Ocfs2 devel - Mar 2018 - [PATCH] ocfs2/dlm: don't handle migrate lockres if already in shutdown

Hi Changwei,

Thanks for your quick reply, please see my comments below.

On 2018/3/1 17:39, Changwei Ge wrote:
> Hi Jun,
> 
> On 2018/3/1 17:27, piaojun wrote:
>> We should not handle migrate lockres if we are already in
>> 'DLM_CTXT_IN_SHUTDOWN', as that will cause lockres remains
after
>> leaving dlm domain. At last other nodes will get stuck into infinite
>> loop when requsting lock from us.
>>
>>      N1                             N2 (owner)
>>                                     touch file
>>
>> access the file,
>> and get pr lock
>>
>> umount
>>
> 
> Before migrating all lock resources, N1 should have already sent 
> DLM_BEGIN_EXIT_DOMAIN_MSG in dlm_begin_exit_domain().
> N2 will set ->exit_domain_map later.
> So N2 can't take N1 as migration target.
Before receiveing N1's DLM_BEGIN_EXIT_DOMAIN_MSG, N2 has picked up N1 as
the migrate target. So N2 will continue sending lockres to N1 even though
N1 has left domain. Sorry for making you misunderstanding, I will give a
more detailed description.

    N1                             N2 (owner)
                                   touch file

access the file,
and get pr lock

                                   begin leave domain and
                                   pick up N1 as new owner

begin leave domain and
migrate all lockres done

                                   begin migrate lockres to N1

end leave domain, but
the lockres left
unexpectedly, because
migrate task has passed

thanks,
Jun
> 
> How can the scenario your changelog describing happen?
> Or if miss something?
> 
> Thanks,
> Changwei
> 
>> migrate all lockres
>>
>>                                     umount and migrate lockres to N1
>>
>> leave dlm domain, but
>> the lockres left
>> unexpectedly, because
>> migrate task has passed
>>
>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>> Reviewed-by: Yiwen Jiang <jiangyiwen at huawei.com>
>> ---
>>   fs/ocfs2/dlm/dlmdomain.c   | 14 ++++++++++++++
>>   fs/ocfs2/dlm/dlmdomain.h   |  1 +
>>   fs/ocfs2/dlm/dlmrecovery.c |  9 +++++++++
>>   3 files changed, 24 insertions(+)
>>
>> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
>> index e1fea14..3b7ec51 100644
>> --- a/fs/ocfs2/dlm/dlmdomain.c
>> +++ b/fs/ocfs2/dlm/dlmdomain.c
>> @@ -675,6 +675,20 @@ static void dlm_leave_domain(struct dlm_ctxt *dlm)
>>   	spin_unlock(&dlm->spinlock);
>>   }
>>
>> +int dlm_joined(struct dlm_ctxt *dlm)
>> +{
>> +	int ret = 0;
>> +
>> +	spin_lock(&dlm_domain_lock);
>> +
>> +	if (dlm->dlm_state == DLM_CTXT_JOINED)
>> +		ret = 1;
>> +
>> +	spin_unlock(&dlm_domain_lock);
>> +
>> +	return ret;
>> +}
>> +
>>   int dlm_shutting_down(struct dlm_ctxt *dlm)
>>   {
>>   	int ret = 0;
>> diff --git a/fs/ocfs2/dlm/dlmdomain.h b/fs/ocfs2/dlm/dlmdomain.h
>> index fd6122a..2f7f60b 100644
>> --- a/fs/ocfs2/dlm/dlmdomain.h
>> +++ b/fs/ocfs2/dlm/dlmdomain.h
>> @@ -28,6 +28,7 @@
>>   extern spinlock_t dlm_domain_lock;
>>   extern struct list_head dlm_domains;
>>
>> +int dlm_joined(struct dlm_ctxt *dlm);
>>   int dlm_shutting_down(struct dlm_ctxt *dlm);
>>   void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
>>   					int node_num);
>> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
>> index ec8f758..9b3bc66 100644
>> --- a/fs/ocfs2/dlm/dlmrecovery.c
>> +++ b/fs/ocfs2/dlm/dlmrecovery.c
>> @@ -1378,6 +1378,15 @@ int dlm_mig_lockres_handler(struct o2net_msg
*msg, u32 len, void *data,
>>   	if (!dlm_grab(dlm))
>>   		return -EINVAL;
>>
>> +	if (!dlm_joined(dlm)) {
>> +		mlog(ML_ERROR, "Domain %s not joined! "
>> +				"lockres %.*s, master %u\n",
>> +				dlm->name, mres->lockname_len,
>> +				mres->lockname, mres->master);
>> +		dlm_put(dlm);
>> +		return -EINVAL;
>> +	}
>> +
>>   	BUG_ON(!(mres->flags &
(DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));
>>
>>   	real_master = mres->master;
>>
> .
>

