Merge remote-tracking branch 'remotes/famz/tags/for-upstream' into staging

# gpg: Signature made Fri 28 Oct 2016 15:47:39 BST
# gpg:                using RSA key 0xCA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021  AD56 CA35 624C 6A91 71C6

* remotes/famz/tags/for-upstream:
  aio: convert from RFifoLock to QemuRecMutex
  qemu-thread: introduce QemuRecMutex
  iothread: release AioContext around aio_poll
  block: only call aio_poll on the current thread's AioContext
  qemu-img: call aio_context_acquire/release around block job
  qemu-io: acquire AioContext
  block: prepare bdrv_reopen_multiple to release AioContext
  replication: pass BlockDriverState to reopen_backing_file
  iothread: detach all block devices before stopping them
  aio: introduce qemu_get_current_aio_context
  sheepdog: use BDRV_POLL_WHILE
  nfs: use BDRV_POLL_WHILE
  nfs: move nfs_set_events out of the while loops
  block: introduce BDRV_POLL_WHILE
  qed: Implement .bdrv_drain
  block: change drain to look only at one child at a time
  block: add BDS field to count in-flight requests
  mirror: use bdrv_drained_begin/bdrv_drained_end
  blockjob: introduce .drain callback for jobs
  replication: interrupt failover if the main device is closed

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

diff --cc tests/Makefile.include
Simple merge