Merge tag 'for-linus-20181012' of git://git.kernel.dk/linux-block

Jens writes:
  "block fix for 4.19-rc

   Just a single fix that should go in, fixing a regression introduced
   in the blk-wbt code."

* tag 'for-linus-20181012' of git://git.kernel.dk/linux-block:
  blk-wbt: wake up all when we scale up, not down