On Sat, Mar 13, 2021 at 12:37:16PM -0800, Andrew Morton wrote:

On Fri,  5 Mar 2021 04:18:45 +0000 "Matthew Wilcox (Oracle)" [off-list ref] wrote:

quoted

folio_index() is the equivalent of page_index() for folios.  folio_page()
finds the page in a folio for a page cache index.  folio_contains()
tells you whether a folio contains a particular page cache index.

copy-paste changelog into each function's covering comment?

Yes, I think documenting all these helpers would be very useful.  The
lack of good commens on some of the page related existing helpers has
driven me insane sometimes.