nfsd4: fix off-by-one-error in SEQUENCE reply

The values here represent highest slotid numbers.  Since slotid's are
numbered starting from zero, the highest should be one less than the
number of slots.

Reported-by: Rick Macklem <rmacklem@uoguelph.ca>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 04ad9a2..f982d85 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3221,9 +3221,9 @@
 	WRITEMEM(seq->sessionid.data, NFS4_MAX_SESSIONID_LEN);
 	WRITE32(seq->seqid);
 	WRITE32(seq->slotid);
-	WRITE32(seq->maxslots);
-	/* For now: target_maxslots = maxslots */
-	WRITE32(seq->maxslots);
+	/* Note slotid's are numbered from zero: */
+	WRITE32(seq->maxslots - 1); /* sr_highest_slotid */
+	WRITE32(seq->maxslots - 1); /* sr_target_highest_slotid */
 	WRITE32(seq->status_flags);
 
 	ADJUST_ARGS();