Merge tag 'dm-3.19-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:
 "Thre stable fixes and one fix for a regression introduced during 3.19
  merge:

   - Fix inability to discard used space when the thin-pool target is in
     out-of-data-space mode and also transition the thin-pool back to
     write mode once free space is made available.

   - Fix DM core bio-based end_io bug that prevented proper
     post-processing of the error code returned from the block layer.

   - Fix crash in DM thin-pool due to thin device being added to the
     pool's active_thins list before properly initializing the thin
     device's refcount"

* tag 'dm-3.19-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: fix missed error code if .end_io isn't implemented by target_type
  dm thin: fix crash by initializing thin device's refcount and completion earlier
  dm thin: fix missing out-of-data-space to write mode transition if blocks are released
  dm thin: fix inability to discard blocks when in out-of-data-space mode