From 206a134b4d8abf57cd34dffacf993869355b9aac Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 3 Dec 2009 15:58:56 -0500 Subject: SUNRPC: Check explicitly for tk_status == 0 in call_transmit_status() The success case, where task->tk_status == 0, is by far the most frequent case in call_transmit_status(). The default: arm of the switch statement in call_transmit_status() handles the 0 case. default: was moved close to the top of the switch statement in call_transmit_status() under the theory that the compiler places object code for the earliest arms of a switch statement first, making the CPU do less work. The default: arm of a switch statement, however, is executed only after all the other cases have been checked. Even if the compiler rearranges the object code, the default: arm is the "last resort", meaning all of the other cases have been explicitly exhausted. That makes the current arrangement about as inefficient as it gets for the common case. To fix this, add an explicit check for zero before the switch statement. That forces the compiler to do the zero check first, no matter what optimizations it might try to do to the switch statement. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/clnt.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 38829e20500b..7bcd931e06ee 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1180,10 +1180,22 @@ static void call_transmit_status(struct rpc_task *task) { task->tk_action = call_status; + + /* + * Common case: success. Force the compiler to put this + * test first. + */ + if (task->tk_status == 0) { + xprt_end_transmit(task); + rpc_task_force_reencode(task); + return; + } + switch (task->tk_status) { case -EAGAIN: break; default: + dprint_status(task); xprt_end_transmit(task); /* * Special cases: if we've been waiting on the -- cgit From 09a21c4102c8f7893368553273d39c0cadedf9af Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 3 Dec 2009 15:58:56 -0500 Subject: SUNRPC: Allow RPCs to fail quickly if the server is unreachable The kernel sometimes makes RPC calls to services that aren't running. Because the kernel's RPC client always assumes the hard retry semantic when reconnecting a connection-oriented RPC transport, the underlying reconnect logic takes a long while to time out, even though the remote may have responded immediately with ECONNREFUSED. In certain cases, like upcalls to our local rpcbind daemon, or for NFS mount requests, we'd like the kernel to fail immediately if the remote service isn't reachable. This allows another transport to be tried immediately, or the pending request can be abandoned quickly. Introduce a per-request flag which controls how call_transmit_status() behaves when request transmission fails because the server cannot be reached. We don't want soft connection semantics to apply to other errors. The default case of the switch statement in call_transmit_status() no longer falls through; the fall through code is copied to the default case, and a "break;" is added. The transport's connection re-establishment timeout is also ignored for such requests. We want the request to fail immediately, so the reconnect delay is skipped. Additionally, we don't want a connect failure here to further increase the reconnect timeout value, since this request will not be retried. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/clnt.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 7bcd931e06ee..68a23583f44c 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1197,6 +1197,8 @@ call_transmit_status(struct rpc_task *task) default: dprint_status(task); xprt_end_transmit(task); + rpc_task_force_reencode(task); + break; /* * Special cases: if we've been waiting on the * socket's write_space() callback, or if the @@ -1204,11 +1206,16 @@ call_transmit_status(struct rpc_task *task) * then hold onto the transport lock. */ case -ECONNREFUSED: - case -ECONNRESET: - case -ENOTCONN: case -EHOSTDOWN: case -EHOSTUNREACH: case -ENETUNREACH: + if (RPC_IS_SOFTCONN(task)) { + xprt_end_transmit(task); + rpc_exit(task, task->tk_status); + break; + } + case -ECONNRESET: + case -ENOTCONN: case -EPIPE: rpc_task_force_reencode(task); } -- cgit From 012da158f636347c4eb28fd1e1cca020fef5e54d Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 3 Dec 2009 15:58:56 -0500 Subject: SUNRPC: Use soft connects for autobinding over TCP Autobinding is handled by the rpciod process, not in user processes that are generating regular RPC requests. Thus autobinding is usually not affected by signals targetting user processes, such as KILL or timer expiration events. In addition, an RPC request generated by a user process that has RPC_TASK_SOFTCONN set and needs to perform an autobind will hang if the remote rpcbind service is not available. For rpcbind queries on connection-oriented transports, let's use the new soft connect semantic to return control to the user's process quickly, if the kernel's rpcbind client can't connect to the remote rpcbind service. Logic is introduced in call_bind_status() to handle connection errors that occurred during an asynchronous rpcbind query. The logic abandons the rpcbind query if the RPC request has SOFTCONN set, and retries after a few seconds in the normal case. