fs: move inode_dio_wait calls into ->setattr

Let filesystems handle waiting for direct I/O requests themselves instead
of doing it beforehand.  This means filesystem-specific locks to prevent
new dio referenes from appearing can be held.  This is important to allow
generalizing i_dio_count to non-DIO_LOCKING filesystems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 2c3a465..736283c 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1142,6 +1142,8 @@
 		if (status)
 			goto bail_unlock;
 
+		inode_dio_wait(inode);
+
 		if (i_size_read(inode) > attr->ia_size) {
 			if (ocfs2_should_order_data(inode)) {
 				status = ocfs2_begin_ordered_truncate(inode,