mm: add __folio_batch_release()

This performs the same role as __pagevec_release(), ie skipping the check
for batch length of 0.

Link: https://lkml.kernel.org/r/20230621164557.3510324-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/pagevec.h

@@ -127,9 +127,15 @@ static inline unsigned folio_batch_add(struct folio_batch *fbatch,
 	return fbatch_space(fbatch);
 }
 
+static inline void __folio_batch_release(struct folio_batch *fbatch)
+{
+	__pagevec_release((struct pagevec *)fbatch);
+}
+
 static inline void folio_batch_release(struct folio_batch *fbatch)
 {
-	pagevec_release((struct pagevec *)fbatch);
+	if (folio_batch_count(fbatch))
+		__folio_batch_release(fbatch);
 }
 
 void folio_batch_remove_exceptionals(struct folio_batch *fbatch);