On Thu, 1 Mar 2018 20:37:50 +0800 piaojun <piaojun at huawei.com> wrote:
> Hi Changwei,
> 
> Thanks for your quick reply, please see my comments below.
> 
> On 2018/3/1 17:39, Changwei Ge wrote:
> > Hi Jun,
> > 
> > On 2018/3/1 17:27, piaojun wrote:
> >> We should not handle migrate lockres if we are already in
> >> 'DLM_CTXT_IN_SHUTDOWN', as that will cause lockres remains
after
> >> leaving dlm domain. At last other nodes will get stuck into
infinite
> >> loop when requsting lock from us.
> >>
> >>      N1                             N2 (owner)
> >>                                     touch file
> >>
> >> access the file,
> >> and get pr lock
> >>
> >> umount
> >>
> > 
> > Before migrating all lock resources, N1 should have already sent 
> > DLM_BEGIN_EXIT_DOMAIN_MSG in dlm_begin_exit_domain().
> > N2 will set ->exit_domain_map later.
> > So N2 can't take N1 as migration target.
> Before receiveing N1's DLM_BEGIN_EXIT_DOMAIN_MSG, N2 has picked up N1
as
> the migrate target. So N2 will continue sending lockres to N1 even though
> N1 has left domain. Sorry for making you misunderstanding, I will give a
> more detailed description.
> 
>     N1                             N2 (owner)
>                                    touch file
> 
> access the file,
> and get pr lock
> 
>                                    begin leave domain and
>                                    pick up N1 as new owner
> 
> begin leave domain and
> migrate all lockres done
> 
>                                    begin migrate lockres to N1
> 
> end leave domain, but
> the lockres left
> unexpectedly, because
> migrate task has passed
If someone asked a question then this is a sign that the changelog was
missing details.  So please do send along a v2 with a more
comprehensive changelog.

Hi Jun,
I still have some doubts about your problematic situation description .
Please check my reply inline your sequence diagram.

On 2018/3/1 20:38, piaojun wrote:
> Hi Changwei,
> 
> Thanks for your quick reply, please see my comments below.
> 
> On 2018/3/1 17:39, Changwei Ge wrote:
>> Hi Jun,
>>
>> On 2018/3/1 17:27, piaojun wrote:
>>> We should not handle migrate lockres if we are already in
>>> 'DLM_CTXT_IN_SHUTDOWN', as that will cause lockres remains
after
>>> leaving dlm domain. At last other nodes will get stuck into
infinite
>>> loop when requsting lock from us.
>>>
>>>       N1                             N2 (owner)
>>>                                      touch file
>>>
>>> access the file,
>>> and get pr lock
>>>
>>> umount
>>>
>>
>> Before migrating all lock resources, N1 should have already sent
>> DLM_BEGIN_EXIT_DOMAIN_MSG in dlm_begin_exit_domain().
>> N2 will set ->exit_domain_map later.
>> So N2 can't take N1 as migration target.
> Before receiveing N1's DLM_BEGIN_EXIT_DOMAIN_MSG, N2 has picked up N1
as
> the migrate target. So N2 will continue sending lockres to N1 even though
> N1 has left domain. Sorry for making you misunderstanding, I will give a
> more detailed description.
> 
>      N1                             N2 (owner)
>                                     touch file
> 
> access the file,
> and get pr lock
> 
>                                     begin leave domain and
>                                     pick up N1 as new owner
> 
> begin leave domain and
Here will clear N1 from N2's dlm->domain_map
> migrate all lockres do >
>                                     begin migrate lockres to N1
As N1 has been cleared, migrating for this lock resource can't continue.

