SUNRPC: Allow RPCs to fail quickly if the server is unreachable (09a21c41) · Commits · 戴 / test

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 <chuck.lever@oracle.com> Signed-off-by:

Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/sched.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -130,12 +130,14 @@ struct rpc_task_setup {
		#define RPC_TASK_DYNAMIC 0x0080 /* task was kmalloc'ed */
		#define RPC_TASK_KILLED 0x0100 /* task was killed */
		#define RPC_TASK_SOFT 0x0200 /* Use soft timeouts */
		#define RPC_TASK_SOFTCONN 0x0400 /* Fail if can't connect */

		#define RPC_IS_ASYNC(t) ((t)->tk_flags & RPC_TASK_ASYNC)
		#define RPC_IS_SWAPPER(t) ((t)->tk_flags & RPC_TASK_SWAPPER)
		#define RPC_DO_ROOTOVERRIDE(t) ((t)->tk_flags & RPC_TASK_ROOTCREDS)
		#define RPC_ASSASSINATED(t) ((t)->tk_flags & RPC_TASK_KILLED)
		#define RPC_IS_SOFT(t) ((t)->tk_flags & RPC_TASK_SOFT)
		#define RPC_IS_SOFTCONN(t) ((t)->tk_flags & RPC_TASK_SOFTCONN)

		#define RPC_TASK_RUNNING 0
		#define RPC_TASK_QUEUED 1

net/sunrpc/clnt.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

net/sunrpc/xprtsock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2033,7 +2033,7 @@ static void xs_connect(struct rpc_task *task)
		if (xprt_test_and_set_connecting(xprt))
		return;

		if (transport->sock != NULL) {
		if (transport->sock != NULL && !RPC_IS_SOFTCONN(task)) {
		dprintk("RPC: xs_connect delayed xprt %p for %lu "
		"seconds\n",
		xprt, xprt->reestablish_timeout / HZ);

Admin message