Introduced a few days ago:
  commit 45bb912b
  Author: Lars Ellenberg <lars.ellenberg@linbit.com>
  Date:   Fri May 14 17:10:48 2010 +0200
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>