If requests are being sent to the local host, then NFS will
need to take care to avoid deadlocks.
So keep track when accepting a connection or sending a UDP request
and set a flag in the svc_xprt when the peer connected to is local.
The interface rpc_is_foreign() is provided to check is a given client
is connected to a foreign server. When it returns zero it is either
not connected or connected to a local server and in either case
greater care is needed.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
include/linux/sunrpc/clnt.h | 1 +
include/linux/sunrpc/xprt.h | 1 +
net/sunrpc/clnt.c | 25 +++++++++++++++++++++++++
net/sunrpc/xprtsock.c | 17 +++++++++++++++++
4 files changed, 44 insertions(+)
diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 8af2804bab16..5d626cc5ab01 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -173,6 +173,7 @@ void rpc_force_rebind(struct rpc_clnt *);
size_t rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t);
const char *rpc_peeraddr2str(struct rpc_clnt *, enum rpc_display_format_t);
int rpc_localaddr(struct rpc_clnt *, struct sockaddr *, size_t);
+int rpc_is_foreign(struct rpc_clnt *);
#endif /* __KERNEL__ */
#endif /* _LINUX_SUNRPC_CLNT_H */
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 8097b9df6773..318ee37bc358 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -340,6 +340,7 @@ int xs_swapper(struct rpc_xprt *xprt, int enable);
#define XPRT_CONNECTION_ABORT (7)
#define XPRT_CONNECTION_CLOSE (8)
#define XPRT_CONGESTED (9)
+#define XPRT_LOCAL (10)
static inline void xprt_set_connected(struct rpc_xprt *xprt)
{
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 0edada973434..454cea69b373 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1109,6 +1109,31 @@ const char *rpc_peeraddr2str(struct rpc_clnt *clnt,
}
EXPORT_SYMBOL_GPL(rpc_peeraddr2str);
+/**
+ * rpc_is_foreign - report is rpc client was recently connected to
+ * remote host
+ * @clnt: RPC client structure
+ *
+ * If the client is not connected, or connected to the local host
+ * (any IP address), then return 0. Only return non-zero if the
+ * most recent state was a connection to a remote host.
+ * For UDP the client always appears to be connected, and the
+ * remoteness of the host is of the destination of the last transmission.
+ */
+int rpc_is_foreign(struct rpc_clnt *clnt)
+{
+ struct rpc_xprt *xprt;
+ int conn_foreign;
+
+ rcu_read_lock();
+ xprt = rcu_dereference(clnt->cl_xprt);
+ conn_foreign = (xprt && xprt_connected(xprt)
+ && !test_bit(XPRT_LOCAL, &xprt->state));
+ rcu_read_unlock();
+ return conn_foreign;
+}
+EXPORT_SYMBOL_GPL(rpc_is_foreign);
+
static const struct sockaddr_in rpc_inaddr_loopback = {
.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY),
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 0addefca8e77..74796cf37d5b 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -642,6 +642,15 @@ static int xs_udp_send_request(struct rpc_task *task)
xdr->len - req->rq_bytes_sent, status);
if (status >= 0) {
+ struct dst_entry *dst;
+ rcu_read_lock();
+ dst = rcu_dereference(transport->sock->sk->sk_dst_cache);
+ if (dst && dst->dev && (dst->dev->features & NETIF_F_LOOPBACK))
+ set_bit(XPRT_LOCAL, &xprt->state);
+ else
+ clear_bit(XPRT_LOCAL, &xprt->state);
+ rcu_read_unlock();
+
req->rq_xmit_bytes_sent += status;
if (status >= req->rq_slen)
return 0;
@@ -1527,6 +1536,7 @@ static void xs_sock_mark_closed(struct rpc_xprt *xprt)
static void xs_tcp_state_change(struct sock *sk)
{
struct rpc_xprt *xprt;
+ struct dst_entry *dst;
read_lock_bh(&sk->sk_callback_lock);
if (!(xprt = xprt_from_sock(sk)))
@@ -1556,6 +1566,13 @@ static void xs_tcp_state_change(struct sock *sk)
xprt_wake_pending_tasks(xprt, -EAGAIN);
}
+ rcu_read_lock();
+ dst = rcu_dereference(sk->sk_dst_cache);
+ if (dst && dst->dev && (dst->dev->features & NETIF_F_LOOPBACK))
+ set_bit(XPRT_LOCAL, &xprt->state);
+ else
+ clear_bit(XPRT_LOCAL, &xprt->state);
+ rcu_read_unlock();
spin_unlock(&xprt->transport_lock);
break;
case TCP_FIN_WAIT1:
--
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