/* Recover failure of one data block plus the P block */
void raid6_datap_recov(int disks, size_t bytes, int faila, uint8_t **ptrs,
int neg_offset)
{
uint8_t *p, *q, *dq;
const uint8_t *qmul; /* Q multiplier table */
if (neg_offset) {
p = ptrs[-1];
q = ptrs[-2];
} else {
p = ptrs[disks-2];
q = ptrs[disks-1];
}
/* Compute syndrome with zero for the missing data page
Use the dead data page as temporary storage for delta q */
dq = ptrs[faila];
ptrs[faila] = zero;
qsyndrome(p, dq, ptrs, disks-2, bytes);
/* Restore pointer table */
ptrs[faila] = dq;
/* 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++;
}
}
void raid6_2data_recov(int disks, size_t bytes, int faila, int failb,
uint8_t **ptrs, int neg_offset)
{
uint8_t *p, *q, *dp, *dq;
uint8_t px, qx, db;
const uint8_t *pbmul; /* P multiplier table for B data */
const uint8_t *qmul; /* Q multiplier table (for both) */
if (faila > failb) {
int t = faila;
faila = failb;
failb = t;
}
if (neg_offset) {
p = ptrs[-1];
q = ptrs[-2];
} else {
p = ptrs[disks-2];
q = 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 = ptrs[faila];
ptrs[faila] = zero;
dq = ptrs[failb];
ptrs[failb] = zero;
qsyndrome(dp, dq, ptrs, disks-2, bytes);
/* Restore pointer table */
ptrs[faila] = dp;
ptrs[failb] = dq;
/* 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++;
}
}
int test_stripes(int *source, unsigned long long *offsets,
int raid_disks, int chunk_size, int level, int layout,
unsigned long long start, unsigned long long length)
{
/* ready the data and p (and q) blocks, and check we got them right */
char *stripe_buf = xmalloc(raid_disks * chunk_size);
char **stripes = xmalloc(raid_disks * sizeof(char*));
char **blocks = xmalloc(raid_disks * sizeof(char*));
char *p = xmalloc(chunk_size);
char *q = xmalloc(chunk_size);
int i;
int diskP, diskQ;
int data_disks = raid_disks - (level == 5 ? 1: 2);
if (!tables_ready)
make_tables();
for ( i = 0 ; i < raid_disks ; i++)
stripes[i] = stripe_buf + i * chunk_size;
while (length > 0) {
int disk;
for (i = 0 ; i < raid_disks ; i++) {
lseek64(source[i], offsets[i]+start, 0);
read(source[i], stripes[i], chunk_size);
}
for (i = 0 ; i < data_disks ; i++) {
int disk = geo_map(i, start/chunk_size, raid_disks,
level, layout);
blocks[i] = stripes[disk];
printf("%d->%d\n", i, disk);
}
switch(level) {
case 6:
qsyndrome(p, q, (uint8_t**)blocks, data_disks, chunk_size);
diskP = geo_map(-1, start/chunk_size, raid_disks,
level, layout);
if (memcmp(p, stripes[diskP], chunk_size) != 0) {
printf("P(%d) wrong at %llu\n", diskP,
start / chunk_size);
}
diskQ = geo_map(-2, start/chunk_size, raid_disks,
level, layout);
if (memcmp(q, stripes[diskQ], chunk_size) != 0) {
printf("Q(%d) wrong at %llu\n", diskQ,
start / chunk_size);
}
disk = raid6_check_disks(data_disks, start, chunk_size,
level, layout, diskP, diskQ,
p, q, stripes);
if(disk >= 0) {
printf("Possible failed disk: %d\n", disk);
}
if(disk == -2) {
printf("Failure detected, but disk unknown\n");
}
break;
}
length -= chunk_size;
start += chunk_size;
}
return 0;
}
/* Restore data:
* We are given:
* A list of 'fds' of the active disks. Some may be '-1' for not-available.
* A geometry: raid_disks, chunk_size, level, layout
* An 'fd' to read from. It is already seeked to the right (Read) location.
* A start and length.
* The length must be a multiple of the stripe size.
*
* We build a full stripe in memory and then write it out.
* We assume that there are enough working devices.
