From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 122812FD1DA; Tue, 10 Mar 2026 14:48:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773154122; cv=none; b=ZGGtL0m9DdW1Yw7olbme9XOa+ul9uGFwE1CcPUP5Co4scP2JaRUP1Jf0qVhxRV6G6IZoeXY38L4qLuhwvXCwSkYe/59QgOmcc7gYaCGuT3FSYYiEPpLMAmH4+iIhkNNaNYJsyK5uU331u7okIFlbJfTljVG3jLs8qAm3qTIu4RE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773154122; c=relaxed/simple; bh=/ERBHzm4gpqPnWOIhVKShzxiAhUaoHBj4twlF09ISLY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ADZB4gzTNCFuHe7YhLzE5Y5M7iYqvdtDY+sM8VPhHH1wAgbZmwiHhw2WeNzU6aHV3hSM5KoLE/mXwQ0/R8YC38HyDgYJXjR7c6cw3BmmukqjiM01kapDEpEdVfOgPvYAkyUNCsYeIYWdy3B9EQdPAOvgibzykJKi1rmWjtNHOQo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QjNRvFVA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QjNRvFVA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B65F4C19423; Tue, 10 Mar 2026 14:48:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773154121; bh=/ERBHzm4gpqPnWOIhVKShzxiAhUaoHBj4twlF09ISLY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QjNRvFVAhYKhcwxcAoC7kakqXSJw+wibAT6J49KsZlMN64uISzN1HbDrd4uaf3KsV uIWnhQPxSyV9U4NWAx1il9+7WgowH04FSx0M4M5tITOwFeAiPoiDVtYeCbWtxp9eWI wIF6B9xVSExHWU5/izTDNYff7MdMkZDyjIOe5ct9IzfXwM1SeR+3P4FYPtE6b5UIYY W94HkoiMZLCSE4uaL35WObyIFWSguJk2Mfqjo3jy+oD/0npRLym4HNRhpl0LEBbuhy nrvoAjb0mCMmKJbnnsTrgeXiVhYM1HldDk6zkBIzfzHjv9+7yqJLl8kfqwv3wIQxcq co9gyL0nhyokQ== Date: Tue, 10 Mar 2026 07:48:41 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Brian Foster , linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v3 2/8] xfs: flush dirty pagecache over hole in zoned mode zero range Message-ID: <20260310144841.GM1105363@frogsfrogsfrogs> References: <20260309134506.167663-1-bfoster@redhat.com> <20260309134506.167663-3-bfoster@redhat.com> <20260309172219.GM6033@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Mar 09, 2026 at 11:47:23PM -0700, Christoph Hellwig wrote: > On Mon, Mar 09, 2026 at 10:22:19AM -0700, Darrick J. Wong wrote: > > Why does the mapping disappear out of both data and cow forks between > > writeback setup and completion? IIRC it is because the writeback ioend > > effectively owns the unwritten mapping. We want another writer thread > > to see the hole and reserve its own out-of-place write because the write > > mapping that writeback's working on is immutable once the disk actually > > writes it. Right? > > Mostly because we don't have good code to turn a COW fork delalloc > mapping into a data fork written one. Unwritten extents do not actually > exist for zoned RT forks. > > > I wonder if we could stash a delalloc mapping in the cow fork with zero > > indlen during writeback to signal "get a real zoned space reservation"? > > What would that help with? Faking out iomap zeroing, and probably not much else. --D