[Ocfs2-devel] [PATCH] ocfs2/dlm: wait for dlm recovery done when migrating all lockres

[Changwei Ge]

Hi Jun,

Thanks for reviewing.
I don't think we have to worry about misusing *dlm_domain_lock* and 
*dlm::spinlock*. I admit my change may look a little different from most 
of other code snippets where using these two spin locks. But our purpose 
is to close the race between __dlm_hb_node_down and 
dlm_unregister_domain, right?  And my change meets that. :-)

I suppose we can do it in a flexible way.

Thanks,
Changwei


On 2017/11/1 15:57, piaojun wrote:
> Hi Changwei,
> 
> thanks for reviewing, and I think waiting for recoverying done before
> migrating seems another solution, but I wonder if new problems will be
> invoked as following comments.
> 
> thanks,
> Jun
> 
> On 2017/11/1 15:13, Changwei Ge wrote:
>> Hi Jun,
>>
>> I probably get your point.
>>
>> You mean that dlm finds no lock resource to be migrated and no more lock
>> resource is managed by its hash table. After that a node dies all of a
>> sudden and the dead node is put into dlm's recovery map, right?
> that is it.
>> Furthermore, a lock resource is migrated from other nodes and local node
>> has already asserted master to them.
>>
>> If so, I want to suggest a easier way to solve it.
>> We don't have to add a new flag to dlm structure, just leverage existed
>> dlm status and bitmap.
>> It will bring a bonus - no lock resource will be marked with RECOVERING,
>> it's a safer way, I suppose.
>>
>> Please take a review.
>>
>> Thanks,
>> Changwei
>>
>>
>> Subject: [PATCH] ocfs2/dlm: a node can't be involved in recovery if it
>> is being shutdown
>>
>> Signed-off-by: Changwei Ge <ge.changwei at h3c.com>
>> ---
>>    fs/ocfs2/dlm/dlmdomain.c   | 4 ++++
>>    fs/ocfs2/dlm/dlmrecovery.c | 3 +++
>>    2 files changed, 7 insertions(+)
>>
>> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
>> index a2b19fbdcf46..5e9283e509a4 100644
>> --- a/fs/ocfs2/dlm/dlmdomain.c
>> +++ b/fs/ocfs2/dlm/dlmdomain.c
>> @@ -707,11 +707,15 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
>>    		 * want new domain joins to communicate with us at
>>    		 * least until we've completed migration of our
>>    		 * resources. */
>> +		spin_lock(&dlm->spinlock);
>>    		dlm->dlm_state = DLM_CTXT_IN_SHUTDOWN;
>> +		spin_unlock(&dlm->spinlock);
> I guess there will be misuse of 'dlm->spinlock' and dlm_domain_lock.
>>    		leave = 1;
>>    	}
>>    	spin_unlock(&dlm_domain_lock);
>>
>> +	dlm_wait_for_recovery(dlm);
>> +
>>    	if (leave) {
>>    		mlog(0, "shutting down domain %s\n", dlm->name);
>>    		dlm_begin_exit_domain(dlm);
>> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
>> index 74407c6dd592..764c95b2b35c 100644
>> --- a/fs/ocfs2/dlm/dlmrecovery.c
>> +++ b/fs/ocfs2/dlm/dlmrecovery.c
>> @@ -2441,6 +2441,9 @@ static void __dlm_hb_node_down(struct dlm_ctxt
>> *dlm, int idx)
>>    {
>>    	assert_spin_locked(&dlm->spinlock);
>>
>> +	if (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN)
>> +		return;
>> +
> 'dlm->dlm_state' probably need be to protected by 'dlm_domain_lock'.
> and I wander if there is more work to be done when in
> 'DLM_CTXT_IN_SHUTDOWN'?
>>    	if (dlm->reco.new_master == idx) {
>>    		mlog(0, "%s: recovery master %d just died\n",
>>    		     dlm->name, idx);
>>
>