*/
int restore_stripes(int *dest, unsigned long long *offsets,
int raid_disks, int chunk_size, int level, int layout,
int source, unsigned long long read_offset,
unsigned long long start, unsigned long long length,
char *src_buf)
{
char *stripe_buf;
char **stripes = xmalloc(raid_disks * sizeof(char*));
char **blocks = xmalloc(raid_disks * sizeof(char*));
int i;
int rv;
int data_disks = raid_disks - (level == 0 ? 0 : level <= 5 ? 1 : 2);
if (posix_memalign((void**)&stripe_buf, 4096, raid_disks * chunk_size))
stripe_buf = NULL;
if (zero == NULL || chunk_size > zero_size) {
if (zero)
free(zero);
zero = xcalloc(1, chunk_size);
zero_size = chunk_size;
}
if (stripe_buf == NULL || stripes == NULL || blocks == NULL
|| zero == NULL) {
rv = -2;
goto abort;
}
for (i = 0; i < raid_disks; i++)
stripes[i] = stripe_buf + i * chunk_size;
while (length > 0) {
unsigned int len = data_disks * chunk_size;
unsigned long long offset;
int disk, qdisk;
int syndrome_disks;
if (length < len) {
rv = -3;
goto abort;
}
for (i = 0; i < data_disks; i++) {
int disk = geo_map(i, start/chunk_size/data_disks,
raid_disks, level, layout);
if (src_buf == NULL) {
/* read from file */
if (lseek64(source, read_offset, 0) !=
(off64_t)read_offset) {
rv = -1;
goto abort;
}
if (read(source,
stripes[disk],
chunk_size) != chunk_size) {
rv = -1;
goto abort;
}
} else {
/* read from input buffer */
memcpy(stripes[disk],
src_buf + read_offset,
chunk_size);
}
read_offset += chunk_size;
}
/* We have the data, now do the parity */
offset = (start/chunk_size/data_disks) * chunk_size;
switch (level) {
case 4:
case 5:
disk = geo_map(-1, start/chunk_size/data_disks,
raid_disks, level, layout);
for (i = 0; i < data_disks; i++)
blocks[i] = stripes[(disk+1+i) % raid_disks];
xor_blocks(stripes[disk], blocks, data_disks, chunk_size);
break;
case 6:
disk = geo_map(-1, start/chunk_size/data_disks,
raid_disks, level, layout);
qdisk = geo_map(-2, start/chunk_size/data_disks,
raid_disks, level, layout);
if (is_ddf(layout)) {
/* q over 'raid_disks' blocks, in device order.
* 'p' and 'q' get to be all zero
*/
for (i = 0; i < raid_disks; i++)
if (i == disk || i == qdisk)
blocks[i] = (char*)zero;
else
blocks[i] = stripes[i];
syndrome_disks = raid_disks;
} else {
/* for md, q is over 'data_disks' blocks,
* starting immediately after 'q'
*/
for (i = 0; i < data_disks; i++)
blocks[i] = stripes[(qdisk+1+i) % raid_disks];
syndrome_disks = data_disks;
}
qsyndrome((uint8_t*)stripes[disk],
(uint8_t*)stripes[qdisk],
(uint8_t**)blocks,
syndrome_disks, chunk_size);
break;
}
for (i=0; i < raid_disks ; i++)
if (dest[i] >= 0) {
if (lseek64(dest[i],
offsets[i]+offset, 0) < 0) {
rv = -1;
goto abort;
}
if (write(dest[i], stripes[i],
chunk_size) != chunk_size) {
rv = -1;
goto abort;
}
}
length -= len;
start += len;
}
rv = 0;
abort:
free(stripe_buf);
free(stripes);
free(blocks);
return rv;
}
int check_stripes(struct mdinfo *info, int *source, unsigned long long *offsets,
int raid_disks, int chunk_size, int level, int layout,
unsigned long long start, unsigned long long length, char *name[],
int repair, int failed_disk1, int failed_disk2)
{
/* read the data and p and q blocks, and check we got them right */
char *stripe_buf = xmalloc(raid_disks * chunk_size);
char **stripes = xmalloc(raid_disks * sizeof(char*));
char **blocks = xmalloc(raid_disks * sizeof(char*));
int *block_index_for_slot = xmalloc(raid_disks * sizeof(int));
uint8_t *p = xmalloc(chunk_size);
uint8_t *q = xmalloc(chunk_size);
int *results = xmalloc(chunk_size * sizeof(int));
sighandler_t *sig = xmalloc(3 * sizeof(sighandler_t));
int i;
int diskP, diskQ;
int data_disks = raid_disks - 2;
int err = 0;
extern int tables_ready;
if (!tables_ready)
make_tables();
for ( i = 0 ; i < raid_disks ; i++)
stripes[i] = stripe_buf + i * chunk_size;
while (length > 0) {
int disk;
printf("pos --> %llu\n", start);
err = lock_stripe(info, start, chunk_size, data_disks, sig);
if(err != 0) {
if (err != 2)
unlock_all_stripes(info, sig);
goto exitCheck;
}
for (i = 0 ; i < raid_disks ; i++) {
lseek64(source[i], offsets[i] + start * chunk_size, 0);
read(source[i], stripes[i], chunk_size);
}
err = unlock_all_stripes(info, sig);
if(err != 0)
goto exitCheck;
for (i = 0 ; i < data_disks ; i++) {
