mm/vmscan: use helper folio_is_file_lru()

Use helper folio_is_file_lru() to check whether folio is file lru.  Minor
readability improvement.

[linmiaohe@huawei.com: use folio_is_file_lru()]
  Link: https://lkml.kernel.org/r/20220428105802.21389-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220425111232.23182-7-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan.c

@@ -1414,14 +1414,14 @@ static enum page_references folio_check_references(struct folio *folio,
 		/*
 		 * Activate file-backed executable folios after first usage.
 		 */
-		if ((vm_flags & VM_EXEC) && !folio_test_swapbacked(folio))
+		if ((vm_flags & VM_EXEC) && folio_is_file_lru(folio))
 			return PAGEREF_ACTIVATE;
 
 		return PAGEREF_KEEP;
 	}
 
 	/* Reclaim if clean, defer dirty folios to writeback */
-	if (referenced_folio && !folio_test_swapbacked(folio))
+	if (referenced_folio && folio_is_file_lru(folio))
 		return PAGEREF_RECLAIM_CLEAN;
 
 	return PAGEREF_RECLAIM;