Hi Steve.
>>>>>> Now if grub is opening the block device and reading out of that, it
>>>>>> is looking at the same pages for metadata that xfs is looking at in
>>>>>> memory. There is a bug where you can get corruption if you access
>>>>>> the block device in parallel with the filesystem. Possibly this is
>>>>>> behind the problem.
>>>>>
>>>>> This will cause an oops on 2.6.x won't it --- so I suspect if this is
>>>>> behind the problem the report will be have been different.
>>>>
>>>> I don't think they're hitting the problem, the symptoms look very
>>>> different.
>>>
>>> And thinking about it some more, having grub make the filesystem
>>> remount readonly would force everything down to disk unlike just
>>> doing a sync
>>> call.
>>
>> Tried and failed :(
>>
>> Tried that before but it didn't help unfortunately.
>
> So what exactly is the sequence of events here, some files are created
> in the boot directory via the kernel, then grub wants to look at them
> via the block device api and its emulation of the filesystem? If we
> can nail this down, then maybe we can really work out what is going
> on here.
>
> Steve
Yup. That's what's happening. It first does one run with --just-copy
where it writes the files using the filesystem then reads the same
files using the blockdevice and it's own filesystem code basically.
// Stefan
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