svcrdma: Add a separate "max data segs macro for svcrdma

The server and client maximum are architecturally independent.
Allow changing one without affecting the other.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

include/linux/sunrpc/svc_rdma.h

@@ -172,6 +172,13 @@ struct svcxprt_rdma {
 #define RDMAXPRT_SQ_PENDING	2
 #define RDMAXPRT_CONN_PENDING	3
 
+#define RPCRDMA_MAX_SVC_SEGS	(64)	/* server max scatter/gather */
+#if RPCSVC_MAXPAYLOAD < (RPCRDMA_MAX_SVC_SEGS << PAGE_SHIFT)
+#define RPCRDMA_MAXPAYLOAD	RPCSVC_MAXPAYLOAD
+#else
+#define RPCRDMA_MAXPAYLOAD	(RPCRDMA_MAX_SVC_SEGS << PAGE_SHIFT)
+#endif
+
 #define RPCRDMA_LISTEN_BACKLOG  10
 /* The default ORD value is based on two outstanding full-size writes with a
  * page size of 4k, or 32k * 2 ops / 4k = 16 outstanding RDMA_READ.  */

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -91,7 +91,7 @@ struct svc_xprt_class svc_rdma_class = {
 	.xcl_name = "rdma",
 	.xcl_owner = THIS_MODULE,
 	.xcl_ops = &svc_rdma_ops,
-	.xcl_max_payload = RPCSVC_MAXPAYLOAD_RDMA,
+	.xcl_max_payload = RPCRDMA_MAXPAYLOAD,
 	.xcl_ident = XPRT_TRANSPORT_RDMA,
 };
 

net/sunrpc/xprtrdma/xprt_rdma.h

@@ -487,10 +487,4 @@ extern struct kmem_cache *svc_rdma_ctxt_cachep;
 /* Workqueue created in svc_rdma.c */
 extern struct workqueue_struct *svc_rdma_wq;
 
-#if RPCSVC_MAXPAYLOAD < (RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT)
-#define RPCSVC_MAXPAYLOAD_RDMA RPCSVC_MAXPAYLOAD
-#else
-#define RPCSVC_MAXPAYLOAD_RDMA (RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT)
-#endif
-
 #endif				/* _LINUX_SUNRPC_XPRT_RDMA_H */