ceph: connect to export targets on cap export

When we get a cap EXPORT message, make sure we are connected to all export
targets to ensure we can handle the matching IMPORT.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 552b934..a546e0d 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -741,6 +741,14 @@
 	}
 }
 
+void ceph_mdsc_open_export_target_sessions(struct ceph_mds_client *mdsc,
+					   struct ceph_mds_session *session)
+{
+	mutex_lock(&mdsc->mutex);
+	__open_export_target_sessions(mdsc, session);
+	mutex_unlock(&mdsc->mutex);
+}
+
 /*
  * session caps
  */