nvme: Add sysfs parameter to show subsystem nqn

Added 'subsysnqn' parameter to /sys/class/nvme-fabrics/ctl/nvmeX/ that shows the subsystem nqn of the configured device.

Signed-off-by Ian Bakshan <ianb at mellanox.com>

---
  drivers/nvme/host/core.c   | 24 ++++++++++++++++++++++++
  drivers/nvme/host/nvme.h   |  1 +
  drivers/nvme/host/rdma.c   | 10 +++++++++-
  drivers/nvme/target/loop.c |  8 ++++++++
  4 files changed, 42 insertions(+), 1 deletion(-)

drivers/nvme/host/core.c +24 -0

index 49c721c..663ad56 100644
@@ -1011,6 +1011,20 @@ static ssize_t nvme_sysfs_delete(struct device *dev,
  }
  static DEVICE_ATTR(delete_controller, S_IWUSR, NULL, nvme_sysfs_delete);
 
+static ssize_t nvme_sysfs_show_subsysnqn(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	ssize_t count = 0;
+
+	if (ctrl->ops->get_subsysnqn)
+		count = sprintf(buf, "%s\n", ctrl->ops->get_subsysnqn(ctrl));
+
+	return count;
+}
+static DEVICE_ATTR(subsysnqn, S_IRUGO, nvme_sysfs_show_subsysnqn, NULL);
+
  static int ns_cmp(void *priv, struct list_head *a, struct list_head *b)
  {
  	struct nvme_ns *nsa = container_of(a, struct nvme_ns, list);

@@ -1246,6 +1260,8 @@ static void nvme_release_instance(struct nvme_ctrl *ctrl)
 
  void nvme_uninit_ctrl(struct nvme_ctrl *ctrl)
  {
+	if (ctrl->ops->get_subsysnqn)
+		device_remove_file(ctrl->device, &dev_attr_subsysnqn);
  	device_remove_file(ctrl->device, &dev_attr_reset_controller);
  	if (ctrl->ops->delete_ctrl)
  		device_remove_file(ctrl->device, &dev_attr_delete_controller);

@@ -1316,12 +1332,20 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
  			goto out_remove_reset_attr;
  	}
 
+	if (ctrl->ops->get_subsysnqn) {
+		ret = device_create_file(ctrl->device, &dev_attr_subsysnqn);
+		if (ret)
+			goto out_remove_delete_attr;
+	}
+
  	spin_lock(&dev_list_lock);
  	list_add_tail(&ctrl->node, &nvme_ctrl_list);
  	spin_unlock(&dev_list_lock);
 
  	return 0;
 
+out_remove_delete_attr:
+	device_remove_file(ctrl->device, &dev_attr_delete_controller);
  out_remove_reset_attr:
  	device_remove_file(ctrl->device, &dev_attr_reset_controller);
  out_put_device:

drivers/nvme/host/nvme.h +1 -0

index 16edf85..8bc6660 100644
@@ -103,6 +103,7 @@ struct nvme_ctrl_ops {
  	int (*reset_ctrl)(struct nvme_ctrl *ctrl);
  	void (*free_ctrl)(struct nvme_ctrl *ctrl);
  	int (*delete_ctrl)(struct nvme_ctrl *ctrl);
+	const char *(*get_subsysnqn)(struct nvme_ctrl *ctrl);
  };
 
  static inline bool nvme_ctrl_ready(struct nvme_ctrl *ctrl)

drivers/nvme/host/rdma.c +9 -1

index 0ce063d..cacecd3 100644
@@ -1443,6 +1443,13 @@ static int nvme_rdma_del_ctrl(struct nvme_ctrl *nctrl)
  	return 0;
  }
 
+static const char *nvme_rdma_get_subsysnqn(struct nvme_ctrl *nctrl)
+{
+	struct nvme_rdma_ctrl *ctrl = to_rdma_ctrl(nctrl);
+
+	return ctrl->subsysnqn;
+}
+
  static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
  	.module			= THIS_MODULE,
  	.reg_read32		= nvmf_reg_read32,

@@ -1451,7 +1458,8 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
  	.io_incapable		= nvme_rdma_io_incapable,
  	.reset_ctrl		= nvme_rdma_reset_ctrl,
  	.free_ctrl		= nvme_rdma_free_ctrl,
-	.delete_ctrl		= nvme_rdma_del_ctrl
+	.delete_ctrl		= nvme_rdma_del_ctrl,
+	.get_subsysnqn		= nvme_rdma_get_subsysnqn,
  };
 
  static int nvme_rdma_create_ctrl(struct device *dev,

drivers/nvme/target/loop.c +8 -0

index a680db6..2feeee2 100644
@@ -353,6 +353,13 @@ static int nvme_loop_del_ctrl(struct nvme_ctrl *nctrl)
  	return 0;
  }
 
+static const char *nvme_loop_get_subsysnqn(struct nvme_ctrl *nctrl)
+{
+	struct nvme_loop_ctrl *ctrl = to_loop_ctrl(nctrl);
+
+	return ctrl->subsysnqn;
+}
+
  static const struct nvme_ctrl_ops nvme_loop_ctrl_ops = {
  	.module			= THIS_MODULE,
  	.reg_read32		= nvmf_reg_read32,

@@ -362,6 +369,7 @@ static const struct nvme_ctrl_ops nvme_loop_ctrl_ops = {
  	.reset_ctrl		= nvme_loop_reset_ctrl,
  	.free_ctrl		= nvme_loop_free_ctrl,
  	.delete_ctrl		= nvme_loop_del_ctrl,
+	.get_subsysnqn		= nvme_loop_get_subsysnqn,
  };
 
  static int nvme_loop_create_ctrl(struct device *dev,