introduce helper to handle return codes

[igaw]

We have plenty of this code pattern which is adds a lot of repetative code. Introduce helper for this

	err = nvme_submit_admin_passthru(hdl, &cmd);
	if (err < 0)
		nvme_show_error("ERROR: nvme_lm_cdq() failed: %s", nvme_strerror(errno));
	else if (err > 0)
		nvme_show_status(err);
	else
		printf("Delete CDQ Successful: CDQID=0x%04x\n", cfg.cdqid);

[igaw]

I think nvme_show_error/nvme_show_status should be merged, something like:

err = nvme_submit_admin_passthru(hdl, &cmd);
if (err)
		nvme_show_error("nvme_lm_cdq", err, cmd.result);
else
	printf("Delete CDQ Successful: CDQID=0x%04x\n", cfg.cdqid);

[ikegami-t]

Just created the PR: linux-nvme#3055 for this issue.

[igaw]

merged