arc_write_callback_t
arc_write_callback_t *callback = zio->io_private;
arc_write_callback_t *callback = zio->io_private;
arc_write_callback_t *cb = zio->io_private;
arc_write_callback_t *callback = zio->io_private;
kmem_free(callback, sizeof (arc_write_callback_t));
arc_write_callback_t *callback;
callback = kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP);