nfs41: cb_sequence proc implementation

Currently, just free up any referring calls information.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfs41: fix csr_{,target}highestslotid]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 2b933ce..576f51f4 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -103,6 +103,9 @@
 	uint32_t			csr_target_highestslotid;
 };
 
+extern unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
+				       struct cb_sequenceres *res);
+
 #endif /* CONFIG_NFS_V4_1 */
 
 extern __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *res);
@@ -119,6 +122,7 @@
  * of slots for the backchannel.
  */
 #define NFS41_BC_MIN_CALLBACKS 1
+#define NFS41_BC_MAX_CALLBACKS 1
 
 extern unsigned int nfs_callback_set_tcpport;
 extern unsigned short nfs_callback_tcpport;