Re: [Qemu-devel] [PATCH 5/5] mirror: Check for bdrv_get_info result

[Fam Zheng <famz@redhat.com>]

On 2013年11月13日 23:34, Jeff Cody wrote:
> On Wed, Nov 13, 2013 at 08:53:14AM +0800, Fam Zheng wrote:
>> bdrv_get_info could fail. Add check before using the returned value.
>>
>> Signed-off-by: Fam Zheng <famz@redhat.com>
>> ---
>>   block/mirror.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/mirror.c b/block/mirror.c
>> index 7b95acf..c0c321b 100644
>> --- a/block/mirror.c
>> +++ b/block/mirror.c
>> @@ -320,8 +320,8 @@ static void coroutine_fn mirror_run(void *opaque)
>>       bdrv_get_backing_filename(s->target, backing_filename,
>>                                 sizeof(backing_filename));
>>       if (backing_filename[0] && !s->target->backing_hd) {
>> -        bdrv_get_info(s->target, &bdi);
>> -        if (s->granularity < bdi.cluster_size) {
>> +        ret = bdrv_get_info(s->target, &bdi);
>> +        if (ret == 0 && s->granularity < bdi.cluster_size) {
>
> For ret < 0, I think we should exit on error (at least in cases where
> ret < 0 && ret != -ENOTSUP).
>

We only need the cluster_size here, which is optional to set up 
operation granularity. Exiting the block job because bdrv_get_info fails 
(which is not a critical error) is worse in fault tolerance sense, so 
I'd like to keep this way.

Paolo, any ideas?

Fam