On Thu, Feb 29, 2024 at 01:08:09PM -0500, Tony Battersby wrote:
> Fix an incorrect number of pages being released for buffers that do not
> start at the beginning of a page.
Oh, I see what I did. Wouldn't a simpler fix be to just set "done" to
offset_in_page(fi.offset)?
> @@ -1152,7 +1152,7 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
>
> bio_for_each_folio_all(fi, bio) {
> struct page *page;
> - size_t done = 0;
> + size_t nr_pages;
>
> if (mark_dirty) {
> folio_lock(fi.folio);
> @@ -1160,10 +1160,11 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
> folio_unlock(fi.folio);
> }
> page = folio_page(fi.folio, fi.offset / PAGE_SIZE);
> + nr_pages = (fi.offset + fi.length - 1) / PAGE_SIZE -
> + fi.offset / PAGE_SIZE + 1;
> do {
> bio_release_page(bio, page++);
> - done += PAGE_SIZE;
> - } while (done < fi.length);
> + } while (--nr_pages != 0);
> }
> }
> EXPORT_SYMBOL_GPL(__bio_release_pages);
The long-term path here, I think, is to replace this bio_release_page()
with a bio_release_folio(folio, offset, length) which calls into
a new unpin_user_folio(folio, nr) which calls gup_put_folio().
