nvmet: add passthru io timeout value attr

NVMeOF controller in the passsthru mode is capable of handling wide set
of I/O commands including vender specific passhtru io comands.

The vendor specific I/O commands are used to read the large drive
logs and can take longer than default NVMe commands, i.e. 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
the NVME_IO_TIMEOUT value when request queuedata is NULL.
Signed-off-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/target/configfs.c

@@ -755,10 +755,30 @@ 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 timeout;
+
+	if (kstrtouint(page, 0, &timeout))
+		return -EINVAL;
+	subsys->io_timeout = timeout;
+	return 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,
 };
 

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 */
 };
 

drivers/nvme/target/passthru.c

@@ -227,7 +227,7 @@ static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
 	struct request_queue *q = ctrl->admin_q;
 	struct nvme_ns *ns = NULL;
 	struct request *rq = NULL;
-	unsigned int timeout = 0;
+	unsigned int timeout;
 	u32 effects;
 	u16 status;
 	int ret;
@@ -243,6 +243,7 @@ static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
 		}
 
 		q = ns->queue;
+		timeout = req->sq->ctrl->subsys->io_timeout;
 	} else {
 		timeout = req->sq->ctrl->subsys->admin_timeout;
 	}