Merge remote-tracking branch 'mreitz/tags/pull-block-2018-06-18' into queue-block

Block patches:
- Active mirror (blockdev-mirror copy-mode=write-blocking)

# gpg: Signature made Mon Jun 18 17:08:19 2018 CEST
# gpg:                using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* mreitz/tags/pull-block-2018-06-18:
  iotests: Add test for active mirroring
  block/mirror: Add copy mode QAPI interface
  block/mirror: Add active mirroring
  job: Add job_progress_increase_remaining()
  block/mirror: Add MirrorBDSOpaque
  block/dirty-bitmap: Add bdrv_dirty_iter_next_area
  test-hbitmap: Add non-advancing iter_next tests
  hbitmap: Add @advance param to hbitmap_iter_next()
  block: Generalize should_update_child() rule
  block/mirror: Use source as a BdrvChild
  block/mirror: Wait for in-flight op conflicts
  block/mirror: Use CoQueue to wait on in-flight ops
  block/mirror: Convert to coroutines
  block/mirror: Pull out mirror_perform()

Signed-off-by: Kevin Wolf <kwolf@redhat.com>