xprtrdma: "Support" call-only RPCs

RPC-over-RDMA version 1 credit accounting relies on there being a
response message for every RPC Call. This means that RPC procedures
that have no reply will disrupt credit accounting, just in the same
way as a retransmit would (since it is sent because no reply has
arrived). Deal with the "no reply" case the same way.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

3 files changed, 13 insertions, 6 deletions

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index ed761f751ecb..9b11b6a0978c 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -217,5 +217,12 @@ void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *, struct rpc_xprt *);
 bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
                         const struct sockaddr *sap);
 void rpc_cleanup_clids(void);
+
+static inline int rpc_reply_expected(struct rpc_task *task)
+{
+        return (task->tk_msg.rpc_proc != NULL) &&
+                (task->tk_msg.rpc_proc->p_decode != NULL);
+}
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_SUNRPC_CLNT_H */
diff --git a/net/sunrpc/sunrpc.h b/net/sunrpc/sunrpc.h
index f2b7cb540e61..09a0315ea77b 100644
--- a/net/sunrpc/sunrpc.h
+++ b/net/sunrpc/sunrpc.h
@@ -37,12 +37,6 @@ struct rpc_buffer {
         char    data[];
 };
 
-static inline int rpc_reply_expected(struct rpc_task *task)
-{
-        return (task->tk_msg.rpc_proc != NULL) &&
-                (task->tk_msg.rpc_proc->p_decode != NULL);
-}
-
 static inline int sock_is_loopback(struct sock *sk)
 {
         struct dst_entry *dst;
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 08196896953d..7e39faa90c41 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -728,6 +728,12 @@ xprt_rdma_send_request(struct rpc_task *task)
 
         rqst->rq_xmit_bytes_sent += rqst->rq_snd_buf.len;
         rqst->rq_bytes_sent = 0;
+
+        /* An RPC with no reply will throw off credit accounting,
+         * so drop the connection to reset the credit grant.
+         */
+        if (!rpc_reply_expected(task))
+                goto drop_connection;
         return 0;
 
 failed_marshal: