Staging: hv: Introduce a function to map a generic driver pointer to a pointer to storvsc_driver_object

In preparation for getting rid of the priv element from struct hv_driver,
introduce a function that maps a generic struct driver pointer to struct
storvsc_driver_object.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/storvsc_api.h

@@ -28,6 +28,7 @@
 #include <linux/kernel.h>
 #include "vstorage.h"
 #include "vmbus_api.h"
+#include "vmbus.h"
 
 /* Defines */
 #define STORVSC_RING_BUFFER_SIZE			(20*PAGE_SIZE)
@@ -153,6 +154,13 @@ static inline struct storvsc_driver_object *hvdr_to_stordr(struct hv_driver *d)
 	return container_of(d, struct storvsc_driver_object, base);
 }
 
+static inline
+struct storvsc_driver_object *drv_to_stordrv(struct device_driver *d)
+{
+	struct hv_driver *hvdrv = drv_to_hv_drv(d);
+	return hvdr_to_stordr(hvdrv);
+}
+
 /* Interface */
 
 int stor_vsc_on_device_add(struct hv_device *device,