HFS+

There’s this arcane(?) filesystem used for example in many Apple OS X installations called HFS+.

One thing in my day job is to work with those kind of things. Ended up finding a bug on the implementation in Linux kernel. This one was just a bug introduced couple of years ago while someone fixed a possible deadlock.

Unfortunately as a side effect it caused possible data loss and corruption. Spent some of my work time to fix this issue, and sent the fix to kernel. In addition to the latest kernel, it was pushed to all current stable kernels as well.

The fix itself is quite simple, but to get there it took a while to understand the filesystem, and it’s implementation in kernel. I don’t know yet if this was useful at all, since Apple is heading towards new AFS, and HFS+ is getting more rare all the time. Well, there’s always need for some legacy stuff, so maybe some day that might end up being useful.

If nothing else, I managed to get another change into Linux kernel.