linux-kernel - Re: [PATCH] ocfs2: call ocfs2

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Date:   Wed, 1 Nov 2023 10:42:53 +0800
From:   Heming Zhao <heming.zhao@...e.com>
To:     Joseph Qi <joseph.qi@...ux.alibaba.com>,
        Srivathsa Dara <srivathsa.d.dara@...cle.com>, mark@...heh.com,
        jlbec@...lplan.org
Cc:     rajesh.sivaramasubramaniom@...cle.com, junxiao.bi@...cle.com,
        ocfs2-devel@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ocfs2: call ocfs2_abort when journal abort

On 11/1/23 09:13, Joseph Qi wrote:
> 
> 
> On 10/30/23 8:00 PM, Srivathsa Dara wrote:
>> From: Ryan Ding <ryan.ding@...cle.com>
>>
>>
>> journal can not recover from abort state, so we should take following
>> action to prevent file system from corruption:
>>
>> 1. change to readonly filesystem when local mount. We can not afford
>>     further write, so change to RO state is reasonable.
>>
>> 2. panic when cluster mount. Because we can not release lock resource in
>>     this state, other node will hung when it require a lock owned by this
>>     node. So panic and remaster is a reasonable choise.
>>
>> ocfs2_abort() will do all the above work.
>>
>> Signed-off-by: Ryan Ding <ryan.ding@...cle.com>
>> Signed-off-by: Srivathsa Dara <srivathsa.d.dara@...cle.com>
>> ---
>>   fs/ocfs2/journal.c | 27 +++++++++++++++------------
>>   1 file changed, 15 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
>> index ce215565d061..6dace475f019 100644
>> --- a/fs/ocfs2/journal.c
>> +++ b/fs/ocfs2/journal.c
>> @@ -14,7 +14,6 @@
>>   #include <linux/kthread.h>
>>   #include <linux/time.h>
>>   #include <linux/random.h>
>> -#include <linux/delay.h>
>>   #include <linux/writeback.h>
>>   
>>   #include <cluster/masklog.h>
>> @@ -2326,7 +2325,7 @@ static int __ocfs2_wait_on_mount(struct ocfs2_super *osb, int quota)
>>   
>>   static int ocfs2_commit_thread(void *arg)
>>   {
>> -	int status;
>> +	int status = 0;
>>   	struct ocfs2_super *osb = arg;
>>   	struct ocfs2_journal *journal = osb->journal;
>>   
>> @@ -2340,21 +2339,25 @@ static int ocfs2_commit_thread(void *arg)
>>   		wait_event_interruptible(osb->checkpoint_event,
>>   					 atomic_read(&journal->j_num_trans)
>>   					 || kthread_should_stop());
>> +		if (status < 0) {
>> +			/* As we can not terminate by ourself, just enter an
>> +			 * empty loop to wait for stop.
>> +			 */
>> +			continue;
>> +		}
>>   
>>   		status = ocfs2_commit_cache(osb);
>>   		if (status < 0) {
>> -			static unsigned long abort_warn_time;
>> -
>> -			/* Warn about this once per minute */
>> -			if (printk_timed_ratelimit(&abort_warn_time, 60*HZ))
>> -				mlog(ML_ERROR, "status = %d, journal is "
>> -						"already aborted.\n", status);
>>   			/*
>> -			 * After ocfs2_commit_cache() fails, j_num_trans has a
>> -			 * non-zero value.  Sleep here to avoid a busy-wait
>> -			 * loop.
>> +			 * journal can not recover from abort state, there is
>> +			 * no need to keep commit cache. So we should either
>> +			 * change to readonly(local mount) or just panic
>> +			 * (cluster mount).
>> +			 * We should also clear j_num_trans to prevent further
>> +			 * commit.
>>   			 */
>> -			msleep_interruptible(1000);
>> +			atomic_set(&journal->j_num_trans, 0);
> 
> Unconditionally clear 'j_num_trans' here seems buggy.
> This may cause other nodes corrupt filesystem.

Yes, you described this buggy condition during review my patch:
https://lore.kernel.org/ocfs2-devel/2b90546e-d23e-7d45-22dd-a887a73f3e61@linux.alibaba.com/

btw, I ever send a v2 patch [1] about handling journal abort:
[1] https://lore.kernel.org/ocfs2-devel/20230626112453.22571-1-heming.zhao@suse.com/
This patch never get any feedback.

And I also send another mail [2] related with above patch:
[2] https://lore.kernel.org/ocfs2-devel/20230626150916.je3egonzb3crvbl5@p15/
please note, [2] is the problems from fsck.ocfs2, which is completely unrelated to [1].

Heming
> 
> Thanks,
> Joseph
> 
>> +			ocfs2_abort(osb->sb, "Detected aborted journal");
>>   		}
>>   
>>   		if (kthread_should_stop() && atomic_read(&journal->j_num_trans)){
>