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From: Peter Lieven <pl@kamp.de>
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Date: Tue, 25 Oct 2016 14:03:13 +0200
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Subject: Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with
 non-power-of-2 discard
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To: Paolo Bonzini <pbonzini@redhat.com>, Eric Blake <eblake@redhat.com>, Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>

Am 01.08.2016 um 11:22 schrieb Paolo Bonzini:
>
> On 28/07/2016 04:39, Eric Blake wrote:
>> On 07/27/2016 01:25 AM, Fam Zheng wrote:
>>> On Thu, 07/21 13:34, Eric Blake wrote:
>>>> +    max_write_zeroes = max_write_zeroes / alignment * alignment;
>>> Not using QEMU_ALIGN_DOWN despite patch 3?
>> Looks like I missed that on the rebase. Can fix if there is a reason for
>> a respin.
> Since Stefan acked this, I'm applying the patch and fixing it to use
> QEMU_ALIGN_DOWN.
>
> Paolo

Hi,

I came across a sort of regression we introduced with the dropping of head and tail
of an unaligned discard.

The discard alignment that we use to trim the discard request is just a hint.

I learned on the equallogics that a page (which is this unusal 15MB large) is
unallocated even if the discard happens in pieces. E.g. in slices of 1MB requests.

 From my point of view I would like to restore the old behaviour. What do you think?

Thanks,
Peter