Worked on enhancing the Filestore component in the ydb-platform/nbs repository by addressing reliability issues in the POSIX test suite. Focused on system programming and testing, the developer implemented a targeted fix to ensure mknod-related tests execute consistently by enabling bind syscall support and extending the misc.sh test harness with create_file and dirgen_max functions. This update resolved issue-4541, aligning the test suite more closely with POSIX compliance standards. All changes were validated through continuous integration, resulting in more deterministic and stable test outcomes. The work was carried out using C and Shell, emphasizing robust test coverage and workflow reliability.