Re: [PATCH v5 5/5] parallels: Image repairing in parallels_open()

[Hanna Czenczek <hreitz@redhat.com>]

On 09.06.23 15:21, Alexander Ivanov wrote:
>
>
> On 6/2/23 16:59, Hanna Czenczek wrote:
>> On 29.05.23 17:15, Alexander Ivanov wrote:
>>> Repair an image at opening if the image is unclean or out-of-image
>>> corruption was detected.
>>>
>>> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
>>> ---
>>>   block/parallels.c | 65 
>>> +++++++++++++++++++++++++----------------------
>>>   1 file changed, 35 insertions(+), 30 deletions(-)
>>>
>>> diff --git a/block/parallels.c b/block/parallels.c
>>> index d64e8007d5..7bbd5cb112 100644
>>> --- a/block/parallels.c
>>> +++ b/block/parallels.c
>>
>> [...]
>>
>>> @@ -1130,6 +1101,40 @@ static int parallels_open(BlockDriverState 
>>> *bs, QDict *options, int flags,
>>>           goto fail;
>>>       }
>>>       qemu_co_mutex_init(&s->lock);
>>> +
>>> +    if (le32_to_cpu(ph.inuse) == HEADER_INUSE_MAGIC) {
>>> +        s->header_unclean = true;
>>> +    }
>>> +
>>> +    for (i = 0; i < s->bat_size; i++) {
>>> +        sector = bat2sect(s, i);
>>> +        if (sector + s->tracks > s->data_end) {
>>> +            s->data_end = sector + s->tracks;
>>> +        }
>>> +    }
>>> +
>>> +    /*
>>> +     * We don't repair the image here if it's opened for checks. 
>>> Also we don't
>>> +     * want to change inactive images and can't change readonly 
>>> images.
>>> +     */
>>> +    if ((flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) || !(flags & 
>>> BDRV_O_RDWR)) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    /*
>>> +     * Repair the image if it's dirty or
>>> +     * out-of-image corruption was detected.
>>> +     */
>>> +    if (s->data_end > file_nb_sectors || s->header_unclean) {
>>> +        BdrvCheckResult res;
>>> +        ret = bdrv_check(bs, &res, BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
>>> +        if (ret < 0) {
>>
>> Should we also verify that res->corruptions == res->corruptions_fixed 
>> && res->check_errors == 0?
> If ret == 0 there must be res->check_errors == 0 and res->corruptions 
> == res->corruptions_fixed.

OK.

>>
>>> + error_free(s->migration_blocker);
>>
>> I’d move this clean-up to a new error path below, then we could even 
>> reuse that where migrate_add_blocker() fails.
> Is this guaranteed that s->migration_blocker is NULL at the function 
> parallels_open() beginning? If so it could be easy to move the clean-up,
> otherwise it could lead to code complication.

Three answers here:

First, I just realized that we probably need to undo the 
migrate_add_blocker() call, too, i.e. call migrate_del_blocker() here.

Second, I’m pretty sure that s->migration_blocker must be NULL before 
the error_setg(&s->migration_blocker) call, because error_setg() asserts 
that the *errp passed to it is NULL.

Third, I meant to add a new path e.g.:

```
fail_blocker:
     error_free(s->migration_blocker);
fail_format:
[...]
```

And then use `goto fail_blocker;` here and in the migrate_add_blocker() 
error path, so it shouldn’t really matter whether s->migration_blocker 
is NULL before the error_setg() call.  But then again, I think the 
probably necessary migrate_del_blocker() call complicates things further.

Hanna

>>
>> Anyway, not wrong as-is, just suggestion, so:
>>
>> Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
>>
>>> +            error_setg_errno(errp, -ret, "Could not repair 
>>> corrupted image");
>>> +            goto fail;
>>> +        }
>>> +    }
>>> +
>>>       return 0;
>>>     fail_format:
>>
>