Merge remote-tracking branch 'kwolf/for-anthony' into staging

* kwolf/for-anthony:
  ATA: Allow WIN_SECURITY_FREEZE_LOCK as nop
  rbd: add discard support
  qcow2: fix the return value -ENOENT -> -EEXIST
  qcow2: Don't hold cache references across yield
  qcow2: Remove unused parameter in do_alloc_cluster_offset
  qemu-iotests: Many parallel allocating I/O requests
  docs: fix one issue in qcow2 specs
  block/qcow2: Add missing GCC_FMT_ATTR to function report_unsupported()
  qemu-iotests: ignore fragmentation information for qed