The DRC is not working at all after an RPC/RDMA transport reconnect.
The problem is that the new connection uses a different source port,
which defeats DRC hash.
An NFS/RDMA client's source port is meaningless for RDMA transports.
The transport layer typically sets the source port value on the
connection to a random ephemeral port. The server already ignores it
for the "secure port" check. See commit 16e4d93f6de7 ("NFSD: Ignore
client's source port on RDMA transports").
I'm not sure why I never noticed this before.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
net/sunrpc/xprtrdma/svc_rdma_transport.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 027a3b0..1b3700b 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -211,9 +211,14 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id,
/* Save client advertised inbound read limit for use later in accept. */
newxprt->sc_ord = param->initiator_depth;
- /* Set the local and remote addresses in the transport */
sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
+ /* The remote port is arbitrary and not under the control of the
+ * ULP. Set it to a fixed value so that the DRC continues to work
+ * after a reconnect.
+ */
+ rpc_set_port((struct sockaddr *)&newxprt->sc_xprt.xpt_remote, 0);
+
sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
