Re: [PATCH v2 18/33] mnt: support ns lookup

On Fri, Sep 12, 2025 at 01:52:41PM +0200, Christian Brauner wrote:

Move the mount namespace to the generic ns lookup infrastructure. This allows us to drop a bunch of members from struct mnt_namespace.

static void mnt_ns_tree_remove(struct mnt_namespace *ns) { /* remove from global mount namespace list */

• if (!is_anon_ns(ns)) {

• mnt_ns_tree_write_lock();
  

• rb_erase(&ns->mnt_ns_tree_node, &mnt_ns_tree);
  

• list_bidir_del_rcu(&ns->mnt_ns_list);
  

• mnt_ns_tree_write_unlock();
  

• }
• call_rcu(&ns->mnt_ns_rcu, mnt_ns_release_rcu);

-}

-static int mnt_ns_find(const void *key, const struct rb_node *node) -{

• const u64 mnt_ns_id = *(u64 *)key;
• const struct mnt_namespace *ns = node_to_mnt_ns(node);

• if (!is_anon_ns(ns))

• ns_tree_remove(ns);
  

Conflicts with "mnt_ns_tree_remove(): DTRT if mnt_ns had never been added to mnt_ns_list".

FWIW, the right thing to do here is

if (!RB_EMPTY_NODE(to_ns_common(ns)->ns_tree_node)) ns_tree_remove(ns);