exfat: fix missing REQ_SYNC in exfat_update_bhs()

If 'dirsync' is enabled, all directory updates within the
filesystem should be done synchronously. exfat_update_bh()
does as this, but exfat_update_bhs() does not.

Reviewed-by: Andy.Wu <Andy.Wu@sony.com>
Reviewed-by: Aoyama, Wataru <wataru.aoyama@sony.com>
Reviewed-by: Kobayashi, Kento <Kento.A.Kobayashi@sony.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Yuezhang.Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
diff --git a/fs/exfat/misc.c b/fs/exfat/misc.c
index d34e619..d5bd8e6 100644
--- a/fs/exfat/misc.c
+++ b/fs/exfat/misc.c
@@ -10,6 +10,7 @@
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/buffer_head.h>
+#include <linux/blk_types.h>
 #include "exfat_raw.h"
 #include "exfat_fs.h"
@@ -180,7 +181,7 @@
 		if (sync)
-			write_dirty_buffer(bhs[i], 0);
+			write_dirty_buffer(bhs[i], REQ_SYNC);
 	for (i = 0; i < nr_bhs && sync; i++) {