virtio_blk_outhdr
bzero(req->vbr_hdr, sizeof(struct virtio_blk_outhdr));
sizeof(struct virtio_blk_outhdr));
sizeof(struct virtio_blk_outhdr), /* alignment */
sizeof(struct virtio_blk_outhdr), /* max request size */
sizeof(struct virtio_blk_outhdr), /* maxsegsize */
struct virtio_blk_outhdr *vbr_hdr;
req->vbr_hdr, sizeof(struct virtio_blk_outhdr),