On Fri, Nov 04, 2022 at 11:32:35AM +1100, Dave Chinner wrote: > At minimum, it needs to be documented, though I'd much prefer that > we explicitly duplicate write_cache_pages() as write_cache_folios() > with a callback that takes a folio and change the code to be fully > multi-page folio safe. Then filesystems that support folios (and > large folios) natively can be passed folios without going through > this crappy "folio->page, page->folio" dance because the writepage > APIs are unaware of multi-page folio constructs. There are a lot of places which go through the folio->page->folio dance, and this one wasn't even close to the top of my list. That said, it has a fairly small number of callers -- ext4, fuse, iomap, mpage, nfs, orangefs. So Vishal, this seems like a good project for you to take on next -- convert write_cache_pages() to write_cache_folios() and writepage_t to write_folio_t.
