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Subject: Re: [PATCH v7 3/8] fsdax: Replace mmap entry in case of CoW
To:     Christoph Hellwig <hch@lst.de>,
        Dan Williams <dan.j.williams@intel.com>
CC:     "Darrick J. Wong" <djwong@kernel.org>,
        linux-xfs <linux-xfs@vger.kernel.org>,
        david <david@fromorbit.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux NVDIMM <nvdimm@lists.linux.dev>,
        Goldwyn Rodrigues <rgoldwyn@suse.de>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Matthew Wilcox <willy@infradead.org>,
        Goldwyn Rodrigues <rgoldwyn@suse.com>,
        Ritesh Harjani <riteshh@linux.ibm.com>
References: <20210816060359.1442450-1-ruansy.fnst@fujitsu.com>
 <20210816060359.1442450-4-ruansy.fnst@fujitsu.com>
 <CAPcyv4iOSxoy-qGfAd3i4uzwfDX0t1xTmyM0pNd+-euVMDUwrQ@mail.gmail.com>
 <20210823125715.GA15536@lst.de>
From:   Shiyang Ruan <ruansy.fnst@fujitsu.com>
Message-ID: <d4f07aef-ad9f-7de9-c112-a40e2022b399@fujitsu.com>
Date:   Fri, 27 Aug 2021 11:22:21 +0800
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On 2021/8/23 20:57, Christoph Hellwig wrote:
> On Thu, Aug 19, 2021 at 03:54:01PM -0700, Dan Williams wrote:
>>
>> static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf,
>>                                const struct iomap_iter *iter, void
>> *entry, pfn_t pfn,
>>                                unsigned long flags)
>>
>>
>>>   {
>>> +       struct address_space *mapping = vmf->vma->vm_file->f_mapping;
>>>          void *new_entry = dax_make_entry(pfn, flags);
>>> +       bool dirty = insert_flags & DAX_IF_DIRTY;
>>> +       bool cow = insert_flags & DAX_IF_COW;
>>
>> ...and then calculate these flags from the source data. I'm just
>> reacting to "yet more flags".
> 
> Except for the overly long line above that seems like a good idea.
> The iomap_iter didn't exist for most of the time this patch has been
> around.
> 

So should I reuse the iter->flags to pass the insert_flags? (left shift 
it to higher bits)

--
Thanks,
Ruan.