Re: [Qemu-devel] [PATCH v6 3/6] tests: in IDE and AHCI tests perform DMA write before flushing

[Eric Blake <eblake@redhat.com>]

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On 07/14/2016 06:29 AM, Denis V. Lunev wrote:
> From: Evgeny Yakovlev <eyakovlev@virtuozzo.com>
> 
> Due to changes in flush behaviour clean disks stopped generating
> flush_to_disk events and IDE and AHCI tests that test flush commands
> started to fail.
> 
> This change adds additional DMA writes to affected tests before sending
> flush commands so that bdrv_flush actually generates flush_to_disk event.
> 
> Signed-off-by: Evgeny Yakovlev <eyakovlev@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Fam Zheng <famz@redhat.com>
> CC: John Snow <jsnow@redhat.com>
> ---
>  tests/ahci-test.c | 34 ++++++++++++++++++++++++++++++++--
>  tests/ide-test.c  | 43 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 75 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/ahci-test.c b/tests/ahci-test.c
> index 57dc44c..d707714 100644
> --- a/tests/ahci-test.c
> +++ b/tests/ahci-test.c
> @@ -1063,11 +1063,34 @@ static void test_dma_fragmented(void)
>      g_free(tx);
>  }
>  
> +/*
> + * Write sector 0 with random data to make AHCI storage dirty

If we ever have a case where we open a disk without specifying -raw, the
random data _might_ resemble some other format and cause probe to
misbehave; as such, we also have code in the block layer that
specifically prevents writes to sector 0 for some data. Should you pick
a different sector than 0, so as to avoid any (remote) possibility that
the random data could change probe results or be rejected?

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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