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/clnt.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 68a23583f44c..4b76ef9336c7 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1060,7 +1060,7 @@ call_bind_status(struct rpc_task *task) goto retry_timeout; case -EPFNOSUPPORT: /* server doesn't support any rpcbind version we know of */ - dprintk("RPC: %5u remote rpcbind service unavailable\n", + dprintk("RPC: %5u unrecognized remote rpcbind service\n", task->tk_pid); break; case -EPROTONOSUPPORT: @@ -1069,6 +1069,21 @@ call_bind_status(struct rpc_task *task) task->tk_status = 0; task->tk_action = call_bind; return; + case -ECONNREFUSED: /* connection problems */ + case -ECONNRESET: + case -ENOTCONN: + case -EHOSTDOWN: + case -EHOSTUNREACH: + case -ENETUNREACH: + case -EPIPE: + dprintk("RPC: %5u remote rpcbind unreachable: %d\n", + task->tk_pid, task->tk_status); + if (!RPC_IS_SOFTCONN(task)) { + rpc_delay(task, 5*HZ); + goto retry_timeout; + } + status = task->tk_status; + break; default: dprintk("RPC: %5u unrecognized rpcbind error (%d)\n", task->tk_pid, -task->tk_status); -- cgit From caabea8a565fb4e16f8e58e16bb9d535e591b709 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 3 Dec 2009 15:58:56 -0500 Subject: SUNRPC: Use soft connect semantics when performing RPC ping Currently, if a remote RPC service is unreachable, an RPC ping will hang until the underlying transport connect attempt times out. A more desirable behavior might be to have the ping fail immediately so upper layers can recover appropriately. In the case of an NFS mount, for instance, this would mean the mount(2) system call could fail immediately if the server isn't listening, rather than hanging uninterruptibly for more than 3 minutes. Change rpc_ping() so that it fails immediately for connection-oriented transports. rpc_create() will then fail immediately for such transports if an RPC ping was requested. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/clnt.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 4b76ef9336c7..97931d9f8579 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -79,7 +79,7 @@ static void call_connect_status(struct rpc_task *task); static __be32 *rpc_encode_header(struct rpc_task *task); static __be32 *rpc_verify_header(struct rpc_task *task); -static int rpc_ping(struct rpc_clnt *clnt, int flags); +static int rpc_ping(struct rpc_clnt *clnt); static void rpc_register_client(struct rpc_clnt *clnt) { @@ -340,7 +340,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args) return clnt; if (!(args->flags & RPC_CLNT_CREATE_NOPING)) { - int err = rpc_ping(clnt, RPC_TASK_SOFT); + int err = rpc_ping(clnt); if (err != 0) { rpc_shutdown_client(clnt); return ERR_PTR(err); @@ -528,7 +528,7 @@ struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old, clnt->cl_prog = program->number; clnt->cl_vers = version->number; clnt->cl_stats = program->stats; - err = rpc_ping(clnt, RPC_TASK_SOFT); + err = rpc_ping(clnt); if (err != 0) { rpc_shutdown_client(clnt); clnt = ERR_PTR(err); @@ -1709,14 +1709,14 @@ static struct rpc_procinfo rpcproc_null = { .p_decode = rpcproc_decode_null, }; -static int rpc_ping(struct rpc_clnt *clnt, int flags) +static int rpc_ping(struct rpc_clnt *clnt) { struct rpc_message msg = { .rpc_proc = &rpcproc_null, }; int err; msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0); - err = rpc_call_sync(clnt, &msg, flags); + err = rpc_call_sync(clnt, &msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN); put_rpccred(msg.rpc_cred); return err; } -- cgit From 3a28becc35e5c8f1fabb707bcd8a473712653de6 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Thu, 3 Dec 2009 15:58:56 -0500 Subject: SUNRPC: soft connect semantics for UDP Introduce soft connect behavior for UDP transports. In this case, a major timeout returns ETIMEDOUT instead of EIO. Signed-off-by: Chuck Lever Signed-off-by: Trond Myklebust --- net/sunrpc/clnt.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/sunrpc/clnt.c') diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 97931d9f8579..154034b675bd 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1380,6 +1380,10 @@ call_timeout(struct rpc_task *task) dprintk("RPC: %5u call_timeout (major)\n", task->tk_pid); task->tk_timeouts++; + if (RPC_IS_SOFTCONN(task)) { + rpc_exit(task, -ETIMEDOUT); + return; + } if (RPC_IS_SOFT(task)) { if (clnt->cl_chatty) printk(KERN_NOTICE "%s: server %s not responding, timed out\n", -- cgit