[libvirt] [PATCH 3/6] Implement virDomainUpdateDeviceFlags API in all drivers with media change

[Daniel P. Berrange]

On Thu, Mar 25, 2010 at 11:47:33AM +0100, Daniel Veillard wrote:
> On Wed, Mar 24, 2010 at 11:46:24AM +0000, Daniel P. Berrange wrote:
> > To allow the new virDomainUpdateDeviceFlags() API to be universally
> > used with all drivers, this patch adds an impl to all the current
> > drivers which support CDROM or Floppy disk media change via the
> > current virDomainAttachDeviceFlags API
> > 
> > * src/qemu/qemu_driver.c, src/vbox/vbox_tmpl.c,
> >   src/xen/proxy_internal.c, src/xen/xen_driver.c,
> >   src/xen/xend_internal.c: Implement media change via the
> >   virDomainUpdateDeviceFlags API
> > * src/xen/xen_driver.h, src/xen/xen_hypervisor.c,
> >   src/xen/xen_inotify.c, src/xen/xm_internal.c,
> >   src/xen/xs_internal.c: Stubs for Xen driver entry points
> [...]
> > +static int qemuDomainUpdateDeviceFlags(virDomainPtr dom,
> > +                                       const char *xml,
> > +                                       unsigned int flags)
> > +{
> [...]
> > +        switch (dev->data.disk->device) {
> > +        case VIR_DOMAIN_DISK_DEVICE_CDROM:
> > +        case VIR_DOMAIN_DISK_DEVICE_FLOPPY:
> > +            ret = qemudDomainChangeEjectableMedia(driver, vm, dev->data.disk);
> > +            if (ret == 0)
> > +                dev->data.disk = NULL;
> > +            break;
> > +
> > +
> > +        default:
> > +            qemuReportError(VIR_ERR_NO_SUPPORT,
> > +                            _("disk bus '%s' cannot be updated."),
> > +                            virDomainDiskBusTypeToString(dev->data.disk->bus));
> > +            break;
> > +        }
> > +
> > +        if (ret != 0 && cgroup) {
> > +            virCgroupDenyDevicePath(cgroup,
> > +                                    dev->data.disk->src);
> > +        }
> 
>   Hum ... I got a bit lost there, qemudDomainChangeEjectableMedia only
> returns -1 on error or 0 on success. But failure to change may mean that
> the previous data is still being used, shouldn't we check that the
> old and new data.disk->src are different before denying access ?

Oh, interesting - this code was only ever about reverting the ACL on the
new media, upon failure. There is n code anywhere that rverts the ACL on
the old media - this is broken in the existing change media method too.
So I should fix both of them with another patch.

Daniel
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