Nfsroot .zfs/snapshot mounted on different mount?

[Freddie Cash]

On Tue, Jul 31, 2018 at 2:25 PM John <jwd at freebsd.org> wrote:

> Hi Folks,
>
>    I ran into something today I didn't expect and was wondering
> how it is accomplished - or something is going on in the NFS
> code I've never seen.
>
>    I have some remote nfs booted systems where the OS lives
> on ZFS volumes (the client is linux):.
>
> 10.121.56.21:/vol/nfsbt_sysgpu01   100G  4.7G   96G   5% /
>
>    After installing the latest gpu drivers I was asked to
> compare a few things and went into the /.zfs/snapshot directory
> as typical. However, I then noticed a 2nd nfs mount had
> appeared:
>
> 10.121.56.21:/vol/nfsbt_sysgpu01/.zfs/snapshot/rb_20180727-185554_drivers
> 100G  4.7G   96G   5% /.zfs/snapshot/rb_20180727-185554_drivers
>
>    To my knowledge, I have no auto-mounter that could have done
> the mount. I'm curious where this is hooked in.
>
>    The server is:
>
> FreeBSD 11.1-STABLE #11 r327104: Sat Dec 23 08:19:22 EST 2017
>
>    with standard nfsv3 exports. Other than this curiousness
> the system is flawless.
>

Not sure about the NFS side of things, but the FreeBSD kernel has
auto-mounted the .zfs/snapshot/<snapname> filesystem upon access from the
first ZFS import into FreeBSD 7.

Depending on how the NFS mount is setup, this may be carrying-over from the
kernel auto-mount.

-- 
Freddie Cash
fjwcash at gmail.com