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Date:   Tue, 18 May 2021 13:21:05 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Dai Ngo <dai.ngo@oracle.com>
Cc:     olga.kornievskaia@gmail.com, linux-nfs@vger.kernel.org,
        trondmy@hammerspace.com, chuck.lever@oracle.com
Subject: Re: [PATCH v5 1/2] NFSD: delay unmount source's export after
 inter-server copy completed.
Message-ID: <20210518172105.GB25205@fieldses.org>
References: <20210517224330.9201-1-dai.ngo@oracle.com>
 <20210517224330.9201-2-dai.ngo@oracle.com>
 <20210518170456.GA25205@fieldses.org>
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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?

--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.