From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B083CCF9E9 for ; Wed, 6 Sep 2023 00:41:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240011AbjIFAle (ORCPT ); Tue, 5 Sep 2023 20:41:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233345AbjIFAlc (ORCPT ); Tue, 5 Sep 2023 20:41:32 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73D599E; Tue, 5 Sep 2023 17:41:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=E7pBRBhK3Jt0eDT1MWkzf/iGRarf5P4om5PK0eit8tA=; b=v/SxE1mymw+1Ba9X0SsuWFk/rh 2PWTEigtMD5GHa7tGO4uIuEEwacTpFK6EHtBFtm12bCOEJoC+H4FMyRdZTrNA96QxjQ+bugm9w6h5 Ve5UbKhE5TceQYcHN2cUi4JAgXs3gEAp2a+uItmHRxVAAyVE9WMk8dsWRbEsKnj4ExKeYFwER8K7z qeBext4m+1sw1osqtEsNkNlSRgU/7aScaXvUwT8WbodHAFcioN2GGV7pBABmsbh2km9tZP9ipBuSC 2UQQ9BhwnXpZp1bsgfBblVVZ+Kx6Cfi1J9GGn4a0RD7npBMsvSn4Nwl6Dzlyt46b9mCqz+ezyP8Ol vwvOyqBw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qdgbi-00F1eQ-8L; Wed, 06 Sep 2023 00:41:22 +0000 Date: Wed, 6 Sep 2023 01:41:22 +0100 From: Matthew Wilcox To: Kent Overstreet Cc: Christoph Hellwig , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-bcachefs@vger.kernel.org, Christian Brauner Subject: Re: [GIT PULL] bcachefs Message-ID: References: <20230903032555.np6lu5mouv5tw4ff@moria.home.lan> <20230906000007.ry5rmk35vt57kppx@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230906000007.ry5rmk35vt57kppx@moria.home.lan> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 05, 2023 at 08:00:07PM -0400, Kent Overstreet wrote: > On Tue, Sep 05, 2023 at 06:24:47AM -0700, Christoph Hellwig wrote: > > Hi Kent, > > > > I thought you'd follow Christians proposal to actually work with > > people to try to use common APIs (i.e. to use iomap once it's been > > even more iter-like, for which I'm still waiting for suggestions), > > and make your new APIs used more widely if they are a good idea > > (which also requires explaining them better) and aim for 6.7 once > > that is done. > > Christoph, I get that iomap is your pet project and you want to make it > better and see it more widely used. > > But the reasons bcachefs doesn't use iomap have been discussed at > length, and I've posted and talked about the bcachefs equivalents of > that code. You were AWOL on those discussions; you consistently say > "bcachefs should use iomap" and then walk away, so those discussions > haven't moved forwards. > > To recap, besides being more iterator like (passing data structures > around with iterators, vs. indirect function calls into the filesystem), > bcachefs also hangs a bit more state off the pagecache, due to being > multi device and also using the same data structure for tracking disk > reservations (because why make the buffered write paths look that up > separately?). I /thought/ the proposal was to use iomap for bcachefs DIO and leave buffered writes for a different day. I agree the iomap buffered write path is inappropriate for bcachefs today. I'd like that to change, but there's a lot of functionality that it would need to support. I don't see the point in keeping bcachefs out of tree for another cycle. Yes, more use of iomap would be great, but I don't think that it being in-tree is going to hinder anything. It's not like it uses bufferheads.