examples/io: Calculate and forward size in number of LBAs

Qemu uses the number of LBAs in order to traverse the "correct" number
of prps for the transfer. If this value is not forwarded it acts like if
there were just one PRP.

Signed-off-by: Joel Granados <[email protected]>

examples/io.c

@@ -45,6 +45,36 @@ static struct opt_table opts[] = {
 	OPT_ENDTABLE,
 };
 
+unsigned int get_lb_bytes(struct nvme_ctrl *ctrl, unsigned long nsid)
+{
+	void *vaddr;
+	ssize_t len;
+	union nvme_cmd cmd;
+	struct nvme_id_ns *id_ns;
+	struct nvme_lbaf *lbaf;
+	unsigned int lb_bytes;
+
+	len = pgmap(&vaddr, NVME_IDENTIFY_DATA_SIZE);
+	if (len < 0)
+		err(1, "could not allocate aligned memory");
+
+	cmd.identify = (struct nvme_cmd_identify) {
+		.opcode = nvme_admin_identify,
+		.cns = NVME_IDENTIFY_CNS_NS,
+		.nsid = cpu_to_le32(nsid),
+	};
+
+	if (nvme_admin(ctrl, &cmd, vaddr, len, NULL))
+		err(1, "nvme_admin");
+
+	id_ns = vaddr;
+	lbaf = &id_ns->lbaf[id_ns->flbas];
+	lb_bytes = 1ULL << lbaf->ds;
+
+	pgunmap(vaddr, len);
+	return lb_bytes;
+}
+
 int main(int argc, char **argv)
 {
 	void *vaddr;
@@ -77,6 +107,8 @@ int main(int argc, char **argv)
 	if (nvme_init(&ctrl, bdf, &ctrl_opts))
 		err(1, "failed to init nvme controller");
 
+	unsigned int lb_nbytes = get_lb_bytes(&ctrl, nsid);
+
 	if (nvme_create_ioqpair(&ctrl, 1, 64, -1, 0x0))
 		err(1, "could not create io queue pair");
 
@@ -100,6 +132,7 @@ int main(int argc, char **argv)
 	cmd.rw = (struct nvme_cmd_rw) {
 		.opcode = op_write ? nvme_cmd_write : nvme_cmd_read,
 		.nsid = cpu_to_le32(nsid),
+		.nlb = (ROUND_UP(op_len, lb_nbytes)/lb_nbytes) - 1,
 	};
 
 	ret = nvme_rq_map_prp(&ctrl, rq, &cmd, iova, op_len);