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, UNPARSEABLE_RELAY,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 088F8C43603 for ; Sat, 21 Dec 2019 07:27:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE3562070B for ; Sat, 21 Dec 2019 07:27:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726074AbfLUH1O (ORCPT ); Sat, 21 Dec 2019 02:27:14 -0500 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:37599 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725838AbfLUH1N (ORCPT ); Sat, 21 Dec 2019 02:27:13 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R821e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=chge@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0TlUIYY6_1576913094; Received: from IT-C02YD3Q7JG5H.local(mailfrom:chge@linux.alibaba.com fp:SMTPD_---0TlUIYY6_1576913094) by smtp.aliyun-inc.com(127.0.0.1); Sat, 21 Dec 2019 15:24:55 +0800 Subject: Re: [Ocfs2-devel] [PATCH v3] ocfs2: call journal flush to mark journal as empty after journal recovery when mount To: Jiangyiwen , Likai , piaojun , Joseph Qi , "mark@fasheh.com" , "jlbec@evilplan.org" Cc: "linux-kernel@vger.kernel.org" , "ocfs2-devel@oss.oracle.com" References: <20191217020140.2197-1-li.kai4@h3c.com> <5DFB860A.6020501@huawei.com> <05cf7457-31f2-0698-14ae-21a9e7b659cb@linux.alibaba.com> <5DFC90C0.7020704@huawei.com> <1faf04ac23384fb2a17a8a569f9fce8f@h3c.com> <5DFCC3F5.7040702@huawei.com> From: Changwei Ge Message-ID: <0ba92e81-5b7d-5d5e-172e-5b18bbee8909@linux.alibaba.com> Date: Sat, 21 Dec 2019 15:24:55 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <5DFCC3F5.7040702@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/20/19 8:52 PM, Jiangyiwen wrote: > On 2019/12/20 17:33, Likai wrote: >> On 2019/12/20 17:14, piaojun wrote: >>> On 2019/12/20 9:11, Joseph Qi wrote: >>>> On 19/12/19 22:15, piaojun wrote: >>>>> On 2019/12/17 10:01, Kai Li wrote: >>>>>> If journal is dirty when mount, it will be replayed but jbd2 sb >>>>>> log tail cannot be updated to mark a new start because >>>>>> journal->j_flag has already been set with JBD2_ABORT first >>>>>> in journal_init_common. When a new transaction is committed, it >>>>>> will be recored in block 1 first(journal->j_tail is set to 1 in >>>>>> journal_reset).If emergency restart happens again before journal >>>>>> super block is updated unfortunately, the new recorded trans will >>>>>> not be replayed in the next mount. >>>>>> >>>>>> The following steps describe this procedure in detail. >>>>>> 1. mount and touch some files >>>>>> 2. these transactions are committed to journal area but not >>>>>> checkpointed >>>>>> 3. emergency restart >>>>>> 4. mount again and its journals are replayed >>>>>> 5. journal super block's first s_start is 1, but its s_seq is not >>>>>> updated >>>>>> 6. touch a new file and its trans is committed but not checkpointed > > Hi, > > I wonder that in this step, does the function > jbd2_journal_commit_transaction() return? > I understand only jbd2_journal_commit_transaction() return it means the > transaction > is committed completely, and the s_seq can be updated in > jbd2_journal_commit_transaction()->jbd2_update_log_tail(), so I don't > know how > this scenario happened. > > If emergency restart happens in before jbd2_journal_commit_transaction() The trick is that jbd2 kernel thread even doesn't have a chance to to update tail. Assuming that a timepoint sits between *mount completion* and the *first iteration* of committing work that jbd2 thread. -Changwei > return, > I think this transaction shouldn't be a valid transaction. > > Can you explain where the specific function is executed? > > Thanks, > Yiwen. > >>>>>> 7. emergency restart again >>>>>> 8. mount and journal is dirty, but trans committed in 6 will not be >>>>>> replayed. >>>>>> >>>>>> This exception happens easily when this lun is used by only one >>>>>> node. If it >>>>>> is used by multi-nodes, other node will replay its journal and its >>>>>> journal super block will be updated after recovery like what this >>>>>> patch >>>>>> does. >>>>>> >>>>>> ocfs2_recover_node->ocfs2_replay_journal. >>>>>> >>>>>> The following jbd2 journal can be generated by touching a new file >>>>>> after >>>>>> journal is replayed, and seq 15 is the first valid commit, but >>>>>> first seq >>>>>> is 13 in journal super