Doing some fiddling around, I wrote a simple 9p server to answer
the Tversion message with an Rversion or Rerror. The thing is,
once the *version comm is done, I terminate the server. At this
point, the 9p driver seems not to clean up resulting in the modules
having an increasing number of references (shown by lsmod). Note:
I 'kill -9' the mount because I want to invoke it again, but differently.

Q. How long will the driver think that the server at the other
end is still alive after the socket has closed?

Q. How can I force the driver to clean up/release what it is
holding on to (even after a kill of the mount)?