From: NeilBrown <neilb@suse.com>
To: Steve Dickson <SteveD@redhat.com>
Date: Fri, 29 Jul 2016 15:03:36 +1000
Subject: [PATCH 4/7] mount: use a public address for IPv6 callback.
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
        Linux NFS Mailing list <linux-nfs@vger.kernel.org>
Message-ID: <146976861673.20186.5857418808913241019.stgit@noble>
In-Reply-To: <146976807524.20186.8871903418718212567.stgit@noble>
References: <146976807524.20186.8871903418718212567.stgit@noble>
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Sender: linux-nfs-owner@vger.kernel.org

If IPv6 address privacy is active, the "clientaddr" given to the server
will likely be a temporary address which will eventually expire, thus
breaking callback.
So ask for a public address to ensure continued service.

Signed-off-by: NeilBrown <neilb@suse.com>
---
 utils/mount/network.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/utils/mount/network.c b/utils/mount/network.c
index 0d12613e86a4..7dceb2db3b93 100644
--- a/utils/mount/network.c
+++ b/utils/mount/network.c
@@ -38,6 +38,7 @@
 #include <sys/socket.h>
 #include <sys/wait.h>
 #include <sys/stat.h>
+#include <linux/in6.h>
 #include <netinet/in.h>
 #include <rpc/rpc.h>
 #include <rpc/pmap_prot.h>
@@ -1113,6 +1114,7 @@ static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen,
 		.sin6_addr		= IN6ADDR_ANY_INIT,
 	};
 	int sock, result = 0;
+	int val;
 
 	sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP);
 	if (sock < 0)
@@ -1124,6 +1126,9 @@ static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen,
 			goto out;
 		break;
 	case AF_INET6:
+		/* Make sure the call-back address is public/permanent */
+		val = IPV6_PREFER_SRC_PUBLIC;
+		setsockopt(sock, SOL_IPV6, IPV6_ADDR_PREFERENCES, &val, sizeof(val));
 		if (bind(sock, SAFE_SOCKADDR(&sin6), sizeof(sin6)) < 0)
 			goto out;
 		break;