NFSv4.1: Fix nfs4_callback_recallslot to work with dynamic slot allocation

Ensure that the NFSv4.1 CB_RECALL_SLOT callback updates the slot table
target max slotid safely.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 42c5869..5d4e82b 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -260,6 +260,8 @@
 
 extern struct nfs4_slot *nfs4_alloc_slots(struct nfs4_slot_table *table,
 		u32 max_slots, gfp_t gfp_flags);
+extern void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
+		u32 target_highest_slotid);
 
 static inline bool
 is_ds_only_client(struct nfs_client *clp)