add Dealmaking.StartEpochSealingBuffer config

extern/storage-sealing/input.go

@@ -274,11 +274,16 @@ func (m *Sealing) SectorAddPieceToAny(ctx context.Context, size abi.UnpaddedPiec
 		return api.SectorOffset{}, xerrors.Errorf("getting proposal CID: %w", err)
 	}
 
+	cfg, err := m.getConfig()
+	if err != nil {
+		return api.SectorOffset{}, xerrors.Errorf("getting config: %w", err)
+	}
+
 	_, head, err := m.Api.ChainHead(ctx)
 	if err != nil {
 		return api.SectorOffset{}, xerrors.Errorf("couldnt get chain head: %w", err)
 	}
-	if head > deal.DealProposal.StartEpoch {
+	if head+cfg.StartEpochSealingBuffer > deal.DealProposal.StartEpoch {
 		return api.SectorOffset{}, xerrors.Errorf(
 			"cannot add piece for deal with piece CID %s: current epoch %d has passed deal proposal start epoch %d",
 			deal.DealProposal.PieceCID, head, deal.DealProposal.StartEpoch)

extern/storage-sealing/sealiface/config.go

@@ -22,6 +22,8 @@ type Config struct {
 
 	CommittedCapacitySectorLifetime time.Duration
 
+	StartEpochSealingBuffer abi.ChainEpoch
+
 	AlwaysKeepUnsealedCopy bool
 
 	FinalizeEarly bool