New code for 5.5: - Make iomap_dio_rw callers explicitly tell us if they want us to wait - Port the xfs writeback code to iomap to complete the buffered io library functions - Refactor the unshare code to share common pieces - Add support for performing copy on write with buffered writes - Other minor fixes - Fix unchecked return in iomap_bmap - Fix a type casting bug in a ternary statement in iomap_dio_bio_actor