[PATCH V6 3/5] 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 a configfs attribute so that user can set the io timeout values.
In case if this configfs value is not set nvme_alloc_request() will set
use the 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 | 32 ++++++++++++++++++++++++++++++++
 drivers/nvme/target/nvmet.h    |  1 +
 drivers/nvme/target/passthru.c |  3 ++-
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 7625f8892fb5..5beae49ba6ad 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -767,10 +767,42 @@ 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)
+{
+	return sprintf(page, "%u\n", to_subsys(item->ci_parent)->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_device_path,
 	&nvmet_passthru_attr_enable,
 	&nvmet_passthru_attr_admin_timeout,
+	&nvmet_passthru_attr_io_timeout,
 	NULL,
 };
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index a0c80e5179a2..2f9635273629 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 93d48b562f6d..d099f288d296 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -225,8 +225,9 @@ static inline unsigned int nvmet_passthru_req_timeout(struct nvmet_req *req,
 						      struct request_queue *q)
 {
 	unsigned int admin_timeout = req->sq->ctrl->subsys->admin_timeout;
+	unsigned int io_timeout = req->sq->ctrl->subsys->io_timeout;
 
-	return q->queuedata == NULL ? admin_timeout : 0;
+	return q->queuedata == NULL ? admin_timeout : io_timeout;
 }
 
 static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
-- 
2.22.1