Printk cleanup

From Linux NFS

The use of printk's and dprintk's in the rpc and nfsd code seems a little arbitrary in places. It would be worth grepping for them all, figuring out how they're currently used, thinking about what we need them for (to help administrators identify problems? to help testers provide debugging information to developers?), and how they might be abused (remote hosts and unprivileged local users shouldn't be able to spam the logs), developing some uniform policies, and submitting patches.

I'm not volunteering, but if someone's interested I think it could be really helpful, especially if it helps increase the usefulness of bug reports.