diff --git a/extern/sector-storage/manager.go b/extern/sector-storage/manager.go
index fe9bf5d4569..73a5eb51e44 100644
--- a/extern/sector-storage/manager.go
+++ b/extern/sector-storage/manager.go
@@ -203,25 +203,26 @@ func schedFetch(sector abi.SectorID, ft stores.SectorFileType, ptype stores.Path
 	}
 }
 
-func (m *Manager) ReadPiece(ctx context.Context, sink io.Writer, sector abi.SectorID, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) error {
+func (m *Manager) tryReadUnsealedPiece(ctx context.Context, sink io.Writer, sector abi.SectorID, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize) (foundUnsealed bool, readOk bool, selector WorkerSelector, returnErr error) {
+
+	// acquire a lock purely for reading unsealed sectors
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	if err := m.index.StorageLock(ctx, sector, stores.FTSealed|stores.FTCache, stores.FTUnsealed); err != nil {
-		return xerrors.Errorf("acquiring sector lock: %w", err)
+	if err := m.index.StorageLock(ctx, sector, stores.FTUnsealed, stores.FTNone); err != nil {
+		returnErr = xerrors.Errorf("acquiring read sector lock: %w", err)
+		return
 	}
 
 	// passing 0 spt because we only need it when allowFetch is true
 	best, err := m.index.StorageFindSector(ctx, sector, stores.FTUnsealed, 0, false)
 	if err != nil {
-		return xerrors.Errorf("read piece: checking for already existing unsealed sector: %w", err)
+		returnErr = xerrors.Errorf("read piece: checking for already existing unsealed sector: %w", err)
+		return
 	}
 
-	var readOk bool
-	var selector WorkerSelector
-	if len(best) == 0 { // new
-		selector = newAllocSelector(m.index, stores.FTUnsealed, stores.PathSealing)
-	} else { // append to existing
+	foundUnsealed = len(best) > 0
+	if foundUnsealed { // append to existing
 		// There is unsealed sector, see if we can read from it
 
 		selector = newExistingSelector(m.index, sector, stores.FTUnsealed, false)
@@ -231,12 +232,27 @@ func (m *Manager) ReadPiece(ctx context.Context, sink io.Writer, sector abi.Sect
 			return err
 		})
 		if err != nil {
-			return xerrors.Errorf("reading piece from sealed sector: %w", err)
+			returnErr = xerrors.Errorf("reading piece from sealed sector: %w", err)
 		}
+	} else {
+		selector = newAllocSelector(m.index, stores.FTUnsealed, stores.PathSealing)
+	}
+	return
+}
 
-		if readOk {
-			return nil
-		}
+func (m *Manager) ReadPiece(ctx context.Context, sink io.Writer, sector abi.SectorID, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) error {
+	foundUnsealed, readOk, selector, err := m.tryReadUnsealedPiece(ctx, sink, sector, offset, size)
+	if err != nil {
+		return err
+	}
+	if readOk {
+		return nil
+	}
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	if err := m.index.StorageLock(ctx, sector, stores.FTSealed|stores.FTCache, stores.FTUnsealed); err != nil {
+		return xerrors.Errorf("acquiring unseal sector lock: %w", err)
 	}
 
 	unsealFetch := func(ctx context.Context, worker Worker) error {
@@ -244,7 +260,7 @@ func (m *Manager) ReadPiece(ctx context.Context, sink io.Writer, sector abi.Sect
 			return xerrors.Errorf("copy sealed/cache sector data: %w", err)
 		}
 
-		if len(best) > 0 {
+		if foundUnsealed {
 			if err := worker.Fetch(ctx, sector, stores.FTUnsealed, stores.PathSealing, stores.AcquireMove); err != nil {
 				return xerrors.Errorf("copy unsealed sector data: %w", err)
 			}