From mboxrd@z Thu Jan 1 00:00:00 1970 From: Trond Myklebust Subject: Re: [linux-cifs-client] Re: mount options for selectively disabling parts of CIFS Unix Extensions Date: Tue, 17 Jul 2007 14:49:29 -0400 Message-ID: <1184698169.19637.19.camel@heimdal.trondhjem.org> References: <524f69650707161540n4f4e785ai6c6039d3240456f9@mail.gmail.com> <524f69650707161611r4e29273cn751ffce503bd2d49@mail.gmail.com> <20070717075714.78af7b69.jlayton@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Steve French , linux-cifs-client@lists.samba.org, samba-technical@lists.samba.org, linux-fsdevel@vger.kernel.org To: Jeff Layton Return-path: Received: from pat.uio.no ([129.240.10.15]:59468 "EHLO pat.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754419AbXGQStj (ORCPT ); Tue, 17 Jul 2007 14:49:39 -0400 In-Reply-To: <20070717075714.78af7b69.jlayton@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, 2007-07-17 at 07:57 -0400, Jeff Layton wrote: > NFS has just gone through a not too dissimilar situation (mounting the > same export twice with different options). It now fails with -EBUSY in > that situation. A new mount option was also introduced (nosharedcache) > that makes it fall back on the previous behavior (not sharing > superblocks between mounts of the same export). Well... The NFS situation was different. NFS has always supported different mount options for different filesystems. What we were having issues with was that people were asking to mount the _same_ filesystem in different places with different mount options. In CIFS parlance, the equivalent would be to mount \\SERVER\SHAREA\foo and \\SERVER\SHAREA\bar with different mount options: I'm not sure that is really what Steve is proposing. Anyhow, the issue with that is you have to deal with potentially caching the same file on two different super blocks if, say foo/a and bar/b happen to be hard linked. We punted on dealing with the dragons hidden in that sort of issue by requiring that users mount with nosharedcache if and only if they know that this is safe. Cheers Trond