VIRTIO_BLK_BSIZE
blkno = bp->b_rawblkno * sc->sc_ld.sc_secsize / VIRTIO_BLK_BSIZE;
nblks = bp->b_bcount / VIRTIO_BLK_BSIZE;
ld->sc_secsize = VIRTIO_BLK_BSIZE;
VIRTIO_BLK_CONFIG_CAPACITY) / (ld->sc_secsize / VIRTIO_BLK_BSIZE);
VIRTIO_BLK_BSIZE);
VIRTIO_BLK_BSIZE);