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Date:   Thu, 23 Sep 2021 20:56:45 -0400
From:   Bruce Fields <bfields@fieldses.org>
To:     Jeremy Allison <jra@samba.org>
Cc:     dai.ngo@oracle.com,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        CIFS <linux-cifs@vger.kernel.org>
Subject: Re: Locking issue between NFSv4 and SMB client
Message-ID: <20210924005645.GA28137@fieldses.org>
References: <5b7be2c0-95a6-048c-581f-17e5e3750daa@oracle.com>
 <20210923215056.GH18334@fieldses.org>
 <90a8f89b-e8ac-2187-2926-d723ebbcb839@oracle.com>
 <YU0hAYLow+8n8siT@jeremy-acer>
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On Thu, Sep 23, 2021 at 05:51:13PM -0700, Jeremy Allison wrote:
> On Thu, Sep 23, 2021 at 03:39:52PM -0700, dai.ngo@oracle.com wrote:
> >
> >On 9/23/21 2:50 PM, Bruce Fields wrote:
> >>On Thu, Jul 15, 2021 at 04:45:22PM -0700, dai.ngo@oracle.com wrote:
> >>>Hi Bruce,
> >>Oops, sorry for neglecting this.
> >>
> >>>I'm doing some locking testing between NFSv4 and SMB client and
> >>>think there are some issues on the server that allows both clients
> >>>to lock the same file at the same time.
> >>It's not too surprising to me that getting consistent locks between the
> >>two would be hard.
> >>
> >>Did you get any review from a Samba expert?  I seem to recall it having
> >>a lot of options, and I wonder if it's configured correctly for this
> >>case.
> >
> >No, I have not heard from any Samba expert.
> >
> >>
> >>It sounds like Samba may be giving out oplocks without getting a lease
> >>from the kernel.
> >
> >I will have to circle back to this when we're done with the 1st
> >phase of courteous server.
> >
> >-Dai
> >
> >>
> >>--b.
> >>
> >>>Here is what I did:
> >>>
> >>>NOTE: lck is a simple program that use lockf(3) to lock a file from
> >>>offset 0 to the length specified by '-l'.
> 
> What does lockf map to in NFS ?
> 
> Samba only uses posix fcntl byte range locks (and only when
> told to map SMB locks onto underlying posix locks), we don't use
> lockf at all.

Yeah, it's the same thing, lockf just maps to fcntl locks.

You're probably thinking of flock.

--b.