Re: [RFC PATCH v2 0/3] realize dax_operations for dm-snapshot

[Dan Williams]

On Tue, Nov 20, 2018 at 7:27 PM Huaisheng Ye <yehs2007@xxxxxxxx> wrote:
>
> From: Huaisheng Ye <yehs1@xxxxxxxxxx>
>
> 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?