RE: [PATCH 1/2] added stream id write support

[Hingkwan Huen <kwan.huen@samsung.com>]

> -----Original Message-----
> From: Jeff Moyer [mailto:jmoyer@redhat.com]
> Sent: Tuesday, April 21, 2015 6:45 AM
> To: kwan.huen
> Cc: Matthew Wilcox; Keith Busch; Jens Axboe; Dimitri John Ledkov; linux-
> nvme@lists.infradead.org; linux-kernel@vger.kernel.org; linux-
> api@vger.kernel.org
> Subject: Re: [PATCH 1/2] added stream id write support
> 
> "kwan.huen" <kwan.huen@samsung.com> writes:
> 
> > ---
> >  drivers/block/nvme-core.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
> > index 85b8036..332341a 100644
> > --- a/drivers/block/nvme-core.c
> > +++ b/drivers/block/nvme-core.c
> > @@ -769,6 +769,9 @@ static int nvme_submit_iod(struct nvme_queue
> *nvmeq, struct nvme_iod *iod,
> >  	if (req->cmd_flags & REQ_RAHEAD)
> >  		dsmgmt |= NVME_RW_DSM_FREQ_PREFETCH;
> >
> > +	if (rq_data_dir(req))
> > +		dsmgmt |= bio_get_streamid(req->bio) << 8;
> > +
> 
> There's no public specification for this, yet.  How many bits are set
aside for
> the stream id?  Do you need to do bounds checking/input validation?  What
> happens on adapters with older firmware when these bits are set?
> 
> Cheers,
> Jeff

Thanks Jeff for the review! 
The patch depends on Jens' recent io-streamid patch set, and the new NVMe
spec we are trying to get approved.
The patch is probably still too early and we'll push this again when Jens'
patches are released and the new spec goes public.
Thanks,
kwan