From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Steve French" Subject: Re: Support for applications which need NFS or CIFS "share_deny" flags on open Date: Tue, 2 Dec 2008 15:26:26 -0600 Message-ID: <524f69650812021326w26ccceb3qb8d93283aca84558@mail.gmail.com> References: <524f69650812020831q4e089b87k9a8306ac37f4234a@mail.gmail.com> <20081202193819.GJ3186@webber.adilger.int> <20081202200621.GA4451@shareable.org> <524f69650812021220n2b7611b9x2eb3b0b6c7ece849@mail.gmail.com> <4935A692.3050300@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Jamie Lokier" , "Andreas Dilger" , linux-fsdevel , LKML , "linux-cifs-client@lists.samba.org" To: "jim owens" Return-path: Received: from ey-out-2122.google.com ([74.125.78.27]:51211 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751064AbYLBV02 (ORCPT ); Tue, 2 Dec 2008 16:26:28 -0500 Received: by ey-out-2122.google.com with SMTP id 6so1375265eyi.37 for ; Tue, 02 Dec 2008 13:26:26 -0800 (PST) In-Reply-To: <4935A692.3050300@hp.com> Content-Disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Dec 2, 2008 at 3:20 PM, jim owens wrote: > Steve French wrote: >> >> On Tue, Dec 2, 2008 at 2:06 PM, Jamie Lokier wrote: >>> >>> The bit I find interesting is that other CIFS clients are said to >>> implement these flags. If that means real unixes, maybe they've >>> worked out a sensible way to handle them? >> >> I thought that MacOS uses these flags (not just Windows, and of course >> older clients too OS/2, DOS etc.). > > The title of their proposal was "client"... as in not the local > filesystem, but the impression of what wine really wanted is > for local linux filesystems to implement these non-posix behaviors > so "wine apps can run just like on windows" on the local machine. > > Thus the strong objection from everyone doing local filesystems. > > Passing exclusive DENYREAD DENYWRITE DENYDELETE network > protocol flags from a linux client to a remote server > is an entirely different and IMO acceptible thing. > > And AFAIK on unix the only local support would be by doing > a client-on-server loopback, where the server implements > these modes as best it can and you are only protected > against wine apps that are also inside the "share drive". Yes, I think that this is more important for network file systems not local file systems (especially since NFSv4 and CIFS and SMB2 all support these flags in the protocol definition). Since wine (or any subsystem running on a single local linux system) can handle its own locks between application instances, the main problem is that byte range locks can't perfectly emulate the application semantics needed when applications are running on two different "clients" (in this case, one Wine/Linux, and one a Windows client) but mounted to the same server -- Thanks, Steve