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 BB4D9C6FD1D for ; Thu, 23 Mar 2023 14:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231960AbjCWOvx (ORCPT ); Thu, 23 Mar 2023 10:51:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56330 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231945AbjCWOvu (ORCPT ); Thu, 23 Mar 2023 10:51:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1203AEFA8; Thu, 23 Mar 2023 07:51:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0B3506277C; Thu, 23 Mar 2023 14:51:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59447C433D2; Thu, 23 Mar 2023 14:51:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679583070; bh=BeVDhTGiIgig9r6zgcWWACDJTJQsieohN3u1+udvr4c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EvSDVKmaRP2hOQQZgVTETO8M7gK7tQu3hLC6odeY4jxOqIyqO+Kti1oz8IQVNIg11 sGODTtCQpDy1cjUtsPUngGa26pR1AnIoK+EETfCayMY94TtFtt/r5fzAWT4D4OOqJB Xn7CS/RfLdGA1MBmIjXg/m7R6PFOPMGnQvdGSg+eINMZVyWliVrDGhqPm0X+7x95sB +KfXx1IYJ5fxLuyo010Ye6lrvbfFUJyMUFTLwanbKPnnMRfLl1G+sGFNebT5pPZ2eJ pMeWlXyfx6v1ig5oj1N+EHuqF/cYGqeynz/nLf4D4Cck/CmHhECww3vBZbccXlxpwd i90Gtl0y4xicw== Date: Thu, 23 Mar 2023 07:51:09 -0700 From: "Darrick J. Wong" To: Matthew Wilcox Cc: Ritesh Harjani , Theodore Tso , Andreas Dilger , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 04/31] ext4: Convert ext4_finish_bio() to use folios Message-ID: <20230323145109.GA466457@frogsfrogsfrogs> References: <20230126202415.1682629-5-willy@infradead.org> <87ttyy1bz4.fsf@doe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Thu, Mar 23, 2023 at 03:26:43AM +0000, Matthew Wilcox wrote: > On Mon, Mar 06, 2023 at 02:40:55PM +0530, Ritesh Harjani wrote: > > "Matthew Wilcox (Oracle)" writes: > > > > > Prepare ext4 to support large folios in the page writeback path. > > > > Sure. I am guessing for ext4 to completely support large folio > > requires more work like fscrypt bounce page handling doesn't > > yet support folios right? > > > > Could you please give a little background on what all would be required > > to add large folio support in ext4 buffered I/O path? > > (I mean ofcourse other than saying move ext4 to iomap ;)) > > > > What I was interested in was, what other components in particular for > > e.g. fscrypt, fsverity, ext4's xyz component needs large folio support? > > > > And how should one go about in adding this support? So can we move > > ext4's read path to have large folio support to get started? > > Have you already identified what all is missing from this path to > > convert it? > > Honestly, I don't know what else needs to be done beyond this patch > series. I can point at some stuff and say "This doesn't work", but in > general, you have to just enable it and see what breaks. A lot of the > buffer_head code is not large-folio safe right now, so that's somewhere > to go and look. Or maybe we "just" convert to iomap, and never bother > fixing the bufferhead code for large folios. Yes. Let's leave bufferheads in the legacy doo-doo-dooooo basement instead of wasting more time on them. Ideally we'd someday run all the filesystems through: bufferheads -> iomap with bufferheads -> iomap with folios -> iomap with large folios -> retire to somewhere cheaper than Hawaii --D > > > Also set the actual error in the mapping, not just -EIO. > > > > Right. I looked at the history and I think it always just had EIO. > > I think setting the actual err in mapping_set_error() is the right thing > > to do here. > > > > > > > > Signed-off-by: Matthew Wilcox (Oracle) > > > > w.r.t this patch series. I reviewed the mechanical changes & error paths > > which converts ext4 ext4_finish_bio() to use folio. > > > > The changes looks good to me from that perspective. Feel free to add - > > Reviewed-by: Ritesh Harjani (IBM) > > Thanks!