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 X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68752C38BFA for ; Mon, 24 Feb 2020 22:17:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 254BC218AC for ; Mon, 24 Feb 2020 22:17:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="pB+5oZWV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 254BC218AC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B5DEC6B0003; Mon, 24 Feb 2020 17:17:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AE7F16B0005; Mon, 24 Feb 2020 17:17:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D6FB6B0006; Mon, 24 Feb 2020 17:17:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0243.hostedemail.com [216.40.44.243]) by kanga.kvack.org (Postfix) with ESMTP id 8149E6B0003 for ; Mon, 24 Feb 2020 17:17:51 -0500 (EST) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 30B81181AC9BF for ; Mon, 24 Feb 2020 22:17:51 +0000 (UTC) X-FDA: 76526433942.15.scale73_619cf595f7a60 X-HE-Tag: scale73_619cf595f7a60 X-Filterd-Recvd-Size: 3208 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Mon, 24 Feb 2020 22:17:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=SD1yx0YoAU9Bzlni+o86AkG96/rc/8SSS4sRPjtuIYU=; b=pB+5oZWVTu+RlW3J/EESOvRbJB BhenyWBT/6m8GOFdFElQJCxMbpx1xaeKthjka5pjD6jbGH4Yb4isWW678N/C1jEWJrUjOlo+gO3Wr Fc+GPx4uW5jDWOEduKUpXye86IX3XAlQeX17eAH1O9MrALkq72vBwumB3SryCX1PQ21Cu5rjB+LH+ LFNujmpdrRUyH0LpGKYHkHsi54xutUiobEdAg4riDPA5mRYuMsyFoBP03wVQn0kFpk94BKaabAiRg qtA4ThIZJjuV+zv0m358v08Y+jltVma43bg6qDq7T97btYMe7X25tdyvSveobCz77SFx4CC7cEIkX lGoig/Dw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6M2v-00087x-1f; Mon, 24 Feb 2020 22:17:49 +0000 Date: Mon, 24 Feb 2020 14:17:49 -0800 From: Christoph Hellwig To: Matthew Wilcox Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org Subject: Re: [PATCH v7 21/24] iomap: Restructure iomap_readpages_actor Message-ID: <20200224221749.GA22231@infradead.org> References: <20200219210103.32400-1-willy@infradead.org> <20200219210103.32400-22-willy@infradead.org> <20200220154741.GB19577@infradead.org> <20200220162404.GY24185@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200220162404.GY24185@bombadil.infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 20, 2020 at 08:24:04AM -0800, Matthew Wilcox wrote: > On Thu, Feb 20, 2020 at 07:47:41AM -0800, Christoph Hellwig wrote: > > On Wed, Feb 19, 2020 at 01:01:00PM -0800, Matthew Wilcox wrote: > > > From: "Matthew Wilcox (Oracle)" > > > > > > By putting the 'have we reached the end of the page' condition at the end > > > of the loop instead of the beginning, we can remove the 'submit the last > > > page' code from iomap_readpages(). Also check that iomap_readpage_actor() > > > didn't return 0, which would lead to an endless loop. > > > > I'm obviously biassed a I wrote the original code, but I find the new > > very much harder to understand (not that the previous one was easy, this > > is tricky code..). > > Agreed, I found the original code hard to understand. I think this is > easier because now cur_page doesn't leak outside this loop, so it has > an obvious lifecycle. I really don't like this patch, and would prefer if the series goes ahead without it, as the current sctructure works just fine even with the readahead changes.