On 1/16/19 9:43 AM, Vladimir Sementsov-Ogievskiy wrote:

>> @@ -839,9 +842,25 @@ static int nbd_list_meta_contexts(QIOChannel *ioc,
>>
>>           ret = nbd_receive_one_meta_context(ioc, NBD_OPT_LIST_META_CONTEXT,
>>                                              &context, NULL, errp);
>> +        if (ret == 0 && seen_any && !seen_qemu) {
>> +            /*
>> +             * Work around qemu 3.0 bug: the server forgot to send
>> +             * "qemu:" replies to 0 queries. If we saw at least one
>> +             * reply (probably base:allocation), but none of them were
> 
> if we are saying about 3.0, it is base:allocation for sure, isn't it?
> 
>> +             * qemu:, then run a more specific query to make sure.

If the server is qemu 3.0, then yes, it is base:allocation. But it could
be some other server that has its own custom return without implementing
base:allocation.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org