Pull device mapper fixes from Mike Snitzer:

 - Fix dm core to use more efficient bio_split() instead of
   bio_clone_bioset(). Also fixes splitting bio that has integrity
   payload.

 - Three fixes related to properly validating DAX capabilities of a
   stacked DM device that will advertise DAX support.

 - Update DM writecache target to use 2-factor allocator arguments. Kees
   says this is the last related change for 4.18.

 - Fix DM zoned target to use GFP_NOIO to avoid triggering reclaim
   during IO submission (caught by lockdep).

 - Fix DM thinp to gracefully recover from running out of data space
   while a previous async discard completes (whereby freeing space).

 - Fix DM thinp's metadata transaction commit to avoid needless work.

* tag 'for-4.18/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm: prevent DAX mounts if not supported
  dax: check for QUEUE_FLAG_DAX in bdev_dax_supported()
  pmem: only set QUEUE_FLAG_DAX for fsdax mode
  dm thin: handle running out of data space vs concurrent discard
  dm raid: don't use 'const' in function return
  dm zoned: avoid triggering reclaim from inside dmz_map()
  dm writecache: use 2-factor allocator arguments
  dm thin metadata: remove needless work from __commit_transaction
  dm: use bio_split() when splitting out the already processed bio