[PATCH V5 4/7] nvme: add sysfs attribute to change IO timeout per controller

[Maurizio Lombardi]

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

The I/O timeout is also applied to the connect queue (connect_q).
In NVMe over Fabrics, the connect queue is utilized specifically to
issue Connect commands that establish the I/O queues.

Reviewed-by: Mohamed Khalfella <mkhalfella at purestorage.com>
Reviewed-by: Daniel Wagner <dwagner at suse.de>
Signed-off-by: Maurizio Lombardi <mlombard at redhat.com>
---
 drivers/nvme/host/core.c  |  4 +++-
 drivers/nvme/host/nvme.h  |  1 +
 drivers/nvme/host/sysfs.c | 47 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fe6dcd19cecb..626db6088dcd 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4207,6 +4207,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
 		mutex_unlock(&ctrl->namespaces_lock);
 		goto out_unlink_ns;
 	}
+	blk_queue_rq_timeout(ns->queue, ctrl->io_timeout);
 	nvme_ns_add_to_ctrl_list(ns);
 	mutex_unlock(&ctrl->namespaces_lock);
 	synchronize_srcu(&ctrl->srcu);
@@ -5145,6 +5146,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 	ctrl->ka_cmd.common.opcode = nvme_admin_keep_alive;
 	ctrl->ka_last_check_time = jiffies;
 	ctrl->admin_timeout = NVME_ADMIN_TIMEOUT;
+	ctrl->io_timeout = NVME_IO_TIMEOUT;
 
 	BUILD_BUG_ON(NVME_DSM_MAX_RANGES * sizeof(struct nvme_dsm_range) >
 			PAGE_SIZE);
@@ -5253,7 +5255,7 @@ EXPORT_SYMBOL_GPL(nvme_unfreeze);
 
 int nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl)
 {
-	unsigned long timeout = NVME_IO_TIMEOUT;
+	unsigned long timeout = ctrl->io_timeout;
 	struct nvme_ns *ns;
 	int srcu_idx;
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 7923533cce00..9ccaed0b9dbf 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -371,6 +371,7 @@ struct nvme_ctrl {
 	u32 ctrl_config;
 	u32 queue_count;
 	u32 admin_timeout;
+	u32 io_timeout;
 
 	u64 cap;
 	u32 max_hw_sectors;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 3b39b64cd9da..b682c1a4b23f 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -663,6 +663,52 @@ static ssize_t nvme_admin_timeout_store(struct device *dev,
 static DEVICE_ATTR(admin_timeout, S_IRUGO | S_IWUSR,
 	nvme_admin_timeout_show, nvme_admin_timeout_store);
 
+static ssize_t nvme_io_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->io_timeout));
+}
+
+static ssize_t nvme_io_timeout_store(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	struct nvme_ns *ns;
+	u32 timeout;
+	int err;
+
+	/*
+	 * Wait until the controller reaches the LIVE state to be sure that
+	 * connect_q is properly initialized.
+	 */
+	if (!test_bit(NVME_CTRL_STARTED_ONCE, &ctrl->flags))
+		return -EBUSY;
+
+	err = kstrtou32(buf, 10, &timeout);
+	if (err || !timeout)
+		return -EINVAL;
+
+	/* Take the namespaces_lock to avoid racing against nvme_alloc_ns() */
+	mutex_lock(&ctrl->namespaces_lock);
+
+	ctrl->io_timeout = msecs_to_jiffies(timeout);
+	list_for_each_entry(ns, &ctrl->namespaces, list)
+		blk_queue_rq_timeout(ns->queue, ctrl->io_timeout);
+
+	mutex_unlock(&ctrl->namespaces_lock);
+
+	if (ctrl->connect_q)
+		blk_queue_rq_timeout(ctrl->connect_q, ctrl->io_timeout);
+
+	return count;
+}
+
+static DEVICE_ATTR(io_timeout, S_IRUGO | S_IWUSR,
+	nvme_io_timeout_show, nvme_io_timeout_store);
+
 #ifdef CONFIG_NVME_HOST_AUTH
 static ssize_t nvme_ctrl_dhchap_secret_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -806,6 +852,7 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_dctype.attr,
 	&dev_attr_quirks.attr,
 	&dev_attr_admin_timeout.attr,
+	&dev_attr_io_timeout.attr,
 #ifdef CONFIG_NVME_HOST_AUTH
 	&dev_attr_dhchap_secret.attr,
 	&dev_attr_dhchap_ctrl_secret.attr,
-- 
2.54.0