Support the generic namespace iterator and lookup infrastructure to
support file handles for namespaces.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 ipc/msgutil.c   | 1 +
 ipc/namespace.c | 3 +++
 ipc/shm.c       | 2 ++
 3 files changed, 6 insertions(+)

diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index c7be0c792647..bbf61275df41 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -15,6 +15,7 @@
 #include <linux/proc_ns.h>
 #include <linux/uaccess.h>
 #include <linux/sched.h>
+#include <linux/nstree.h>
 
 #include "util.h"
 
diff --git a/ipc/namespace.c b/ipc/namespace.c
index d4188a88ee57..9f923c1a1eb3 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -15,6 +15,7 @@
 #include <linux/mount.h>
 #include <linux/user_namespace.h>
 #include <linux/proc_ns.h>
+#include <linux/nstree.h>
 #include <linux/sched/task.h>
 
 #include "util.h"
@@ -85,6 +86,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
 
 	sem_init_ns(ns);
 	shm_init_ns(ns);
+	ns_tree_add(ns);
 
 	return ns;
 
@@ -201,6 +203,7 @@ void put_ipc_ns(struct ipc_namespace *ns)
 		mq_clear_sbinfo(ns);
 		spin_unlock(&mq_lock);
 
+		ns_tree_remove(ns);
 		if (llist_add(&ns->mnt_llist, &free_ipc_list))
 			schedule_work(&free_ipc_work);
 	}
diff --git a/ipc/shm.c b/ipc/shm.c
index a9310b6dbbc3..3db36773dd10 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -45,6 +45,7 @@
 #include <linux/mount.h>
 #include <linux/ipc_namespace.h>
 #include <linux/rhashtable.h>
+#include <linux/nstree.h>
 
 #include <linux/uaccess.h>
 
@@ -148,6 +149,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
 static int __init ipc_ns_init(void)
 {
 	shm_init_ns(&init_ipc_ns);
+	ns_tree_add(&init_ipc_ns);
 	return 0;
 }
 

-- 
2.47.3