linux-kernel - [PATCH v5 32/45] nfsd: dynamically allocate the nfsd-client shrinker

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Message-Id: <20230824034304.37411-33-zhengqi.arch@bytedance.com>
Date:   Thu, 24 Aug 2023 11:42:51 +0800
From:   Qi Zheng <zhengqi.arch@...edance.com>
To:     akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
        vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
        brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
        steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
        yujie.liu@...el.com, gregkh@...uxfoundation.org,
        muchun.song@...ux.dev
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Qi Zheng <zhengqi.arch@...edance.com>,
        Chuck Lever <chuck.lever@...cle.com>,
        Jeff Layton <jlayton@...nel.org>,
        Olga Kornievskaia <kolga@...app.com>,
        Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
        linux-nfs@...r.kernel.org
Subject: [PATCH v5 32/45] nfsd: dynamically allocate the nfsd-client shrinker

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the nfsd-client shrinker, so that it can be freed
asynchronously via 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@...edance.com>
Acked-by: Chuck Lever <chuck.lever@...cle.com>
Acked-by: Jeff Layton <jlayton@...nel.org>
CC: Jeff Layton <jlayton@...nel.org>
CC: Olga Kornievskaia <kolga@...app.com>
CC: Dai Ngo <Dai.Ngo@...cle.com>
CC: Tom Talpey <tom@...pey.com>
CC: linux-nfs@...r.kernel.org
---
 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 4c6a94a9699d..b2742065a813 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4400,8 +4400,7 @@ 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)
@@ -8149,12 +8148,17 @@ 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(0, "nfsd-client");
+	if (!nn->nfsd_client_shrinker)
 		goto err_shrinker;
+
+	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;
+	nn->nfsd_client_shrinker->private_data = nn;
+
+	shrinker_register(nn->nfsd_client_shrinker);
+
 	return 0;
 
 err_shrinker:
@@ -8252,7 +8256,7 @@ 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);
+	shrinker_free(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