Merge branch 'for-linus' of git://neil.brown.name/md

* 'for-linus' of git://neil.brown.name/md:
  md: protect against NULL reference when waiting to start a raid10.
  md: fix bug with re-adding of partially recovered device.
  md: fix possible deadlock in handling flush requests.
  md: move code in to submit_flushes.
  md: remove handling of flush_pending in md_submit_flush_data