pid namespaces: changes to show virtual ids to user

This is the largest patch in the set. Make all (I hope) the places where
the pid is shown to or get from user operate on the virtual pids.

The idea is:
 - all in-kernel data structures must store either struct pid itself
   or the pid's global nr, obtained with pid_nr() call;
 - when seeking the task from kernel code with the stored id one
   should use find_task_by_pid() call that works with global pids;
 - when showing pid's numerical value to the user the virtual one
   should be used, but however when one shows task's pid outside this
   task's namespace the global one is to be used;
 - when getting the pid from userspace one need to consider this as
   the virtual one and use appropriate task/pid-searching functions.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: yet nuther build fix]
[akpm@linux-foundation.org: remove unneeded casts]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/fs/ioprio.c b/fs/ioprio.c
index 10d2c211d18b..0a615f87142e 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -25,6 +25,7 @@
 #include <linux/capability.h>
 #include <linux/syscalls.h>
 #include <linux/security.h>
+#include <linux/pid_namespace.h>
 
 static int set_task_ioprio(struct task_struct *task, int ioprio)
 {
@@ -93,7 +94,8 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                         if (!who)
                                 p = current;
                         else
-                                p = find_task_by_pid(who);
+                                p = find_task_by_pid_ns(who,
+                                                current->nsproxy->pid_ns);
                         if (p)
                                 ret = set_task_ioprio(p, ioprio);
                         break;
@@ -101,7 +103,7 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                         if (!who)
                                 pgrp = task_pgrp(current);
                         else
-                                pgrp = find_pid(who);
+                                pgrp = find_vpid(who);
                         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
                                 ret = set_task_ioprio(p, ioprio);
                                 if (ret)
@@ -180,7 +182,8 @@ asmlinkage long sys_ioprio_get(int which, int who)
                         if (!who)
                                 p = current;
                         else
-                                p = find_task_by_pid(who);
+                                p = find_task_by_pid_ns(who,
+                                                current->nsproxy->pid_ns);
                         if (p)
                                 ret = get_task_ioprio(p);
                         break;
@@ -188,7 +191,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                         if (!who)
                                 pgrp = task_pgrp(current);
                         else
-                                pgrp = find_pid(who);
+                                pgrp = find_vpid(who);
                         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
                                 tmpio = get_task_ioprio(p);
                                 if (tmpio < 0)