userns: Convert drm to use kuid and kgid and struct pid where appropriate

Blink Blink this had not been converted to use struct pid ages ago?

- On drm open capture the openers kuid and struct pid.
- On drm close release the kuid and struct pid
- When reporting the uid and pid convert the kuid and struct pid
  into values in the appropriate namespace.

Cc: dri-devel@lists.freedesktop.org
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/drivers/gpu/drm/drm_info.c b/drivers/gpu/drm/drm_info.c
index 8928edb..eb0af39 100644
--- a/drivers/gpu/drm/drm_info.c
+++ b/drivers/gpu/drm/drm_info.c
@@ -191,8 +191,9 @@
 		seq_printf(m, "%c %3d %5d %5d %10u %10lu\n",
 			   priv->authenticated ? 'y' : 'n',
 			   priv->minor->index,
-			   priv->pid,
-			   priv->uid, priv->magic, priv->ioctl_count);
+			   pid_vnr(priv->pid),
+			   from_kuid_munged(seq_user_ns(m), priv->uid),
+			   priv->magic, priv->ioctl_count);
 	}
 	mutex_unlock(&dev->struct_mutex);
 	return 0;