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=-5.8 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 E3A1FC636C9 for ; Mon, 19 Jul 2021 18:27:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDD19610F7 for ; Mon, 19 Jul 2021 18:27:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382503AbhGSRjY (ORCPT ); Mon, 19 Jul 2021 13:39:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352737AbhGSQOd (ORCPT ); Mon, 19 Jul 2021 12:14:33 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B70A3C05BD3D; Mon, 19 Jul 2021 09:09:15 -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:To:From:Date:Sender:Reply-To:Cc: Content-Transfer-Encoding:Content-ID:Content-Description; bh=t0i+7tXFhVAJI+nlAjaCd7T6XGAQwmoipG3wOX3BNN4=; b=aukGzst6WKaOLTfMq0IMTJVP/W oW4ss9z0jiy2pgZaSBv/ZXarhM3VSBxdESUqy1kE7h1qXvBgiIdjbm1D5q+RQYj4PbqsL/t0+kqlh dy6KPznHqP5JpRsC8Xa6dnhQQapIQxbmuO7likzE6uh9ZP2tXjdzgXqWkCJ4c1q/Fai8CAtY7t6Ac t+jsX6iBmhYsMWUt6mBRrwDTTms5h2MroCNEe7CqBtzOy3GiC/Ba8I8TUexNnYJy7PGganCeqDRpn nmt7X3oDM8G4sFx6X+DCZ1DvbmiOAMgQs2eLqI2bNgkE2ElmUrjlqjBK82Y04+jrqh5xZE024sN6A tfAYcc4A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m5WAg-0075UR-UE; Mon, 19 Jul 2021 16:31:29 +0000 Date: Mon, 19 Jul 2021 17:31:10 +0100 From: Matthew Wilcox To: Christoph Hellwig , linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, LKML , "Darrick J . Wong" , Andreas Gruenbacher Subject: Re: [PATCH v3] iomap: support tail packing inline read Message-ID: References: <20210719144747.189634-1-hsiangkao@linux.alibaba.com> <20210719151310.GA22355@lst.de> 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-kernel@vger.kernel.org On Tue, Jul 20, 2021 at 12:11:49AM +0800, Gao Xiang wrote: > On Mon, Jul 19, 2021 at 05:13:10PM +0200, Christoph Hellwig wrote: > > On Mon, Jul 19, 2021 at 04:02:30PM +0100, Matthew Wilcox wrote: > > > > + if (iomap->type == IOMAP_INLINE) { > > > > + iomap_read_inline_data(inode, page, iomap, pos); > > > > + plen = PAGE_SIZE - poff; > > > > + goto done; > > > > + } > > > > > > This is going to break Andreas' case that he just patched to work. > > > GFS2 needs for there to _not_ be an iop for inline data. That's > > > why I said we need to sort out when to create an iop before moving > > > the IOMAP_INLINE case below the creation of the iop. > > > > > > If we're not going to do that first, then I recommend leaving the > > > IOMAP_INLINE case where it is and changing it to ... > > > > > > if (iomap->type == IOMAP_INLINE) > > > return iomap_read_inline_data(inode, page, iomap, pos); > > > > > > ... and have iomap_read_inline_data() return the number of bytes that > > > it copied + zeroed (ie PAGE_SIZE - poff). > > > > Returning the bytes is much cleaner anyway. But we still need to deal > > with the sub-page uptodate status in one form or another. > > There is another iomap_read_inline_data() caller as in: > +static int iomap_write_begin_inline(struct inode *inode, loff_t pos, > + struct page *page, struct iomap *srcmap) > +{ > + /* needs more work for the tailpacking case, disable for now */ > + if (WARN_ON_ONCE(pos != 0)) > + return -EIO; > + if (PageUptodate(page)) > + return 0; > + iomap_read_inline_data(inode, page, srcmap, pos); > + return 0; > +} > > I'd like to avoid it as (void)iomap_read_inline_data(...). That's why it > left as void return type. You don't need to cast away the return value in C.