blkfront: Remove obsolete info->users

This is just bd_openers, protected by the bd_mutex.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/block/xen-blkfront.c

@@ -1168,9 +1168,6 @@ static int blkif_open(struct block_device *bdev, fmode_t mode)
 
 	mutex_unlock(&info->mutex);
 
-	if (!err)
-		++info->users;
-
 out:
 	unlock_kernel();
 	return err;
@@ -1183,12 +1180,13 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
 	struct xenbus_device *xbdev;
 
 	lock_kernel();
-	if (--info->users)
-		goto out;
 
 	bdev = bdget_disk(disk, 0);
 	bdput(bdev);
 
+	if (bdev->bd_openers)
+		goto out;
+
 	/*
 	 * Check if we have been instructed to close. We will have
 	 * deferred this request, because the bdev was still open.
@@ -1212,7 +1210,6 @@ static int blkif_release(struct gendisk *disk, fmode_t mode)
 		kfree(info);
 	}
 
-out:
 	unlock_kernel();
 	return 0;
 }