[libvirt] [RFC PATCH 02/30] qemu: domain: Format storage source node names into private data

[Kevin Wolf]

Am 19.04.2018 um 17:24 hat Peter Krempa geschrieben:
> Save and restore node names if we know them in the status XML so that we
> don't need to recalculate them or don't lose them in some cases.
> 
> Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> ---
>  src/qemu/qemu_domain.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index e2a8450e2e..224b3b0478 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -1934,6 +1934,9 @@ static int
>  qemuStorageSourcePrivateDataParse(xmlXPathContextPtr ctxt,
>                                    virStorageSourcePtr src)
>  {
> +    src->nodestorage = virXPathString("string(./nodename/@storage)", ctxt);
> +    src->nodeformat = virXPathString("string(./nodename/@format)", ctxt);
> +
>      if (virStorageSourcePrivateDataParseRelPath(ctxt, src) < 0)
>          return -1;

This format doesn't look very future-proof. I can see that using
x->nodestorage and x->nodeformat internally are probably easier for now,
but while the assumption of exactly two layers (except for backing
files) is probably correct for most cases, it will become less and less
common the more we use filter drivers.

Representing an arbitrary tree (or even non-tree graph) in the XML may
be unpractical now, but please be aware that you'll probably need this
change in the long run.

Kevin