PROFESSIONAL EXPERIENCE

Ministry of Defence [Feb 2023 - Present]

  • Build cyber and cognitive defensive capabilities
  • Lead a team designing, developing, and maintaining technical systems
  • Set technical direction and grow engineers through mentoring and training
  • Design and run cyber exercises with realistic technical and information-operation scenarios
  • Focus on resilience, clarity, and long-term operational effectiveness

I build cyber and cognitive defensive capabilities in an environment where assumptions get challenged and failure has consequences outside the office. The role sits between systems engineering, security and strategy, which in practice means turning vague threats into concrete technical solutions that hold up.

I also lead the team that designs, develops and maintains those solutions, and a large part of that job is growing people: setting technical direction, mentoring engineers, and keeping training continuous. I design and prepare cyber exercises as well, combining deep technical scenarios with information-operation storylines so the conditions are realistic. Building the system is the easier half. The harder one is building a team that can think, adapt and keep working under pressure.

Red Hat, Senior Software Engineer [Jan 2011 - Feb 2023]

  • Kernel engineer in the Red Hat Kernel / File Systems team
  • Core contributor and maintainer of the ext4 file system and jbd2 journaling layer across all RHEL releases
  • Maintainer of e2fsprogs and quota for RHEL and Fedora
  • Long-term contributor to xfstests, the regression test suite Linux file systems are tested with
  • Upstream-focused development: feature design, bug fixing, and long-term backporting into RHEL
  • Deep cross-subsystem work spanning VFS, block layer, and memory management
  • Regular presenter at international conferences (Kernel Summit, LSF/MM, DevConf) and university courses
  • Mentor for junior engineers, interns, and university students working on theses

As a member of the kernel and file systems team, I worked primarily on the ext4 file system and the related user-space utilities. Day to day that meant debugging customer issues, fixing bugs, developing new features upstream, and backporting upstream code into Red Hat Enterprise Linux (RHEL).

Over the years I became a maintainer of ext4 and the jbd2 journaling layer across all RHEL releases, and maintained e2fsprogs and quota for both RHEL and Fedora.

File system work rarely stays inside the file system. Mine regularly extended into VFS, the block layer and memory management, and occasionally a good deal further out, when the root cause of what looked like a file system bug turned out to be somewhere else entirely. One of the more interesting ones was a CPU firmware bug.

Beyond the engineering itself, the role included presenting my work at international conferences (Kernel Summit, LSF/MM, DevConf, etc.) and delivering lectures in an Operating Systems course at a local university.

I never held a formal team lead position at Red Hat, but I mentored junior engineers and several interns, and served as technical advisor for a number of students working on their Bachelor’s and Master’s theses at local universities.

WebStep, System Administrator [Mar 2008 - Dec 2010]

  • Assisted system administrators with day-to-day operations
  • Created and managed mailboxes and web hosting accounts
  • Registered and maintained internet domains
  • Installed, configured, and maintained servers
  • Set up and administered network and application services

I assisted the system administrators and handled the routine operational work: creating mailboxes and web hosting accounts, registering domains, installing and maintaining servers, and configuring the services running on them.

PROJECTS

Here is a list of the most interesting publicly available projects I have contributed to. They are open source, so the work is there for anyone to review. Most of my contributions were made under my Red Hat email address lczerner@redhat.com. Links to the public repositories and selected contribution statistics are included as well.

EDUCATION

Brno University of Technology - Faculty of Information Technology [2008 - 2010]

  • Computer Systems and Networks
  • Master’s Degree
  • Thesis: Porting of RedirFS on Other OS

Brno University of Technology - Faculty of Electrical Engineering and Communications [2003 - 2008]

  • Teleinformatics
  • Bachelor’s Degree
  • Thesis: Scripts for configuration of Fedora operating system in PlanetLab

ABOUT ME

I’m a systems-focused software engineer with over a decade of Linux kernel work behind me, most of it in core subsystems such as file systems. Low-level infrastructure leaves you with certain habits: correctness first, performance measured rather than assumed, and a healthy suspicion of code that has only ever been tested on a good day. In recent years I have moved away from doing the deep technical work myself toward leading teams, mentoring engineers, and passing the knowledge on, which reaches further than my own hands do. I now work at the Czech Ministry of Defence on cybersecurity and defensive capabilities, where the adversary is real and the assumptions get tested. My interests run to operating systems, cybersecurity and cognitive security, with a particular pull toward the invisible infrastructure everything else stands on.

SKILLS

  • Programming: C, Bash, Python, automation
  • Systems: Linux kernel, File Systems, Docker, Ansible