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From:   Benjamin Coddington <bcodding@redhat.com>
To:     bfields@fieldses.org, chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH] NFSD: Keep existing listners on portlist error
Date:   Wed,  6 Oct 2021 13:16:46 -0400
Message-Id: <74ed9f09bc3e3efbc70ff0414fb13c533b810a20.1633540569.git.bcodding@redhat.com>
In-Reply-To: <45b916f1aa3fb7c059a574f61188a8f2f615410e.1633529847.git.bcodding@redhat.com>
References: <45b916f1aa3fb7c059a574f61188a8f2f615410e.1633529847.git.bcodding@redhat.com>
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If nfsd has existing listening sockets without any processes, then an error
returned from svc_create_xprt() for an additional transport will remove
those existing listeners.  We're seeing this in practice when userspace
attempts to create rpcrdma transports without having the rpcrdma modules
present before creating nfsd kernel processes.  Fix this by checking for
existing sockets before callingn nfsd_destroy().

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfsd/nfsctl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index c2c3d9077dc5..696a217255fc 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -793,7 +793,10 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr
 		svc_xprt_put(xprt);
 	}
 out_err:
-	nfsd_destroy(net);
+	if (!list_empty(&nn->nfsd_serv->sv_permsocks))
+		nn->nfsd_serv->sv_nrthreads--;
+	 else
+		nfsd_destroy(net);
 	return err;
 }
 
-- 
2.30.2