[PATCH V2 5/6] nvmet: add passthru io timeout value attr

[Chaitanya Kulkarni]

NVMe controller in the passsthru mode is capable of handling wide set
of admin commands including Vender unique passhtru I/O comands
(VUICs).

The VUICs can take longer than default NVMe commands, that is for
passthru requests the timeout value may differ from the passthru
controller's default timeout values (nvme-core:io_timeout).

Add configfs attribute so that user can set the I/O timeout values.
In case if this configfs value is not set default to NVME_IO_TIMEOUT
value.

This attribute setting is only allowed when ctrl is disable to avoid
rcu calls in the fast path, in future when needed we can always make it
fast path friendly using RCU.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 drivers/nvme/target/configfs.c | 34 ++++++++++++++++++++++++++++++++++
 drivers/nvme/target/nvmet.h    |  1 +
 drivers/nvme/target/passthru.c |  6 +++++-
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index b3b57add53d1..506da13ac083 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -769,8 +769,42 @@ static ssize_t nvmet_passthru_admin_timeout_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_passthru_, admin_timeout);
 
+static ssize_t nvmet_passthru_io_timeout_show(struct config_item *item,
+		char *page)
+{
+	struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
+
+	return sprintf(page, "%u\n", subsys->io_timeout);
+}
+
+static ssize_t nvmet_passthru_io_timeout_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item->ci_parent);
+	unsigned int io_timeout;
+	int ret = 0;
+
+	mutex_lock(&subsys->lock);
+	if (subsys->passthru_ctrl) {
+		pr_err("disable passthru ctrl before setting io_timeout\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (kstrtouint(page, 0, &io_timeout)) {
+		ret = -EINVAL;
+		goto out;
+	}
+	subsys->io_timeout = io_timeout;
+out:
+	mutex_unlock(&subsys->lock);
+	return ret ? ret : count;
+}
+CONFIGFS_ATTR(nvmet_passthru_, io_timeout);
+
 static struct configfs_attribute *nvmet_passthru_attrs[] = {
 	&nvmet_passthru_attr_admin_timeout,
+	&nvmet_passthru_attr_io_timeout,
 	&nvmet_passthru_attr_device_path,
 	&nvmet_passthru_attr_enable,
 	NULL,
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 13266e413ccb..a24b4c7a3ab4 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -250,6 +250,7 @@ struct nvmet_subsys {
 	char			*passthru_ctrl_path;
 	struct config_group	passthru_group;
 	unsigned int		admin_timeout;
+	unsigned int		io_timeout;
 #endif /* CONFIG_NVME_TARGET_PASSTHRU */
 };
 
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 3a364a12e8c9..2564b6769b9e 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -216,6 +216,7 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
 static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
 {
 	unsigned int admin_timeout = req->sq->ctrl->subsys->admin_timeout;
+	unsigned int io_timeout = req->sq->ctrl->subsys->io_timeout;
 	struct nvme_ctrl *ctrl = nvmet_req_passthru_ctrl(req);
 	struct request_queue *q = ctrl->admin_q;
 	struct nvme_ns *ns = NULL;
@@ -243,7 +244,7 @@ static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
 		goto out_put_ns;
 	}
 
-	rq->timeout = q->queuedata ? NVME_IO_TIMEOUT : admin_timeout;
+	rq->timeout = q->queuedata ? io_timeout : admin_timeout;
 
 	if (req->sg_cnt) {
 		ret = nvmet_passthru_map_sg(req, rq);
@@ -523,6 +524,9 @@ int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
 	if (!subsys->admin_timeout)
 		subsys->admin_timeout = ADMIN_TIMEOUT;
 
+	if (!subsys->io_timeout)
+		subsys->io_timeout = NVME_IO_TIMEOUT;
+
 	mutex_unlock(&subsys->lock);
 	return 0;
 
-- 
2.22.1