Re: [PATCH 2/2] Enable v4 mounts when either "nfsvers=4" or "vers=4" option are set (vers-02)

[Steve Dickson <SteveD@redhat.com>]

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.