Clean up some bio_vec abuses to prepare for saner handling of multipage bio_vecs.
- a few cleanups to prepare for multipage bio_vecs Christoph Hellwig
- [PATCH 1/3] block: simplify bio_check_pages_dirty Christoph Hellwig
- [PATCH 2/3] block: bio_set_pages_dirty can't see NU... Christoph Hellwig
- [PATCH 3/3] block: use bio_add_page in bio_iov_iter... Christoph Hellwig
