Re: [PATCH RFC] nfs: remove nfs_show_devname

[Jeff Layton <jlayton@redhat.com>]

On Thu, 9 Jan 2014 14:06:54 -0500
Trond Myklebust <trond.myklebust@primarydata.com> wrote:

> 
> On Jan 9, 2014, at 13:59, Jeff Layton <jlayton@redhat.com> wrote:
> 
> > The nfs code will currently construct a devname to show in places like
> > /proc/mounts by turning a dentry into a path. Unfortunately, that's
> > somewhat problematic if the user ended up mounting through a symlink on
> > the server. The devname that then shows up in /proc/mounts now doesn't
> > match the one that was originally passed into the mount request.
> 
> This is 100% according to design. Why is it suddenly a problem?
> 
> By displaying the original pathname, you also end up bypassing referral resolution, etc. This is exactly why the .show_devname operation was introduced in the first place.
> 

AFAIU, the main issue is that when /etc/mtab is a symlink
to /proc/mounts, you can't do this in the example in the patch
description:

    # mount server:/export/bar /mnt/bar
    # umount server:/export/bar

...since umount will try to ID the mountpoint by looking up the devname
in /etc/mtab. What exactly would this break with referrals?

-- 
Jeff Layton <jlayton@redhat.com>