fuse: factor out helper for FUSE_DEV_IOC_CLONE

In preparation to adding more fuse dev ioctls.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dev.c

@@ -2251,17 +2251,14 @@ static int fuse_device_clone(struct fuse_conn *fc, struct file *new)
 	return 0;
 }
 
-static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
-			   unsigned long arg)
+static long fuse_dev_ioctl_clone(struct file *file, __u32 __user *argp)
 {
 	int res;
 	int oldfd;
 	struct fuse_dev *fud = NULL;
 	struct fd f;
 
-	switch (cmd) {
-	case FUSE_DEV_IOC_CLONE:
-		if (get_user(oldfd, (__u32 __user *)arg))
+	if (get_user(oldfd, argp))
 		return -EFAULT;
 
 	f = fdget(oldfd);
@@ -2281,13 +2278,23 @@ static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
 		res = fuse_device_clone(fud->fc, file);
 		mutex_unlock(&fuse_mutex);
 	}
+
 	fdput(f);
-		break;
+	return res;
+}
+
+static long fuse_dev_ioctl(struct file *file, unsigned int cmd,
+			   unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	case FUSE_DEV_IOC_CLONE:
+		return fuse_dev_ioctl_clone(file, argp);
+
 	default:
-		res = -ENOTTY;
-		break;
+		return -ENOTTY;
 	}
-	return res;
 }
 
 const struct file_operations fuse_dev_operations = {