linux-kernel - Re: [PATCH v7 8/8] fsdax: add exception for reflinked files

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Message-ID: <YWkh3mNc2+roMn40@infradead.org>
Date:   Thu, 14 Oct 2021 23:38:22 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     "Darrick J. Wong" <djwong@...nel.org>
Cc:     Shiyang Ruan <ruansy.fnst@...itsu.com>,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, dan.j.williams@...el.com,
        david@...morbit.com, hch@...radead.org, jane.chu@...cle.com
Subject: Re: [PATCH v7 8/8] fsdax: add exception for reflinked files

On Thu, Oct 14, 2021 at 12:24:50PM -0700, Darrick J. Wong wrote:
> It feels a little dangerous to have page->mapping for shared storage
> point to an actual address_space when there are really multiple
> potential address_spaces out there.  If the mm or dax folks are ok with
> doing this this way then I'll live with it, but it seems like you'd want
> to leave /some/ kind of marker once you know that the page has multiple
> owners and therefore regular mm rmap via page->mapping won't work.

Yes, I thing poisoning page->mapping for the rmap enabled case seems
like a better idea.