Hi Neil,
I am testing the following simple scenario:
- RAID1 with two drives
- First drive has a bad block marked in the bad block list
- "repair" is triggered
What is happening is that the code in raid1.c:sync_request() selects
candidates for reading. If it encounters a bad block recorded, it
skips this particular drive:
if (is_badblock(rdev, sector_nr, good_sectors,
&first_bad, &bad_sectors)) {
if (first_bad > sector_nr)
.../* we don't go here*/
else {
/* we go here*/
bad_sectors -= (sector_nr - first_bad);
if (min_bad == 0 ||
min_bad > bad_sectors)
min_bad = bad_sectors;
}
}
if (sector_nr < first_bad) {
/* we don't go here */
...
But the second drive has no bad blocks recorded, so it is selected.
So we end up with read_targets=1 and min_bad>0.
Then the following code:
if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
/* extra read targets are also write targets */
write_targets += read_targets-1;
leaves write_targets=0
Then the following code:
if (write_targets == 0 || read_targets == 0) {
/* There is nowhere to write, so all non-sync
* drives must be failed - so we are finished
*/
sector_t rv = max_sector - sector_nr;
aborts the resync.
Is this the intended behavior? Because it looks like this bit does not
take into account the bad-blocks existence.
I am not sure about which logic would solve it, but something like "If
we did not select a drive for reading because of bad blocks, and as a
result we have only one read_target, and MD_RECOVERY_REQUESTED, then
let's report only the bad block as skipped and not the whole drive".
Something like that, but there are probably many cases I am not
thinking about.
What do you think?
Thanks,
Alex.
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