[S390] tape: cleanup reference counting

Rename tape_get_device to tape_find_device and tape_get_device_reference
to tape_get_device. The old names didn't make too much sense.

Follow the get_device()/put_device() semantic and convert tape_put_device
to a void function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/tape_block.c b/drivers/s390/char/tape_block.c
index 0c0705b..c97c6aa 100644
--- a/drivers/s390/char/tape_block.c
+++ b/drivers/s390/char/tape_block.c
@@ -239,7 +239,7 @@
 	disk->major = tapeblock_major;
 	disk->first_minor = device->first_minor;
 	disk->fops = &tapeblock_fops;
-	disk->private_data = tape_get_device_reference(device);
+	disk->private_data = tape_get_device(device);
 	disk->queue = blkdat->request_queue;
 	set_capacity(disk, 0);
 	sprintf(disk->disk_name, "btibm%d",
@@ -247,11 +247,11 @@
 
 	blkdat->disk = disk;
 	blkdat->medium_changed = 1;
-	blkdat->request_queue->queuedata = tape_get_device_reference(device);
+	blkdat->request_queue->queuedata = tape_get_device(device);
 
 	add_disk(disk);
 
-	tape_get_device_reference(device);
+	tape_get_device(device);
 	INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
 
 	return 0;
@@ -274,13 +274,14 @@
 	}
 
 	del_gendisk(device->blk_data.disk);
-	device->blk_data.disk->private_data =
-		tape_put_device(device->blk_data.disk->private_data);
+	device->blk_data.disk->private_data = NULL;
+	tape_put_device(device);
 	put_disk(device->blk_data.disk);
 
 	device->blk_data.disk = NULL;
 cleanup_queue:
-	device->blk_data.request_queue->queuedata = tape_put_device(device);
+	device->blk_data.request_queue->queuedata = NULL;
+	tape_put_device(device);
 
 	blk_cleanup_queue(device->blk_data.request_queue);
 	device->blk_data.request_queue = NULL;
@@ -363,7 +364,7 @@
 	struct tape_device *	device;
 	int			rc;
 
-	device = tape_get_device_reference(disk->private_data);
+	device = tape_get_device(disk->private_data);
 
 	if (device->required_tapemarks) {
 		DBF_EVENT(2, "TBLOCK: missing tapemarks\n");