On Mon 03 Sep 2018 05:03:11 PM CEST, Kevin Wolf wrote:
>> libvirt-3-format is read-write and all other node names are readonly in
>> the above example.
>>
>> The same also happens when using filenames:
>>
>> {"execute":"block-commit",
>> "arguments" : {"device":"libvirt-3-format",
>> "job-id":"libvirt-3-format",
>> "top":"/var/lib/libvirt/images/rhel7.3.1483615252",
>> "base":"/var/lib/libvirt/images/rhel7.3.1483605924",
>> "auto-finalize":true,
>> "auto-dismiss":false},
>> "id":"libvirt-13"}
>>
>> {"id":"libvirt-13","error":{"class":"GenericError","desc":"Block node is
>> read-only"}}
>
> I see what's happening here. So we have a graph like this:
>
> guest device
> |
> v
> overlay-format -------> backing-format
> [read-only=off] [read-only=on]
> | |
> v v
> overlay-proto backing-proto
> [read-only=off] [read-only=on]
>
> The difference between your -blockdev use and -drive is that you
> explicitly specify the read-only option for backing-proto (and you use
> a separate -blockdev option anyway), so it doesn't just inherit it
> from backing-format.
Are these format and protocol block devices opened with four separate
-blockdev parameters? Is that how libvirt does it?
Berto
