Re: [RFC] Should lockd get into grace_period when statd start but not stop?

[Mi Jinlong <mijinlong@cn.fujitsu.com>]

J. Bruce Fields :
> On Wed, Mar 10, 2010 at 06:22:35PM +0800, Mi Jinlong wrote:
>> Hi,
>>
>>    When using command "service nfslock stop" and "service nfsklock start"
>> to restart the nfslock service at RHEL with kernel 2.6.31, if start the service
>> after stop it more than the grace_period time, lock which lockd get before
>> cann't be reclaimed for the grace_period is timeout.
>>
>> So, IMO, the lockd should get into grace_period when statd start not stop?
> 
> Sorry, I'm not sure I understand.
> 
> Are you saying that lockd's grace period starts when the last lock is
> shut down, instead of when the new lockd is started?  That would be a
> bug, I agree.

  I means that using command "service nfslock stop" to stop the nfslock service
  at RHEL, it only case statd stop, but lockd is still running. 

  When statd stop, it send a KILL signal to lockd, lockd will release all locks
  and get into grace_period state to wait reclaimed lock request. It means lockd
  get into grace_period state when statd stop.

  But the reclaimed lock request only be caused when client receive a SM_NOTIFY 
  which is send by server's statd at start. If statd start when lockd isn't at 
  grace_period state, the reclaimed lock cann't be reclaimed.

  So, I think, lockd should get into grace_period state when statd start, not stop.

> 
> But are you really shutting down lockd completely?

  Lockd don't shut down when nfslock service stop, the service stop only case lockd stop
  at RHEL.

> 
> --b.
> 
>> Some code at kernel: fs/lockd/svclock.c
>>  ....
>>  411         if (locks_in_grace() && !reclaim) {
>>  412                 ret = nlm_lck_denied_grace_period;
>>  413                 goto out;
>>  414         }
>>  415         if (reclaim && !locks_in_grace()) {
>>  416                 ret = nlm_lck_denied_grace_period;
>>  417                 goto out;
>>  418         }
>>  ....
>>
>> I think it can implement it like that:
>>   1) When statd stop, it send a KILL signal to lockd,
>>      and lockd only release the lock, but don't get into grace_period.
>>   2) When statd start, it send one some other signal to lockd,
>>      and lockd only get into grace_period. The lock will be reclaimed.
>>
>> thanks,
>> Mi Jinlong
>>
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> 
> 
> 

-- 
Regards
Mi Jinlong