# Re: \[PATCH v6 4/5\] fs, xfs: introduce MAP\_DIRECT for creating block-map-atomic file ranges

- From: Christoph Hellwig \<hidden\>
- Date: 2017-08-24 16:11:52 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2017/08/125603
- Thread: https://ratatoskr.run/linux-api/2017/08/125104/t.md

```text
I still can't make any sense of this description.  What is an external
agent?  Userspace obviously can't ever see a change in the extent
map, so it can't be meant.

It would help a lot if you could come up with a concrete user for this,
including example code.
```