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Date: Thu, 22 Oct 2009 10:31:56 +0200
From: Christoph Hellwig <hch@lst.de>
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Subject: [Qemu-devel] Re: [PATCH] raw/linux-aio: Also initialize POSIX AIO
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To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>

On Tue, Oct 20, 2009 at 12:12:55PM +0200, Kevin Wolf wrote:
> On that note, falling back to POSIX AIO means that paio_submit is called
> with a Linux AIO aio_ctx. Which works because this parameter is unused
> anyway, but am I the only one to find this ugly?
> 
> What is the public interface of paio_submit meant to look like at all?
> If aio_ctx is guaranteed to be unused, why not drop it or pass NULL at
> least? And if it could be used some time in the future, the raw block
> driver needs to be fixed.

Agreed.  Cared to send a patch?

> That said, I don't even think that the raw block driver is the right
> place to distinguish between different AIO variants. Having a generic
> aio_submit that calls the right AIO driver depending on the context
> would be much cleaner. This would also mean that laio_submit handles the
> fallback to paio_submit on its own, which I think is much cleaner than
> teaching raw about the capabilities of each driver.

Seems a bit overkill until we get even more AIO variants at least.  And
yes, that whole area is really ugly.