Merge branch 'bcache-for-upstream' of http://evilpiepirate.org/git/linux-bcache into...

Kent writes:

Hey Jens, this is everything I've got ready for 3.10 - there's _still_
one more bug I'm trying to track down.

Andrew - I've got patches that rip out the pkey() and pbtree() macros,
but they're somewhat tied up with some other nontrivial refactorings so
I think I'm going to wait a bit on those.