consolidate the reassignments of ->f_op in ->open() instances

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index 401ef64..983db75 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -74,22 +74,15 @@
 
 	if (dvbdev && dvbdev->fops) {
 		int err = 0;
-		const struct file_operations *old_fops;
+		const struct file_operations *new_fops;
 
-		file->private_data = dvbdev;
-		old_fops = file->f_op;
-		file->f_op = fops_get(dvbdev->fops);
-		if (file->f_op == NULL) {
-			file->f_op = old_fops;
+		new_fops = fops_get(dvbdev->fops);
+		if (!new_fops)
 			goto fail;
-		}
-		if(file->f_op->open)
+		file->private_data = dvbdev;
+		replace_fops(file, new_fops);
+		if (file->f_op->open)
 			err = file->f_op->open(inode,file);
-		if (err) {
-			fops_put(file->f_op);
-			file->f_op = fops_get(old_fops);
-		}
-		fops_put(old_fops);
 		up_read(&minor_rwsem);
 		mutex_unlock(&dvbdev_mutex);
 		return err;