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 09:06:32 -0800 [thread overview]
Message-ID: <CAPcyv4g8jUhaKXhoh-1cvE4oi2v0JQcLrnFUW9zsRiC4F-7-zQ@mail.gmail.com> (raw)
In-Reply-To: <20200207170150.GC11998@redhat.com>
On Fri, Feb 7, 2020 at 9:02 AM Vivek Goyal <vgoyal@redhat.com> wrote:
>
> On Fri, Feb 07, 2020 at 08:57:39AM -0800, Dan Williams wrote:
> > On Wed, Feb 5, 2020 at 11:41 PM Christoph Hellwig <hch@infradead.org> wrote:
> > >
> > > On Wed, Feb 05, 2020 at 04:40:44PM -0800, Dan Williams wrote:
> > > > > 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.
> > >
> > > Maybe phys_addr_t was the wrong type - but why do we split the offset
> > > into the block device argument into a pgoff and offset into page instead
> > > of a single 64-bit value?
> >
> > Oh, got it yes, that looks odd for sub-page zeroing. Yes, let's just
> > have one device relative byte-offset.
>
> So what's the best type to represent this offset. "u64" or "phys_addr_t"
> or "loff_t" or something else. I like phys_addr_t followed by u64.
Let's make it u64.
phys_addr_t has already led to confusion in this thread because the
first question I ask when I read it is "why call ->direct_access() to
do the translation when you already have the physical address?".
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next prev parent reply other threads:[~2020-02-07 17:06 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 [this message]
2020-02-06 14:34 ` Vivek Goyal
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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