Patch: Implement FSCTL_LMR_REQUEST_RESILIENCY

[Jeremy Allison]

On Fri, Oct 10, 2014 at 12:07:14AM +0200, Stefan (metze) Metzmacher wrote:
> Am 09.10.2014 um 23:58 schrieb Michael Adam:
> > On 2014-10-09 at 14:45 -0700, Richard Sharpe wrote:
> >> On Wed, Oct 8, 2014 at 7:29 AM, Richard Sharpe
> >> <realrichardsharpe at gmail.com> wrote:
> >>> Hi folks,
> >>>
> >>> There are indications that HyperV requires the server to implement
> >>> FSCTL_LMR_REQUEST_RESILIENCY, so I have a proposed implementation of
> >>> it.
> >>>
> >>> Attached is a patch for both FSCTL_LMR_REQUEST_RESILIENCY and a small
> >>> torture test for it (doesn't do much as yet.)
> >>>
> >>> Eventually, we will also have to deal with the GUID-tagged blob that
> >>> is an Extra Info (Extra Create Parameter) that was in the CREATE
> >>> request that precedes the FSCTL as well, I imagine.
> >>
> >> While we are arguing about all the abstruse technical details, the
> >> people I did this work for have reported that this change, along with
> >> one other thing, seems to be enough to have HyperV create a Virtual
> >> Disk on a Samba server, start the VM and install Windows.
> >>
> >> I hope to be able to write up the steps involved soon.
> > 
> > That is great to hear!
> > 
> > But these details are not so abstruse at all I'd say,
> > but essential to our implementation of these features.
> > After all, if we offer the possiblity to run vm images
> > off a samba server, we have to make it vaguely safe I think.
> 
> We already have a "fake oplocks" option, we could also have a "fake
> resilient handles" option...

Perfect :-). Of course we should deprecate it as soon
as the real underlying code is working :-).