nfsd: calculate the missing length of bitmap in EXCHANGE_ID

commit 58cd57bfd9db3bc213bf9d6a10920f82095f0114
"nfsd: Fix SP4_MACH_CRED negotiation in EXCHANGE_ID"
miss calculating the length of bitmap for spo_must_enforce and spo_must_allow.

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 419572f..7bac4bd 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1524,7 +1524,8 @@
 static inline u32 nfsd4_exchange_id_rsize(struct svc_rqst *rqstp, struct nfsd4_op *op)
 {
 	return (op_encode_hdr_size + 2 + 1 + /* eir_clientid, eir_sequenceid */\
-		1 + 1 + 2 + /* eir_flags, spr_how, spo_must_enforce & _allow */\
+		1 + 1 + /* eir_flags, spr_how */\
+		4 + /* spo_must_enforce & _allow with bitmap */\
 		2 + /*eir_server_owner.so_minor_id */\
 		/* eir_server_owner.so_major_id<> */\
 		XDR_QUADLEN(NFS4_OPAQUE_LIMIT) + 1 +\