Merge tag 'dm-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper fixes from Alasdair G Kergon:
 "Fix reported data loss with discards and thin snapshots; avoid a
  deadlock observed in dm verity; fix a race in the new dm cache code
  along with some other minor bugs; store the cache policy version on
  disk to make the stored hints format future-proof."

* tag 'dm-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm cache: policy ignore hints if generated by different version
  dm cache: policy change version from string to integer set
  dm cache: fix race in writethrough implementation
  dm cache: metadata clear dirty bits on clean shutdown
  dm cache: avoid calling policy destructor twice on error
  dm cache: detect cache_create failure
  dm cache: avoid 64 bit division on 32 bit
  dm verity: avoid deadlock
  dm thin: fix non power of two discard granularity calc
  dm thin: fix discard corruption