[PATCH] identifier to nsproxy

Add an identifier to nsproxy.  The default init_ns_proxy has identifier 0 and
allocated nsproxies are given -1.

This identifier will be used by a new syscall sys_bind_ns.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/init_task.h

@@ -75,6 +75,7 @@ extern struct nsproxy init_nsproxy;
 #define INIT_NSPROXY(nsproxy) {						\
 	.count		= ATOMIC_INIT(1),				\
 	.nslock		= __SPIN_LOCK_UNLOCKED(nsproxy.nslock),		\
+	.id		= 0,						\
 	.uts_ns		= &init_uts_ns,					\
 	.mnt_ns		= NULL,						\
 	INIT_IPC_NS(ipc_ns)						\

include/linux/nsproxy.h

@@ -23,6 +23,7 @@ struct ipc_namespace;
 struct nsproxy {
 	atomic_t count;
 	spinlock_t nslock;
+	unsigned long id;
 	struct uts_namespace *uts_ns;
 	struct ipc_namespace *ipc_ns;
 	struct mnt_namespace *mnt_ns;

kernel/nsproxy.c

@@ -45,8 +45,10 @@ static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
 	struct nsproxy *ns;
 
 	ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
-	if (ns)
+	if (ns) {
 		atomic_set(&ns->count, 1);
+		ns->id = -1;
+	}
 	return ns;
 }