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Date: Mon, 23 Feb 2015 13:23:08 +0100
From: Alberto Garcia <berto@igalia.com>
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Subject: Re: [Qemu-devel] [PATCH 2/3] block: Add QMP support for streaming
 to an intermediate layer
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To: Eric Blake <eblake@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>

On Fri, Feb 20, 2015 at 03:38:04PM -0700, Eric Blake wrote:

> > +    if (has_top) {
> > +        top_bs = bdrv_find_backing_image(bs, top);
> > +        if (top_bs == NULL) {
> > +            error_set(errp, QERR_TOP_NOT_FOUND, top);
> > +            goto out;
> > +        }
> 
> If I understand correctly, bdrv_find_backing_image has problems for
> backing nodes that don't have a file name.  Given our shift towards
> node names, I think we really want to target node names rather than
> file names when specifying which node we will use as the top bound
> receiving the stream operations.

Sure I can change that, but note that the 'base' parameter also
receives a file name and uses bdrv_find_backing_image, so I guess it
makes sense to change it in both sides.

> > +#define QERR_TOP_NOT_FOUND \
> > +    ERROR_CLASS_GENERIC_ERROR, "Top '%s' not found"
> > +
> 
> Please don't.  Just use error_setg() at the right place with the
> direct message (existing QERR_ macros are a legacy holdover, and we
> shouldn't be creating more of them).

Ok, I'll fix that.

I'll wait for more comments regarding the top / base parameters before
resubmitting the patches.

Thanks,

Berto