Re: [Qemu-devel] [PATCH v4 2/3] linux-aio: implement io plug, unplug and flush io queue

[Paolo Bonzini]

Il 03/07/2014 12:45, Ming Lei ha scritto:
> I think it may be needed:
>
> - following requests coming inside handle_notify():
>          req0, req1, req2-flush, req3
> - both req0 and req1 queued
> - start to handle req2-flush
> - bdrv_co_flush() calls bdrv_co_flush(bs->file), which finally
> call raw_aio_flush() to send command, but the 1st two requests
> should have been submitted to fs before the flush action

No, bdrv_aio_flush is only guaranteed to flush requests that _completed_ 
before it was sent.

Since we haven't yet told the guest that req0 and req1 are complete, 
there is no need to submit them before req2-flush.

Paolo