This is like people that think they have designed their own even better encryption algorithm. Voodoo. You are not solving a problem better than the kernel and filesystem (and hypervisor in this case) has already done. If you are not writing the kernel or a driver or bootloader itself, then fsync() is not your problem or responsibility and you aren't filling any holes left by anyone else. You're just rubbing the belly of the budda statue for good luck to feel better.
You didn't answer any of the questions proposed by the outlined scenario.
Until you answer how you've solved the "I want to make sure my data is written to disk before the hypervisor powers off the virtual machine at the end of the successful run" problem, then I claim that this is absolutely not voodoo.
I suggest you actually read the documentation of all of these things before you start claiming that `fsync()` is exclusively the purpose of kernel, driver, or bootloader developers.
