linux-kernel - [PATCH RFC] nfsd: fix error handling in nfsd

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Date:   Mon, 30 Oct 2023 13:32:54 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>,
        Olga Kornievskaia <kolga@...app.com>,
        Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>
Cc:     linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Zhi Li <yieli@...hat.com>, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH RFC] nfsd: fix error handling in nfsd_svc

Once we've set the nfsd_serv pointer in nfsd_svc, we still need to call
nfsd_last_thread if the server fails to be started. Remove the special
casing for nfsd_up_before case since shutting down the per-net stuff is
also handled by nfsd_last_thread.

Finally, add a new special case at the start and skip doing anything if
the service already exists, 0 threads were requested and
serv->sv_nrthreads is 0.

Fixes: 9f28a971ee9f ("nfsd: separate nfsd_last_thread() from nfsd_put()")
Reported-by: Zhi Li <yieli@...hat.com>
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
Here's what I was thinking for a targeted patch for stable. Testing it
now, but I won't have results until tomorrow.
---
 fs/nfsd/nfssvc.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 3deef000afa9..187b68769815 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -787,7 +787,6 @@ int
 nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
 {
 	int	error;
-	bool	nfsd_up_before;
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 	struct svc_serv *serv;
 
@@ -797,8 +796,9 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
 	nrservs = max(nrservs, 0);
 	nrservs = min(nrservs, NFSD_MAXSERVS);
 	error = 0;
+	serv = nn->nfsd_serv;
 
-	if (nrservs == 0 && nn->nfsd_serv == NULL)
+	if (nrservs == 0 && (serv == NULL || serv->sv_nrthreads == 0))
 		goto out;
 
 	strscpy(nn->nfsd_name, utsname()->nodename,
@@ -808,22 +808,17 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
 	if (error)
 		goto out;
 
-	nfsd_up_before = nn->nfsd_net_up;
 	serv = nn->nfsd_serv;
 
 	error = nfsd_startup_net(net, cred);
 	if (error)
 		goto out_put;
 	error = svc_set_num_threads(serv, NULL, nrservs);
-	if (error)
-		goto out_shutdown;
-	error = serv->sv_nrthreads;
 	if (error == 0)
-		nfsd_last_thread(net);
-out_shutdown:
-	if (error < 0 && !nfsd_up_before)
-		nfsd_shutdown_net(net);
+		error = serv->sv_nrthreads;
 out_put:
+	if (serv->sv_nrthreads == 0)
+		nfsd_last_thread(net);
 	/* Threads now hold service active */
 	if (xchg(&nn->keep_active, 0))
 		svc_put(serv);

---
base-commit: 31b5a36c4b88b44c91cdd523997b1e86fb47339d
change-id: 20231030-kdevops-5f7366897ef4

Best regards,
-- 
Jeff Layton <jlayton@...nel.org>