thn makes up for the extra 100 bytes of text added to the various

s/thn/

 	return read_cache_page(mapping, index, NULL, data);
 }
 
+static inline struct folio *read_mapping_folio(struct address_space *mapping,
+				pgoff_t index, void *data)
+{
+	return read_cache_folio(mapping, index, NULL, data);
+}

Is there much of a point in this wrapper?

+static struct page *do_read_cache_page(struct address_space *mapping,
+		pgoff_t index, filler_t *filler, void *data, gfp_t gfp)
+{
+	struct folio *folio = read_cache_folio(mapping, index, filler, data);
+	if (IS_ERR(folio))
+		return &folio->page;
+	return folio_file_page(folio, index);
+}

This drops the gfp on the floor.