CIFS: Separate protocol-specific code from cifs_readv_receive code

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 34a897e..a403398 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -341,6 +341,18 @@
 	return num > 0;
 }
 
+static inline size_t
+header_size(void)
+{
+	return sizeof(struct smb_hdr);
+}
+
+static inline size_t
+max_header_size(void)
+{
+	return MAX_CIFS_HDR_SIZE;
+}
+
 /*
  * Macros to allow the TCP_Server_Info->net field and related code to drop out
  * when CONFIG_NET_NS isn't set.