Re: [Qemu-devel] [PATCH 3/3] block: allow BLOCK_IMAGE_CORRUPTED to have a node name

[Alberto Garcia <berto@igalia.com>]

On Thu, Mar 19, 2015 at 04:15:49PM -0600, Eric Blake wrote:

> >>> -# @device: device name
> >>> +# @device: device name, or node name if not present
> >>
> >> I think just adding a @node-name field and keeping @device as it
> >> is should be good enough here.
> > 
> > I was doing the same that we discussed for BlockJobInfo here, where
> > option b) seemed to have a bit more support:
> > 
> > https://lists.gnu.org/archive/html/qemu-devel/2015-03/msg03651.html
> > 
> > But yeah I personally don't mind extending the event with a new field.
> > Would we make 'device' optional in this case?
> 
> How hard is it to output both 'device' and 'node' in the same event,
> if both are available?

It's a trivial change, there's no problem at all. I assume that, for
compatibility reasons, 'device' would continue to be present even if
it's empty, but would you prefer to have 'node-name' as an optional
field?

> And for this particular event, which is not tied to block jobs but
> to generic block operation, isn't it possible that we could be
> reporting a corrupted backing chain where we have neither a device
> name (it is not the active layer) nor a node name (if we don't add
> Jeff's patch to auto-name all nodes)?  In such a case, I don't know
> that we can do much better anyways.

Yes, it is perfectly possible. I guess any software that wants to
handle those scenarios probably wants to give names to all nodes.

From the QEMU side, apart from giving automatic names to all nodes I
don't see any other solution.

Berto