make the blkcg and blkcg structures private

[Christoph Hellwig]

Hi all,

this series cleans up various lose end in the blk-cgroup code to make it
easier to follow in preparation of reworking the blkcg assignment for
bios.  The biggest change is that most of <linux/blk-cgroup.h> is now
taken private into block/.

Diffstat:
 block/Makefile                |    1 
 block/bfq-iosched.h           |    4 
 block/blk-cgroup-fc-appid.c   |   57 +++++++++
 block/blk-cgroup.c            |  154 ++++++++++++++++++++-----
 block/blk-cgroup.h            |  138 +++++++++++++++-------
 block/blk-throttle.c          |    2 
 drivers/block/loop.c          |   12 +
 drivers/nvme/host/fc.c        |   26 +---
 drivers/scsi/lpfc/lpfc_scsi.c |    4 
 include/linux/backing-dev.h   |    6 
 include/linux/blk-cgroup.h    |  258 ++----------------------------------------
 include/linux/blktrace_api.h  |   10 -
 include/linux/kthread.h       |    4 
 kernel/kthread.c              |    1 
 kernel/trace/blktrace.c       |   26 ++--
 mm/backing-dev.c              |   19 +--
 mm/readahead.c                |    1 
 mm/swapfile.c                 |    1 
 18 files changed, 343 insertions(+), 381 deletions(-)