There are a couple of issues
- loff_t is defined as long long on Linux. On FreeBSD it's defined as long. For all intents and purposes we only care about 64-bit so we'll just pretend like that always DTRT. It would be easier to interoperate with FreeBSD code if we just used off_t. I could go either way and convert the debugfs consumer back to using loff_t if we agree to actually use the type Linux uses.
- struct linux_file is what we actually pass around, using struct file and redefining it leads to conflicts in build, let's just use linux_file.