direct-io: move aio_complete into ->end_io

Filesystems with unwritten extent support must not complete an AIO request
until the transaction to convert the extent has been commited.  That means
the aio_complete calls needs to be moved into the ->end_io callback so
that the filesystem can control when to call it exactly.

This makes a bit of a mess out of dio_complete and the ->end_io callback
prototype even more complicated.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Alex Elder <aelder@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 8abbf05..95d1e26 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1406,7 +1406,9 @@
 	struct kiocb	*iocb,
 	loff_t		offset,
 	ssize_t		size,
-	void		*private)
+	void		*private,
+	int		ret,
+	bool		is_async)
 {
 	xfs_ioend_t	*ioend = iocb->private;
 
@@ -1452,6 +1454,9 @@
 	 * against double-freeing.
 	 */
 	iocb->private = NULL;
+
+	if (is_async)
+		aio_complete(iocb, ret, 0);
 }
 
 STATIC ssize_t