Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Tue 07 Jun 2016 15:26:09 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/block-pull-request:
  throttle: refuse iops-size without iops-total/read/write
  block: Drop bdrv_ioctl_bh_cb
  block: Move BlockRequest type to io.c
  block/io: optimize bdrv_co_pwritev for small requests
  iostatus: fix comments for block_job_iostatus_reset
  block/io: Remove unused bdrv_aio_write_zeroes()
  virtio: drop duplicate virtio_queue_get_id() function
  virtio-scsi: Remove op blocker for dataplane
  virtio-blk: Remove op blocker for dataplane
  blockdev-backup: Don't move target AioContext if it's attached
  blockdev-backup: Use bdrv_lookup_bs on target
  tests: avoid coroutine pool test crash

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