On Mon, Jun 19, 2017 at 10:02:09AM -0600, Jens Axboe wrote:

Actually, one good use case is O_DIRECT on a block device. Since I'm
not a huge fan of having per-call hints that is only useful for a
single case, how about we add the hints to the struct file as well?
For buffered IO, just grab it from the inode. If we have a file
available, then that overrides the per-inode setting.

Even for buffered I/O per-fіle would seem more useful to be honest.
For the buffer_head based file systems this could even be done fairly
easily.