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

Qi Zheng
2023-06-24T11:18:05Z

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@bytedance.com>
>
> For 15/29 and 16/29 of this series:
>
> Acked-by: Chuck Lever <chuck.lever@oracle.com>

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
>>