direct-io: eliminate the offset argument to ->direct_IO

Including blkdev_direct_IO and dax_do_io.  It has to be ki_pos to actually
work, so eliminate the superflous argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 1bbbee9..8524c0e 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -1042,13 +1042,13 @@
 
 
 
-static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
-			      loff_t offset)
+static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
 	struct address_space *mapping = inode->i_mapping;
 	struct gfs2_inode *ip = GFS2_I(inode);
+	loff_t offset = iocb->ki_pos;
 	struct gfs2_holder gh;
 	int rv;
 
@@ -1099,7 +1099,7 @@
 	}
 
 	rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
-				  offset, gfs2_get_block_direct, NULL, NULL, 0);
+				  gfs2_get_block_direct, NULL, NULL, 0);
 out:
 	gfs2_glock_dq(&gh);
 	gfs2_holder_uninit(&gh);