Re: [Qemu-devel] [PATCH 2/3] block: Add 'blockdev-del' QMP command

[Alberto Garcia]

On Sat 17 Oct 2015 08:23:26 PM CEST, Max Reitz <address@hidden> wrote:
>> +void qmp_blockdev_del(const char *device, Error **errp)
>> +{
>> +    AioContext *aio_context;
>> +    BlockBackend *blk;
>> +    BlockDriverState *bs;
>> +
>> +    blk = blk_by_name(device);
>> +    if (blk) {
>> +        bs = blk_bs(blk);
>> +        aio_context = blk_get_aio_context(blk);
>> +    } else {
>> +        bs = bdrv_find_node(device);
>> +        if (!bs) {
>> +            error_setg(errp, "Cannot find block device %s", device);
>> +            return;
>> +        }
>> +        blk = bs->blk;
>
> After seeing testBlockBackendUsingNodeName() in patch 3, I don't know
> about this. We often have this notion of "If you need a BDS, you can
> specify both the BB and the node name", but here it's the other way
> around: One "needs" a BB (at least that's what the command will work
> on) and one gets it by specifying a node name. That seems a bit
> strange to me.

I'm also not completely sure about this to be honest and I'm not
surprised that you don't like it. I was thinking about this these last
couple of days and I think that this alternative is probably better:

 - If you specify the name of a backend, delete the backend and its BDS
   (if there's any).
 - If you specify the name of a BDS (using its node name), delete the
   BDS and only the BDS.

Berto