Device-mapper updates for 3.6: - Flip the thin target into new read-only or failed modes if errors are detected; - Handle chunk sizes that are not powers of two in the snapshot and thin targets; - Provide a way for userspace to avoid replacing an already-loaded multipath hardware handler while booting; - Reduce dm_thin_endio_hook slab size to avoid allocation failures; - Numerous small changes and cleanups to the code.