userns: Add an explicit reference to the parent user namespace
I am about to remove the struct user_namespace reference from struct user_struct.
So keep an explicit track of the parent user namespace.
Take advantage of this new reference and replace instances of user_ns->creator->user_ns
with user_ns->parent.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index faf4679..dc2d85a 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -12,6 +12,7 @@
struct user_namespace {
struct kref kref;
struct hlist_head uidhash_table[UIDHASH_SZ];
+ struct user_namespace *parent;
struct user_struct *creator;
struct work_struct destroyer;
};