ext4: Code cleanup for EXT4_IOC_MOVE_EXT ioctl

a) Fix sparse warning in ext4_ioctl()
b) Remove unneeded variable in mext_leaf_block()
c) Fix spelling typo in mext_check_arguments()

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 2220feb..016d024 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -258,7 +258,8 @@
 		if (me.moved_len > 0)
 			file_remove_suid(donor_filp);
 
-		if (copy_to_user((struct move_extent *)arg, &me, sizeof(me)))
+		if (copy_to_user((struct move_extent __user *)arg, 
+				 &me, sizeof(me)))
 			err = -EFAULT;
 mext_out:
 		fput(donor_filp);