From: Vivek Goyal <vgoyal@redhat.com>
To: Dan Williams <dan.j.williams@intel.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: Thu, 6 Feb 2020 09:34:43 -0500 [thread overview]
Message-ID: <20200206143443.GB12036@redhat.com> (raw)
In-Reply-To: <CAPcyv4iY=gw86UDLqpiCtathGXRUuxOMuU=unwxzA-cm=0x+Sg@mail.gmail.com>
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?
pgoff_t = phys_addr_t/PAGE_SIZE;
offset = phys_addr_t & (PAGE_SIZE - 1);
And pgoff can easily be converted into sectors which dm/md can use for
mapping and come up with pgoff in target device.
Anyway, I am fine with anything.
Thanks
Vivek
next prev parent reply other threads:[~2020-02-06 14:34 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 [this message]
2020-02-07 16:58 ` Dan Williams
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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