[PATCH v4 net-next 07/21] nvme-tcp: Add DDP data-path

[Boris Pismenny]

On 17/02/2021 19:00, David Ahern wrote:
> On 2/17/21 7:01 AM, Or Gerlitz wrote:
>>>> @@ -1136,6 +1265,10 @@ static int nvme_tcp_try_send_cmd_pdu(struct nvme_tcp_request *req)
>>>>       else
>>>>               flags |= MSG_EOR;
>>>>
>>>> +     if (test_bit(NVME_TCP_Q_OFF_DDP, &queue->flags) &&
>>>> +         blk_rq_nr_phys_segments(rq) && rq_data_dir(rq) == READ)
>>>> +             nvme_tcp_setup_ddp(queue, pdu->cmd.common.command_id, rq);
>>>> +
>>>
>>> For consistency, shouldn't this be wrapped in the CONFIG_TCP_DDP check too?
>>
>> We tried to avoid the wrapping in some places where it was
>> possible to do without adding confusion, this one is a good
>> example IMOH.
>>
>>
> 
> The above (and other locations like it) can easily be put into a helper
> that has logic when the CONFIG is enabled and compiles out when not.
> Consistency makes for simpler, cleaner code for optional features.
> 

The above is consistent in the sense that we wrap only places that are
absolutely necessary, so as to avoid ifdefs as much as possible.

Specifically, here and in ddp_teardown, we will add a wrapper to reduce
clutter if offload is not used.