[PATCH RFC 2/5] nvme: add sysfs attribute to change admin timeout per nvme controller

[Maurizio Lombardi <mlombard@redhat.com>]

Currently, there is no method to adjust the timeout values
on a per controller basis with nvme admin queues.
Add an admin_timeout attribute to nvme so that different
nvme controllers which may have different timeout
requirements can have custom admin timeouts set.

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
---
 drivers/nvme/host/sysfs.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 29430949ce2f..149cd1ab3b3d 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -601,6 +601,36 @@ static ssize_t dctype_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(dctype);
 
+static ssize_t nvme_admin_timeout_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%u\n",
+				jiffies_to_msecs(ctrl->admin_q->rq_timeout));
+}
+
+static ssize_t nvme_admin_timeout_store(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	u32 timeout;
+	int err;
+
+	err = kstrtou32(buf, 10, &timeout);
+	if (err || !timeout)
+		return -EINVAL;
+
+	blk_queue_rq_timeout(ctrl->admin_q, msecs_to_jiffies(timeout));
+
+	return count;
+}
+
+static struct device_attribute dev_attr_admin_timeout =  \
+	__ATTR(admin_timeout, S_IRUGO | S_IWUSR, \
+	nvme_admin_timeout_show, nvme_admin_timeout_store);
+
 #ifdef CONFIG_NVME_HOST_AUTH
 static ssize_t nvme_ctrl_dhchap_secret_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -742,6 +772,7 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_kato.attr,
 	&dev_attr_cntrltype.attr,
 	&dev_attr_dctype.attr,
+	&dev_attr_admin_timeout.attr,
 #ifdef CONFIG_NVME_HOST_AUTH
 	&dev_attr_dhchap_secret.attr,
 	&dev_attr_dhchap_ctrl_secret.attr,
-- 
2.53.0