From: Amir Goldstein <amir73il@gmail.com>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: "jlayton@kernel.org" <jlayton@kernel.org>,
"bfields@fieldses.org" <bfields@fieldses.org>,
"samba-technical@lists.samba.org"
<samba-technical@lists.samba.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"Volker.Lendecke@sernet.de" <Volker.Lendecke@sernet.de>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"pshilov@microsoft.com" <pshilov@microsoft.com>
Subject: Re: Better interop for NFS/SMB file share mode/reservation
Date: Sun, 28 Apr 2019 18:00:32 -0400 [thread overview]
Message-ID: <CAOQ4uxjUBRt99efZMY8EV6SAH+9eyf6t82uQuKWHQ56yjpjqMw@mail.gmail.com> (raw)
In-Reply-To: <1d5265510116ece75d6eb7af6314e6709e551c6e.camel@hammerspace.com>
On Sun, Apr 28, 2019 at 11:06 AM Trond Myklebust
<trondmy@hammerspace.com> wrote:
>
> On Sun, 2019-04-28 at 09:45 -0400, Amir Goldstein wrote:
> > On Sun, Apr 28, 2019 at 8:09 AM Jeff Layton <jlayton@kernel.org>
> > wrote:
> > > On Sat, 2019-04-27 at 16:16 -0400, Amir Goldstein wrote:
> > > > [adding back samba/nfs and fsdevel]
> > > >
> > >
> > > cc'ing Pavel too -- he did a bunch of work in this area a few years
> > > ago.
> > >
> > > > On Fri, Apr 26, 2019 at 6:22 PM Jeff Layton <jlayton@kernel.org>
> > > > wrote:
> > > > > On Fri, 2019-04-26 at 10:50 -0400, J. Bruce Fields wrote:
> > > > > > On Fri, Apr 26, 2019 at 04:11:00PM +0200, Amir Goldstein
> > > > > > wrote:
> > > > > > > On Fri, Apr 26, 2019, 4:00 PM J. Bruce Fields <
> > > > > > > bfields@fieldses.org> wrote:
> > > > > > >
> > > > > That said, we could also look at a vfs-level mount option that
> > > > > would
> > > > > make the kernel enforce these for any opener. That could also
> > > > > be useful,
> > > > > and shouldn't be too hard to implement. Maybe even make it a
> > > > > vfsmount-
> > > > > level option (like -o ro is).
> > > > >
> > > >
> > > > Yeh, I am humbly going to leave this struggle to someone else.
> > > > Not important enough IMO and completely independent effort to the
> > > > advisory atomic open&lock API.
> > >
> > > Having the kernel allow setting deny modes on any open call is a
> > > non-
> > > starter, for the reasons Bruce outlined earlier. This _must_ be
> > > restricted in some fashion or we'll be opening up a ginormous DoS
> > > mechanism.
> > >
> > > My proposal was to make this only be enforced by applications that
> > > explicitly opt-in by setting O_SH*/O_EX* flags. It wouldn't be too
> > > difficult to also allow them to be enforced on a per-fs basis via
> > > mount
> > > option or something. Maybe we could expand the meaning of '-o mand'
> > > ?
> > >
> > > How would you propose that we restrict this?
> > >
> >
> > Our communication channel is broken.
> > I did not intend to propose any implicit locking.
> > If samba and nfsd can opt-in with O_SHARE flags, I do not
> > understand why a mount option is helpful for the cause of
> > samba/nfsd interop.
> >
> > If someone else is interested in samba/local interop than
> > yes, a mount option like suggested by Pavel could be a good option,
> > but it is an orthogonal effort IMO.
>
> If an NFS client 'opts in' to set share deny, then that still makes it
> a non-optional lock for the other NFS clients, because all ordinary
> open() calls will be gated by the server whether or not their
> application specifies the O_SHARE flag. There is no flag in the NFS
> protocol that could tell the server to ignore deny modes.
