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Subject: Re: [PATCH RFC] NFSD: Fix possible sleep during
 nfsd4_release_lockowner()
From:   Jeff Layton <jlayton@kernel.org>
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Date:   Mon, 23 May 2022 15:43:28 -0400
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On Mon, 2022-05-23 at 19:35 +0000, Chuck Lever III wrote:
>=20
> > On May 23, 2022, at 1:38 PM, Jeff Layton <jlayton@kernel.org> wrote:
> >=20
> > On Mon, 2022-05-23 at 17:25 +0000, Chuck Lever III wrote:
> > >=20
> > > > On May 23, 2022, at 12:37 PM, Jeff Layton <jlayton@kernel.org> wrot=
e:
> > > >=20
> > > > His suggestion was just to keep a counter in the lockowner of how m=
any
> > > > locks are associated with it. That seems like a good suggestion, th=
ough
> > > > you'd probably need to add a parameter to lm_get_owner to indicate
> > > > whether you were adding a new lock or just doing a conflock copy.
> > >=20
> > > locks_copy_conflock() would need to take a boolean parameter
> > > that callers would set when they actually manipulate a lock.
> > >=20
> >=20
> > Yep. You'd also have to add a bool arg to lm_put_owner so that you know
> > whether you need to decrement the counter.
>=20
> It's the lm_put_owner() side that looks less than straightforward.
> Suggestions and advice welcome there.
>=20

Maybe add a new fl_flags value that indicates that a particular lock is
a conflock and not a lock record? Then locks_release_private could use
that to pass the appropriate argument to lm_put_owner.

That's probably simpler overall than trying to audit all of the
locks_free_lock callers.
--=20
Jeff Layton <jlayton@kernel.org>