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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 34510C433E1 for ; Thu, 16 Jul 2020 01:17:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11A3220787 for ; Thu, 16 Jul 2020 01:17:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727042AbgGPBRR (ORCPT ); Wed, 15 Jul 2020 21:17:17 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:54490 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726479AbgGPBRQ (ORCPT ); Wed, 15 Jul 2020 21:17:16 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id D206E9A1729195C2524B; Thu, 16 Jul 2020 09:17:13 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.202) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 16 Jul 2020 09:17:06 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: don't skip writeback of quota data To: Jaegeuk Kim CC: , , References: <20200709190545.GA3001066@google.com> <20200710032616.GC545837@google.com> <01d0db54-eee1-f6cd-76c3-ebe59a7abae4@huawei.com> <20200710035053.GH545837@google.com> <77041117-f615-e6e6-591c-b02bf99e58c2@huawei.com> <20200713175926.GB2910046@google.com> <20200715191037.GB2232118@google.com> <4edac8af-0ae8-65e1-e3a0-a633cf81d761@huawei.com> <20200716011047.GA2540332@google.com> From: Chao Yu Message-ID: Date: Thu, 16 Jul 2020 09:17:05 +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: <20200716011047.GA2540332@google.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 2020/7/16 9:10, Jaegeuk Kim wrote: > On 07/16, Chao Yu wrote: >> On 2020/7/16 3:10, Jaegeuk Kim wrote: >>> On 07/14, Chao Yu wrote: >>>> On 2020/7/14 1:59, Jaegeuk Kim wrote: >>>>> On 07/10, Chao Yu wrote: >>>>>> On 2020/7/10 11:50, Jaegeuk Kim wrote: >>>>>>> On 07/10, Chao Yu wrote: >>>>>>>> On 2020/7/10 11:26, Jaegeuk Kim wrote: >>>>>>>>> On 07/10, Chao Yu wrote: >>>>>>>>>> On 2020/7/10 3:05, Jaegeuk Kim wrote: >>>>>>>>>>> On 07/09, Chao Yu wrote: >>>>>>>>>>>> On 2020/7/9 13:30, Jaegeuk Kim wrote: >>>>>>>>>>>>> It doesn't need to bypass flushing quota data in background. >>>>>>>>>>>> >>>>>>>>>>>> The condition is used to flush quota data in batch to avoid random >>>>>>>>>>>> small-sized udpate, did you hit any problem here? >>>>>>>>>>> >>>>>>>>>>> I suspect this causes fault injection test being stuck by waiting for inode >>>>>>>>>>> writeback completion. With this patch, it has been running w/o any issue so far. >>>>>>>>>>> I keep an eye on this. >>>>>>>>>> >>>>>>>>>> Hmmm.. so that this patch may not fix the root cause, and it may hiding the >>>>>>>>>> issue deeper. >>>>>>>>>> >>>>>>>>>> How about just keeping this patch in our private branch to let fault injection >>>>>>>>>> test not be stuck? until we find the root cause in upstream codes. >>>>>>>>> >>>>>>>>> Well, I don't think this hides something. When the issue happens, I saw inodes >>>>>>>>> being stuck due to writeback while only quota has some dirty data. At that time, >>>>>>>>> there was no dirty data page from other inodes. >>>>>>>> >>>>>>>> Okay, >>>>>>>> >>>>>>>>> >>>>>>>>> More specifically, I suspect __writeback_inodes_sb_nr() gives WB_SYNC_NONE and >>>>>>>>> waits for wb_wait_for_completion(). >>>>>>>> >>>>>>>> Did you record any callstack after the issue happened? >>>>>>> >>>>>>> I found this. >>>>>>> >>>>>>> [213389.297642] __schedule+0x2dd/0x780^M >>>>>>> [213389.299224] schedule+0x55/0xc0^M >>>>>>> [213389.300745] wb_wait_for_completion+0x56/0x90^M >>>>>>> [213389.302469] ? wait_woken+0x80/0x80^M >>>>>>> [213389.303997] __writeback_inodes_sb_nr+0xa8/0xd0^M >>>>>>> [213389.305760] writeback_inodes_sb+0x4b/0x60^M >>>>>>> [213389.307439] sync_filesystem+0x2e/0xa0^M >>>>>>> [213389.308999] generic_shutdown_super+0x27/0x110^M >>>>>>> [213389.310738] kill_block_super+0x27/0x50^M >>>>>>> [213389.312327] kill_f2fs_super+0x76/0xe0 [f2fs]^M >>>>>>> [213389.314014] deactivate_locked_super+0x3b/0x80^M >>>>>>> [213389.315692] deactivate_super+0x3e/0x50^M >>>>>>> [213389.317226] cleanup_mnt+0x109/0x160^M >>>>>>> [213389.318718] __cleanup_mnt+0x12/0x20^M >>>>>>> [213389.320177] task_work_run+0x70/0xb0^M >>>>>>> [213389.321609] exit_to_usermode_loop+0x131/0x160^M >>>>>>> [213389.323306] do_syscall_64+0x170/0x1b0^M >>>>>>> [213389.324762] entry_SYSCALL_64_after_hwframe+0x44/0xa9^M >>>>>>> [213389.326477] RIP: 0033:0x7fc4b5e6a35b^M >>>>>> >>>>>> Does this only happen during umount? If so, will below change help? >>>>>> >>>>>> if ((S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) && >>>>>> + !is_sbi_flag_set(sbi, SBI_IS_CLOSE) && >>>>>> wbc->sync_mode == WB_SYNC_NONE && >>>>>> get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) && >>>>>> f2fs_available_free_memory(sbi, DIRTY_DENTS)) >>>>>> goto skip_write; >>>>> >>>>> Hmm, this doesn't work. The writeback was called before put_super? >>>> >>>> Oops, still be confused about this issue. :( >>> >>> Huam, I hit the problem with the patch. >>> I need to return back and think in other way. :( >> >> Still quota data was left? what about dentry? > > Huh, at this time, only node and meta pages were left as dirty. I saw both meta and node's writepages() called from background will skip flushing dirty pages if dirty page count didn't touch the threshold. /* collect a number of dirty node pages and write together */ if (wbc->sync_mode != WB_SYNC_ALL && get_pages(sbi, F2FS_DIRTY_NODES) < nr_pages_to_skip(sbi, NODE)) goto skip_write; /* collect a number of dirty meta pages and write together */ if (wbc->sync_mode != WB_SYNC_ALL && get_pages(sbi, F2FS_DIRTY_META) < nr_pages_to_skip(sbi, META)) goto skip_write; At that time, would syncfs (type sync command via shell) help? > >> >> Thanks, >> >>> >>>> >>>> Thanks, >>>> >>>>> I'll try the original patch one more time. >>>>> >>>>>> >>>>>>> >>>>>>>> >>>>>>>> Still I'm confused that why directory's data written could be skipped, but >>>>>>>> quota's data couldn't, what's the difference? >>>>>>> >>>>>>> I suspect different blocking timing from cp_error between quota and dentry. >>>>>>> e.g., we block dir operations right after cp_error, while quota can make >>>>>> >>>>>> No guarantee that there is no dirty dentry being created after >>>>>> cp_error, right? >>>>>> >>>>>> e.g. >>>>>> >>>>>> Thread A Thread B >>>>>> - f2fs_create >>>>>> - bypass f2fs_cp_error >>>>>> - set cp_error >>>>>> - create dirty dentry >>>>>> >>>>>> BTW, do you know what __writeback_inodes_sb_nr is waiting for? >>>>>> >>>>>>> dirty pages in more fine granularity. >>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Thanks, >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Thanks, >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Thanks, >>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> Signed-off-by: Jaegeuk Kim >>>>>>>>>>>>> --- >>>>>>>>>>>>> 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 44645f4f914b6..72e8b50e588c1 100644 >>>>>>>>>>>>> --- a/fs/f2fs/data.c >>>>>>>>>>>>> +++ b/fs/f2fs/data.c >>>>>>>>>>>>> @@ -3148,7 +3148,7 @@ static int __f2fs_write_data_pages(struct address_space *mapping, >>>>>>>>>>>>> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING))) >>>>>>>>>>>>> goto skip_write; >>>>>>>>>>>>> >>>>>>>>>>>>> - if ((S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) && >>>>>>>>>>>>> + if (S_ISDIR(inode->i_mode) && >>>>>>>>>>>>> wbc->sync_mode == WB_SYNC_NONE && >>>>>>>>>>>>> get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) && >>>>>>>>>>>>> f2fs_available_free_memory(sbi, DIRTY_DENTS)) >>>>>>>>>>>>> >>>>>>>>>>> . >>>>>>>>>>> >>>>>>>>> . >>>>>>>>> >>>>>>> . >>>>>>> >>>>> . >>>>> >>> . >>> > . >