libceph: delay debugfs initialization until we learn global_id

The debugfs directory includes the cluster fsid and our unique global_id.
We need to delay the initialization of the debug entry until we have
learned both the fsid and our global_id from the monitor or else the
second client can't create its debugfs entry and will fail (and multiple
client instances aren't properly reflected in debugfs).

Reported by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
diff --git a/net/ceph/debugfs.c b/net/ceph/debugfs.c
index 54b531a..38b5dc1 100644
--- a/net/ceph/debugfs.c
+++ b/net/ceph/debugfs.c
@@ -189,6 +189,9 @@
 	snprintf(name, sizeof(name), "%pU.client%lld", &client->fsid,
 		 client->monc.auth->global_id);
 
+	dout("ceph_debugfs_client_init %p %s\n", client, name);
+
+	BUG_ON(client->debugfs_dir);
 	client->debugfs_dir = debugfs_create_dir(name, ceph_debugfs_dir);
 	if (!client->debugfs_dir)
 		goto out;
@@ -234,6 +237,7 @@
 
 void ceph_debugfs_client_cleanup(struct ceph_client *client)
 {
+	dout("ceph_debugfs_client_cleanup %p\n", client);
 	debugfs_remove(client->debugfs_osdmap);
 	debugfs_remove(client->debugfs_monmap);
 	debugfs_remove(client->osdc.debugfs_file);