Re: [Qemu-devel] Re: [PATCH 09/21] Introduce event-tap.

Yoshiaki Tamura
2010-11-30T09:28:58Z

2010/11/30 Marcelo Tosatti <mtosatti@redhat.com>:
> On Thu, Nov 25, 2010 at 03:06:48PM +0900, Yoshiaki Tamura wrote:
>> event-tap controls when to start FT transaction, and provides proxy
>> functions to called from net/block devices.  While FT transaction, it
>> queues up net/block requests, and flush them when the transaction gets
>> completed.
>>
>> Signed-off-by: Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>
>> Signed-off-by: OHMURA Kei <ohmura.kei@lab.ntt.co.jp>
>
>> +static void event_tap_alloc_blk_req(EventTapBlkReq *blk_req,
>> +                                    BlockDriverState *bs, BlockRequest *reqs,
>> +                                    int num_reqs, BlockDriverCompletionFunc *cb,
>> +                                    void *opaque, bool is_multiwrite)
>> +{
>> +    int i;
>> +
>> +    blk_req->num_reqs = num_reqs;
>> +    blk_req->num_cbs = num_reqs;
>> +    blk_req->device_name = qemu_strdup(bs->device_name);
>> +    blk_req->is_multiwrite = is_multiwrite;
>> +
>> +    for (i = 0; i < num_reqs; i++) {
>> +        blk_req->reqs[i].sector = reqs[i].sector;
>> +        blk_req->reqs[i].nb_sectors = reqs[i].nb_sectors;
>> +        blk_req->reqs[i].qiov = reqs[i].qiov;
>> +        blk_req->reqs[i].cb = cb;
>> +        blk_req->reqs[i].opaque = opaque;
>> +        blk_req->cb[i] = reqs[i].cb;
>> +        blk_req->opaque[i] = reqs[i].opaque;
>> +    }
>> +}
>
> bdrv_aio_flush should also be logged, so that guest initiated flush is
> respected on replay.

In the current implementation w/o flush logging, there might be
order inversion after replay?

Yoshi