more partition handling cleanups v2

Christoph Hellwig
2020-04-14T07:29:08Z

Hi Jens,

this series cleans up more lose ends in the partitioning code. It also
removes a rather annoying use of ioctl_by_bdev in the s390 dasd driver.

Changes since v1:
- fix a brown paperbag typo in blkpg_do_ioctl
- fix a commit message typo