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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 AE035C433E0 for ; Mon, 1 Jun 2020 11:43:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 904842074B for ; Mon, 1 Jun 2020 11:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726218AbgFALn5 (ORCPT ); Mon, 1 Jun 2020 07:43:57 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:49782 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725925AbgFALn5 (ORCPT ); Mon, 1 Jun 2020 07:43:57 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 6FD09ECC3EF7D00DC03F; Mon, 1 Jun 2020 19:43:54 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.207) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 1 Jun 2020 19:43:53 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: fix retry logic in f2fs_write_cache_pages() To: Sahitya Tummala , Jaegeuk Kim CC: , References: <1590546056-17871-1-git-send-email-stummala@codeaurora.org> <1d54379e-35c7-76e0-0c8a-d89bfcecb935@huawei.com> <78d2f29b-3ec0-39bc-46cf-88e82f1970c9@huawei.com> <20200528191839.GA180586@google.com> <20200601092035.GA19831@codeaurora.org> From: Chao Yu Message-ID: <8e938d5c-251c-9922-34a0-5e606cdb4afb@huawei.com> Date: Mon, 1 Jun 2020 19:43:52 +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: <20200601092035.GA19831@codeaurora.org> 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 2020/6/1 17:20, Sahitya Tummala wrote: > Hi Chao, > > Can you please help review the diff given by Jaegeuk below? > If it looks good, I can post a v2. Oops, I missed to review that patch... > > Thanks, > > On Thu, May 28, 2020 at 12:18:39PM -0700, Jaegeuk Kim wrote: >> On 05/28, Chao Yu wrote: >>> 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") >> >> Is that something like this? >> >> --- >> fs/f2fs/data.c | 11 ++--------- >> 1 file changed, 2 insertions(+), 9 deletions(-) >> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >> index 48a622b95b76e..28fcdf0d4dcb9 100644 >> --- a/fs/f2fs/data.c >> +++ b/fs/f2fs/data.c >> @@ -2861,7 +2861,6 @@ static int f2fs_write_cache_pages(struct address_space *mapping, >> pgoff_t index; >> pgoff_t end; /* Inclusive */ >> pgoff_t done_index; >> - int cycled; >> int range_whole = 0; >> xa_mark_t tag; >> int nwritten = 0; >> @@ -2879,17 +2878,12 @@ static int f2fs_write_cache_pages(struct address_space *mapping, >> if (wbc->range_cyclic) { >> writeback_index = mapping->writeback_index; /* prev offset */ >> index = writeback_index; >> - if (index == 0) >> - cycled = 1; >> - else >> - cycled = 0; >> end = -1; >> } else { >> index = wbc->range_start >> PAGE_SHIFT; >> end = wbc->range_end >> PAGE_SHIFT; >> if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) >> range_whole = 1; >> - cycled = 1; /* ignore range_cyclic tests */ >> } >> if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) >> tag = PAGECACHE_TAG_TOWRITE; >> @@ -3054,10 +3048,9 @@ static int f2fs_write_cache_pages(struct address_space *mapping, >> } >> } >> #endif >> - if ((!cycled && !done) || retry) { >> - cycled = 1; >> + if (retry) { >> index = 0; >> - end = writeback_index - 1; >> + end = -1; >> goto retry; >> } + if (wbc->range_cyclic && !done) + done_index = 0; Thanks, >> if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) >> -- >> 2.27.0.rc0.183.gde8f92d652-goog >> >