On Wed, Feb 01, 2017 at 01:28:14PM +0100, Jan Kara wrote:

OK, I'll do that. Another cleanup I was considering is to remove all other
embedded occurences of backing_dev_info and make the structure only
dynamically allocated. It would unify the handling of backing_dev_info and
allow us to make bdi_init(), bdi_destroy(), etc. static inside
mm/backing_dev.c. What do you think?

Yes, that would be great.  I have vague memories trying to do that
a long time ago, but I don't remember why it didn't go anywhere.