NFSv4.1: Don't rebind to the same source port when reconnecting to the server

NFSv2, v3 and NFSv4 servers often have duplicate replay caches that look
at the source port when deciding whether or not an RPC call is a replay
of a previous call. This requires clients to perform strange TCP gymnastics
in order to ensure that when they reconnect to the server, they bind
to the same source port.

NFSv4.1 and NFSv4.2 have sessions that provide proper replay semantics,
that do not look at the source port of the connection. This patch therefore
ensures they can ignore the rebind requirement.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 7d46faf..0afb6d5 100644 (file)
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -464,7 +464,8 @@ nlm_bind_host(struct nlm_host *host)
                        .version        = host->h_version,
                        .authflavor     = RPC_AUTH_UNIX,
                        .flags          = (RPC_CLNT_CREATE_NOPING |
-                                          RPC_CLNT_CREATE_AUTOBIND),
+                                          RPC_CLNT_CREATE_AUTOBIND |
+                                          RPC_CLNT_CREATE_REUSEPORT),
                        .cred           = host->h_cred,
                };
 

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index bd6575e..02110a3 100644 (file)
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -523,6 +523,8 @@ int nfs_create_rpc_client(struct nfs_client *clp,
                args.flags |= RPC_CLNT_CREATE_INFINITE_SLOTS;
        if (test_bit(NFS_CS_NOPING, &clp->cl_flags))
                args.flags |= RPC_CLNT_CREATE_NOPING;
+       if (test_bit(NFS_CS_REUSEPORT, &clp->cl_flags))
+               args.flags |= RPC_CLNT_CREATE_REUSEPORT;
 
        if (!IS_ERR(clp->cl_rpcclient))
                return 0;
@@ -670,6 +672,7 @@ static int nfs_init_server(struct nfs_server *server,
                .timeparms = &timeparms,
                .cred = server->cred,
                .nconnect = data->nfs_server.nconnect,
+               .init_flags = (1UL << NFS_CS_REUSEPORT),
        };
        struct nfs_client *clp;
        int error;

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index ebc960d..abd5af7 100644 (file)
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -879,8 +879,11 @@ static int nfs4_set_client(struct nfs_server *server,
        };
        struct nfs_client *clp;
 
-       if (minorversion > 0 && proto == XPRT_TRANSPORT_TCP)
+       if (minorversion == 0)
+               __set_bit(NFS_CS_REUSEPORT, &cl_init.init_flags);
+       else if (proto == XPRT_TRANSPORT_TCP)
                cl_init.nconnect = nconnect;
+
        if (server->flags & NFS_MOUNT_NORESVPORT)
                __set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
        if (server->options & NFS_OPTION_MIGRATION)

diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 69e80ce..df61ff8 100644 (file)
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -47,6 +47,7 @@ struct nfs_client {
 #define NFS_CS_TSM_POSSIBLE    5               /* - Maybe state migration */
 #define NFS_CS_NOPING          6               /* - don't ping on connect */
 #define NFS_CS_DS              7               /* - Server is a DS */
+#define NFS_CS_REUSEPORT       8               /* - reuse src port on reconnect */
        struct sockaddr_storage cl_addr;        /* server identifier */
        size_t                  cl_addrlen;
        char *                  cl_hostname;    /* hostname of server */

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index abc63bd..ec52e78 100644 (file)
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -149,6 +149,7 @@ struct rpc_add_xprt_test {
 #define RPC_CLNT_CREATE_NO_IDLE_TIMEOUT        (1UL << 8)
 #define RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT     (1UL << 9)
 #define RPC_CLNT_CREATE_SOFTERR                (1UL << 10)
+#define RPC_CLNT_CREATE_REUSEPORT      (1UL << 11)
 
 struct rpc_clnt *rpc_create(struct rpc_create_args *args);
 struct rpc_clnt        *rpc_bind_new_program(struct rpc_clnt *,

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index d783e15..ccd35cf 100644 (file)
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -207,7 +207,8 @@ struct rpc_xprt {
        unsigned int            min_reqs;       /* min number of slots */
        unsigned int            num_reqs;       /* total slots */
        unsigned long           state;          /* transport state */
-       unsigned char           resvport   : 1; /* use a reserved port */
+       unsigned char           resvport   : 1, /* use a reserved port */
+                               reuseport  : 1; /* reuse port on reconnect */
        atomic_t                swapper;        /* we're swapping over this
                                                   transport */
        unsigned int            bind_index;     /* bind function index */

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f7f7856..5baf9b9 100644 (file)
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -591,6 +591,9 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
        xprt->resvport = 1;
        if (args->flags & RPC_CLNT_CREATE_NONPRIVPORT)
                xprt->resvport = 0;
+       xprt->reuseport = 0;
+       if (args->flags & RPC_CLNT_CREATE_REUSEPORT)
+               xprt->reuseport = 1;
 
        clnt = rpc_create_xprt(args, xprt);
        if (IS_ERR(clnt) || args->nconnect <= 1)
@@ -2906,7 +2909,7 @@ int rpc_clnt_add_xprt(struct rpc_clnt *clnt,
        struct rpc_xprt *xprt;
        unsigned long connect_timeout;
        unsigned long reconnect_timeout;
-       unsigned char resvport;
+       unsigned char resvport, reuseport;
        int ret = 0;
 
        rcu_read_lock();
@@ -2918,6 +2921,7 @@ int rpc_clnt_add_xprt(struct rpc_clnt *clnt,
                return -EAGAIN;
        }
        resvport = xprt->resvport;
+       reuseport = xprt->reuseport;
        connect_timeout = xprt->connect_timeout;
        reconnect_timeout = xprt->max_reconnect_timeout;
        rcu_read_unlock();
@@ -2928,6 +2932,7 @@ int rpc_clnt_add_xprt(struct rpc_clnt *clnt,
                goto out_put_switch;
        }
        xprt->resvport = resvport;
+       xprt->reuseport = reuseport;
        if (xprt->ops->set_connect_timeout != NULL)
                xprt->ops->set_connect_timeout(xprt,
                                connect_timeout,

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 70e52f5..98e2d40 100644 (file)
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1752,7 +1752,7 @@ static void xs_set_port(struct rpc_xprt *xprt, unsigned short port)
 
 static void xs_set_srcport(struct sock_xprt *transport, struct socket *sock)
 {
-       if (transport->srcport == 0)
+       if (transport->srcport == 0 && transport->xprt.reuseport)
                transport->srcport = xs_sock_getport(sock);
 }