Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 19 Sep 2019 05:11:28 +0800
From:   Gao Xiang <hsiangkao@aol.com>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, devel@linuxdriverproject.org
Subject: Re: [GIT PULL] Staging/IIO driver patches for 5.4-rc1
Message-ID: <20190918211123.GA22600@hsiangkao-HP-ZHAN-66-Pro-G1>
References: <20190918114754.GA1899504@kroah.com>
 <20190918182412.GA9924@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190918182412.GA9924@infradead.org>
User-Agent: Mutt/1.9.4 (2018-02-28)
Content-Length: 774
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Christoph,

On Wed, Sep 18, 2019 at 11:24:12AM -0700, Christoph Hellwig wrote:
> Just as a note of record:  I don't think either file system move
> is a good idea.  erofs still needs a lot of work, especially in
> interacting with the mm code like abusing page->mapping.

I know what you mean, that is a known stuff in the TODO list,
Z_EROFS_MAPPING_STAGING page->mapping just be used as a temporary
page mark since page->private is already pointed to another
structure, It's now be marked as an non-movable and anon pseudo
mapping and most mm code just skip this case.

I think a better way is to use a real address_space structure for
page->mapping to point. It's easy to update but I need some time
to verify. If I am wrong, please point it out...

Thanks,
Gao Xiang