>
> IOW: it would suffice for 1 client to use O_SHARE|O_DENY* to opt all
> the other clients in.
>
Sorry for being thick, I don't understand if we are in agreement or not.
My understanding is that the network file server implementations
(i.e. samba, knfds, Ganesha) will always use share/deny modes.
So for example nfs v3 opens will always use O_DENY_NONE
in order to have correct interop with samba and nfs v4.
If I am misunderstanding something, please enlighten me.
If there is a reason why mount option is needed for the sole purpose
of interop between network filesystem servers, please enlighten me.
Thanks,
Amir.
next prev parent reply other threads:[~2019-04-28 22:00 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 11:20 Better interop for NFS/SMB file share mode/reservation Amir Goldstein
2019-02-08 13:10 ` Jeff Layton
2019-02-08 14:45 ` Amir Goldstein
2019-02-08 15:50 ` J. Bruce Fields
2019-02-08 20:02 ` Amir Goldstein
2019-02-08 20:16 ` J. Bruce Fields
2019-02-08 20:31 ` Amir Goldstein
2019-02-14 20:51 ` J. Bruce Fields
2019-02-15 7:31 ` Amir Goldstein
2019-02-15 20:09 ` J. Bruce Fields
2019-02-08 22:12 ` Jeremy Allison
2019-02-09 4:04 ` Amir Goldstein
2019-02-14 21:06 ` J. Bruce Fields
2019-03-05 21:47 ` J. Bruce Fields
2019-03-06 7:09 ` Amir Goldstein
2019-03-06 15:17 ` J. Bruce Fields
2019-03-06 15:37 ` [NFS-Ganesha-Devel] " Frank Filz
2019-03-08 21:38 ` 'J. Bruce Fields'
2019-03-08 21:53 ` Frank Filz
2019-03-06 15:11 ` J. Bruce Fields
2019-03-06 20:31 ` Jeff Layton
2019-03-06 21:07 ` Jeremy Allison
2019-03-06 21:25 ` Ralph Böhme
2019-03-07 11:03 ` Stefan Metzmacher
2019-03-07 16:47 ` Simo
2019-04-25 18:11 ` Amir Goldstein
2019-05-24 7:12 ` Amir Goldstein
2019-05-24 13:15 ` Ralph Boehme
2019-05-24 15:07 ` J. Bruce Fields
2019-03-06 21:55 ` Jeff Layton
2019-02-08 16:03 ` Jeff Layton
2019-02-08 16:28 ` Jeffrey Layton
[not found] ` <CAOQ4uxgQsRaEOxz1aYzP1_1fzRpQbOm2-wuzG=ABAphPB=7Mxg@mail.gmail.com>
[not found] ` <20190426140023.GB25827@fieldses.org>
[not found] ` <CAOQ4uxhuxoEsoBbvenJ8eLGstPc4AH-msrxDC-tBFRhvDxRSNg@mail.gmail.com>
[not found] ` <20190426145006.GD25827@fieldses.org>
[not found] ` <e69d149c80187b84833fec369ad8a51247871f26.camel@kernel.org>
2019-04-27 20:16 ` Amir Goldstein
2019-04-28 12:09 ` Jeff Layton
2019-04-28 13:45 ` Amir Goldstein
2019-04-28 15:06 ` Trond Myklebust
2019-04-28 22:00 ` Amir Goldstein [this message]
2019-04-28 22:08 ` Trond Myklebust
2019-04-28 22:33 ` Amir Goldstein
2019-04-29 0:57 ` Trond Myklebust
2019-04-29 11:42 ` Amir Goldstein
2019-04-29 13:10 ` Trond Myklebust
2019-04-29 20:29 ` Jeff Layton
2019-04-29 22:33 ` Pavel Shilovskiy
2019-04-30 0:31 ` Amir Goldstein
2019-04-30 8:12 ` Uri Simchoni
2019-04-30 9:22 ` Amir Goldstein
2019-02-11 5:31 ` ronnie sahlberg
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