nr >= 3 && ir[1] >= ir[2]);
123 11255 : BUG_ON(nr >= 4 && ir[2] >= ir[3]);
124 11255 : BUG_ON(nr >= 5 && ir[3] >= ir[4]);
125 11255 : BUG_ON(nr >= 6 && ir[4] >= ir[5]);
126 :
127 : /* enforce limit on index vector */
128 11255 : BUG_ON(nr > 0 && ir[nr-1] >= nd + np);
129 :
130 : /* count failed data disk */
131 11255 : rd = 0;
132 41316 : while (rd < nr && ir[rd] < nd)
133 30061 : ++rd;
134 :
135 : /* put valid parities into ip[] */
136 11255 : vp = 0;
137 76488 : for (i = rd, j = 0; j < np; ++j) {
138 : /* if parity is failed */
139 65233 : if (i < nr && ir[i] == nd + j) {
140 : /* skip broken parity */
141 10664 : ++i;
142 : } else {
143 : /* store valid parity */
144 54569 : ip[vp] = j;
145 54569 : ++vp;
146 : }
147 : }
148 :
149 11255 : return raid_validate(rd, ir, vp, ip, nd, size, v);
150 : }
151 :
152 7 : int raid_scan(int *ir, int nd, int np, size_t size, void **v)
153 : {
154 : int r;
155 :
156 : /* check the special case of no failure */
157 7 : if (np != 0 && raid_check(0, 0, nd, np, size, v) == 0)
158 1 : return 0;
159 :
160 : /* for each number of possible failures */
161 16 : for (r = 1; r < np; ++r) {
162 : /* try all combinations of r failures on n disks */
163 15 : combination_first(r, nd + np, ir);
164 : do {
165 : /* verify if the combination is a valid one */
166 11249 : if (raid_check(r, ir, nd, np, size, v) == 0)
167 5 : return r;
168 22488 : } while (combination_next(r, nd + np, ir));
169 : }
170 :
171 : /* no solution found */
172 1 : return -1;
173 : }
174 :
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