Re: [Qemu-devel] [PATCH] bdrv_aio_flush

[Ian Jackson]

Jens Axboe writes ("Re: [Qemu-devel] [PATCH] bdrv_aio_flush"):
> Given that this case refers to PATA/SATA and that you can't queue the
> flush operation, it looks something like:
>
>         submit IO 1 to device
>         IO 1 completes
>         submit flush
>         flush completes

That's what I thought.

> and at this point, flush completion either ends in error (in which case
> we can't rely on IO 1 being safely stored), or it suceeds and Linux then
> expects IO 1 to be on disk. If it isn't, then the device is broken (as
> simple as that).

Yes.  I agree.  And I think that (with my recent error handling and
cache flushing patchsets - 5 patches total) that's what qemu
implements.

> > What spec should I be referring to ?
> 
> ata spec, see t13.org

Thanks.  I was looking at an older spec I found a link to from
wikipedia ...

Ian.