Merge tag 'ceph-for-4.12-rc4' of git://github.com/ceph/ceph-client

Pull ceph fix from Ilya Dryomov:
 "A small fix for rbd FALLOC_FL_ZERO_RANGE/PUNCH_HOLE handling breakage
  introduced in -rc1"

* tag 'ceph-for-4.12-rc4' of git://github.com/ceph/ceph-client:
  rbd: implement REQ_OP_WRITE_ZEROES