sunrpc: Advertise maximum backchannel payload size

RPC-over-RDMA transports have a limit on how large a backward
direction (backchannel) RPC message can be. Ensure that the NFSv4.x
CREATE_SESSION operation advertises this limit to servers.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 9a7ddbaf116e..19c659d1c0f8 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -176,6 +176,7 @@ void		rpc_setbufsize(struct rpc_clnt *, unsigned int, unsigned int);
 int             rpc_protocol(struct rpc_clnt *);
 struct net *    rpc_net_ns(struct rpc_clnt *);
 size_t          rpc_max_payload(struct rpc_clnt *);
+size_t          rpc_max_bc_payload(struct rpc_clnt *);
 unsigned long   rpc_get_timeout(struct rpc_clnt *clnt);
 void            rpc_force_rebind(struct rpc_clnt *);
 size_t          rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t);
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index fb0d212e0d3a..5aa3834619a8 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -142,6 +142,7 @@ struct rpc_xprt_ops {
         int             (*bc_setup)(struct rpc_xprt *xprt,
                                     unsigned int min_reqs);
         int             (*bc_up)(struct svc_serv *serv, struct net *net);
+        size_t          (*bc_maxpayload)(struct rpc_xprt *xprt);
         void            (*bc_free_rqst)(struct rpc_rqst *rqst);
         void            (*bc_destroy)(struct rpc_xprt *xprt,
                                       unsigned int max_reqs);