Re: [libvirt] [PATCH] qemuDomainDiskChangeSupported: Forbid alias change
On 01/05/2018 01:15 AM, John Ferlan wrote:
On 12/13/2017 09:30 AM, Michal Privoznik wrote:
> Since we have user aliases it may happen that users want to
> change it using 'update-device'. Instead of ignoring it silently,
> error out loudly.
>
> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
> ---
> src/qemu/qemu_domain.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
So IIUC this would be adding a check that the libvirt supplied alias
matches, true? But your goal is to check if a "ua-" prefixed alias was
being used - so should the check use of the prefix?
I don't think this is limited to user provided aliases only. For
instance, libvirt generates the following aliases for disks: scsi0-0-0,
ide0-1-0, fdc0-0-0.
Now, what should happen if an user provides new disk XML trying to
change nothing but 'scsi0-0-0' to say 'scsi0-0-1' (for live domain)? I
think it should be forbidden - we don't have way to change IDs in qemu,
do we? We certainly lack implementation to support it.
Therefore, I think we don't have to limit the check just for 'ua-' prefixes.
There's probably a few more info. fields that could be considered - any
thoughts on those? Perhaps fairly difficult to keep up with the various
_virDomainDiskDef and friends alterations for what this function is
indicating...
Yeah, probably. I'm not sure. Maybe we will find some more.
Michal