user_ns: improve the user_ns on-the-slab packaging

#include <linux/sched.h>

#include <linux/err.h>

#define UIDHASH_BITS	(CONFIG_BASE_SMALL ? 3 : 8)

#define UIDHASH_BITS	(CONFIG_BASE_SMALL ? 3 : 7)

#define UIDHASH_SZ	(1 << UIDHASH_BITS)

struct user_namespace {

#include <linux/highuid.h>

#include <linux/cred.h>

static struct kmem_cache *user_ns_cachep __read_mostly;

/*

 * Create a new user namespace, deriving the creator from the user in the

 * passed credentials, and replacing that user with the new root user for the

	struct user_struct *root_user;

	int n;

	ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);

	ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);

	if (!ns)

		return -ENOMEM;

	/* Alloc new root user.  */

	root_user = alloc_uid(ns, 0);

	if (!root_user) {

		kfree(ns);

		kmem_cache_free(user_ns_cachep, ns);

		return -ENOMEM;

	}

	struct user_namespace *ns =

		container_of(work, struct user_namespace, destroyer);

	free_uid(ns->creator);

	kfree(ns);

	kmem_cache_free(user_ns_cachep, ns);

}

void free_user_ns(struct kref *kref)

	/* No useful relationship so no mapping */

	return overflowgid;

}

static __init int user_namespaces_init(void)

{

	user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);

	return 0;

}

module_init(user_namespaces_init);