Re: [RFC 02/23] pagemap: use mapping_min_order in fgf_set_order()

[Matthew Wilcox]

On Fri, Sep 15, 2023 at 08:38:27PM +0200, Pankaj Raghav wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
> 
> fgf_set_order() encodes optimal order in fgp flags. Set it to at least
> mapping_min_order from the page cache. Default to the old behaviour if
> min_order is not set.

Why not simply:

+++ b/mm/filemap.c
@@ -1906,9 +1906,12 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
                folio_wait_stable(folio);
 no_page:
        if (!folio && (fgp_flags & FGP_CREAT)) {
-               unsigned order = FGF_GET_ORDER(fgp_flags);
+               unsigned order;
                int err;

+               order = min(mapping_min_folio_order(mapping),
+                               FGF_GET_ORDER(fgp_flags));