[PATCH RFC v23 3/7] NFSD: move create/destroy of laundry_wq to init_nfsd and exit_nfsd

[Dai Ngo <dai.ngo@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 fs/nfsd/nfs4state.c | 28 ++++++++++++++++------------
 fs/nfsd/nfsctl.c    |  4 ++++
 fs/nfsd/nfsd.h      |  4 ++++
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d2cb820de0ab..5b0777a24017 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -127,6 +127,21 @@ static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
 
 static struct workqueue_struct *laundry_wq;
 
+int nfsd4_create_laundry_wq(void)
+{
+	int rc = 0;
+
+	laundry_wq = alloc_workqueue("%s", WQ_UNBOUND, 0, "nfsd4");
+	if (laundry_wq == NULL)
+		rc = -ENOMEM;
+	return rc;
+}
+
+void nfsd4_destroy_laundry_wq(void)
+{
+	destroy_workqueue(laundry_wq);
+}
+
 static bool is_session_dead(struct nfsd4_session *ses)
 {
 	return ses->se_flags & NFS4_SESSION_DEAD;
@@ -7751,22 +7766,12 @@ 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
@@ -7803,7 +7808,6 @@ 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..322a208878f2 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1544,6 +1544,9 @@ static int __init init_nfsd(void)
 	retval = register_cld_notifier();
 	if (retval)
 		goto out_free_all;
+	retval = nfsd4_create_laundry_wq();
+	if (retval)
+		goto out_free_all;
 	return 0;
 out_free_all:
 	unregister_pernet_subsys(&nfsd_net_ops);
@@ -1566,6 +1569,7 @@ static int __init init_nfsd(void)
 
 static void __exit exit_nfsd(void)
 {
+	nfsd4_destroy_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..624a6c7da522 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -162,6 +162,8 @@ void nfs4_state_shutdown_net(struct net *net);
 int nfs4_reset_recoverydir(char *recdir);
 char * nfs4_recoverydir(void);
 bool nfsd4_spo_must_allow(struct svc_rqst *rqstp);
+int nfsd4_create_laundry_wq(void);
+void nfsd4_destroy_laundry_wq(void);
 #else
 static inline int nfsd4_init_slabs(void) { return 0; }
 static inline void nfsd4_free_slabs(void) { }
@@ -175,6 +177,8 @@ static inline bool nfsd4_spo_must_allow(struct svc_rqst *rqstp)
 {
 	return false;
 }
+static inline int nfsd4_create_laundry_wq(void) { return 0 };
+static inline void nfsd4_destroy_laundry_wq(void) {};
 #endif
 
 /*
-- 
2.9.5