Re: [PATCH 2/7] clstated: reattempt the pipe open if it fails on ENOENT

[Steve Dickson <SteveD@redhat.com>]

On 12/14/2011 11:00 AM, Jeff Layton wrote:
> On Wed, 14 Dec 2011 10:56:46 -0500
> Steve Dickson <SteveD@redhat.com> wrote:
> 
>>
>>
>> On 12/14/2011 10:37 AM, Jeff Layton wrote:
>>> On Wed, 14 Dec 2011 10:29:49 -0500
>>> Steve Dickson <SteveD@redhat.com> wrote:
>>>
>>>>
>>>>
>>>> On 12/14/2011 10:19 AM, Jeff Layton wrote:
>>>>> On Wed, 14 Dec 2011 10:09:04 -0500
>>>>> Steve Dickson <SteveD@redhat.com> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On 12/14/2011 08:57 AM, Jeff Layton wrote:
>>>>>>> Generally, we want this daemon started before nfsd starts. Deal with the
>>>>>>> situation where the pipe hasn't shown up yet.
>>>>>> This can be done with your systemd start up script. Plus I'm not sure its 
>>>>>> a good idea to steal cpu cycles waiting for an event that may never happen...
>>>>>>
>>>>>
>>>>> Presumably you just wouldn't start the daemon if you have no intent to
>>>>> use it.
>>>>>
>>>>> It does sleep 1s between each check, so the time is fairly minimal,
>>>>> but I'm definitely open to doing this differently. What may be
>>>>> reasonable is adding code to the daemon to check and see if the
>>>>> v4recoverydir is present. If it is, then just exit. Otherwise, wait for
>>>>> the pipe to show up.
>>>> Why just let the systemd scrips worry about the order of when to start
>>>> things up... To be honest, that is one thing systemd does do fairly well.
>>>>
>>>
>>> Because not everyone uses systemd, and we have to deal with the
>>> "legacy" case too for the transition phase.
>>>
>>> It's generally preferable not to start up nfsd until everything it
>>> needs is up. If we do what you suggest, then we're basically mandating
>>> that this daemon can't start until nfsd is up and running.
>> Order has ways been a part of how and when things are started which
>> have always been handled by initscripts. That's their job, to start
>> things in the correct order. 
>>
>> I understand you want to make the daemon bullet proof... but starting
>> things up in the wrong order is an error... IMHO... 
>>
>>>
>>> Could you give some details on how you think this ought to work?
>>>
>> I would think a error message stating unable to open whatever and then 
>> say something like please make sure the nfs server is up and running,
>> would work... It seems to me this is a pretty common way of handling 
>> this type of situation.... although I can not come up with a 
>> explicit example, atm. 
>>
> 
> That's doable simply by dropping this patch. I think it'll make this
> more fragile, but if that's the consensus, I'll go along with it.
> 
If that is the only fragile part then I you are in very good shape! ;-) 

Thanks again! 

steved.