ceph: handle SESSION_FORCE_RO message

mark session as readonly and wake up all cap waiters.

Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
index 69e2c9e..31eb03d 100644
--- a/include/linux/ceph/ceph_fs.h
+++ b/include/linux/ceph/ceph_fs.h
@@ -271,6 +271,7 @@
 	CEPH_SESSION_RECALL_STATE,
 	CEPH_SESSION_FLUSHMSG,
 	CEPH_SESSION_FLUSHMSG_ACK,
+	CEPH_SESSION_FORCE_RO,
 };
 
 extern const char *ceph_session_op_name(int op);