Re: [PATCH 1/1] NFSD: register/unregister of nfsd-client shrinker at nfsd startup/shutdown time

[dai.ngo@xxxxxxxxxx]

On 1/10/23 2:24 AM, Jeff Layton wrote:
> On Mon, 2023-01-09 at 22:43 -0800, Dai Ngo wrote:
> > Currently the nfsd-client shrinker is registered and unregistered at
> > the time the nfsd module is loaded and unloaded. This means after the
> > nfsd service is shutdown, the nfsd-client shrinker is still registered
> > in the system. This causes the nfsd-client shrinker to be called when
> > memory is low even thought nfsd service is not running. This is also
> > true for the nfsd_reply_cache_shrinker.
> But this patch doesn't move the reply cache shrinker. Do you intend to
> do that too?

yes, I plan to do that soon in a separate patch.

> > This patch moves the register/unregister of nfsd-client shrinker from
> > module load/unload time to nfsd startup/shutdown time.
> >
> > Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
> > ---
> >   fs/nfsd/nfs4state.c | 18 ++++++------------
> >   fs/nfsd/nfsctl.c    |  7 +------
> >   fs/nfsd/nfsd.h      |  6 ++----
> >   3 files changed, 9 insertions(+), 22 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 7b2ee535ade8..ee56c9466304 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -4421,7 +4421,7 @@ nfsd4_state_shrinker_scan(struct shrinker *shrink, struct shrink_control *sc)
> >   	return SHRINK_STOP;
> >   }
> >   
> > -int
> > +void
> >   nfsd4_init_leases_net(struct nfsd_net *nn)
> >   {
> >   	struct sysinfo si;
> > @@ -4443,16 +4443,6 @@ nfsd4_init_leases_net(struct nfsd_net *nn)
> >   	nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);
> >   
> >   	atomic_set(&nn->nfsd_courtesy_clients, 0);
> > -	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;
> > -	return register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client");
> > -}
> > -
> > -void
> > -nfsd4_leases_net_shutdown(struct nfsd_net *nn)
> > -{
> > -	unregister_shrinker(&nn->nfsd_client_shrinker);
> >   }
> >   
> >   static void init_nfs4_replay(struct nfs4_replay *rp)
> > @@ -8077,7 +8067,10 @@ static int nfs4_state_create_net(struct net *net)
> >   	INIT_DELAYED_WORK(&nn->nfsd_shrinker_work, nfsd4_state_shrinker_worker);
> >   	get_net(net);
> >   
> > -	return 0;
> > +	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;
> > +	return register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client");
> >   
> >   err_sessionid:
> >   	kfree(nn->unconf_id_hashtbl);
> > @@ -8171,6 +8164,7 @@ 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);
> >   	cancel_delayed_work_sync(&nn->laundromat_work);
> >   	locks_end_grace(&nn->nfsd4_manager);
> >   
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index d1e581a60480..c2577ee7ffb2 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -1457,9 +1457,7 @@ static __net_init int nfsd_init_net(struct net *net)
> >   		goto out_idmap_error;
> >   	nn->nfsd_versions = NULL;
> >   	nn->nfsd4_minorversions = NULL;
> > -	retval = nfsd4_init_leases_net(nn);
> > -	if (retval)
> > -		goto out_drc_error;
> > +	nfsd4_init_leases_net(nn);
> >   	retval = nfsd_reply_cache_init(nn);
> >   	if (retval)
> >   		goto out_cache_error;
> > @@ -1469,8 +1467,6 @@ static __net_init int nfsd_init_net(struct net *net)
> >   	return 0;
> >   
> >   out_cache_error:
> > -	nfsd4_leases_net_shutdown(nn);
> > -out_drc_error:
> >   	nfsd_idmap_shutdown(net);
> >   out_idmap_error:
> >   	nfsd_export_shutdown(net);
> > @@ -1486,7 +1482,6 @@ static __net_exit void nfsd_exit_net(struct net *net)
> >   	nfsd_idmap_shutdown(net);
> >   	nfsd_export_shutdown(net);
> >   	nfsd_netns_free_versions(net_generic(net, nfsd_net_id));
> > -	nfsd4_leases_net_shutdown(nn);
> >   }
> >   
> >   static struct pernet_operations nfsd_net_ops = {
> > diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> > index 93b42ef9ed91..fa0144a74267 100644
> > --- a/fs/nfsd/nfsd.h
> > +++ b/fs/nfsd/nfsd.h
> > @@ -504,8 +504,7 @@ extern void unregister_cld_notifier(void);
> >   extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);
> >   #endif
> >   
> > -extern int nfsd4_init_leases_net(struct nfsd_net *nn);
> > -extern void nfsd4_leases_net_shutdown(struct nfsd_net *nn);
> > +extern void nfsd4_init_leases_net(struct nfsd_net *nn);
> >   
> >   #else /* CONFIG_NFSD_V4 */
> >   static inline int nfsd4_is_junction(struct dentry *dentry)
> > @@ -513,8 +512,7 @@ static inline int nfsd4_is_junction(struct dentry *dentry)
> >   	return 0;
> >   }
> >   
> > -static inline int nfsd4_init_leases_net(struct nfsd_net *nn) { return 0; };
> > -static inline void nfsd4_leases_net_shutdown(struct nfsd_net *nn) {};
> > +static inline void nfsd4_init_leases_net(struct nfsd_net *nn) { };
> >   
> >   #define register_cld_notifier() 0
> >   #define unregister_cld_notifier() do { } while(0)
>
>
> Patch looks reasonable. It might be good to also move the reply cache
> init in a similar way (as you pointed out in the patch description).

Thank you for reviewing.

-Dai

> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>