new helpers: ns_alloc_inum/ns_free_inum

take struct ns_common *, for now simply wrappers around proc_{alloc,free}_inum()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 29cd5cc..6bf8177 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -86,7 +86,7 @@
 	if (!ns)
 		return -ENOMEM;
 
-	ret = proc_alloc_inum(&ns->ns.inum);
+	ret = ns_alloc_inum(&ns->ns);
 	if (ret) {
 		kmem_cache_free(user_ns_cachep, ns);
 		return ret;
@@ -136,7 +136,7 @@
 #ifdef CONFIG_PERSISTENT_KEYRINGS
 		key_put(ns->persistent_keyring_register);
 #endif
-		proc_free_inum(ns->ns.inum);
+		ns_free_inum(&ns->ns);
 		kmem_cache_free(user_ns_cachep, ns);
 		ns = parent;
 	} while (atomic_dec_and_test(&parent->count));