linux-kernel - Re: [PATCH] ocfs2: call journal flush to mark journal as empty after journal recovery when mount

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Date:   Thu, 12 Dec 2019 13:51:45 +0800
From:   Joseph Qi <joseph.qi@...ux.alibaba.com>
To:     Changwei Ge <chge@...ux.alibaba.com>, Kai Li <li.kai4@....com>,
        mark@...heh.com, jlbec@...lplan.org
Cc:     ocfs2-devel@....oracle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ocfs2: call journal flush to mark journal as empty after
 journal recovery when mount



On 19/12/12 11:55, Changwei Ge wrote:
> Hi Joseph,
> 
> On 12/11/19 9:17 PM, Joseph Qi wrote:
>>
>>
>> On 19/12/11 18:03, 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.
>>>
>> I think I've finally understood the problem. But I don't think it has
>> been clearly described for reviewing. I strongly suggest you describe
>> the problem in the way of timeline, such as in which step, do what
>> operation, and what is the status, etc.
>>
>>
>>> This exception happens 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 sb block will be updated after recovery.
>>>
>>> To fix this problem, use jbd2_journal_flush to mark journal as empty as
>>> ocfs2_replay_journal has done.>
>> Sounds reasonable. But IMO, it is really a corner use scenario, using
>> cluster filesystem in single node...
> 
> True, this use case should be rare.
> But considering that fixing this is not complicated and does no harm at least, I am inclining taking this in. We can only merge it to mainline rather than -stable branches. :-)
> 
Okay, let's move it on.

Thanks,
Joseph