clean up is partition checks

[Christoph Hellwig]

Hi Jens,

this series add a new helepr to check if a struct block_device represents
a parition, and removes most direct access to ->bd_contained from
drivers.

Diffstat:
 Documentation/userspace-api/ioctl/hdio.rst |   24 ++++++++++++------------
 block/blk-lib.c                            |    2 +-
 block/genhd.c                              |    2 +-
 block/ioctl.c                              |    4 ++--
 block/scsi_ioctl.c                         |    2 +-
 drivers/block/drbd/drbd_main.c             |    2 --
 drivers/block/drbd/drbd_receiver.c         |    2 +-
 drivers/block/drbd/drbd_worker.c           |    2 +-
 drivers/ide/ide-ioctls.c                   |    4 ++--
 drivers/md/dm-table.c                      |    2 +-
 drivers/md/md.c                            |    9 ++++-----
 drivers/md/md.h                            |    2 +-
 drivers/mmc/core/block.c                   |    2 +-
 drivers/s390/block/dasd_ioctl.c            |    8 ++++----
 drivers/target/target_core_iblock.c        |    5 ++---
 fs/nfsd/blocklayout.c                      |    4 ++--
 include/linux/blkdev.h                     |    9 +++++++--
 kernel/trace/blktrace.c                    |    2 +-
 lib/vsprintf.c                             |    4 ++--
 19 files changed, 46 insertions(+), 45 deletions(-)