direct-io: rearrange fields in dio/dio_submit to avoid holes

Fix most problems reported by pahole.

There is still a weird 104 byte hole after map_bh. I'm not sure what
causes this.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

fs/direct-io.c

@@ -73,10 +73,10 @@ struct dio_submit {
 	sector_t block_in_file;		/* Current offset into the underlying
 					   file in dio_block units. */
 	unsigned blocks_available;	/* At block_in_file.  changes */
+	int reap_counter;		/* rate limit reaping */
 	sector_t final_block_in_request;/* doesn't change */
 	unsigned first_block_in_page;	/* doesn't change, Used only once */
 	int boundary;			/* prev block is at a boundary */
-	int reap_counter;		/* rate limit reaping */
 	get_block_t *get_block;		/* block mapping function */
 	dio_submit_t *submit_io;	/* IO submition function */
 
@@ -114,27 +114,26 @@ struct dio_submit {
 /* dio_state communicated between submission path and end_io */
 struct dio {
 	int flags;			/* doesn't change */
-	struct inode *inode;
 	int rw;
+	struct inode *inode;
 	loff_t i_size;			/* i_size when submitted */
 	dio_iodone_t *end_io;		/* IO completion function */
-	struct buffer_head map_bh;	/* last get_block() result */
 
 
 	/* BIO completion state */
 	spinlock_t bio_lock;		/* protects BIO fields below */
+	int page_errors;		/* errno from get_user_pages() */
+	int is_async;			/* is IO async ? */
+	int io_error;			/* IO error in completion path */
 	unsigned long refcount;		/* direct_io_worker() and bios */
 	struct bio *bio_list;		/* singly linked via bi_private */
 	struct task_struct *waiter;	/* waiting task (NULL if none) */
 
 	/* AIO related stuff */
 	struct kiocb *iocb;		/* kiocb */
-	int is_async;			/* is IO async ? */
-	int io_error;			/* IO error in completion path */
 	ssize_t result;                 /* IO result */
 
-	int page_errors;		/* errno from get_user_pages() */
-
+	struct buffer_head map_bh;	/* last get_block() result */
 	/*
 	 * pages[] (and any fields placed after it) are not zeroed out at
 	 * allocation time.  Don't add new fields after pages[] unless you