write DAG XOR tree consistency fixes to disk (#3363)

network/dag/consistency.go

@@ -120,6 +120,10 @@ func (f *xorTreeRepair) checkPage() {
 			if err != nil {
 				return err
 			}
+			err = f.state.xorTree.writeWithoutLock(txn)
+			if err != nil {
+				return err
+			}
 			log.Logger().Warnf("detected XOR tree mismatch for page %d, fixed using recalculated values", f.currentPage)
 		}
 

network/dag/treestore.go

@@ -63,12 +63,18 @@ func (store *treeStore) write(tx stoabs.WriteTx, transaction Transaction) error
 	store.mutex.Lock()
 	defer store.mutex.Unlock()
 
-	writer := tx.GetShelfWriter(store.bucketName)
-
 	store.tree.Insert(transaction.Ref(), transaction.Clock())
+	return store.writeWithoutLock(tx)
+}
+
+// writeWithoutLock writes all current changes in the treeStore to disk.
+// It is the callers responsibility to prevent race conditions on treeStore. Use treeStore.mutex if needed.
+func (store *treeStore) writeWithoutLock(tx stoabs.WriteTx) error {
 	dirties, orphaned := store.tree.Updates()
 	store.tree.ResetUpdates() // failure after this point results in rollback anyway
 
+	writer := tx.GetShelfWriter(store.bucketName)
+
 	// delete orphaned leaves
 	for _, orphan := range orphaned { // always zero
 		err := writer.Delete(clockToKey(orphan))