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Subject[PATCH] refine RPC over TCP socket connect behavior
further refine TCP socket connect behavior in the RPC client.  this patch 
implements the following behavior changes:

+ the TCP connect timeout is now the same as the TCP retransmit timeout
value, giving sysadmins a means to adjust the connect timeout for
links with long RTTs.

+ if multiple RPC requests notice the TCP transport socket is
disconnected, cause them all to wait at least RPC_REESTABLISH_TIMEOUT
seconds before retrying to connect. before, only one would wait, and
the rest would retry immediately.

+ if an unrecognized error occurs when trying to establish a connection,
just exit without retrying.

against 2.5.47.


diff -ruN 05-odirect2/include/linux/sunrpc/xprt.h 10-connect3/include/linux/sunrpc/xprt.h
--- 05-odirect2/include/linux/sunrpc/xprt.h Sun Nov 10 22:28:27 2002
+++ 10-connect3/include/linux/sunrpc/xprt.h Tue Nov 12 16:18:57 2002
@@ -45,13 +45,6 @@
#define RPC_MAX_TCP_TIMEOUT (600*HZ)

/*
- * Wait duration for an RPC TCP connection to be established. Solaris
- * NFS over TCP uses 60 seconds, for example, which is in line with how
- * long a server takes to reboot.
- */
-#define RPC_CONNECT_TIMEOUT (60*HZ)
-
-/*
* Delay an arbitrary number of seconds before attempting to reconnect
* after an error.
*/
diff -ruN 05-odirect2/net/sunrpc/clnt.c 10-connect3/net/sunrpc/clnt.c
--- 05-odirect2/net/sunrpc/clnt.c Sun Nov 10 22:28:10 2002
+++ 10-connect3/net/sunrpc/clnt.c Tue Nov 12 16:19:25 2002
@@ -566,7 +566,7 @@

if (!clnt->cl_port) {
task->tk_action = call_connect;
- task->tk_timeout = RPC_CONNECT_TIMEOUT;
+ task->tk_timeout = xprt->timeout.to_initval;
rpc_getport(task, clnt);
}
}
diff -ruN 05-odirect2/net/sunrpc/xprt.c 10-connect3/net/sunrpc/xprt.c
--- 05-odirect2/net/sunrpc/xprt.c Sun Nov 10 22:28:26 2002
+++ 10-connect3/net/sunrpc/xprt.c Tue Nov 12 16:31:08 2002
@@ -461,7 +461,7 @@
if (inet->state != TCP_ESTABLISHED) {
dprintk("RPC: %4d waiting for connection\n",
task->tk_pid);
- task->tk_timeout = RPC_CONNECT_TIMEOUT;
+ task->tk_timeout = xprt->timeout.to_initval;
/* if the socket is already closing, delay briefly */
if ((1 << inet->state) & ~(TCPF_SYN_SENT|TCPF_SYN_RECV))
task->tk_timeout = RPC_REESTABLISH_TIMEOUT;
@@ -481,7 +481,7 @@
if (inet->state != TCP_ESTABLISHED) {
xprt_close(xprt);
task->tk_status = -EAGAIN;
- goto out_write;
+ break;
}

/* Otherwise, the connection is already established. */
@@ -491,24 +491,14 @@
case -EPIPE:
xprt_close(xprt);
task->tk_status = -ENOTCONN;
- goto out_write;
+ break;

default:
- /* Report myriad other possible returns. If this file
- * system is soft mounted, just error out, like Solaris. */
+ /* Report myriad other possible returns, and exit. */
xprt_close(xprt);
- if (task->tk_client->cl_softrtry) {
- printk(KERN_WARNING
+ printk(KERN_WARNING
"RPC: error %d connecting to server %s, exiting\n",
-status, task->tk_client->cl_server);
- task->tk_status = -EIO;
- } else {
- printk(KERN_WARNING
- "RPC: error %d connecting to server %s\n",
- -status, task->tk_client->cl_server);
- rpc_delay(task, RPC_REESTABLISH_TIMEOUT);
- task->tk_status = status;
- }
break;
}

@@ -528,26 +518,37 @@
case 0:
dprintk("RPC: %4d xprt_conn_status: connection established\n",
task->tk_pid);
- goto out;
+ xprt_release_write(xprt, task);
+ return;
case -ETIMEDOUT:
dprintk("RPC: %4d xprt_conn_status: timed out\n",
task->tk_pid);
- /* prevent TCP from continuing to retry SYNs */
- xprt_close(xprt);
+ task->tk_status = -EAGAIN;
+ if (task->tk_client->cl_softrtry)
+ task->tk_status = -EIO;
+ break;
+ case -ENOTCONN:
+ dprintk("RPC: %4d xprt_conn_status: no network path\n",
+ task->tk_pid);
+ if (!task->tk_client->cl_softrtry) {
+ rpc_delay(task, RPC_REESTABLISH_TIMEOUT);
+ task->tk_status = -EAGAIN;
+ } else
+ task->tk_status = -EIO;
break;
default:
- printk(KERN_ERR "RPC: error %d connecting to server %s\n",
+ printk(KERN_WARNING
+ "RPC: error %d connecting to server %s, exiting\n",
-task->tk_status, task->tk_client->cl_server);
- xprt_close(xprt);
- rpc_delay(task, RPC_REESTABLISH_TIMEOUT);
break;
}
- /* if soft mounted, cause this RPC to fail */
- if (task->tk_client->cl_softrtry)
- task->tk_status = -EIO;
+ /* prevent TCP from continuing to retry SYNs */
+ xprt_close(xprt);

- out:
- xprt_release_write(xprt, task);
+ /* if we're retrying, hold the write lock to prevent other
+ * requests from retrying the connect */
+ if (task->tk_status != -EAGAIN)
+ xprt_release_write(xprt, task);
}

/*
-
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