Add fallback dir const

Author: boris-ilijic

pbm/restore/physical.go

@@ -46,13 +46,16 @@ import (
 const (
 	defaultRSdbpath   = "/data/db"
 	defaultCSRSdbpath = "/data/configdb"
+	fallbackDir       = ".fallbackDbPath"
 
 	mongofslock = "mongod.lock"
 
 	defaultPort = 27017
 
 	tryConnCount   = 5
 	tryConnTimeout = 5 * time.Minute
+
+	internalMongodLog = "pbm.restore.log"
 )
 
 type files struct {
@@ -1787,8 +1790,6 @@ func tryConn(port int, logpath string) (*mongo.Client, error) {
 	return nil, errors.Errorf("failed to  connect after %d tries: %v", tryConnCount, err)
 }
 
-const internalMongodLog = "pbm.restore.log"
-
 func (r *PhysRestore) startMongo(opts ...string) error {
 	if r.tmpConf != nil {
 		opts = append(opts, []string{"-f", r.tmpConf.Name()}...)