CIFS: Add SMB2 support for cifs_iovec_write

Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsfs.c

@@ -89,6 +89,10 @@ extern mempool_t *cifs_mid_poolp;
 
 struct workqueue_struct	*cifsiod_wq;
 
+#ifdef CONFIG_HIGHMEM
+DEFINE_MUTEX(cifs_kmap_mutex);
+#endif
+
 static int
 cifs_read_super(struct super_block *sb)
 {