From: Chuck Lever Subject: Re: [PATCH 2/2] Enable v4 mounts when either "nfsvers=4" or "vers=4" option are set (vers-02) Date: Wed, 26 Aug 2009 15:50:21 -0400 Message-ID: References: <4A9424DB.2040303@RedHat.com> <4A942593.8030101@RedHat.com> <4A943914.9020104@RedHat.com> <7AB7BC01-F9E5-4611-BB4B-2B6E27069631@oracle.com> <4A944645.1020003@RedHat.com> <1251233345.25372.67.camel@heimdal.trondhjem.org> <4A954FBF.3030606@RedHat.com> <23199F1A-EA23-4DE1-AAB8-92D4B508C865@oracle.com> <4A956BF2.6000902@RedHat.com> <4A95760C.9000604@RedHat.com> Mime-Version: 1.0 (Apple Message framework v936) Content-Type: text/plain; charset="us-ascii"; Format="flowed"; DelSp="yes" Cc: Linux NFS Mailing list , Linux NFSv4 mailing list To: Steve Dickson Return-path: In-Reply-To: <4A95760C.9000604@RedHat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfsv4-bounces@linux-nfs.org Errors-To: nfsv4-bounces@linux-nfs.org List-ID: On Aug 26, 2009, at 1:51 PM, Steve Dickson wrote: > On 08/26/2009 01:22 PM, Chuck Lever wrote: >>>> and if your proposed method to handle -t nfs -o vers=4 will make >>>> it more complicated to get there. >>> No. I'm proposing a simple shorthand patch that will make mounting >>> nfs4 >>> file systems easier in hope of moving the technology forward by >>> making >>> it more accessible... What I believe you are proposing is >>> architecture >>> change to hide the fact nfs and nfs4 are separate file systems... >> >> Nope, we're proposing doing the simple method in the kernel instead >> of >> in the mount command. >> > My apologize then... I was misinterpreting what you guys were > suggesting.. > (email sometimes causes that... :-\ ) > > I don't think the -o v4 translation will be as easy as a > "simple method in the kernel" and it surely will not be as simple > and unintrusive as the patch I'm proposing.... Here is why... > > From an Linux architecture standpoint the mount command *always* > know what file system its mounting. There not been a precedence set > where mount, mounts one file system which turns into mounting a > different file system. Meaning there is no kernel support for > nfs_get_sb() to all of sudden decide to roll back the system call > and jump into nfs4_get_sb() (or vice a versa depending on which is the > default). Yeah, switching file system types in the mount(2) system call is the fly in the ointment. I'm just wondering if Trond had some thoughts about making that more feasible. > Of course we could set that precedence and quit frank we would have > to. I'm not totally against that, although other in the kernel > community > might be... > > But there is no way that re-architecturing of kernel will as simple > and straightforward as following the Linux standard architecture of > having mount, mount the correct file system. -- Chuck Lever chuck[dot]lever[at]oracle[dot]com