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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 BC60EC2D0A3 for ; Tue, 3 Nov 2020 07:49:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E5F222384 for ; Tue, 3 Nov 2020 07:49:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725988AbgKCHts (ORCPT ); Tue, 3 Nov 2020 02:49:48 -0500 Received: from verein.lst.de ([213.95.11.211]:36075 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbgKCHtr (ORCPT ); Tue, 3 Nov 2020 02:49:47 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id AEF6B67373; Tue, 3 Nov 2020 08:49:44 +0100 (CET) Date: Tue, 3 Nov 2020 08:49:44 +0100 From: Christoph Hellwig To: "Matthew Wilcox (Oracle)" Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, hch@lst.de, kent.overstreet@gmail.com Subject: Re: [PATCH 11/17] mm/filemap: Add filemap_range_uptodate Message-ID: <20201103074944.GK8389@lst.de> References: <20201102184312.25926-1-willy@infradead.org> <20201102184312.25926-12-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201102184312.25926-12-willy@infradead.org> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Nov 02, 2020 at 06:43:06PM +0000, Matthew Wilcox (Oracle) wrote: > Move the complicated condition and the calculations out of > filemap_update_page() into its own function. The logic looks good, but the flow inside of filemap_update_page looks odd. The patch below relative to this commit shows how I'd do it: diff --git a/mm/filemap.c b/mm/filemap.c index 81b569d818a3f8..304180c022d38a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2266,40 +2266,39 @@ static int filemap_update_page(struct kiocb *iocb, if (!trylock_page(page)) { if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) goto error; - if (iocb->ki_flags & IOCB_WAITQ) { - if (!first) - goto error; - error = __lock_page_async(page, iocb->ki_waitq); - if (error) - goto error; - } else { + if (!(iocb->ki_flags & IOCB_WAITQ)) { put_and_wait_on_page_locked(page, TASK_KILLABLE); return AOP_TRUNCATED_PAGE; } + if (!first) + goto error; + error = __lock_page_async(page, iocb->ki_waitq); + if (error) + goto error; } + error = AOP_TRUNCATED_PAGE; if (!page->mapping) - goto truncated; - if (filemap_range_uptodate(iocb, mapping, iter, page)) { - unlock_page(page); - return 0; - } + goto error_unlock_page; - if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) { - unlock_page(page); + if (!filemap_range_uptodate(iocb, mapping, iter, page)) { error = -EAGAIN; - } else { + if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) + goto error_unlock_page; error = filemap_read_page(iocb->ki_filp, mapping, page); - if (!error) - return 0; + if (error) + goto error; + return 0; /* filemap_read_page unlocks the page */ } + + unlock_page(page); + return 0; + +error_unlock_page: + unlock_page(page); error: put_page(page); return error; -truncated: - unlock_page(page); - put_page(page); - return AOP_TRUNCATED_PAGE; } static struct page *filemap_create_page(struct file *file,