Merge tag 'dm-3.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper fixes from Alasdair G Kergon:
 "Fix a couple of serious memory leaks in device-mapper thin
  provisioning and tidy its MODULE_DESCRIPTION.

  Mitigate occasional reported hangs associated with multipath scsi_dh
  module loading."

* tag 'dm-3.4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm mpath: check if scsi_dh module already loaded before trying to load
  dm thin: correct module description
  dm thin: fix unprotected use of prepared_discards list
  dm thin: reinstate missing mempool_free in cell_release_singleton