nvme-fabrics: rework nvmf_get_address() for variable options

Revise nvmf_get_address() string to account for not all options being
present.
Signed-off-by: James Smart <james.smart@broadcom.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

drivers/nvme/host/fabrics.c

@@ -109,8 +109,16 @@ static void nvmf_host_put(struct nvmf_host *host)
  */
 int nvmf_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
 {
-	return snprintf(buf, size, "traddr=%s,trsvcid=%s\n",
-			ctrl->opts->traddr, ctrl->opts->trsvcid);
+	int len = 0;
+
+	if (ctrl->opts->mask & NVMF_OPT_TRADDR)
+		len += snprintf(buf, size, "traddr=%s", ctrl->opts->traddr);
+	if (ctrl->opts->mask & NVMF_OPT_TRSVCID)
+		len += snprintf(buf + len, size - len, "%strsvcid=%s",
+				(len) ? "," : "", ctrl->opts->trsvcid);
+	len += snprintf(buf + len, size - len, "\n");
+
+	return len;
 }
 EXPORT_SYMBOL_GPL(nvmf_get_address);