Pidns: make full use of xxx_vnr() calls

Some time ago the xxx_vnr() calls (e.g.  pid_vnr or find_task_by_vpid) were
_all_ converted to operate on the current pid namespace.  After this each call
like xxx_nr_ns(foo, current->nsproxy->pid_ns) is nothing but a xxx_vnr(foo)
one.

Switch all the xxx_nr_ns() callers to use the xxx_vnr() calls where
appropriate.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Reviewed-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/exit.c b/kernel/exit.c
index 2567de3..81345ba 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1174,7 +1174,7 @@
 {
 	unsigned long state;
 	int retval, status, traced;
-	pid_t pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
+	pid_t pid = task_pid_vnr(p);
 
 	if (unlikely(noreap)) {
 		uid_t uid = p->uid;
@@ -1369,7 +1369,7 @@
 	 * possibly take page faults for user memory.
 	 */
 	get_task_struct(p);
-	pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
+	pid = task_pid_vnr(p);
 	why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
 	read_unlock(&tasklist_lock);
 
@@ -1428,7 +1428,7 @@
 		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
 	spin_unlock_irq(&p->sighand->siglock);
 
-	pid = task_pid_nr_ns(p, current->nsproxy->pid_ns);
+	pid = task_pid_vnr(p);
 	uid = p->uid;
 	get_task_struct(p);
 	read_unlock(&tasklist_lock);