Re: [libvirt] New QEMU daemon for persistent reservations

On Tue, Oct 03, 2017 at 06:53:56PM +0200, Paolo Bonzini wrote: > On 03/10/2017 18:39, Daniel P. Berrange wrote: >> On Tue, Oct 03, 2017 at 06:35:03PM +0200, Paolo Bonzini wrote: >>> And later on we might have other ways to implement persistent >>> reservations in QEMU. So while I'm not a big fan(*) of the >>> driver='helper' moniker, I don't think an attribute is enough. Maybe >>> driver='external'?... >> >> Yes, if there's a choice of ways to manage reservations, we could >> reflect that as 'reservations=passthrough|emulated' or something >> like that. >> >> I just don't think the concept of a helper program should be visible >> in the XML, as it is an impl detail that is totally QEMU specific and >> could conceivably change eg not even needed with unpriv_sgio, > > Not sure about that, the mpathpersist behavior is somewhat magic and I > am not really sure we should enable it by default, even with unpriv_sgio. > >> and if >> kernel were enhanced could be usable without needing a helper elsewhere >> too. > > It's an implementation detail for system mode, but not for user mode > (where ACLs on the socket are used to allow access to a privileged > operation). > > So: > > <reservations enable='yes'/> > > (uses helper from global configuration if not a libiscsi drive) vs. > > <reservations enable='yes'/> > <source ... /> > </pr> What do you mean by <source> here ? If that's the chardev source I would really prefer not to have that visible.

> > (for user mode) vs. > > <reservations enable='no'> > > (fails if libiscsi || CAP_SYS_RAWIO || unpriv_sgio)? Regards, Daniel