acct: eliminate compile warning

If ACCT_VERSION is not defined to 3, below warning appears:
  CC      kernel/acct.o
  kernel/acct.c: In function `do_acct_process':
  kernel/acct.c:475:24: warning: unused variable `ns' [-Wunused-variable]

[akpm@linux-foundation.org: retain the local for code size improvements
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/kernel/acct.c b/kernel/acct.c
index b4c667d22e79..33738ef972f3 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -472,7 +472,6 @@ static void do_acct_process(struct bsd_acct_struct *acct)
         acct_t ac;
         unsigned long flim;
         const struct cred *orig_cred;
-        struct pid_namespace *ns = acct->ns;
         struct file *file = acct->file;
 
         /*
@@ -500,10 +499,15 @@ static void do_acct_process(struct bsd_acct_struct *acct)
         ac.ac_gid16 = ac.ac_gid;
 #endif
 #if ACCT_VERSION == 3
-        ac.ac_pid = task_tgid_nr_ns(current, ns);
-        rcu_read_lock();
-        ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), ns);
-        rcu_read_unlock();
+        {
+                struct pid_namespace *ns = acct->ns;
+
+                ac.ac_pid = task_tgid_nr_ns(current, ns);
+                rcu_read_lock();
+                ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent),
+                                             ns);
+                rcu_read_unlock();
+        }
 #endif
         /*
          * Get freeze protection. If the fs is frozen, just skip the write