linux-kernel - Re: [PATCH] NFSD: Fix the share reservation conflict to courteous server logic in nfs4_upgrade

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Message-ID: <FB543B1D-A3BF-4403-9BFD-CE3AA40A89B5@oracle.com>
Date:   Sun, 30 Oct 2022 15:26:27 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Dai Ngo <dai.ngo@...cle.com>
CC:     Jeff Layton <jlayton@...nel.org>,
        Bruce Fields <bfields@...ldses.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: [PATCH] NFSD: Fix the share reservation conflict to courteous
 server logic in nfs4_upgrade_open()



> On Oct 30, 2022, at 3:26 AM, Christophe JAILLET <christophe.jaillet@...adoo.fr> wrote:
> 
> 'status != nfserr_share_denied' is known to be true because we test
> 'status == nfs_ok' the line just above.
> 
> So nfs4_resolve_deny_conflicts_locked() can never be called.
> 
> Fix the logic and avoid the dead code.
> 
> Fixes: 3d6942715180 ("NFSD: add support for share reservation conflict to courteous server")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> This patch is speculative.
> It is compile tested only.
> 
> REVIEW WITH CARE.
> ---
> fs/nfsd/nfs4state.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 1ded89235111..de0565e9485c 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5260,15 +5260,13 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp,
> 	spin_lock(&fp->fi_lock);
> 	status = nfs4_file_check_deny(fp, open->op_share_deny);

I agree there's dead code here. I believe the bug is the first check is
supposed to be "if (status != nfs_ok)". I will let Dai have a look at
this to confirm.

But, in the fix, let's replace this logic with "switch (status) { }".


> 	if (status == nfs_ok) {
> -		if (status != nfserr_share_denied) {
> -			set_deny(open->op_share_deny, stp);
> -			fp->fi_share_deny |=
> +		set_deny(open->op_share_deny, stp);
> +		fp->fi_share_deny |=
> 				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
> -		} else {
> -			if (nfs4_resolve_deny_conflicts_locked(fp, false,
> -					stp, open->op_share_deny, false))
> -				status = nfserr_jukebox;
> -		}
> +	} else if (status == nfserr_share_denied) {
> +		if (nfs4_resolve_deny_conflicts_locked(fp, false, stp,
> +				open->op_share_deny, false))
> +			status = nfserr_jukebox;
> 	}
> 	spin_unlock(&fp->fi_lock);
> 
> -- 
> 2.34.1
> 

--
Chuck Lever