nfsd: remove blocked locks on client teardown

We had some reports of panics in nfsd4_lm_notify, and that showed a
nfs4_lockowner that had outlived its so_client.

Ensure that we walk any leftover lockowners after tearing down all of
the stateids, and remove any blocked locks that they hold.

With this change, we also don't need to walk the nbl_lru on nfsd_net
shutdown, as that will happen naturally when we tear down the clients.

Fixes: 76d348fadff5 (nfsd: have nfsd4_lock use blocking locks for v4.1+ locks)
Reported-by: Frank Sorenson <fsorenso@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: stable@vger.kernel.org # 4.9
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -268,6 +268,35 @@ free_blocked_lock(struct nfsd4_blocked_lock *nbl)
 	kfree(nbl);
 }
 
+static void
+remove_blocked_locks(struct nfs4_lockowner *lo)
+{
+	struct nfs4_client *clp = lo->lo_owner.so_client;
+	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+	struct nfsd4_blocked_lock *nbl;
+	LIST_HEAD(reaplist);
+
+	/* Dequeue all blocked locks */
+	spin_lock(&nn->blocked_locks_lock);
+	while (!list_empty(&lo->lo_blocked)) {
+		nbl = list_first_entry(&lo->lo_blocked,
+					struct nfsd4_blocked_lock,
+					nbl_list);
+		list_del_init(&nbl->nbl_list);
+		list_move(&nbl->nbl_lru, &reaplist);
+	}
+	spin_unlock(&nn->blocked_locks_lock);
+
+	/* Now free them */
+	while (!list_empty(&reaplist)) {
+		nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
+					nbl_lru);
+		list_del_init(&nbl->nbl_lru);
+		posix_unblock_lock(&nbl->nbl_lock);
+		free_blocked_lock(nbl);
+	}
+}
+
 static int
 nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
 {
@@ -1866,6 +1895,7 @@ static __be32 mark_client_expired_locked(struct nfs4_client *clp)
 static void
 __destroy_client(struct nfs4_client *clp)
 {
+	int i;
 	struct nfs4_openowner *oo;
 	struct nfs4_delegation *dp;
 	struct list_head reaplist;
@@ -1895,6 +1925,16 @@ __destroy_client(struct nfs4_client *clp)
 		nfs4_get_stateowner(&oo->oo_owner);
 		release_openowner(oo);
 	}
+	for (i = 0; i < OWNER_HASH_SIZE; i++) {
+		struct nfs4_stateowner *so, *tmp;
+
+		list_for_each_entry_safe(so, tmp, &clp->cl_ownerstr_hashtbl[i],
+					 so_strhash) {
+			/* Should be no openowners at this point */
+			WARN_ON_ONCE(so->so_is_open_owner);
+			remove_blocked_locks(lockowner(so));
+		}
+	}
 	nfsd4_return_all_client_layouts(clp);
 	nfsd4_shutdown_callback(clp);
 	if (clp->cl_cb_conn.cb_xprt)
@@ -6355,6 +6395,7 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
 	}
 	spin_unlock(&clp->cl_lock);
 	free_ol_stateid_reaplist(&reaplist);
+	remove_blocked_locks(lo);
 	nfs4_put_stateowner(&lo->lo_owner);
 
 	return status;
@@ -7140,6 +7181,8 @@ nfs4_state_destroy_net(struct net *net)
 		}
 	}
 
+	WARN_ON(!list_empty(&nn->blocked_locks_lru));
+
 	for (i = 0; i < CLIENT_HASH_SIZE; i++) {
 		while (!list_empty(&nn->unconf_id_hashtbl[i])) {
 			clp = list_entry(nn->unconf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
@@ -7206,7 +7249,6 @@ nfs4_state_shutdown_net(struct net *net)
 	struct nfs4_delegation *dp = NULL;
 	struct list_head *pos, *next, reaplist;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	struct nfsd4_blocked_lock *nbl;
 
 	cancel_delayed_work_sync(&nn->laundromat_work);
 	locks_end_grace(&nn->nfsd4_manager);
@@ -7227,24 +7269,6 @@ nfs4_state_shutdown_net(struct net *net)
 		nfs4_put_stid(&dp->dl_stid);
 	}
 
-	BUG_ON(!list_empty(&reaplist));
-	spin_lock(&nn->blocked_locks_lock);
-	while (!list_empty(&nn->blocked_locks_lru)) {
-		nbl = list_first_entry(&nn->blocked_locks_lru,
-					struct nfsd4_blocked_lock, nbl_lru);
-		list_move(&nbl->nbl_lru, &reaplist);
-		list_del_init(&nbl->nbl_list);
-	}
-	spin_unlock(&nn->blocked_locks_lock);
-
-	while (!list_empty(&reaplist)) {
-		nbl = list_first_entry(&reaplist,
-					struct nfsd4_blocked_lock, nbl_lru);
-		list_del_init(&nbl->nbl_lru);
-		posix_unblock_lock(&nbl->nbl_lock);
-		free_blocked_lock(nbl);
-	}
-
 	nfsd4_client_tracking_exit(net);
 	nfs4_state_destroy_net(net);
 }