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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 26D6EC433DF for ; Thu, 28 May 2020 02:55:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 093F520888 for ; Thu, 28 May 2020 02:55:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726960AbgE1Cz5 (ORCPT ); Wed, 27 May 2020 22:55:57 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5296 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725896AbgE1Cz4 (ORCPT ); Wed, 27 May 2020 22:55:56 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 4CD5841269D84886E90E; Thu, 28 May 2020 10:55:55 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.211) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 28 May 2020 10:55:52 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: fix retry logic in f2fs_write_cache_pages() From: Chao Yu To: Sahitya Tummala , Jaegeuk Kim , CC: References: <1590546056-17871-1-git-send-email-stummala@codeaurora.org> <1d54379e-35c7-76e0-0c8a-d89bfcecb935@huawei.com> Message-ID: <78d2f29b-3ec0-39bc-46cf-88e82f1970c9@huawei.com> Date: Thu, 28 May 2020 10:55:50 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1d54379e-35c7-76e0-0c8a-d89bfcecb935@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/5/28 10:45, Chao Yu wrote: > On 2020/5/27 10:20, Sahitya Tummala wrote: >> In case a compressed file is getting overwritten, the current retry >> logic doesn't include the current page to be retried now as it sets >> the new start index as 0 and new end index as writeback_index - 1. >> This causes the corresponding cluster to be uncompressed and written >> as normal pages without compression. Fix this by allowing writeback to >> be retried for the current page as well (in case of compressed page >> getting retried due to index mismatch with cluster index). So that >> this cluster can be written compressed in case of overwrite. >> >> Signed-off-by: Sahitya Tummala >> --- >> fs/f2fs/data.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 4af5fcd..bfd1df4 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -3024,7 +3024,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping, >> if ((!cycled && !done) || retry) { > > IMO, we add retry logic in wrong place, you can see that cycled value is > zero only if wbc->range_cyclic is true, in that case writeback_index is valid. > > However if retry is true and wbc->range_cyclic is false, then writeback_index > would be uninitialized variable. > > Thoughts? > > Thanks, > >> cycled = 1; >> index = 0; >> - end = writeback_index - 1; BTW, I notice that range_cyclic writeback flow was refactored in below commit, and skeleton of f2fs.writepages was copied from mm/page-writeback.c::write_cache_pages(), I guess we need follow that change. 64081362e8ff ("mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock") Thanks, >> + end = retry ? -1 : writeback_index - 1; >> goto retry; >> } >> if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) >> > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > . >