userns: Disassociate user_struct from the user_namespace.

Modify alloc_uid to take a kuid and make the user hash table global.
Stop holding a reference to the user namespace in struct user_struct.

This simplifies the code and makes the per user accounting not
care about which user namespace a uid happens to appear in.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 4 insertions, 8 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6867ae9bc8a0..5fdc1ebbcbc4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -90,6 +90,7 @@ struct sched_param {
 #include <linux/latencytop.h>
 #include <linux/cred.h>
 #include <linux/llist.h>
+#include <linux/uidgid.h>
 
 #include <asm/processor.h>
 
@@ -728,8 +729,7 @@ struct user_struct {
 
         /* Hash table maintenance information */
         struct hlist_node uidhash_node;
-        uid_t uid;
-        struct user_namespace *_user_ns; /* Don't use will be removed soon */
+        kuid_t uid;
 
 #ifdef CONFIG_PERF_EVENTS
         atomic_long_t locked_vm;
@@ -738,7 +738,7 @@ struct user_struct {
 
 extern int uids_sysfs_init(void);
 
-extern struct user_struct *find_user(uid_t);
+extern struct user_struct *find_user(kuid_t);
 
 extern struct user_struct root_user;
 #define INIT_USER (&root_user)
@@ -2177,7 +2177,7 @@ extern struct task_struct *find_task_by_pid_ns(pid_t nr,
 extern void __set_special_pids(struct pid *pid);
 
 /* per-UID process charging. */
-extern struct user_struct * alloc_uid(struct user_namespace *, uid_t);
+extern struct user_struct * alloc_uid(kuid_t);
 static inline struct user_struct *get_uid(struct user_struct *u)
 {
         atomic_inc(&u->__count);
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index dc2d85a76376..d767508db4f9 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -6,12 +6,8 @@
 #include <linux/sched.h>
 #include <linux/err.h>
 
-#define UIDHASH_BITS    (CONFIG_BASE_SMALL ? 3 : 7)
-#define UIDHASH_SZ      (1 << UIDHASH_BITS)
-
 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;