[dm-devel] make the blk-mq stacking interface optional

[Christoph Hellwig]

Hi Jens,

this series requires an explicit select to use the blk-mq stacking
interfaces.  This means they don't get build without dm support, and
thus the buildbot should catch abuses like the one we had in the ufs
driver more easily.  And while I touched this code I also ended up
cleaning up various loose ends.

Diffstat:
 block/Kconfig          |    3 +++
 block/blk-mq.c         |   45 +++++++++------------------------------------
 drivers/md/Kconfig     |    1 +
 drivers/md/dm-rq.c     |   26 +++++++++-----------------
 include/linux/blk-mq.h |    3 +--
 5 files changed, 23 insertions(+), 55 deletions(-)