[libvirt] [PATCH] conf: reattach interface taps to correct bridge on restart

[Daniel P. Berrangé]

On Fri, Sep 20, 2019 at 10:06:35AM -0400, Laine Stump wrote:
> When the bridge re-attach handling was moved out of the network driver
> and into the hypervisor driver (commit b806a60e) as a part of the
> refactor to split the network driver into a separate daemon, the check
> was accidentally changed to only check for type='bridge'. The check for
> type in this case needs to check for type='network' as well.
> 
> (at the time we thought that type='network' and type='bridge' could be
> conflated for interface actual type, but this turned out to be too
> problematic to do).
> 
> Signed-off-by: Laine Stump <laine at redhat.com>

Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>

> (This fixes the reconnect of taps to their bridges, but the count
> maintained in the network object still isn't being updated in these
> cases. I've tried removing the !virUUIDIsValid() check in this same
> chunk, along with preserving the original port uuid if it's already
> valid in virDomainNetDefActualToNetworkPort(), and that results in
> fixing the usage count for type='network' when it's a libvirt-managed
> bridge or a macvtap passthrough pool, but leads to errors in other
> cases.)

IIUC, we need to do is use something like

   bool reclaim = false;
   if (!virUUIDIsValid(portid)) {
     reclaim = true;
   } else {
     port = virNetworkLookupPortByUUID(net, portid);
     if (port == NULL)
       reclaim = true;
     else
       virObjectUnref(port)
   }

   if (reclaim)
      virDomainNetCreatePort...

> 
> 
>  src/conf/domain_conf.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 848c831330..24223bceb2 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -30971,13 +30971,16 @@ virDomainNetNotifyActualDevice(virConnectPtr conn,
>                                 virDomainDefPtr dom,
>                                 virDomainNetDefPtr iface)
>  {
> +    virDomainNetType actualType = virDomainNetGetActualType(iface);
> +
>      if (!virUUIDIsValid(iface->data.network.portid)) {
>          if (virDomainNetCreatePort(conn, dom, iface,
>                                     VIR_NETWORK_PORT_CREATE_RECLAIM) < 0)
>              return;
>      }
>  
> -    if (virDomainNetGetActualType(iface) == VIR_DOMAIN_NET_TYPE_BRIDGE) {
> +    if (actualType == VIR_DOMAIN_NET_TYPE_NETWORK ||
> +        actualType == VIR_DOMAIN_NET_TYPE_BRIDGE) {
>          /*
>           * NB: we can't notify the guest of any MTU change anyway,
>           * so there is no point in trying to learn the actualMTU
> -- 
> 2.21.0
> 

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|