linux-kernel - Re: [PATCH] NFSD: fix deny mode logic in nfs4_upgrade

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Message-ID: <CE064BB1-510B-4268-A92E-8DAC680AAA22@oracle.com>
Date:   Fri, 3 Feb 2023 14:50:53 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Jeff Layton <jlayton@...nel.org>
CC:     Dai Ngo <dai.ngo@...cle.com>, Pumpkin <cc85nod@...il.com>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] NFSD: fix deny mode logic in nfs4_upgrade_open



> On Feb 2, 2023, at 4:22 PM, Jeff Layton <jlayton@...nel.org> wrote:
> 
> On Thu, 2023-02-02 at 19:41 +0000, Chuck Lever III wrote:
>> 
>>> On Feb 2, 2023, at 2:36 AM, Pumpkin <cc85nod@...il.com> wrote:
>>> 
>>> If the upgrading deny mode is invalid or conflicts with other client, we
>>> should try to resolve it, but the if-condition makes those error handling
>>> cannot be executed.
>>> 
>>> Signed-off-by: Pumpkin <cc85nod@...il.com>
>>> ---
>>> fs/nfsd/nfs4state.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>> index 4ef529379..ebdfaf0f9 100644
>>> --- a/fs/nfsd/nfs4state.c
>>> +++ b/fs/nfsd/nfs4state.c
>>> @@ -5298,7 +5298,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp,
>>> 	/* test and set deny mode */
>>> 	spin_lock(&fp->fi_lock);
>>> 	status = nfs4_file_check_deny(fp, open->op_share_deny);
>>> -	if (status == nfs_ok) {
>>> +	if (status != nfs_ok) {
>>> 		if (status != nfserr_share_denied) {
>> 
>> if status == nfs_ok then status will definitely not equal
>> share_denied. So this check is a bit nonsensical as it stands.
>> 
>> Usually I prefer "switch (status)" in situations like this
>> because that avoids this kind of issue and I find it easier
>> to read quickly.
>> 
>> Jeff, you are the original author of this function, and
>> Dai, your commit is the last one to touch this area. Can
>> you guys have a look? The one-liner looks correct, but I
>> might be missing something.
>> 
> 
> Yeah, that code is clearly broken and it looks like it was done in
> 3d69427151806 (NFSD: add support for share reservation conflict to
> courteous server).
> 
> I don't believe that one-liner is correct though. If the result is
> nfs_ok, then we want to set the deny mode here and that won't happen.
> 
> Something like this maybe? (completely untested):
> 
> ---------------8<-------------------
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index c39e43742dd6..af22dfdc6fcc 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5282,16 +5282,17 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp,
>        /* test and set deny mode */
>        spin_lock(&fp->fi_lock);
>        status = nfs4_file_check_deny(fp, open->op_share_deny);
> -       if (status == nfs_ok) {
> -               if (status != nfserr_share_denied) {
> -                       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;
> -               }
> +       switch (status) {
> +       case nfs_ok:
> +               set_deny(open->op_share_deny, stp);
> +               fp->fi_share_deny |=
> +                       (open->op_share_deny & NFS4_SHARE_DENY_BOTH);
> +               break;
> +       case nfserr_share_denied:
> +               if (nfs4_resolve_deny_conflicts_locked(fp, false,
> +                               stp, open->op_share_deny, false))
> +                       status = nfserr_jukebox;
> +               break;
>        }
>        spin_unlock(&fp->fi_lock);

Would pynfs have a case or two that could test this?

Can you post an official version of this patch with Reported-by
and Fixes tags?


--
Chuck Lever