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

[Sagi Grimberg]

> > > 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).

I think that the accounting exclude I/O that is yielded from the flush
sequence. Don't think its relevant here...