[PATCH] Convert Samba to OFD locking.

[Jeremy Allison]

On Thu, May 19, 2016 at 07:25:45AM -0700, Richard Sharpe wrote:
> On Thu, May 19, 2016 at 1:44 AM, Stefan Metzmacher <metze at samba.org> wrote:
> > Am 19.05.2016 um 07:14 schrieb Uri Simchoni:
> >> On 05/19/2016 12:42 AM, Jeremy Allison wrote:
> >>> Hi Jeff, Steve and Simo,
> >>>
> >>> Here is the patchset we discussed to convert
> >>> smbd to open file description locking on
> >>> modern kernels. It also includes a regression
> >>> test to ensure we stay working even on systems
> >>> that don't have the required kernels :-).
> >>>
> >>> Now all we need is the fix you and I discussed
> >>> to the calls to CIFSSMBPosixLock() to convert
> >>> the lock context from current->tgid for process-associated
> >>> record locks to a handle-specific lock context
> >>> for open file description record locks.
> >>>
> >>> This will put us in really good shape for
> >>> doing the OFD-POSIX locks we need in the
> >>> SMB2+ UNIX extensions protocol changes.
> >>>
> >>> Please review and let me know !
> >>>
> >>> Cheers,
> >>>
> >>> Jeremy.
> >>>
> >> Seems like the wscript test is a compile-time test. Should be a test
> >> that runs code to verify the kernel actually supports it (or gets it
> >> from the answer file and fails if there's no answer). The fcntl_lock
> >> test just above it can be a good reference.
> >>
> >> Just my 2c, I have some learning curve to understand locking.
> >
> > I think we also need a runtime test similar to the robust mutex tests.
> >
> > It's not uncommon to run samba in an lxc container these days and there
> > it could
> > happen that the kernel is older or newer than the distribution within
> > the container.
> 
> I am not sure that I believe the bit about the kernel being older than
> the distro because glibc usually depends on (or uses) newer kernel
> features, doesn't it?

Yes. I don't think Metze's case is a realistic failure
scenario.