nfs41: Adjust max cache response size value

For the CREATE_SESSION attribute ca_maxresponsesize_cached, calculate
the value based on the rpc reply header size plus the maximum nfs compound
reply size.
Signed-off-by: NMike Sager <sager@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -4805,16 +4805,14 @@ static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)
 	args->fc_attrs.headerpadsz = 0;
 	args->fc_attrs.max_rqst_sz = mxrqst_sz;
 	args->fc_attrs.max_resp_sz = mxresp_sz;
-	args->fc_attrs.max_resp_sz_cached = mxresp_sz;
 	args->fc_attrs.max_ops = NFS4_MAX_OPS;
 	args->fc_attrs.max_reqs = session->clp->cl_rpcclient->cl_xprt->max_reqs;
 
 	dprintk("%s: Fore Channel : max_rqst_sz=%u max_resp_sz=%u "
-		"max_resp_sz_cached=%u max_ops=%u max_reqs=%u\n",
+		"max_ops=%u max_reqs=%u\n",
 		__func__,
 		args->fc_attrs.max_rqst_sz, args->fc_attrs.max_resp_sz,
-		args->fc_attrs.max_resp_sz_cached, args->fc_attrs.max_ops,
-		args->fc_attrs.max_reqs);
+		args->fc_attrs.max_ops, args->fc_attrs.max_reqs);
 
 	/* Back channel attributes */
 	args->bc_attrs.headerpadsz = 0;

fs/nfs/nfs4xdr.c

@@ -1578,6 +1578,14 @@ static void encode_create_session(struct xdr_stream *xdr,
 	char machine_name[NFS4_MAX_MACHINE_NAME_LEN];
 	uint32_t len;
 	struct nfs_client *clp = args->client;
+	u32 max_resp_sz_cached;
+
+	/*
+	 * Assumes OPEN is the biggest non-idempotent compound.
+	 * 2 is the verifier.
+	 */
+	max_resp_sz_cached = (NFS4_dec_open_sz + RPC_REPHDRSIZE +
+			      RPC_MAX_AUTH_SIZE + 2) * XDR_UNIT;
 
 	len = scnprintf(machine_name, sizeof(machine_name), "%s",
 			clp->cl_ipaddr);
@@ -1592,7 +1600,7 @@ static void encode_create_session(struct xdr_stream *xdr,
 	*p++ = cpu_to_be32(args->fc_attrs.headerpadsz);	/* header padding size */
 	*p++ = cpu_to_be32(args->fc_attrs.max_rqst_sz);	/* max req size */
 	*p++ = cpu_to_be32(args->fc_attrs.max_resp_sz);	/* max resp size */
-	*p++ = cpu_to_be32(args->fc_attrs.max_resp_sz_cached);	/* Max resp sz cached */
+	*p++ = cpu_to_be32(max_resp_sz_cached);		/* Max resp sz cached */
 	*p++ = cpu_to_be32(args->fc_attrs.max_ops);	/* max operations */
 	*p++ = cpu_to_be32(args->fc_attrs.max_reqs);	/* max requests */
 	*p++ = cpu_to_be32(0);				/* rdmachannel_attrs */