block. >>>>>> logdump: >>>>>> Block 0: Journal Superblock >>>>>> Seq: 0   Type: 4 (JBD2_SUPERBLOCK_V2) >>>>>> Blocksize: 4096   Total Blocks: 32768   First Block: 1 >>>>>> First Commit ID: 13   Start Log Blknum: 1 >>>>>> Error: 0 >>>>>> Feature Compat: 0 >>>>>> Feature Incompat: 2 block64 >>>>>> Feature RO compat: 0 >>>>>> Journal UUID: 4ED3822C54294467A4F8E87D2BA4BC36 >>>>>> FS Share Cnt: 1   Dynamic Superblk Blknum: 0 >>>>>> Per Txn Block Limit    Journal: 0    Data: 0 >>>>>> >>>>>> Block 1: Journal Commit Block >>>>>> Seq: 14   Type: 2 (JBD2_COMMIT_BLOCK) >>>>>> >>>>>> Block 2: Journal Descriptor >>>>>> Seq: 15   Type: 1 (JBD2_DESCRIPTOR_BLOCK) >>>>>> No. Blocknum        Flags >>>>>>   0. 587             none >>>>>> UUID: 00000000000000000000000000000000 >>>>>>   1. 8257792         JBD2_FLAG_SAME_UUID >>>>>>   2. 619             JBD2_FLAG_SAME_UUID >>>>>>   3. 24772864        JBD2_FLAG_SAME_UUID >>>>>>   4. 8257802         JBD2_FLAG_SAME_UUID >>>>>>   5. 513             JBD2_FLAG_SAME_UUID JBD2_FLAG_LAST_TAG >>>>>> ... >>>>>> Block 7: Inode >>>>>> Inode: 8257802   Mode: 0640   Generation: 57157641 (0x3682809) >>>>>> FS Generation: 2839773110 (0xa9437fb6) >>>>>> CRC32: 00000000   ECC: 0000 >>>>>> Type: Regular   Attr: 0x0   Flags: Valid >>>>>> Dynamic Features: (0x1) InlineData >>>>>> User: 0 (root)   Group: 0 (root)   Size: 7 >>>>>> Links: 1   Clusters: 0 >>>>>> ctime: 0x5de5d870 0x11104c61 -- Tue Dec  3 11:37:20.286280801 2019 >>>>>> atime: 0x5de5d870 0x113181a1 -- Tue Dec  3 11:37:20.288457121 2019 >>>>>> mtime: 0x5de5d870 0x11104c61 -- Tue Dec  3 11:37:20.286280801 2019 >>>>>> dtime: 0x0 -- Thu Jan  1 08:00:00 1970 >>>>>> ... >>>>>> Block 9: Journal Commit Block >>>>>> Seq: 15   Type: 2 (JBD2_COMMIT_BLOCK) >>>>>> >>>>>> The following is jouranl recovery log when recovering the upper jbd2 >>>>>> journal when mount again. >>>>>> syslog: >>>>>> [ 2265.648622] ocfs2: File system on device (252,1) was not >>>>>> unmounted cleanly, recovering it. >>>>>> [ 2265.649695] fs/jbd2/recovery.c:(do_one_pass, 449): Starting >>>>>> recovery pass 0 >>>>>> [ 2265.650407] fs/jbd2/recovery.c:(do_one_pass, 449): Starting >>>>>> recovery pass 1 >>>>>> [ 2265.650409] fs/jbd2/recovery.c:(do_one_pass, 449): Starting >>>>>> recovery pass 2 >>>>>> [ 2265.650410] fs/jbd2/recovery.c:(jbd2_journal_recover, 278): >>>>>> JBD2: recovery, exit status 0, recovered transactions 13 to 13 >>>>>> >>>>>> Due to first commit seq 13 recorded in journal super is not >>>>>> consistent >>>>>> with the value recorded in block 1(seq is 14), journal recovery >>>>>> will be >>>>>> terminated before seq 15 even though it is an unbroken commit, inode >>>>>> 8257802 is a new file and it will be lost. >>>>>> >>>>>> Signed-off-by: Kai Li >>>>>> --- >>>>>>   fs/ocfs2/journal.c | 8 ++++++++ >>>>>>   1 file changed, 8 insertions(+) >>>>>> >>>>>> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c >>>>>> index 1afe57f425a0..68ba354cf361 100644 >>>>>> --- a/fs/ocfs2/journal.c >>>>>> +++ b/fs/ocfs2/journal.c >>>>>> @@ -1066,6 +1066,14 @@ int ocfs2_journal_load(struct ocfs2_journal >>>>>> *journal, int local, int replayed) >>>>>>       ocfs2_clear_journal_error(osb->sb, journal->j_journal, >>>>>> osb->slot_num); >>>>>> +    if (replayed) { >>>>>> +        jbd2_journal_lock_updates(journal->j_journal); >>>>>> +        status = jbd2_journal_flush(journal->j_journal); >>>>> What if jbd2_journal_flush gets failed? The 's_sequence' and 's_start' >>>>> won't be reset, and I wonder if the problem still remains. >>>>> >>>> Yes, but we don't want this to fail the mount process, instead we >>>> just log >>>> an error and system administrator should know the result. >>>> >>> Thanks for your reply and I have another question about this issue. IMO >>> the second trans is not complete as jbd2 sb has not been updated, so we >>> do not need to replay it when mount again. >>> >>> Jun >>> >>> >> I don't think so. The problem is that jbd2 sb should be updated to mark >> a new start after mount rather than whether trans committed later is >> complete or not. >> >> In fact , the trans is complete too as the commit log described. >> >> Thanks >> >> >> _______________________________________________ >> Ocfs2-devel mailing list >> Ocfs2-devel@oss.oracle.com >> https://oss.oracle.com/mailman/listinfo/ocfs2-devel >> >> . >> >