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

[Stefan Hajnoczi]

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;
>> -
>> -    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
request processing - bdrv_co_do_writev() must do everything that
bdrv_aio_writev() and bdrv_write() did.

Stefan