rpcrdma: Fix SQ size calculation when memreg is FRMR

This patch updates the computation to include the worst case situation
where three FRMR are required to map a single RPC REQ.

Signed-off-by: Tom Tucker <tom@ogc.us>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index e5e28d1..2ac3f6e 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -249,6 +249,8 @@
 	req->rl_nchunks = nchunks;
 
 	BUG_ON(nchunks == 0);
+	BUG_ON((r_xprt->rx_ia.ri_memreg_strategy == RPCRDMA_FRMR)
+	       && (nchunks > 3));
 
 	/*
 	 * finish off header. If write, marshal discrim and nchunks.