From: Steve Dickson Subject: Re: [PATCH 2/2] Enable v4 mounts when either "nfsvers=4" or "vers=4" option are set (vers-02) Date: Thu, 27 Aug 2009 10:14:42 -0400 Message-ID: <4A9694D2.2030205@RedHat.com> 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> <1251316764.5226.21.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Linux NFS Mailing list , Linux NFSv4 mailing list To: Trond Myklebust Return-path: In-Reply-To: <1251316764.5226.21.camel@heimdal.trondhjem.org> 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 08/26/2009 03:59 PM, Trond Myklebust wrote: > On Wed, 2009-08-26 at 15:50 -0400, Chuck Lever wrote: >> 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. > > Just look at what we're already doing for NFSv4. Inside nfs4_get_sb, we > basically do a kernel mount in order to get the real super block. We > then simply have to attach it to the vfsmount that the sys_mount() call > passed down to us. Well its not nfs4_get_sb() that would have to change its nfs_get_sb() that would have to do an nfs4 mount after it discovered the -o vers=4. It would get very messy very quickly for absolutely no reason since the propose mount patch is straightforward, it works and better yet its done! ;-) > > This really isn't anything new or difficult... Granted, mounting from the kernel is not new, but giving sys_mount() on file system type which ends up mounting a complete different file system is new... Plus architecturally that just seems wrong... A abit incestual... would you say! ;-) I say we go with the proposed patch since its simple, architecturally sound, will not cause problems down the road as long as nfs4 remains a standalone file system and its done! Plus I have a patch waiting in the wings that actually does make v4 the first mount that is tried... making v4 the default version... steved.