nfsd: New counter for generating client confirm verifier

If using clientid_counter, it seems possible that gen_confirm could
generate the same verifier for the same client in some situations.

Add a new counter for client confirm verifier to make sure gen_confirm
generates a different verifier on each call for the same clientid.
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/netns.h

@@ -110,6 +110,7 @@ struct nfsd_net {
 	unsigned int max_connections;
 
 	u32 clientid_counter;
+	u32 clverifier_counter;
 
 	struct svc_serv *nfsd_serv;
 };

fs/nfsd/nfs4state.c

@@ -1899,7 +1899,7 @@ static void gen_confirm(struct nfs4_client *clp, struct nfsd_net *nn)
 	 * __force to keep sparse happy
 	 */
 	verf[0] = (__force __be32)get_seconds();
-	verf[1] = (__force __be32)nn->clientid_counter;
+	verf[1] = (__force __be32)nn->clverifier_counter++;
 	memcpy(clp->cl_confirm.data, verf, sizeof(clp->cl_confirm.data));
 }