Re: [Qemu-devel] [PATCH 3/6] block: switch bdrv_read()/bdrv_write() to coroutines

[Zhi Yong Wu]

On Wed, Oct 12, 2011 at 5:03 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Tue, Oct 11, 2011 at 7:44 AM, Zhi Yong Wu <address@hidden> wrote:
>> On Thu, Oct 6, 2011 at 12:17 AM, Stefan Hajnoczi
>> <address@hidden> wrote:
>>> @@ -1101,36 +1144,7 @@ static void set_dirty_bitmap(BlockDriverState *bs, 
>>> int64_t sector_num,
>>>  int bdrv_write(BlockDriverState *bs, int64_t sector_num,
>>>                const uint8_t *buf, int nb_sectors)
>>>  {
>>> -    BlockDriver *drv = bs->drv;
>>> -
>>> -    if (!bs->drv)
>>> -        return -ENOMEDIUM;
>>> -
>>> -    if (bdrv_has_async_rw(drv) && qemu_in_coroutine()) {
>>> -        QEMUIOVector qiov;
>>> -        struct iovec iov = {
>>> -            .iov_base = (void *)buf,
>>> -            .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
>>> -        };
>>> -
>>> -        qemu_iovec_init_external(&qiov, &iov, 1);
>>> -        return bdrv_co_writev(bs, sector_num, nb_sectors, &qiov);
>>> -    }
>>> -
>>> -    if (bs->read_only)
>>> -        return -EACCES;
>>> -    if (bdrv_check_request(bs, sector_num, nb_sectors))
>>> -        return -EIO;
How about the above four lines of codes?
>>> -
>>> -    if (bs->dirty_bitmap) {
>>> -        set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
>>> -    }
>>> -
>>> -    if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
>>> -        bs->wr_highest_sector = sector_num + nb_sectors - 1;
>>> -    }
>> The above codes are removed, will it be safe?
>
> If you are checking that removing bs->wr_highest_sector code is okay,
> then yes, it is safe because bdrv_co_do_writev() does the dirty bitmap
> and wr_highest_sector updates.  We haven't lost any code by unifying
OK. got it. thanks.
> request processing - bdrv_co_do_writev() must do everything that
> bdrv_aio_writev() and bdrv_write() did.
>
> Stefan
>



-- 
Regards,

Zhi Yong Wu