On Mon, Apr 22, 2024 at 02:39:18PM +0000, John Garry wrote: > Borrowed from: > > https://lore.kernel.org/linux-fsdevel/20240213093713.1753368-2-kernel@xxxxxxxxxxxxxxxx/ > (credit given in due course) > > We will need to be able to only use a single folio order for buffered > atomic writes, so allow the mapping folio order min and max be set. > > We still have the restriction of not being able to support order-1 > folios - it will be required to lift this limit at some stage. This is already supported upstream for file-backed folios: commit: 8897277acfef7f70fdecc054073bea2542fc7a1b > index fc8eb9c94e9c..c22455fa28a1 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -363,9 +363,10 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) > #endif > > /* > - * mapping_set_folio_min_order() - Set the minimum folio order > + * mapping_set_folio_orders() - Set the minimum and max folio order In the new series (sorry forgot to CC you), I added a new helper called mapping_set_folio_order_range() which does something similar to avoid confusion based on willy's suggestion: https://lore.kernel.org/linux-xfs/20240425113746.335530-3-kernel@xxxxxxxxxxxxxxxx/ mapping_set_folio_min_order() also sets max folio order to be MAX_PAGECACHE_ORDER order anyway. So no need of explicitly calling it here? > /** > @@ -400,7 +406,7 @@ static inline void mapping_set_folio_min_order(struct address_space *mapping, > */ > static inline void mapping_set_large_folios(struct address_space *mapping) > { > - mapping_set_folio_min_order(mapping, 0); > + mapping_set_folio_orders(mapping, 0, MAX_PAGECACHE_ORDER); > } > > static inline unsigned int mapping_max_folio_order(struct address_space *mapping) > diff --git a/mm/filemap.c b/mm/filemap.c > index d81530b0aac0..d5effe50ddcb 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1898,9 +1898,15 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > no_page: > if (!folio && (fgp_flags & FGP_CREAT)) { > unsigned int min_order = mapping_min_folio_order(mapping); > - unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags)); > + unsigned int max_order = mapping_max_folio_order(mapping); > + unsigned int order = FGF_GET_ORDER(fgp_flags); > int err; > > + if (order > max_order) > + order = max_order; > + else if (order < min_order) > + order = max_order; order = min_order; ? -- Pankaj
