dlm: init per node debugfs before add to node hash

Avoiding potential issues when a node is added to the hash but the
debugfs is not NULL or IS_ERR() so a potential iteration over the hash
and debugfs_remove() will not fail like in dlm_midcomms_exit().

However dlm_midcomms_exit() will be called in module init/exit function
and the hash should be empty anyway at those stages. We change the
behavior as cleanup to avoid potential issues.

Reported-by: Ginger <ginger.jzllee@gmail.com>
Closes: https://lore.kernel.org/gfs2/CAGp+u1ZE7UsQ4sSUHBKQXU8x3M_jwK=ek1urSjEtd3jXQGFmVg@mail.gmail.com
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

Author: Alexander Aring

fs/dlm/midcomms.c

@@ -356,6 +356,7 @@ int dlm_midcomms_addr(int nodeid, struct sockaddr_storage *addr)
 	if (!node)
 		return -ENOMEM;
 
+	node->debugfs = dlm_create_debug_comms_file(nodeid, node);
 	node->nodeid = nodeid;
 	spin_lock_init(&node->state_lock);
 	spin_lock_init(&node->send_queue_lock);
@@ -369,7 +370,6 @@ int dlm_midcomms_addr(int nodeid, struct sockaddr_storage *addr)
 	hlist_add_head_rcu(&node->hlist, &node_hash[r]);
 	spin_unlock_bh(&nodes_lock);
 
-	node->debugfs = dlm_create_debug_comms_file(nodeid, node);
 	return 0;
 }