From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7878E72 for ; Tue, 21 Sep 2021 08:14:18 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 241FF67373; Tue, 21 Sep 2021 10:14:15 +0200 (CEST) Date: Tue, 21 Sep 2021 10:14:14 +0200 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , Shiyang Ruan , linux-xfs@vger.kernel.org, dan.j.williams@intel.com, david@fromorbit.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, rgoldwyn@suse.de, viro@zeniv.linux.org.uk, willy@infradead.org Subject: Re: [PATCH v9 7/8] xfs: support CoW in fsdax mode Message-ID: <20210921081414.GA28927@lst.de> References: <20210915104501.4146910-1-ruansy.fnst@fujitsu.com> <20210915104501.4146910-8-ruansy.fnst@fujitsu.com> <20210916002227.GD34830@magnolia> <20210916063251.GE13306@lst.de> <20210917153304.GB10250@magnolia> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210917153304.GB10250@magnolia> User-Agent: Mutt/1.5.17 (2007-11-01) On Fri, Sep 17, 2021 at 08:33:04AM -0700, Darrick J. Wong wrote: > > More importantly before we can merge this series we also need the VM > > level support for reflink-aware reverse mapping. So while this series > > here is no in a good enough shape I don't see how we could merge it > > without that other series as we'd have to disallow mmap for reflink+dax > > files otherwise. > > I've forgotten why we need mm level reverse mapping again? The pmem > poison stuff can use ->media_failure (or whatever it was called, > memory_failure?) to find all the owners and notify them. Was there > some other accounting reason that fell out of my brain? > > I'm more afraid of 'sharing pages between files needs mm support' > sparking another multi-year folioesque fight with the mm people. Because of the way page->mapping is used by DAX. But I think this is mostly under control in the other series.