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Date: Mon, 24 Oct 2011 11:26:06 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 0/2] block: Write out internal caches even
	with cache=unsafe
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To: Kevin Wolf <kwolf@redhat.com>
Cc: avi@redhat.com, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org

On 10/24/2011 10:54 AM, Kevin Wolf wrote:
> >  I don't know... checking BDRV_O_NO_FLUSH in the drivers rather than in
> >  the generic code sounds like a layering violation.  Perhaps what you're
> >  after is a separation of bdrv_co_flush from bdrv_{,co_,aio_}fsync?  Then
> >  BDRV_O_NO_FLUSH (better renamed to BDRV_O_NO_FSYNC...) would only
> >  inhibit the latter.
>
> Why? All other cache related BDRV_O_* flags are interpreted by the block
> drivers, so why should BDRV_O_NO_FLUSH be special?

You're changing the API and asking for possibly non-trivial changes in 
all protocol drivers, in order to accomodate semantics that all format 
drivers potentially could desire.  So I wonder if the problem is simply 
that the current API is not expressive enough.

Paolo