[lvm-devel] [PATCH] handle transient errors in lvconvert --repair

[Takahiro Yasui]

Hi Petr,

On 05/19/10 08:06, Petr Rockai wrote:
> Takahiro Yasui <tyasui at redhat.com> writes:
>> On 05/14/10 18:52, Takahiro Yasui wrote:
>>> I also tested this patch for a lvm mirror with core/disk log. When
>>> a mirror log failed, the mirror log was removed from a mirror volume,
>>> but a log voluem is not removed from its volume group. This always
>>> happens both on a transient and persistent error.
>>
>> This issue seems related to this part of your patch.
>>
>> @@ -1139,6 +1163,8 @@ static int _lvconvert_mirrors_repair(str
>> ...
>> -	/*
>> -	 * Remove all failed_pvs
>> -	 */
>> -	if (!_lvconvert_mirrors_aux(cmd, lv, lp, failed_pvs,
>> -				    lp->mirrors, new_log_count))
>> -		return 0;
>> +	if (failed_mirrors) {
>> +		if (!lv_remove_mirrors(cmd, lv, failed_mirrors, new_log_count,
>> +				       _is_partial_lv, NULL, 0))
>> +			return 0;
>> +
>> +		if (!_reload_lv(cmd, lv))
>> +			return 0;
>> +	}
>>
>> When I removed this modification, a log volume was removed as expected.
>> And also other my test cases also passed.
> 
> The catch is that this won't work correctly in other cases, especially
> with transient errors. I suspect the real problem is in not calling
> _lv_update_log_type in the new code path -- but see below: I cannot
> reliably fix this without having a reproducer. Also, I would very much
> like to have the tests you had failing on our regression suite, to avoid
> similar problem in the future.

I checked this code, but the value of failed_mirrors is '0' when
no mirror leg has error. So this code path was not executed in
my test. This is the reason why log was not removed with
mirror_log_fault_policy = "remove".

mirror_log_fault_policy = "allocate," on the other hand, the log
was removed in the following path.

        while (replace_mirrors || replace_log) {
                ...
                if (_lvconvert_mirrors_aux(cmd, lv, lp, NULL,
                                           lp->mirrors, log_count))
                        break;

We need to change the condition so that lv_remove_mirrors() is
executed.

>> -	 * Remove all failed_pvs
>> -	 */
>> -	if (!_lvconvert_mirrors_aux(cmd, lv, lp, failed_pvs,
>> -				    lp->mirrors, new_log_count))
>> -		return 0;
>> +	if (failed_mirrors) {

Thanks,
Taka