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Date: Wed, 13 Aug 2008 17:13:46 +0300
From: Gleb Natapov <gleb@qumranet.com>
Subject: Re: [Qemu-devel] [PATCH] Flush pending AIO on reboot and shutdown.
Message-ID: <20080813141346.GC17567@minantech.com>
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To: qemu-devel@nongnu.org

On Wed, Aug 13, 2008 at 08:52:50AM -0500, Anthony Liguori wrote:
> Gleb Natapov wrote:
>> If there is outstanding IDE IO when BIOS starts execution then IDE
>> commands sent by BIOS will interfere with it and will leave IDE
>> subsystem in unpredictable state. This can happen when system reboots
>> unexpectedly without waiting for IO completion. Flushing IO before exit
>> prevents data lose.
>>
>> Signed-off-by: Gleb Natapov <gleb@qumranet.com>
>> ---
>>
>>  vl.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/vl.c b/vl.c
>> index e42ae64..afa2a3a 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -7553,6 +7553,7 @@ static int main_loop(void)
>>              if (reset_requested) {
>>                  reset_requested = 0;
>>                  qemu_system_reset();
>> +                qemu_aio_flush();
>>   
>
> Perhaps the aio block layer should do qemu_register_reset() with a  
> handler that does a flush.
>
I though about doing it this way, but then I saw that qemu_register_reset()
is used for HW reset notification only. I don't think that hw/ide.c is the
right place to register the notifier though, so I decided to call it
explicitly. Do you think I should do qemu_register_reset() in block.c?

--
			Gleb.