drive-by blk-cgroup cleanups

[Christoph Hellwig]

Hi all,

while looking into another "project" I ended up wading through the
blkcq code for research and found a bunch of lose ends.  So here is
a bunch of drive-by cleanups for the code.

Diffstat:
 block/bio.c                |  143 +----------------------------------
 block/blk-cgroup.c         |  182 +++++++++++++++++++++++++++++++++++++--------
 block/blk-core.c           |    7 +
 block/blk-throttle.c       |   10 +-
 block/blk.h                |    2 
 drivers/md/dm.c            |    5 -
 include/linux/bio.h        |    9 --
 include/linux/blk-cgroup.h |  101 ------------------------
 kernel/cgroup/rstat.c      |    1 
 mm/page_io.c               |   17 ++++
 10 files changed, 192 insertions(+), 285 deletions(-)