# Re: Question about loop device DIO/AIO and FLUSH

- From: Ming Lei \<hidden\>
- Date: 2016-07-01 06:57:47 
- List: linux-block
- Page: https://ratatoskr.run/linux-block/2016/07/109605
- Thread: https://ratatoskr.run/linux-fsdevel/2016/06/109361/t.md

```text
On Fri, Jul 1, 2016 at 4:54 AM, Amir Goldstein [ref] wrote:
> Hi Ming,
>
> I was reading through the code of loop DIO/AIO
> and I was wondering whether lo_req_flush() really
> honors REQ_FLUSH by calling  vfs_fsync() on a backing file
> that is open with O_DIRECT?

>From view of device, REQ_FLUSH just flushs the cache inside
drive to medium.

>
> Shouldn't lo_req_flush() actually wait for completion of
> all the in-flight loop AIO requests to complete?

I think it isn't needed, just like the flush handling in blk-flush.c, and
it just works for completed I/O.

> Am I missing something?
>
> Thanks,
> Amir.
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```