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Subject: Re: Locking issue between NFSv4 and SMB client
To:     Trond Myklebust <trondmy@hammerspace.com>,
        "bfields@fieldses.org" <bfields@fieldses.org>,
        "jra@samba.org" <jra@samba.org>,
        "dai.ngo@oracle.com" <dai.ngo@oracle.com>
Cc:     "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "linux-cifs@vger.kernel.org" <linux-cifs@vger.kernel.org>
References: <5b7be2c0-95a6-048c-581f-17e5e3750daa@oracle.com>
 <20210923215056.GH18334@fieldses.org>
 <48b3a41e2dbea7948b0df3fea002208a273409fd.camel@hammerspace.com>
From:   Ralph Boehme <slow@samba.org>
Message-ID: <f4b9eb02-73e6-f082-6657-87a007b99198@samba.org>
Date:   Fri, 24 Sep 2021 05:46:28 +0200
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From: Ralph Boehme <slow@samba.org>
To: Trond Myklebust <trondmy@hammerspace.com>,
 "bfields@fieldses.org" <bfields@fieldses.org>, "jra@samba.org"
 <jra@samba.org>, "dai.ngo@oracle.com" <dai.ngo@oracle.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
 "linux-cifs@vger.kernel.org" <linux-cifs@vger.kernel.org>
Message-ID: <f4b9eb02-73e6-f082-6657-87a007b99198@samba.org>
Subject: Re: Locking issue between NFSv4 and SMB client
References: <5b7be2c0-95a6-048c-581f-17e5e3750daa@oracle.com>
 <20210923215056.GH18334@fieldses.org>
 <48b3a41e2dbea7948b0df3fea002208a273409fd.camel@hammerspace.com>
In-Reply-To: <48b3a41e2dbea7948b0df3fea002208a273409fd.camel@hammerspace.com>

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Am 24.09.21 um 05:35 schrieb Trond Myklebust:
> Not if you set the "kernel oplocks" parameter in the smb.conf file. We
> just added support for this in the Linux 5.14 kernel NFSv4 client.
>=20
> Now that said, "kernel oplocks" will currently only support basic level=

> I oplocks, and cannot support level II or leases. According to the
> smb.conf manpage, this is due to some incompleteness in the current VFS=

> lease implementation.
>=20
> I'd love to get some more info from the Samba team about what is
> missing from the kernel lease implementation that prevents us from
> implementing these more advanced oplock/lease features. From the
> description in Microsoft's docs, I'm pretty sure that NFSv4 delegations=

> should be able to provide all the guarantees that are required.

leases can be shared among file handles. When someone requests a lease=20
he passes a cookie. Then when he opens the same file with the same=20
cookie the lease is not broken.

Maybe others can comment on the level II oplock problem. Afaik this was=20
more a lack of testing.

-slow

--=20
Ralph Boehme, Samba Team                 https://samba.org/
SerNet Samba Team Lead      https://sernet.de/en/team-samba


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