Re: [Qemu-devel] [PATCH v3] sheepdog: implement SD_OP_FLUSH_VDI operation

[MORITA Kazutaka]

At Tue,  3 Apr 2012 16:35:00 +0800,
Liu Yuan wrote:
>  
> +static int coroutine_fn sd_co_flush_to_disk(BlockDriverState *bs)
> +{
> +    BDRVSheepdogState *s = bs->opaque;
> +    SheepdogObjReq hdr = { 0 };
> +    SheepdogObjRsp *rsp = (SheepdogObjRsp *)&hdr;
> +    SheepdogInode *inode = &s->inode;
> +    int ret;
> +    unsigned int wlen = 0, rlen = 0;
> +
> +    if (!s->cache_enabled) {
> +        return 0;
> +    }
> +
> +    hdr.opcode = SD_OP_FLUSH_VDI;
> +    hdr.oid = vid_to_vdi_oid(inode->vdi_id);
> +
> +    ret = do_co_req(s->fd, (SheepdogReq *)&hdr, NULL, &wlen, &rlen);

This will mix the flush request with I/O requests on s->fd.  We can
read s->fd only in aio_read_response() and write only in
add_aio_request(), so please create another connection for flush
operations.

Thanks,

Kazutaka