On Mon, May 23, 2022 at 05:15:55PM -0400, Jeff Layton wrote:
> On Mon, 2022-05-23 at 16:29 -0400, J. Bruce Fields wrote:
> > On Mon, May 23, 2022 at 03:36:27PM -0400, Jeff Layton wrote:
> > > The other lockowner _is_ involved. It's the one holding the conflicting
> > > lock. nfs4_set_lock_denied copies info from the conflicting lockowner
> > > into the LOCK/LOCKT response. That's safe now because it holds a
> > > reference to the owner. At one point it wasn't (see commit aef9583b234a4
> > > "NFSD: Get reference of lockowner when coping file_lock", which fixed
> > > that).
> >
> > I doubt that commit fixed the whole problem, for what it's worth. What
> > if the client holding the conflicting lock expires before we get to
> > nfs4_set_lock_denied?
> >
>
> Good point -- stateowners can't hold a client reference.
>
> clientid_t is 64 bits, so one thing we could do is just keep a copy of
> that in the lockowner. That way we wouldn't need to dereference
> so_client in nfs4_set_lock_denied.
>
> Maybe there are better ways to fix it though.
I kinda feel like lock and testlock should both take a
struct conflock {
void *data
void (*copier)(struct file_lock, struct conflock)
}
and the caller should provide a "copier" that they can use to extract
the data they want while the flc_lock is held.
I'm probably overthinking it.
--b.
