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Date:   Fri, 5 Oct 2018 09:07:20 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     Sagi Grimberg <sagi@grimberg.me>, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-rdma@vger.kernel.org, linux-nvdimm@lists.01.org,
        linux-block@vger.kernel.org, Stephen Bates <sbates@raithlin.com>,
        Christoph Hellwig <hch@lst.de>,
        Keith Busch <keith.busch@intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jason Gunthorpe <jgg@mellanox.com>,
        Max Gurtovoy <maxg@mellanox.com>,
        Dan Williams <dan.j.williams@intel.com>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Alex Williamson <alex.williamson@redhat.com>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        Jens Axboe <axboe@kernel.dk>,
        Steve Wise <swise@opengridcomputing.com>
Subject: Re: [PATCH v9 13/13] nvmet: Optionally use PCI P2P memory
Message-ID: <20181005070720.GA23725@lst.de>
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On Thu, Oct 04, 2018 at 04:29:19PM -0600, Logan Gunthorpe wrote:
> 
> 
> On 2018-10-04 4:20 p.m., Sagi Grimberg wrote:
> >> +static inline struct device *nvmet_ns_dev(struct nvmet_ns *ns)
> >> +{
> >> +	return disk_to_dev(ns->bdev->bd_disk);
> >> +}
> > 
> > This needs to handle non bdev namespaces.
> 
> As it's coded now the helper never gets called unless ns->bdev is not
> null. But in general, yes you are right, we should probably return NULL
> if ns->bdev is NULL.

I'd rather skip that for now.

> > index ef286b72d958..3d12f5f4568d 100644
> > --- a/drivers/nvme/target/fc.c
> > +++ b/drivers/nvme/target/fc.c
> > @@ -2280,6 +2280,7 @@ nvmet_fc_handle_fcp_rqst(struct nvmet_fc_tgtport 
> > *tgtport,
> >          fod->req.cmd = &fod->cmdiubuf.sqe;
> >          fod->req.rsp = &fod->rspiubuf.cqe;
> >          fod->req.port = tgtport->pe->port;
> > +       fod->req.p2p_client = tgtport->dev;
> > 
> >          /* clear any response payload */
> >          memset(&fod->rspiubuf, 0, sizeof(fod->rspiubuf));
> > --
> 
> Sure, I guess that makes sense. I've never tried it with fc hardware but
> I assume there's no reason it wouldn't work.
> 
> I'll queue these changes up for a v10.

And I'd wait until someone has actually tested this case.