Re: [PATCH 15/29] NFSD: dynamically allocate the nfsd-client shrinker

[Qi Zheng]

Hi Chuck,

On 2023/6/24 05:49, Chuck Lever wrote:
> On Thu, Jun 22, 2023 at 04:53:21PM +0800, Qi Zheng wrote:
> > In preparation for implementing lockless slab shrink,
> > we need to dynamically allocate the nfsd-client shrinker,
> > so that it can be freed asynchronously using kfree_rcu().
> > Then it doesn't need to wait for RCU read-side critical
> > section when releasing the struct nfsd_net.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
>
> For 15/29 and 16/29 of this series:
>
> Acked-by: Chuck Lever <chuck.lever@xxxxxxxxxx>

Thanks for your review! :)

And I will implement the APIs suggested by Dave in 02/29 in
the v2, so there will be some changes here, but it should
not be much. So I will keep your Acked-bys in the v2.

Thanks,
Qi

> > ---
> >   fs/nfsd/netns.h     |  2 +-
> >   fs/nfsd/nfs4state.c | 20 ++++++++++++--------
> >   2 files changed, 13 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> > index ec49b200b797..f669444d5336 100644
> > --- a/fs/nfsd/netns.h
> > +++ b/fs/nfsd/netns.h
> > @@ -195,7 +195,7 @@ struct nfsd_net {
> >   	int			nfs4_max_clients;
> >   
> >   	atomic_t		nfsd_courtesy_clients;
> > -	struct shrinker		nfsd_client_shrinker;
> > +	struct shrinker		*nfsd_client_shrinker;
> >   	struct work_struct	nfsd_shrinker_work;
> >   };
> >   
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 6e61fa3acaf1..a06184270548 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -4388,8 +4388,7 @@ static unsigned long
> >   nfsd4_state_shrinker_count(struct shrinker *shrink, struct shrink_control *sc)
> >   {
> >   	int count;
> > -	struct nfsd_net *nn = container_of(shrink,
> > -			struct nfsd_net, nfsd_client_shrinker);
> > +	struct nfsd_net *nn = shrink->private_data;
> >   
> >   	count = atomic_read(&nn->nfsd_courtesy_clients);
> >   	if (!count)
> > @@ -8094,14 +8093,19 @@ static int nfs4_state_create_net(struct net *net)
> >   	INIT_WORK(&nn->nfsd_shrinker_work, nfsd4_state_shrinker_worker);
> >   	get_net(net);
> >   
> > -	nn->nfsd_client_shrinker.scan_objects = nfsd4_state_shrinker_scan;
> > -	nn->nfsd_client_shrinker.count_objects = nfsd4_state_shrinker_count;
> > -	nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;
> > -
> > -	if (register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client"))
> > +	nn->nfsd_client_shrinker = shrinker_alloc_and_init(nfsd4_state_shrinker_count,
> > +							   nfsd4_state_shrinker_scan,
> > +							   0, DEFAULT_SEEKS, 0,
> > +							   nn);
> > +	if (!nn->nfsd_client_shrinker)
> >   		goto err_shrinker;
> > +
> > +	if (register_shrinker(nn->nfsd_client_shrinker, "nfsd-client"))
> > +		goto err_register;
> >   	return 0;
> >   
> > +err_register:
> > +	shrinker_free(nn->nfsd_client_shrinker);
> >   err_shrinker:
> >   	put_net(net);
> >   	kfree(nn->sessionid_hashtbl);
> > @@ -8197,7 +8201,7 @@ nfs4_state_shutdown_net(struct net *net)
> >   	struct list_head *pos, *next, reaplist;
> >   	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> >   
> > -	unregister_shrinker(&nn->nfsd_client_shrinker);
> > +	unregister_and_free_shrinker(nn->nfsd_client_shrinker);
> >   	cancel_work(&nn->nfsd_shrinker_work);
> >   	cancel_delayed_work_sync(&nn->laundromat_work);
> >   	locks_end_grace(&nn->nfsd4_manager);
> > --
> > 2.30.2