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

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Message-ID: <184cf63f-d9c3-4948-aae0-efb23a49e188@oracle.com>
Date: Sat, 8 Feb 2025 11:57:37 -0500
From: Chuck Lever <chuck.lever@...cle.com>
To: Jeff Layton <jlayton@...nel.org>, 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 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? 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().

-- 
Chuck Lever