ocfs2/cluster: Pin the remote node item in configfs

o2net pins the node item of the remote node in configfs before initiating
the connection. It is unpinned on disconnect. This is to prevent the node
item from being unlinked while it is still in use.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/cluster/tcp.c

@@ -355,6 +355,7 @@ static void sc_kref_release(struct kref *kref)
 		sc->sc_sock = NULL;
 	}
 
+	o2nm_undepend_item(&sc->sc_node->nd_item);
 	o2nm_node_put(sc->sc_node);
 	sc->sc_node = NULL;
 
@@ -376,6 +377,7 @@ static struct o2net_sock_container *sc_alloc(struct o2nm_node *node)
 {
 	struct o2net_sock_container *sc, *ret = NULL;
 	struct page *page = NULL;
+	int status = 0;
 
 	page = alloc_page(GFP_NOFS);
 	sc = kzalloc(sizeof(*sc), GFP_NOFS);
@@ -386,6 +388,13 @@ static struct o2net_sock_container *sc_alloc(struct o2nm_node *node)
 	o2nm_node_get(node);
 	sc->sc_node = node;
 
+	/* pin the node item of the remote node */
+	status = o2nm_depend_item(&node->nd_item);
+	if (status) {
+		mlog_errno(status);
+		o2nm_node_put(node);
+		goto out;
+	}
 	INIT_WORK(&sc->sc_connect_work, o2net_sc_connect_completed);
 	INIT_WORK(&sc->sc_rx_work, o2net_rx_until_empty);
 	INIT_WORK(&sc->sc_shutdown_work, o2net_shutdown_sc);