Re: [PATCH v8 13/13] nvmet-passthru: support block accounting

[Logan Gunthorpe]

On 2019-09-06 6:00 p.m., Sagi Grimberg wrote:
> 
>> Support block disk accounting by setting the RQF_IO_STAT flag
>> and gendisk in the request.
>>
>> After this change, IO counts will be reflected correctly in
>> /proc/diskstats for drives being used by passthru.
>>
>> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
>> ---
>>   drivers/nvme/target/io-cmd-passthru.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvme/target/io-cmd-passthru.c b/drivers/nvme/target/io-cmd-passthru.c
>> index 7557927a3451..63f12750a80d 100644
>> --- a/drivers/nvme/target/io-cmd-passthru.c
>> +++ b/drivers/nvme/target/io-cmd-passthru.c
>> @@ -410,6 +410,9 @@ static struct request *nvmet_passthru_blk_make_request(struct nvmet_req *req,
>>   	if (unlikely(IS_ERR(rq)))
>>   		return rq;
>>   
>> +	if (blk_queue_io_stat(q) && cmd->common.opcode != nvme_cmd_flush)
>> +		rq->rq_flags |= RQF_IO_STAT;

Thanks for the review!

> Does flush has data bytes in the request? Why the special casing?

Well it was special cased in the vanilla blk account flow... But I think
it's required to be special cased so the IO and in_flight counts don't
count flushes (as they do not for regular block device traffic).

Logan