3:55 p.m.
On Wed, 2019-03-06 at 13:07 -0800, Jeremy Allison wrote:
On Wed, Mar 06, 2019 at 03:31:08PM -0500, Jeff Layton wrote:
> On Wed, 2019-03-06 at 10:11 -0500, J. Bruce Fields wrote:
> > On Tue, Mar 05, 2019 at 04:47:48PM -0500, J. Bruce Fields wrote:
> > > On Thu, Feb 14, 2019 at 04:06:52PM -0500, J. Bruce Fields wrote:
> > > > After this:
> > > >
> > > > https://marc.info/?l=linux-nfs&m=154966239918297&w=2
> > > >
> > > > delegations would no longer conflict with opens from the same tgid.
So
> > > > if your threads all run in the same process and you're willing to
manage
> > > > conflicts among your own clients, that should still allow you to do
> > > > multiple opens of the same file without giving up your
lease/delegation.
> > > >
> > > > I'd be curious to know whether that works with Samba's
design.
> > >
> > > Any idea whether that would work?
> > >
> > > (Easy? Impossible? Possible, but realistically the changes required to
> > > Samba would be painful enough that it'd be unlikely to get done?)
> >
> > Volker reminds me off-list that he'd like to see Ganesha and Samba work
> > out an API in userspace first before commiting to a user<->kernel API.
> >
> > Jeff, wasn't there some work (on Ceph maybe?) on a userspace delegation
> > API? Is that close to what's needed?
> >
>
> Here's the C headers for that stuff:
>
>
https://github.com/ceph/ceph/blob/7ba6bece4187eda5d05a9b84211fe6ba8dd287b...
>
> It's simple enough and works for us in ganesha, and I think we can
> probably adapt it to samba without too much difficulty. The callback
> doesn't seem like it'll do for a kernel API though -- you'd almost
> certainly need to do something different there (signals? inotify?).
SMB3 leases have R/RW and Handle-based leases.
Handle leases allow multiple opens of the same pathname
that get different handles to share the lease, allowing
a client redirector to delay opens or closes locally
so long as it has a handle lease.
Here are the semantics:
https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/d8df...
I'm not sure a simple file-descriptor based API is
enough for us. Can he have a uuid or token based
API instead where the server can chose what fd's
to cover with a token ?
The libcephfs API takes an opaque void * that could hold such a token.
It gets passed back to the callback function when it's called to handle
a delegation break.
I could envision a delegation storing something similar (maybe an
unsigned long or uint64_t) and pass it back in a delegation break. With
that you could set multiple delegations on a fd, and use that to store a
key for each one.
Would something like that work for samba, or am I misunderstanding what
it needs?
--
Jeff Layton <jlayton(a)kernel.org>