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From:   Dai Ngo <dai.ngo@oracle.com>
To:     chuck.lever@oracle.com, bfields@fieldses.org
Cc:     jlayton@redhat.com, viro@zeniv.linux.org.uk,
        linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH RFC v21 3/7] NFSD: move create/destroy of laundry_wq to init_nfsd and exit_nfsd
Date:   Sat, 23 Apr 2022 11:44:11 -0700
Message-Id: <1650739455-26096-4-git-send-email-dai.ngo@oracle.com>
In-Reply-To: <1650739455-26096-1-git-send-email-dai.ngo@oracle.com>
References: <1650739455-26096-1-git-send-email-dai.ngo@oracle.com>
Precedence: bulk

This patch moves create/destroy of laundry_wq from nfs4_state_start
and nfs4_state_shutdown_net to init_nfsd and exit_nfsd to prevent
the laundromat from being freed while a thread is processing a
conflicting lock.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 15 ++-------------
 fs/nfsd/nfsctl.c    |  6 ++++++
 fs/nfsd/nfsd.h      |  1 +
 3 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b08c132648b9..b70ba2eb5665 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -125,7 +125,7 @@ static void free_session(struct nfsd4_session *);
 static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
 static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
 
-static struct workqueue_struct *laundry_wq;
+struct workqueue_struct *laundry_wq;
 
 static bool is_session_dead(struct nfsd4_session *ses)
 {
@@ -7798,22 +7798,12 @@ nfs4_state_start(void)
 {
 	int ret;
 
-	laundry_wq = alloc_workqueue("%s", WQ_UNBOUND, 0, "nfsd4");
-	if (laundry_wq == NULL) {
-		ret = -ENOMEM;
-		goto out;
-	}
 	ret = nfsd4_create_callback_queue();
 	if (ret)
-		goto out_free_laundry;
+		return ret;
 
 	set_max_delegations();
 	return 0;
-
-out_free_laundry:
-	destroy_workqueue(laundry_wq);
-out:
-	return ret;
 }
 
 void
@@ -7850,7 +7840,6 @@ nfs4_state_shutdown_net(struct net *net)
 void
 nfs4_state_shutdown(void)
 {
-	destroy_workqueue(laundry_wq);
 	nfsd4_destroy_callback_queue();
 }
 
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 16920e4512bd..884e873b46ad 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1544,6 +1544,11 @@ static int __init init_nfsd(void)
 	retval = register_cld_notifier();
 	if (retval)
 		goto out_free_all;
+	laundry_wq = alloc_workqueue("%s", WQ_UNBOUND, 0, "nfsd4");
+	if (laundry_wq == NULL) {
+		retval = -ENOMEM;
+		goto out_free_all;
+	}
 	return 0;
 out_free_all:
 	unregister_pernet_subsys(&nfsd_net_ops);
@@ -1566,6 +1571,7 @@ static int __init init_nfsd(void)
 
 static void __exit exit_nfsd(void)
 {
+	destroy_workqueue(laundry_wq);
 	unregister_cld_notifier();
 	unregister_pernet_subsys(&nfsd_net_ops);
 	nfsd_drc_slab_free();
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 23996c6ca75e..d41dcf1c4312 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -72,6 +72,7 @@ extern unsigned long		nfsd_drc_max_mem;
 extern unsigned long		nfsd_drc_mem_used;
 
 extern const struct seq_operations nfs_exports_op;
+extern struct workqueue_struct *laundry_wq;
 
 /*
  * Common void argument and result helpers
-- 
2.9.5