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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 C6C60C433E7 for ; Thu, 15 Oct 2020 17:59:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5792D22263 for ; Thu, 15 Oct 2020 17:59:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="m21slifx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732170AbgJOR6v (ORCPT ); Thu, 15 Oct 2020 13:58:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732156AbgJOR6u (ORCPT ); Thu, 15 Oct 2020 13:58:50 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40A34C061755; Thu, 15 Oct 2020 10:58:50 -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=x+XQ7VEyYNfvRvizRGPoAdTEAMGVk8qPQWatjzYSgQw=; b=m21slifxK1bGUo9NkuLnasLmGW W7j1mSzLsl8lqkNcmNBEmyamMl2n/iSza8Fv9vJdGtVQIw2/kDlRcMmM4PWbe5eP6FTvI4xm0WOWP 4Adx+LchNEcYX2u8R/hnI8+L4xfRz5R7/ZW9gYaZ59Wva288nDtTL0QGvEDQcyQNBdTqXo87Bl3HW E62GWuauRw2KoIGK3HW5V9LXG8lMy3MQUVaq3gY0yr4/hMeSjIpZfqFbIV5olX2c1do/vAiTNpYlO 890vukb4WHYvxnqK7wVoxPPIDsWceSIRHULvymZsZRjmZLVpToKJoS//KCJAy1r/TgDXANhlomCkj PpgfwI1A==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT7Wa-00018B-31; Thu, 15 Oct 2020 17:58:48 +0000 Date: Thu, 15 Oct 2020 18:58:48 +0100 From: Christoph Hellwig To: Matthew Wilcox Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, v9fs-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, linux-mtd@lists.infradead.org, Richard Weinberger , linux-xfs@vger.kernel.org Subject: Re: [PATCH v2 16/16] iomap: Make readpage synchronous Message-ID: <20201015175848.GA4145@infradead.org> References: <20201009143104.22673-1-willy@infradead.org> <20201009143104.22673-17-willy@infradead.org> <20201015094203.GA21420@infradead.org> <20201015164333.GA20115@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201015164333.GA20115@casper.infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Oct 15, 2020 at 05:43:33PM +0100, Matthew Wilcox wrote: > On Thu, Oct 15, 2020 at 10:42:03AM +0100, Christoph Hellwig wrote: > > > +static void iomap_read_page_end_io(struct bio_vec *bvec, > > > + struct completion *done, bool error) > > > > I really don't like the parameters here. Part of the problem is > > that ctx is only assigned to bi_private conditionally, which can > > easily be fixed. The other part is the strange bool error when > > we can just pass on bi_stats. See the patch at the end of what > > I'd do intead. > > I prefer assigning ctx conditionally to propagating the knowledge > that !rac means synchronous. I've gone with this: And I really hate these kinds of conditional assignments. If the ->rac check is too raw please just add an explicit bool synchronous : 1; flag. > @@ -340,16 +335,12 @@ iomap_readpage(struct page *page, const struct iomap_ops * > ops) > > if (ctx.bio) { > submit_bio(ctx.bio); > + if (ret > 0) > + ret = blk_status_to_errno(ctx.status); > } > > - wait_for_completion(&ctx.done); > if (ret >= 0) > - ret = blk_status_to_errno(ctx.status); > - if (ret == 0) > return AOP_UPDATED_PAGE; > unlock_page(page); > return ret; > > > ... there's no need to call blk_status_to_errno if we never submitted a bio. True. I'd still prefer the AOP_UPDATED_PAGE as the fallthrough case and an explicit goto out_unlock, though.