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Subject: Re: [PATCH v5 1/2] NFSD: delay unmount source's export after
 inter-server copy completed.
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     olga.kornievskaia@gmail.com, linux-nfs@vger.kernel.org,
        trondmy@hammerspace.com, chuck.lever@oracle.com
References: <20210517224330.9201-1-dai.ngo@oracle.com>
 <20210517224330.9201-2-dai.ngo@oracle.com>
 <20210518170456.GA25205@fieldses.org> <20210518172105.GB25205@fieldses.org>
From:   dai.ngo@oracle.com
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On 5/18/21 10:21 AM, J. Bruce Fields wrote:
> On Tue, May 18, 2021 at 01:04:56PM -0400, J. Bruce Fields wrote:
>> On Mon, May 17, 2021 at 06:43:29PM -0400, Dai Ngo wrote:
>>> +struct nfsd4_ssc_umount;
>>>   
>>>   enum {
>>>   	/* cache misses due only to checksum comparison failures */
>>> @@ -176,6 +177,10 @@ struct nfsd_net {
>>>   	unsigned int             longest_chain_cachesize;
>>>   
>>>   	struct shrinker		nfsd_reply_cache_shrinker;
>>> +
>>> +	spinlock_t              nfsd_ssc_lock;
>>> +	struct nfsd4_ssc_umount	*nfsd_ssc_umount;
>> ...
>>
>>> +void nfsd4_ssc_init_umount_work(struct nfsd_net *nn)
>>> +{
>>> +	nn->nfsd_ssc_umount = kzalloc(sizeof(struct nfsd4_ssc_umount),
>>> +					GFP_KERNEL);
>>> +	if (!nn->nfsd_ssc_umount)
>>> +		return;
>> Is there any reason this needs to be allocated dynamically?  Let's just
>> embed it in nfsd_net.
>>
>> Actually, I'm not convinced the separate structure definition's really
>> that helpful:
>>
>>> +struct nfsd4_ssc_umount {
>>> +	struct list_head nsu_list;
>>> +	unsigned long nsu_expire;
> Also: doesn't look like nsu_expire is actually used.  Am I missing
> something, or is this a leftover from the conversion to the using the
> laundromat thread?

Yes, will be cleaned up in v6.

-Dai

>
> --b.
>
>>> +	wait_queue_head_t nsu_waitq;
>>> +};
>> How about just:
>>
>> 	struct nfsd_net {
>> 	...
>> 	/* tracking server-to-server copy mounts: */
>> 	spinlock_t		nfsd_ssc_lock;
>> 	struct list_head	nfsd_ssc_mount_list;
>> 	unsigned long		nfsd_ssc_mount_expire;
>> 	wait_queeu_head_t	nfsd_ssc_mount_waitq;
>>
>> or something along those lines?
>>
>> --b.