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From:   "NeilBrown" <neilb@suse.de>
To:     Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Cc:     Olga Kornievskaia <kolga@netapp.com>, Dai Ngo <Dai.Ngo@oracle.com>,
        Tom Talpey <tom@talpey.com>,
        Linux NFS list <linux-nfs@vger.kernel.org>
Subject: [PATCH nfsd-next] NFSD: simplify error paths in nfsd_svc()
Date:   Mon, 25 Sep 2023 12:06:44 +1000
Message-id: <169561203735.19404.6014131036692240448@noble.neil.brown.name>
Precedence: bulk


The error paths in nfsd_svc() are needlessly complex and can result in a
final call to svc_put() without nfsd_last_thread() being called.  This
results in the listening sockets not being closed properly.

The per-netns setup provided by nfsd_startup_new() and removed by
nfsd_shutdown_net() is needed precisely when there are running threads.
So we don't need nfsd_up_before.  We don't need to know if it *was* up.
We only need to know if any threads are left.  If none are, then we must
call nfsd_shutdown_net().  But we don't need to do that explicitly as
nfsd_last_thread() does that for us.

So simply call nfsd_last_thread() before the last svc_put() if there are
no running threads.  That will always do the right thing.

Also discard:
 pr_info("nfsd: last server has exited, flushing export cache\n");
It may not be true if an attempt to start the first server failed, and
it isn't particularly helpful and it simply reports normal behaviour.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/nfsd/nfssvc.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index c5890cdfe97b..d6122bb2d167 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -572,7 +572,6 @@ static void nfsd_last_thread(struct net *net)
 		return;
=20
 	nfsd_shutdown_net(net);
-	pr_info("nfsd: last server has exited, flushing export cache\n");
 	nfsd_export_flush(net);
 }
=20
@@ -786,7 +785,6 @@ int
 nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
 {
 	int	error;
-	bool	nfsd_up_before;
 	struct nfsd_net *nn =3D net_generic(net, nfsd_net_id);
 	struct svc_serv *serv;
=20
@@ -806,8 +804,6 @@ nfsd_svc(int nrservs, struct net *net, const struct cred =
*cred)
 	error =3D nfsd_create_serv(net);
 	if (error)
 		goto out;
-
-	nfsd_up_before =3D nn->nfsd_net_up;
 	serv =3D nn->nfsd_serv;
=20
 	error =3D nfsd_startup_net(net, cred);
@@ -815,17 +811,15 @@ nfsd_svc(int nrservs, struct net *net, const struct cre=
d *cred)
 		goto out_put;
 	error =3D svc_set_num_threads(serv, NULL, nrservs);
 	if (error)
-		goto out_shutdown;
+		goto out_put;
 	error =3D serv->sv_nrthreads;
-	if (error =3D=3D 0)
-		nfsd_last_thread(net);
-out_shutdown:
-	if (error < 0 && !nfsd_up_before)
-		nfsd_shutdown_net(net);
 out_put:
 	/* Threads now hold service active */
 	if (xchg(&nn->keep_active, 0))
 		svc_put(serv);
+
+	if (serv->sv_nrthreads =3D=3D 0)
+		nfsd_last_thread(net);
 	svc_put(serv);
 out:
 	mutex_unlock(&nfsd_mutex);
--=20
2.42.0