Return-Path: linux-nfs-owner@vger.kernel.org Received: from cantor2.suse.de ([195.135.220.15]:52752 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755997AbaDWDst (ORCPT ); Tue, 22 Apr 2014 23:48:49 -0400 From: NeilBrown To: Jan Kara , Jeff Layton , Trond Myklebust , Dave Chinner , "J. Bruce Fields" , Mel Gorman , Andrew Morton Date: Wed, 23 Apr 2014 12:40:58 +1000 Subject: [PATCH 4/5] SUNRPC: track when a client connection is routed to the local host. Cc: linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <20140423024058.4725.7703.stgit@notabene.brown> In-Reply-To: <20140423022441.4725.89693.stgit@notabene.brown> References: <20140423022441.4725.89693.stgit@notabene.brown> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: 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 --- 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: