On Fri, Dec 16, 2022 at 04:06:21PM +0100, Andreas Gruenbacher wrote:
> +static void iomap_folio_done(struct iomap_iter *iter, loff_t pos, size_t ret,
> + struct folio *folio)
> +{
> + const struct iomap_page_ops *page_ops = iter->iomap.page_ops;
> +
> + if (folio)
> + folio_unlock(folio);
> + if (page_ops && page_ops->page_done)
> + page_ops->page_done(iter->inode, pos, ret, &folio->page);
> + if (folio)
> + folio_put(folio);
> +}
How is the folio derefence going to work if folio is NULL?
That being said, I really wonder if the current API is the right way to
go. Can't we just have a ->get_folio method with the same signature as
__filemap_get_folio, and then do the __filemap_get_folio from the file
system and avoid the page/folio == NULL clean path entirely? Then on
the done side move the unlock and put into the done method as well.
> if (!folio) {
> status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM;
> - goto out_no_page;
> + iomap_folio_done(iter, pos, 0, NULL);
> + return status;
> }
>
> /*
> @@ -656,13 +670,9 @@ static int iomap_write_begin(struct iomap_iter *iter,
> loff_t pos,
> return 0;
>
> out_unlock:
> - folio_unlock(folio);
> - folio_put(folio);
> + iomap_folio_done(iter, pos, 0, folio);
> iomap_write_failed(iter->inode, pos, len);
>
> -out_no_page:
> - if (page_ops && page_ops->page_done)
> - page_ops->page_done(iter->inode, pos, 0, NULL);
> return status;
But for the current version I don't really understand why the error
unwinding changes here.
