ext4: Return exchanged blocks count to user space in failure

Return exchanged blocks count (moved_len) to user space,
if ext4_move_extents() failed on the way.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ioctl.c

@@ -243,10 +243,9 @@ setversion_out:
 					me.donor_start, me.len, &me.moved_len);
 		fput(donor_filp);
 
-		if (!err)
+		if (copy_to_user((struct move_extent *)arg, &me, sizeof(me)))
-			if (copy_to_user((struct move_extent *)arg,
-				&me, sizeof(me)))
 			return -EFAULT;
+
 		return err;
 	}