From: Daniel Wagner <dwagner@suse.de>
Date: Mon, 29 Aug 2022 11:28:39 +0200
Subject: nvmet: Expose max queues to configfs
Patch-mainline: v6.1-rc1
Git-commit: 3e980f5995e0bb4d86fef873a9c9ad66721580d0
References: bsc#1201865

Allow to set the max queues the target supports. This is useful for
testing the reconnect attempt of the host with changing numbers of
supported queues.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/nvme/target/configfs.c |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1298,6 +1298,34 @@ static ssize_t nvmet_subsys_attr_pi_enab
 CONFIGFS_ATTR(nvmet_subsys_, attr_pi_enable);
 #endif
 
+static ssize_t nvmet_subsys_attr_qid_max_show(struct config_item *item,
+					      char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%u\n", to_subsys(item)->max_qid);
+}
+
+static ssize_t nvmet_subsys_attr_qid_max_store(struct config_item *item,
+					       const char *page, size_t cnt)
+{
+	struct nvmet_port *port = to_nvmet_port(item);
+	u16 qid_max;
+
+	if (nvmet_is_port_enabled(port, __func__))
+		return -EACCES;
+
+	if (sscanf(page, "%hu\n", &qid_max) != 1)
+		return -EINVAL;
+
+	if (qid_max < 1 || qid_max > NVMET_NR_QUEUES)
+		return -EINVAL;
+
+	down_write(&nvmet_config_sem);
+	to_subsys(item)->max_qid = qid_max;
+	up_write(&nvmet_config_sem);
+	return cnt;
+}
+CONFIGFS_ATTR(nvmet_subsys_, attr_qid_max);
+
 static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_allow_any_host,
 	&nvmet_subsys_attr_attr_version,
@@ -1306,6 +1334,7 @@ static struct configfs_attribute *nvmet_
 	&nvmet_subsys_attr_attr_cntlid_max,
 	&nvmet_subsys_attr_attr_model,
 	&nvmet_subsys_attr_attr_discovery_nqn,
+	&nvmet_subsys_attr_attr_qid_max,
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 	&nvmet_subsys_attr_attr_pi_enable,
 #endif