Merge remote-tracking branch 'remotes/jnsnow/tags/ide-pull-request' into staging

# gpg: Signature made Tue 17 Nov 2015 20:06:58 GMT using RSA key ID AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"

* remotes/jnsnow/tags/ide-pull-request:
  ide: enable buffered requests for PIO read requests
  ide: enable buffered requests for ATAPI devices
  ide: orphan all buffered requests on DMA cancel
  ide: add support for IDEBufferedRequest
  block: add blk_abort_aio_request
  ide/atapi: make PIO read requests async

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>