diff options
Diffstat (limited to 'grub-core/disk/raid6_recover.c')
| -rw-r--r-- | grub-core/disk/raid6_recover.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c new file mode 100644 index 0000000..25b50eb --- /dev/null +++ b/grub-core/disk/raid6_recover.c @@ -0,0 +1,230 @@ +/* raid6_recover.c - module to recover from faulty RAID6 arrays. */ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2006,2007,2008,2009 Free Software Foundation, Inc. + * + * GRUB is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * GRUB is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with GRUB. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <grub/dl.h> +#include <grub/disk.h> +#include <grub/mm.h> +#include <grub/err.h> +#include <grub/misc.h> +#include <grub/raid.h> + +GRUB_MOD_LICENSE ("GPLv3+"); + +static grub_uint8_t raid6_table1[256][256]; +static grub_uint8_t raid6_table2[256][256]; + +static void +grub_raid_block_mul (grub_uint8_t mul, char *buf, int size) +{ + int i; + grub_uint8_t *p; + + p = (grub_uint8_t *) buf; + for (i = 0; i < size; i++, p++) + *p = raid6_table1[mul][*p]; +} + +static void +grub_raid6_init_table (void) +{ + int i, j; + + for (i = 0; i < 256; i++) + raid6_table1[i][1] = raid6_table1[1][i] = i; + + for (i = 2; i < 256; i++) + for (j = i; j < 256; j++) + { + int n; + grub_uint8_t c; + + n = i >> 1; + + c = raid6_table1[n][j]; + c = (c << 1) ^ ((c & 0x80) ? 0x1d : 0); + if (i & 1) + c ^= j; + + raid6_table1[j][i] = raid6_table1[i][j] = c; + } + + raid6_table2[0][0] = 1; + for (i = 1; i < 256; i++) + raid6_table2[i][i] = raid6_table1[raid6_table2[i - 1][i - 1]][2]; + + for (i = 0; i < 254; i++) + for (j = 0; j < 254; j++) + { + grub_uint8_t c, n; + int k; + + if (i == j) + continue; + + k = i - j; + if (k < 0) + k += 255; + + c = n = raid6_table2[k][k] ^ 1; + for (k = 0; k < 253; k++) + c = raid6_table1[c][n]; + + raid6_table2[i][j] = raid6_table1[raid6_table2[255 - j][255 - j]][c]; + } +} + +static grub_err_t +grub_raid6_recover (struct grub_raid_array *array, int disknr, int p, + char *buf, grub_disk_addr_t sector, int size) +{ + int i, q, pos; + int bad1 = -1, bad2 = -1; + char *pbuf = 0, *qbuf = 0; + + size <<= GRUB_DISK_SECTOR_BITS; + pbuf = grub_zalloc (size); + if (!pbuf) + goto quit; + + qbuf = grub_zalloc (size); + if (!qbuf) + goto quit; + + q = p + 1; + if (q == (int) array->total_devs) + q = 0; + + pos = q + 1; + if (pos == (int) array->total_devs) + pos = 0; + + for (i = 0; i < (int) array->total_devs - 2; i++) + { + if (pos == disknr) + bad1 = i; + else + { + if ((array->members[pos].device) && + (! grub_disk_read (array->members[pos].device, + array->members[i].start_sector + sector, + 0, size, buf))) + { + grub_raid_block_xor (pbuf, buf, size); + grub_raid_block_mul (raid6_table2[i][i], buf, size); + grub_raid_block_xor (qbuf, buf, size); + } + else + { + /* Too many bad devices */ + if (bad2 >= 0) + goto quit; + + bad2 = i; + grub_errno = GRUB_ERR_NONE; + } + } + + pos++; + if (pos == (int) array->total_devs) + pos = 0; + } + + /* Invalid disknr or p */ + if (bad1 < 0) + goto quit; + + if (bad2 < 0) + { + /* One bad device */ + if ((array->members[p].device) && + (! grub_disk_read (array->members[p].device, + array->members[i].start_sector + sector, + 0, size, buf))) + { + grub_raid_block_xor (buf, pbuf, size); + goto quit; + } + + if (! array->members[q].device) + { + grub_error (GRUB_ERR_READ_ERROR, "not enough disk to restore"); + goto quit; + } + + grub_errno = GRUB_ERR_NONE; + if (grub_disk_read (array->members[q].device, + array->members[i].start_sector + sector, 0, size, buf)) + goto quit; + + grub_raid_block_xor (buf, qbuf, size); + grub_raid_block_mul (raid6_table2[255 - bad1][255 - bad1], buf, + size); + } + else + { + /* Two bad devices */ + grub_uint8_t c; + + if ((! array->members[p].device) || (! array->members[q].device)) + { + grub_error (GRUB_ERR_READ_ERROR, "not enough disk to restore"); + goto quit; + } + + if (grub_disk_read (array->members[p].device, + array->members[i].start_sector + sector, + 0, size, buf)) + goto quit; + + grub_raid_block_xor (pbuf, buf, size); + + if (grub_disk_read (array->members[q].device, + array->members[i].start_sector + sector, + 0, size, buf)) + goto quit; + + grub_raid_block_xor (qbuf, buf, size); + + c = raid6_table2[bad2][bad1]; + grub_raid_block_mul (c, qbuf, size); + + c = raid6_table1[raid6_table2[bad2][bad2]][c]; + grub_raid_block_mul (c, pbuf, size); + + grub_raid_block_xor (pbuf, qbuf, size); + grub_memcpy (buf, pbuf, size); + } + +quit: + grub_free (pbuf); + grub_free (qbuf); + + return grub_errno; +} + +GRUB_MOD_INIT(raid6rec) +{ + grub_raid6_init_table (); + grub_raid6_recover_func = grub_raid6_recover; +} + +GRUB_MOD_FINI(raid6rec) +{ + grub_raid6_recover_func = 0; +} |