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/udf/inode.c b/fs/udf/inode.c
index 2dc461e..f323aff 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -214,8 +214,7 @@
 	return ret;
 }
 
-static ssize_t udf_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
-			     loff_t offset)
+static ssize_t udf_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
@@ -223,9 +222,9 @@
 	size_t count = iov_iter_count(iter);
 	ssize_t ret;
 
-	ret = blockdev_direct_IO(iocb, inode, iter, offset, udf_get_block);
+	ret = blockdev_direct_IO(iocb, inode, iter, udf_get_block);
 	if (unlikely(ret < 0 && iov_iter_rw(iter) == WRITE))
-		udf_write_failed(mapping, offset + count);
+		udf_write_failed(mapping, iocb->ki_pos + count);
 	return ret;
 }