On Thu, 2010-12-30 at 04:05 -0600, Rob Landley wrote: 

On 12/30/2010 03:44 AM, Kirill A. Shutemov wrote:

quoted

quoted

quoted

If no rpcmount mountoption, no rpc_pipefs was found at
'/var/lib/nfs/rpc_pipefs' and we are in init's mount namespace, we use
init_rpc_pipefs.

It's the "we are in init's mount namespace" that I was wondering about.

So if I naievely chroot, nfs mount stops working the way it did before I
chrooted unless I do an extra setup step?

No. It will work as before since you are still in init's mount namespace.
Creating new mount namespace changes rules.

Ah, CLONE_NEWNS and then you need /var/lib/nfs/rpc_pipefs.  Got it.

I'm kind of surprised that the kernel cares about a specific path under 
/var/lib.  (Seems like policy in the kernel somehow.)  Can't it just 
check the current process's mount list to see if an instance of 
rpc_pipefs is mounted in the current namespace the way lxc looks for 
cgroups?  Or are there potential performance/scalability issues with that?

The kernel doesn't give a damn about the /var/lib/nfs/rpc_pipefs bit.
That's all for the benefit of the userland utilities.

  Trond

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org
www.netapp.com

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