ceph: close out mds, osd connections before stopping auth

The auth module (part of the mon_client) is needed to free any
ceph_authorizer(s) used by the mds and osd connections.  Flush the msgr
workqueue before stopping monc to ensure that the destroy_authorizer
auth op is available when those connections are closed out.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 9b46bb9..5cf6fba 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -669,9 +669,17 @@
 
 	/* unmount */
 	ceph_mdsc_stop(&client->mdsc);
-	ceph_monc_stop(&client->monc);
 	ceph_osdc_stop(&client->osdc);
 
+	/*
+	 * make sure mds and osd connections close out before destroying
+	 * the auth module, which is needed to free those connections'
+	 * ceph_authorizers.
+	 */
+	ceph_msgr_flush();
+
+	ceph_monc_stop(&client->monc);
+
 	ceph_adjust_min_caps(-client->min_caps);
 
 	ceph_debugfs_client_cleanup(client);