nfs41: implement cb_recall_slot

Drain the fore channel and reset the max_slots to the new value.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 34fc6be..ecd9e6c 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -193,6 +193,8 @@
 	int		max_slots;		/* # slots in table */
 	int		highest_used_slotid;	/* sent to server on each SEQ.
 						 * op for dynamic resizing */
+	int		target_max_slots;	/* Set by CB_RECALL_SLOT as
+						 * the new max_slots */
 };
 
 static inline int slot_idx(struct nfs4_slot_table *tbl, struct nfs4_slot *sp)