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, so that another transport can be tried or the
pending request can be abandoned quickly.
Introduce a per-request flag which controls how call_transmit_status()
behaves when transmitting the request fails because the server cannot
be reached. The transport's connection re-establishment timeout is
also ignored for such requests.
We don't want soft connection semantics to apply to other errors, nor
when the RPC was successfully transmitted. 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.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/sunrpc/sched.h | 2 ++
net/sunrpc/clnt.c | 7 +++++++
net/sunrpc/xprtsock.c | 2 +-
3 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index 4010977..1906782 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -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
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 38829e2..57f39b7 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1185,6 +1185,8 @@ call_transmit_status(struct rpc_task *task)
break;
default:
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
@@ -1198,6 +1200,11 @@ call_transmit_status(struct rpc_task *task)
case -EHOSTUNREACH:
case -ENETUNREACH:
case -EPIPE:
+ if (RPC_IS_SOFTCONN(task)) {
+ xprt_end_transmit(task);
+ rpc_exit(task, task->tk_status);
+ break;
+ }
rpc_task_force_reencode(task);
}
}
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 032d714..c94b3f2 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -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)) {
if (xprt->reestablish_timeout != 0)
dprintk("RPC: xs_connect delayed xprt %p "
"for %lu seconds\n",
--
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