Posted by dxdxdt 2 days ago
Sir, this is a correctness issue.
Will call it a human slop. AI may've given them some code but they certainly haven't use it fully. I uploaded the defrag.c in ChatGPT asking to review on performance/correctness/safety and pointed the sames issues as you (alongside bunch of others but not interested at the moment to review them).
The code base is huge for an LLM to handle, perhaps it was generated over multiple prompts idk. Not sure if someone can train a model on the kernel code or exfatprogs and generate the code. I doubt someone with such expertise would even go through the process when they can just write the code themselves which is much easier.
Seems like they are very new to tbings and didn't expect it to be adopted, but were hoping for a bit of feedback.
If a user has double storage available, it's probably best to do the old-fashioned "defrag" by single-threaded copying all files and file metadata to a newly-formatted volume.
Read the defrag code in other well-established fs like ext4 or btrfs. They all have limitations(or caveats, if you will). It's one of those problems where you just have to throw money at it and hope for the best. Even Microsoft kinda just gave up on it because it's really a pointless exercise at this point in time and age.
At our size and use case the timing was usually close to perfect. The pools were getting close to full and fragmented as larger disks became inexpensive.