[RFC][PATCH 2/5] Virtualization/containers: UIDs

[Kirill Korotaev <dev@sw.ru>]

The simplest virtualization of UID hashes, just to demonstrate our 
approach. Each container has it's own set of uids and should simply 
allocate hash/initialize it on startup.

Kirill

--- ./include/linux/vps_info.h.vps_uid_hash	2006-02-03 16:49:26.000000000 +0300
+++ ./include/linux/vps_info.h	2006-02-03 16:49:51.000000000 +0300
@@ -5,11 +5,14 @@
 #include <asm/atomic.h>
 
 struct task_struct;
+struct list_head;
 
 struct vps_info {
 	u32 id;
 	struct task_struct *init_task;
 	atomic_t refcnt;
+
+	struct list_head *vps_uid_hash;
 };
 
 extern struct vps_info host_vps_info;
--- ./kernel/user.c.vps_uid_hash	2006-02-03 16:49:08.000000000 +0300
+++ ./kernel/user.c	2006-02-03 16:49:51.000000000 +0300
@@ -14,6 +14,7 @@
 #include <linux/bitops.h>
 #include <linux/key.h>
 #include <linux/interrupt.h>
+#include <linux/vps_info.h>
 
 /*
  * UID task count cache, to get fast user lookup in "alloc_uid"
@@ -24,7 +25,8 @@
 #define UIDHASH_SZ		(1 << UIDHASH_BITS)
 #define UIDHASH_MASK		(UIDHASH_SZ - 1)
 #define __uidhashfn(uid)	(((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
-#define uidhashentry(uid)	(uidhash_table + __uidhashfn((uid)))
+#define uidhashentry(uid)	(current_vps()->vps_uid_hash +	\
+						__uidhashfn((uid)))
 
 static kmem_cache_t *uid_cachep;
 static struct list_head uidhash_table[UIDHASH_SZ];
@@ -200,6 +202,7 @@
 
 	/* Insert the root user immediately (init already runs as root) */
 	spin_lock_irq(&uidhash_lock);
+	host_vps_info.vps_uid_hash = uidhash_table;
 	uid_hash_insert(&root_user, uidhashentry(0));
 	spin_unlock_irq(&uidhash_lock);