vdev_disk_read_rootlabel
if (vdev_disk_read_rootlabel(devpath, devid, &config) != 0)
if (vdev_disk_read_rootlabel(vd->vdev_physpath, vd->vdev_devid,
extern int vdev_disk_read_rootlabel(const char *, const char *, nvlist_t **);
if ((r = vdev_disk_read_rootlabel(devpath, NULL, &cfg)) != 0) {