On Wed, Dec 22, 2021 at 11:00:40PM -0800, Christoph Hellwig wrote:

quoted

-int put_and_wait_on_page_locked(struct page *page, int state);
+int folio_put_wait_locked(struct folio *folio, int state);

This could actually move to mm/internal.h.

It doesn't have any callers outside mm/ for now (and actually a couple
of the callers are going away), but conceptually it's part of the
lock_page() family of functions.  Some other places might benefit from
waiting without the reference held.