[PATCH 22/35] conn-db: add simple connection registry

[Sagi Grimberg]

> From: Martin Wilck <mwilck at suse.com>
> 
> The monitor works best if it maintains a discovery controller connection
> to every transport address that provides a discovery subsystem.
> 
> While controllers are easily tracked in sysfs, addresses ("connections"),
> i.e. (transport, traddr, trsvid, host_traddr) tuples, are not. Create
> a simple registry that tracks the state of "connections" and their
> associated discovery controllers.
> 
> A detailed description of the API is provided in the header file conn-db.h.

If this is more flexible, perhaps also the main fabrics 
discover/connect/connect-all can be converted to use it as well.