NTB: Correct debugfs to work with more than 1 NTB Device

Debugfs was setup in NTB to only have a single debugfs directory.  This
resulted in the leaking of debugfs directories and files when multiple
NTB devices were present, due to each device stomping on the variables
containing the previous device's values (thus preventing them from being
freed on cleanup).  Correct this by creating a secondary directory of
the PCI BDF for each device present, and nesting the previously existing
information in those directories.

Signed-off-by: Jon Mason <jon.mason@intel.com>
diff --git a/drivers/ntb/ntb_hw.h b/drivers/ntb/ntb_hw.h
index 3a3038c..6a4f56f 100644
--- a/drivers/ntb/ntb_hw.h
+++ b/drivers/ntb/ntb_hw.h
@@ -127,6 +127,8 @@
 	unsigned char link_status;
 	struct delayed_work hb_timer;
 	unsigned long last_ts;
+
+	struct dentry *debugfs_dir;
 };
 
 /**
@@ -155,6 +157,20 @@
 	return ndev->pdev;
 }
 
+/**
+ * ntb_query_debugfs() - return the debugfs pointer
+ * @ndev: pointer to ntb_device instance
+ *
+ * Given the ntb pointer, return the debugfs directory pointer for the NTB
+ * hardware device
+ *
+ * RETURNS: a pointer to the debugfs directory
+ */
+static inline struct dentry *ntb_query_debugfs(struct ntb_device *ndev)
+{
+	return ndev->debugfs_dir;
+}
+
 struct ntb_device *ntb_register_transport(struct pci_dev *pdev,
 					  void *transport);
 void ntb_unregister_transport(struct ntb_device *ndev);