pidns: Use task_active_pid_ns where appropriate

The expressions tsk->nsproxy->pid_ns and task_active_pid_ns
aka ns_of_pid(task_pid(tsk)) should have the same number of
cache line misses with the practical difference that
ns_of_pid(task_pid(tsk)) is released later in a processes life.

Furthermore by using task_active_pid_ns it becomes trivial
to write an unshare implementation for the the pid namespace.

So I have used task_active_pid_ns everywhere I can.

In fork since the pid has not yet been attached to the
process I use ns_of_pid, to achieve the same effect.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/fs/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index 78f21f8dc2ec..43b315f2002b 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -710,7 +710,7 @@ static int hppfs_fill_super(struct super_block *sb, void *d, int silent)
         struct vfsmount *proc_mnt;
         int err = -ENOENT;
 
-        proc_mnt = mntget(current->nsproxy->pid_ns->proc_mnt);
+        proc_mnt = mntget(task_active_pid_ns(current)->proc_mnt);
         if (IS_ERR(proc_mnt))
                 goto out;
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 13ef6247e7a3..fc1609321a78 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -106,7 +106,7 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
                 ns = (struct pid_namespace *)data;
                 options = NULL;
         } else {
-                ns = current->nsproxy->pid_ns;
+                ns = task_active_pid_ns(current);
                 options = data;
         }