stores: Support RemoveCopies on remote store

extern/sector-storage/stores/remote.go

@@ -44,12 +44,36 @@ type Remote struct {
 	pfHandler PartialFileHandler
 }
 
-func (r *Remote) RemoveCopies(ctx context.Context, s abi.SectorID, types storiface.SectorFileType) error {
+func (r *Remote) RemoveCopies(ctx context.Context, s abi.SectorID, typ storiface.SectorFileType) error {
-	// TODO: do this on remotes too
+	if bits.OnesCount(uint(typ)) != 1 {
-	//  (not that we really need to do that since it's always called by the
+		return xerrors.New("delete expects one file type")
-	//   worker which pulled the copy)
+	}
 
-	return r.local.RemoveCopies(ctx, s, types)
+	if err := r.local.RemoveCopies(ctx, s, typ); err != nil {
+		return xerrors.Errorf("removing local copies: %w", err)
+	}
+
+	si, err := r.index.StorageFindSector(ctx, s, typ, 0, false)
+	if err != nil {
+		return xerrors.Errorf("finding existing sector %d(t:%d) failed: %w", s, typ, err)
+	}
+
+	var hasPrimary bool
+	var keep []ID
+	for _, info := range si {
+		if info.Primary {
+			hasPrimary = true
+			keep = append(keep, info.ID)
+			break
+		}
+	}
+
+	if !hasPrimary {
+		log.Warnf("remote RemoveCopies: no primary copies of sector %v (%s), not removing anything", s, typ)
+		return nil
+	}
+
+	return r.Remove(ctx, s, typ, true, keep)
 }
 
 func NewRemote(local Store, index SectorIndex, auth http.Header, fetchLimit int, pfHandler PartialFileHandler) *Remote {