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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Sun, 25 Nov 2018 12:59:59 -0800
Message-ID: <CAPcyv4hmCsNOZPEAzOLxhFCQpyaG0_9TJvJnyuytQAVEU7_wbA@mail.gmail.com>
Subject: Re: [RFC PATCH v2 0/3] realize dax_operations for dm-snapshot
To:     Huaisheng Ye <yehs2007@zoho.com>
Cc:     linux-nvdimm <linux-nvdimm@lists.01.org>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@redhat.com>,
        device-mapper development <dm-devel@redhat.com>,
        Matthew Wilcox <willy@infradead.org>, zwisler@kernel.org,
        Jan Kara <jack@suse.cz>, Dave Jiang <dave.jiang@intel.com>,
        Vishal L Verma <vishal.l.verma@intel.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        NingTing Cheng <chengnt@lenovo.com>,
        Huaisheng Ye <yehs1@lenovo.com>
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On Tue, Nov 20, 2018 at 7:27 PM Huaisheng Ye <yehs2007@zoho.com> wrote:
>
> From: Huaisheng Ye <yehs1@lenovo.com>
>
> Changes
> v1->v2:
>         Add NULL funtions for origin_dax_direct_access and
>         origin_dax_copy_from/to_iter in order to avoid building
>         error when CONFIG_DAX_DRIVER has NOT been enabled.
>
> [v1]: https://lkml.org/lkml/2018/11/20/759
>
> This series patches are used to realize the dax_operations for dm-snapshot
> with persistent memory device.

How does this interact with mmap write faults if the mapping is dax
and the page needs to be cow'd?