bdevvp
int bdevvp (cdev_t dev, struct vnode **vpp);
error = bdevvp(dev, &devvp);
error = bdevvp(kgetdiskbyname(path), &vp);
if ((error = bdevvp(rootdev, &rootvp))) {
if( bdevvp( rootdev, &rootvp))
if ((error = bdevvp(rootdev, &rootvp))) {
error = bdevvp(kgetdiskbyname(path), &vp);