linux-kernel - Re: [PATCH v5 2/7] nfsd: always release slot when requeueing callback

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Message-ID: <223fe6cde92d9b47d12fa47e48f0bc6b8960c1f0.camel@kernel.org>
Date: Sat, 08 Feb 2025 12:55:59 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>, Olga
 Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, Tom
 Talpey <tom@...pey.com>, "J. Bruce Fields" <bfields@...ldses.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/7] nfsd: always release slot when requeueing
 callback

On Sat, 2025-02-08 at 11:57 -0500, Chuck Lever wrote:
> On 2/7/25 4:53 PM, Jeff Layton wrote:
> > If the callback is going to be requeued to the workqueue, then release
> > the slot. The callback client and session could change and the slot may
> > no longer be valid after that point.
> > 
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> > ---
> >  fs/nfsd/nfs4callback.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> > index 79abc981e6416a88d9a81497e03e12faa3ce6d0e..bb5356e8713a8840bb714859618ff88130825efd 100644
> > --- a/fs/nfsd/nfs4callback.c
> > +++ b/fs/nfsd/nfs4callback.c
> > @@ -1411,6 +1411,7 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
> >  	rpc_restart_call_prepare(task);
> >  	goto out;
> >  requeue:
> > +	nfsd41_cb_release_slot(cb);
> >  	if (!test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags)) {
> >  		trace_nfsd_cb_restart(clp, cb);
> >  		task->tk_status = 0;
> > 
> 
> The NFSv4.0 case also goes to the requeue label. Is
> nfsd41_cb_release_slot() a no-op for NFSv4.0?
> 

Yes.

> Even if it is, this is a
> little confusing. Later, in 7/7, the nfsd41_cb_release_slot() call is
> carried into the helper that is called by both NFSv4.0 and NFSv4.1, and
> that doesn't seem necessary.
> 
> Perhaps this change should be done /after/ the NFSv4.0 error flow is
> hoisted into nfsd4_cb_done().
> 

Fair point. I'll move the v4.0 rework ahead of this patch and only call
nfsd41_cb_release_slot for v4.1+. I'll also fix the changelog of #3
like you suggested.
-- 
Jeff Layton <jlayton@...nel.org>