ext4: pack ioend structure better

On 64-bit architectures we have two 4-byte holes in struct ext4_io_end.
Order entries better to avoid this and thus make the structure occupy
64 instead of 72 bytes for 64-bit architectures.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -182,9 +182,9 @@ typedef struct ext4_io_end {
 	struct bio		*bio;		/* Linked list of completed
 						 * bios covering the extent */
 	unsigned int		flag;		/* unwritten or not */
+	atomic_t		count;		/* reference counter */
 	loff_t			offset;		/* offset in the file */
 	ssize_t			size;		/* size of the extent */
-	atomic_t		count;		/* reference counter */
 } ext4_io_end_t;
 
 struct ext4_io_submit {