int disk = geo_map(i, start, raid_disks, level, layout);
blocks[i] = stripes[disk];
block_index_for_slot[disk] = i;
printf("%d->%d\n", i, disk);
}
qsyndrome(p, q, (uint8_t**)blocks, data_disks, chunk_size);
diskP = geo_map(-1, start, raid_disks, level, layout);
diskQ = geo_map(-2, start, raid_disks, level, layout);
blocks[data_disks] = stripes[diskP];
block_index_for_slot[diskP] = data_disks;
blocks[data_disks+1] = stripes[diskQ];
block_index_for_slot[diskQ] = data_disks+1;
if (memcmp(p, stripes[diskP], chunk_size) != 0) {
printf("P(%d) wrong at %llu\n", diskP, start);
}
if (memcmp(q, stripes[diskQ], chunk_size) != 0) {
printf("Q(%d) wrong at %llu\n", diskQ, start);
}
raid6_collect(chunk_size, p, q, stripes[diskP], stripes[diskQ], results);
disk = raid6_stats(results, raid_disks, chunk_size);
if(disk >= -2) {
disk = geo_map(disk, start, raid_disks, level, layout);
}
if(disk >= 0) {
printf("Error detected at %llu: possible failed disk slot: %d --> %s\n",
start, disk, name[disk]);
}
if(disk == -65535) {
printf("Error detected at %llu: disk slot unknown\n", start);
}
if(repair == 1) {
printf("Repairing stripe %llu\n", start);
printf("Assuming slots %d (%s) and %d (%s) are incorrect\n",
failed_disk1, name[failed_disk1],
failed_disk2, name[failed_disk2]);
if (failed_disk1 == diskQ || failed_disk2 == diskQ) {
char *all_but_failed_blocks[data_disks];
int failed_data_or_p;
int failed_block_index;
if (failed_disk1 == diskQ)
failed_data_or_p = failed_disk2;
else
failed_data_or_p = failed_disk1;
printf("Repairing D/P(%d) and Q\n", failed_data_or_p);
failed_block_index = block_index_for_slot[failed_data_or_p];
for (i=0; i < data_disks; i++)
if (failed_block_index == i)
all_but_failed_blocks[i] = stripes[diskP];
else
all_but_failed_blocks[i] = blocks[i];
xor_blocks(stripes[failed_data_or_p],
all_but_failed_blocks, data_disks, chunk_size);
qsyndrome(p, (uint8_t*)stripes[diskQ], (uint8_t**)blocks, data_disks, chunk_size);
} else {
ensure_zero_has_size(chunk_size);
if (failed_disk1 == diskP || failed_disk2 == diskP) {
int failed_data, failed_block_index;
if (failed_disk1 == diskP)
failed_data = failed_disk2;
else
failed_data = failed_disk1;
failed_block_index = block_index_for_slot[failed_data];
printf("Repairing D(%d) and P\n", failed_data);
raid6_datap_recov(raid_disks, chunk_size, failed_block_index, (uint8_t**)blocks);
} else {
printf("Repairing D and D\n");
int failed_block_index1 = block_index_for_slot[failed_disk1];
int failed_block_index2 = block_index_for_slot[failed_disk2];
if (failed_block_index1 > failed_block_index2) {
int t = failed_block_index1;
failed_block_index1 = failed_block_index2;
failed_block_index2 = t;
}
raid6_2data_recov(raid_disks, chunk_size, failed_block_index1, failed_block_index2, (uint8_t**)blocks);
}
}
err = lock_stripe(info, start, chunk_size, data_disks, sig);
if(err != 0) {
if (err != 2)
unlock_all_stripes(info, sig);
goto exitCheck;
}
lseek64(source[failed_disk1], offsets[failed_disk1] + start * chunk_size, 0);
write(source[failed_disk1], stripes[failed_disk1], chunk_size);
lseek64(source[failed_disk2], offsets[failed_disk2] + start * chunk_size, 0);
write(source[failed_disk2], stripes[failed_disk2], chunk_size);
err = unlock_all_stripes(info, sig);
if(err != 0)
goto exitCheck;
} else if (disk >= 0 && repair == 2) {
printf("Auto-repairing slot %d (%s)\n", disk, name[disk]);
if (disk == diskQ) {
qsyndrome(p, (uint8_t*)stripes[diskQ], (uint8_t**)blocks, data_disks, chunk_size);
} else {
char *all_but_failed_blocks[data_disks];
int failed_block_index = block_index_for_slot[disk];
for (i=0; i < data_disks; i++)
if (failed_block_index == i)
all_but_failed_blocks[i] = stripes[diskP];
else
all_but_failed_blocks[i] = blocks[i];
xor_blocks(stripes[disk],
all_but_failed_blocks, data_disks, chunk_size);
}
err = lock_stripe(info, start, chunk_size, data_disks, sig);
if(err != 0) {
if (err != 2)
unlock_all_stripes(info, sig);
goto exitCheck;
}
lseek64(source[disk], offsets[disk] + start * chunk_size, 0);
write(source[disk], stripes[disk], chunk_size);
err = unlock_all_stripes(info, sig);
if(err != 0)
goto exitCheck;
}
length--;
start++;
}
exitCheck:
free(stripe_buf);
free(stripes);
free(blocks);
free(p);
free(q);
free(results);
return err;
}