Merge tag 'md/3.19-fixes' of git://neil.brown.name/md

Pull two fixes for md from Neil Brown:

 - Another live lock, needs backporting

 - work-around false positive with new warnings.

* tag 'md/3.19-fixes' of git://neil.brown.name/md:
  md/bitmap: fix a might_sleep() warning.
  md/raid5: fix another livelock caused by non-aligned writes.