Adding a mount after container is running?

[Michael Tokarev <mjt-XAri/EZa3C4vJsYlp49lxw@public.gmane.org>]

Hello.

What is the way to add a new filesystem mount to
an already running container?  I want to "propagate"
a newly created filesystem, or another part of host
filesystem, to a container without restarting it.

I can imagine a way to "propagate" a new filesystem -
by (maybe temporarily) granting access for the
block device in question to the container and
doing a real mount from there.  I'm not sure if
it's equivalent to a bind-mount in terms of
resulting behavour (I sent this question to
lkml a few mins ago), but at least this is
easily doable.

But if I want to add a part of existing filesystem
tree to my container, things becomes somewhat less
clean.  Still doable in a similar way - by mounting
it in container in a temp place, bind-mounting a
needed part to the right place, and umounting the
temp one.  But it's not clean ;)

Is there a better way?

Thanks!

/mjt