[dm-devel] Another cache target

[Joe Thornber]

Here's a cache target that Heinz Mauelshagen, Mike Snitzer and I
have been working on.

It's also available in the thin-dev branch of my git tree:

git at github.com:jthornber/linux-2.6.git

The main features are a plug-in architecture for policies which decide
what data gets cached, and reuse of the metadata library from the thin
provisioning target.

These patches apply on top of the dm patches that agk has got queued
for 3.8.

If anyone has the time to try it out I'd love to hear how you get on.