mm/vmalloc: add a helper to optimize vmalloc allocation gfps

vm_area_alloc_pages() attempts to use different gfp flags as a way to
optimize allocations. This has been done inline which makes things harder
to read.

Add a helper function to make the code more readable.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vishal Moola (Oracle) <[e-mail]>
Reviewed-by: "Uladzislau Rezki (Sony)" <[e-mail]>
Acked-by: SeongJae Park <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

mm/vmalloc.c

···
 EXPORT_SYMBOL_GPL(vmap_pfn);
 #endif /* CONFIG_VMAP_PFN */
 
+/*
+ * Helper for vmalloc to adjust the gfp flags for certain allocations.
+ */
+static inline gfp_t vmalloc_gfp_adjust(gfp_t flags, const bool large)
+{
+	flags |= __GFP_NOWARN;
+	if (large)
+		flags &= ~__GFP_NOFAIL;
+	return flags;
+}
+
 static inline unsigned int
 vm_area_alloc_pages(gfp_t gfp, int nid,
 		unsigned int order, unsigned int nr_pages, struct page **pages)
···
 	 * Please note, the __vmalloc_node_range_noprof() falls-back
 	 * to order-0 pages if high-order attempt is unsuccessful.
 	 */
-	area->nr_pages = vm_area_alloc_pages((page_order ?
-		gfp_mask & ~__GFP_NOFAIL : gfp_mask) | __GFP_NOWARN,
-		node, page_order, nr_small_pages, area->pages);
+	area->nr_pages = vm_area_alloc_pages(
+			vmalloc_gfp_adjust(gfp_mask, page_order), node,
+			page_order, nr_small_pages, area->pages);
 
 	atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
 	/* All pages of vm should be charged to same memcg, so use first one. */