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Date: Wed, 23 Apr 2014 12:40:58 +1000
From: NeilBrown <neilb@...e.de>
To: Jan Kara <jack@...e.cz>, Jeff Layton <jlayton@...hat.com>,
Trond Myklebust <trond.myklebust@...marydata.com>,
Dave Chinner <david@...morbit.com>,
"J. Bruce Fields" <bfields@...ldses.org>,
Mel Gorman <mgorman@...e.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-nfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] SUNRPC: track when a client connection is routed to the
local host.
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@...e.de>
---
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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