From: Dan Williams <dan.j.williams@intel.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
device-mapper development <dm-devel@redhat.com>
Subject: Re: [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range
Date: Fri, 7 Feb 2020 08:58:45 -0800 [thread overview]
Message-ID: <CAPcyv4j_SN3cyeVfkVQBEniGBZ+XgmCx3ezBJ_KwiUpawaq40g@mail.gmail.com> (raw)
In-Reply-To: <20200206143443.GB12036@redhat.com>
On Thu, Feb 6, 2020 at 6:35 AM Vivek Goyal <vgoyal@redhat.com> wrote:
>
> On Wed, Feb 05, 2020 at 04:40:44PM -0800, Dan Williams wrote:
> > On Wed, Feb 5, 2020 at 12:03 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> > >
> > > On Wed, Feb 05, 2020 at 10:30:50AM -0800, Christoph Hellwig wrote:
> > > > > + /*
> > > > > + * There are no users as of now. Once users are there, fix dm code
> > > > > + * to be able to split a long range across targets.
> > > > > + */
> > > >
> > > > This comment confused me. I think this wants to say something like:
> > > >
> > > > /*
> > > > * There are now callers that want to zero across a page boundary as of
> > > > * now. Once there are users this check can be removed after the
> > > > * device mapper code has been updated to split ranges across targets.
> > > > */
> > >
> > > Yes, that's what I wanted to say but I missed one line. Thanks. Will fix
> > > it.
> > >
> > > >
> > > > > +static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
> > > > > + unsigned int offset, size_t len)
> > > > > +{
> > > > > + int rc = 0;
> > > > > + phys_addr_t phys_pos = pgoff * PAGE_SIZE + offset;
> > > >
> > > > Any reason not to pass a phys_addr_t in the calling convention for the
> > > > method and maybe also for dax_zero_page_range itself?
> > >
> > > I don't have any reason not to pass phys_addr_t. If that sounds better,
> > > will make changes.
> >
> > The problem is device-mapper. That wants to use offset to route
> > through the map to the leaf device. If it weren't for the firmware
> > communication requirement you could do:
> >
> > dax_direct_access(...)
> > generic_dax_zero_page_range(...)
> >
> > ...but as long as the firmware error clearing path is required I think
> > we need to do pass the pgoff through the interface and do the pgoff to
> > virt / phys translation inside the ops handler.
>
> Hi Dan,
>
> Drivers can easily convert offset into dax device (say phys_addr_t) to
> pgoff and offset into page, isn't it?
It's not a phys_addr_t it's a 64-bit device relative offset.
next prev parent reply other threads:[~2020-02-07 16:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 20:00 [RFC PATCH 0/5][V2] dax,pmem: Provide a dax operation to zero range of memory Vivek Goyal
2020-02-03 20:00 ` [PATCH 1/5] dax, pmem: Add a dax operation zero_page_range Vivek Goyal
2020-02-05 18:30 ` Christoph Hellwig
2020-02-05 20:02 ` Vivek Goyal
2020-02-06 0:40 ` Dan Williams
2020-02-06 7:41 ` Christoph Hellwig
2020-02-07 16:57 ` Dan Williams
2020-02-07 17:01 ` Vivek Goyal
2020-02-07 17:06 ` Dan Williams
2020-02-06 14:34 ` Vivek Goyal
2020-02-07 16:58 ` Dan Williams [this message]
2020-02-03 20:00 ` [PATCH 2/5] s390,dax: Add dax zero_page_range operation to dcssblk driver Vivek Goyal
2020-02-05 18:32 ` Christoph Hellwig
2020-02-05 20:04 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 3/5] dm,dax: Add dax zero_page_range operation Vivek Goyal
2020-02-05 18:33 ` Christoph Hellwig
2020-02-07 16:34 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 4/5] dax,iomap: Start using dax native zero_page_range() Vivek Goyal
2020-02-05 18:33 ` Christoph Hellwig
2020-02-05 20:10 ` Vivek Goyal
2020-02-07 15:31 ` Vivek Goyal
2020-02-03 20:00 ` [PATCH 5/5] dax,iomap: Add helper dax_iomap_zero() to zero a range Vivek Goyal
2020-02-04 5:17 ` kbuild test robot
2020-02-05 18:36 ` Christoph Hellwig
2020-02-05 20:15 ` Vivek Goyal
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