nbd: allow seamless reconnects

THIS SHOULD NEVER GO UPSTREAM.

All in all this is ok, the only questionable thing is the abuse of the
server flags so we know the client cares about having things retried.
This patch will come back when the netlink interface is in place, so
basically the same just minus the special flag.

Signed-off-by: Josef Bacik <jbacik@fb.com>
2 files changed