Besides,
I wonder what kind of problem you encountered?
A bug crash? A hang situation?
It's better to share some issue appearance.So perhaps I can help to
analyze.:)

Thanks,
Changwei
> 
> end leave domain, but
> the lockres left
> unexpectedly, because
> migrate task has passed
> 
> thanks,
> Jun
>>
>> How can the scenario your changelog describing happen?
>> Or if miss something?
>>
>> Thanks,
>> Changwei
>>
>>> migrate all lockres
>>>
>>>                                      umount and migrate lockres to
N1
>>>
>>> leave dlm domain, but
>>> the lockres left
>>> unexpectedly, because
>>> migrate task has passed
>>>
>>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>>> Reviewed-by: Yiwen Jiang <jiangyiwen at huawei.com>
>>> ---
>>>    fs/ocfs2/dlm/dlmdomain.c   | 14 ++++++++++++++
>>>    fs/ocfs2/dlm/dlmdomain.h   |  1 +
>>>    fs/ocfs2/dlm/dlmrecovery.c |  9 +++++++++
>>>    3 files changed, 24 insertions(+)
>>>
>>> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
>>> index e1fea14..3b7ec51 100644
>>> --- a/fs/ocfs2/dlm/dlmdomain.c
>>> +++ b/fs/ocfs2/dlm/dlmdomain.c
>>> @@ -675,6 +675,20 @@ static void dlm_leave_domain(struct dlm_ctxt
*dlm)
>>>    	spin_unlock(&dlm->spinlock);
>>>    }
>>>
>>> +int dlm_joined(struct dlm_ctxt *dlm)
>>> +{
>>> +	int ret = 0;
>>> +
>>> +	spin_lock(&dlm_domain_lock);
>>> +
>>> +	if (dlm->dlm_state == DLM_CTXT_JOINED)
>>> +		ret = 1;
>>> +
>>> +	spin_unlock(&dlm_domain_lock);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>>    int dlm_shutting_down(struct dlm_ctxt *dlm)
>>>    {
>>>    	int ret = 0;
>>> diff --git a/fs/ocfs2/dlm/dlmdomain.h b/fs/ocfs2/dlm/dlmdomain.h
>>> index fd6122a..2f7f60b 100644
>>> --- a/fs/ocfs2/dlm/dlmdomain.h
>>> +++ b/fs/ocfs2/dlm/dlmdomain.h
>>> @@ -28,6 +28,7 @@
>>>    extern spinlock_t dlm_domain_lock;
>>>    extern struct list_head dlm_domains;
>>>
>>> +int dlm_joined(struct dlm_ctxt *dlm);
>>>    int dlm_shutting_down(struct dlm_ctxt *dlm);
>>>    void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
>>>    					int node_num);
>>> diff --git a/fs/ocfs2/dlm/dlmrecovery.c
b/fs/ocfs2/dlm/dlmrecovery.c
>>> index ec8f758..9b3bc66 100644
>>> --- a/fs/ocfs2/dlm/dlmrecovery.c
>>> +++ b/fs/ocfs2/dlm/dlmrecovery.c
>>> @@ -1378,6 +1378,15 @@ int dlm_mig_lockres_handler(struct o2net_msg
*msg, u32 len, void *data,
>>>    	if (!dlm_grab(dlm))
>>>    		return -EINVAL;
>>>
>>> +	if (!dlm_joined(dlm)) {
>>> +		mlog(ML_ERROR, "Domain %s not joined! "
>>> +				"lockres %.*s, master %u\n",
>>> +				dlm->name, mres->lockname_len,
>>> +				mres->lockname, mres->master);
>>> +		dlm_put(dlm);
>>> +		return -EINVAL;
>>> +	}
>>> +
>>>    	BUG_ON(!(mres->flags &
(DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));
>>>
>>>    	real_master = mres->master;
>>>
>> .
>>
>