linux-kernel - Re: [PATCH 2/5] dax: fix offset to physical address translation

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Message-ID: <CAPcyv4jqsPuOMMbkjUtNSxd+vJXaoyJXvX_ttGfS12bCyRDtfg@mail.gmail.com>
Date:   Fri, 9 Sep 2016 18:00:14 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>
Cc:     Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH 2/5] dax: fix offset to physical address translation

On Tue, Sep 6, 2016 at 9:49 AM, Dan Williams <dan.j.williams@...el.com> wrote:
> In pgoff_to_phys() 'pgoff' is already relative to base of the dax
> device, so we only need to compare if the current offset is within the
> current resource extent.  Otherwise, we are double accounting the
> resource start offset when translating pgoff to a physical address.
>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

On second look this results in the exact same translation, correct in
both cases.  This is also confirmed by a new ndctl unit test that does
data verification by writing through a /dev/pmem device and the
verifying via a /dev/dax device associated with the same namespace, so
I'm dropping this patch.