1.problem :
- when running xtrabackup as a non-root user, Due to a security issue, the following error occurs and the redo_log_arch_dir function cannot be used.

2.issue purpose :
- Using the redo_log_arch_dir_direct new parameter, write archive redo log directly without creating archive.subdir folder in innodb_redo_log_archive_dirs os path.

3.changed Archived_Redo_Log_Monitor::thread_func function pseudo code :
- source code path : storage/innobase/xtrabackup/src/redo_log.cc
- source code function : Archived_Redo_Log_Monitor::thread_func()

4.full text of the changed Archived_Redo_Log_Monitor::thread_func function :
- appendix ( additional comment of “add var”, “add if” )

5.changed Archived_Redo_Log_Monitor::thread_func function xtrabackup log :

If you need further explanation, please comment.

thank you.