Re: [PATCH] fix page_count in ->iomap_migrate_page()

[Christoph Hellwig]

FYI, for iomap we got a patch to just increment the page count when
setting the private data, and it finally got merged into mainline after
a while.

Not that it totally makes sense to me, but it is what it is.  It would
just be nice if set_page_private took care of it and we had a
clear_page_private to undo it, making the whole scheme at lot more
obvious.