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

* kwolf/for-anthony:
  dataplane: handle misaligned virtio-blk requests
  dataplane: extract virtio-blk read/write processing into do_rdwr_cmd()
  block: make qiov_is_aligned() public
  raw-posix: fix bdrv_aio_ioctl
  sheepdog: implement direct write semantics
  block: do not probe zero-sized disks

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>