nfsd4: check backchannel attributes on create_session

Make sure the client gives us an adequate backchannel.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index be3ff0f..7f05cd1 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -37,6 +37,7 @@
 #include "nfsd.h"
 #include "state.h"
 #include "netns.h"
+#include "xdr4cb.h"
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
@@ -53,30 +54,6 @@
 	NFSPROC4_CLNT_CB_SEQUENCE,
 };
 
-#define NFS4_MAXTAGLEN		20
-
-#define NFS4_enc_cb_null_sz		0
-#define NFS4_dec_cb_null_sz		0
-#define cb_compound_enc_hdr_sz		4
-#define cb_compound_dec_hdr_sz		(3 + (NFS4_MAXTAGLEN >> 2))
-#define sessionid_sz			(NFS4_MAX_SESSIONID_LEN >> 2)
-#define cb_sequence_enc_sz		(sessionid_sz + 4 +             \
-					1 /* no referring calls list yet */)
-#define cb_sequence_dec_sz		(op_dec_sz + sessionid_sz + 4)
-
-#define op_enc_sz			1
-#define op_dec_sz			2
-#define enc_nfs4_fh_sz			(1 + (NFS4_FHSIZE >> 2))
-#define enc_stateid_sz			(NFS4_STATEID_SIZE >> 2)
-#define NFS4_enc_cb_recall_sz		(cb_compound_enc_hdr_sz +       \
-					cb_sequence_enc_sz +            \
-					1 + enc_stateid_sz +            \
-					enc_nfs4_fh_sz)
-
-#define NFS4_dec_cb_recall_sz		(cb_compound_dec_hdr_sz  +      \
-					cb_sequence_dec_sz +            \
-					op_dec_sz)
-
 struct nfs4_cb_compound_hdr {
 	/* args */
 	u32		ident;	/* minorversion 0 only */