linux-kernel - Re: [PATCH v5 6/7] nfsd: handle CB_SEQUENCE NFS4ERR_SEQ

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Message-ID: <28174296-129d-4459-aa23-a94bbf00d257@oracle.com>
Date: Sat, 8 Feb 2025 12:01:18 -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 6/7] nfsd: handle CB_SEQUENCE NFS4ERR_SEQ_MISORDERED
 error better

On 2/7/25 4:53 PM, Jeff Layton wrote:
> For NFS4ERR_SEQ_MISORDERED, do one attempt with a seqid of 1, and then
> fall back to treating it like a BADSLOT if that fails.
> 
> Signed-off-by: Jeff Layton <jlayton@...nel.org>
> ---
>  fs/nfsd/nfs4callback.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 10067a34db3afff8d4e4383854ab9abd9767c2d6..d6e3e8bb2efabadda9f922318880e12e1cb2c23f 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -1393,6 +1393,16 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
>  			goto requeue;
>  		rpc_delay(task, 2 * HZ);
>  		return false;
> +	case -NFS4ERR_SEQ_MISORDERED:
> +		/*
> +		 * Reattempt once with seq_nr 1. If that fails, treat this
> +		 * like BADSLOT.
> +		 */

Nit: this comment says exactly what the code says. If it were me, I'd
remove it. Is there a "why" statement that could be made here? Like,
why retry with a seq_nr of 1 instead of just failing immediately?


> +		if (session->se_cb_seq_nr[cb->cb_held_slot] != 1) {
> +			session->se_cb_seq_nr[cb->cb_held_slot] = 1;
> +			goto retry_nowait;
> +		}
> +		fallthrough;
>  	case -NFS4ERR_BADSLOT:
>  		/*
>  		 * BADSLOT means that the client and server are out of sync
> @@ -1403,12 +1413,6 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
>  		nfsd4_mark_cb_fault(cb->cb_clp);
>  		cb->cb_held_slot = -1;
>  		goto retry_nowait;
> -	case -NFS4ERR_SEQ_MISORDERED:
> -		if (session->se_cb_seq_nr[cb->cb_held_slot] != 1) {
> -			session->se_cb_seq_nr[cb->cb_held_slot] = 1;
> -			goto retry_nowait;
> -		}
> -		break;
>  	default:
>  		nfsd4_mark_cb_fault(cb->cb_clp);
>  	}
> 


-- 
Chuck Lever