On 30/12/2020 17:06, John Stoffel wrote:
Danny> "Provide a way for stacking block device to re-submit
Danny> the bio which should be handled first."
Danny> I will fix it.
Great, though my second question is*why* it needs to be handled
first? What is the difference between stacked and un-stacked devices
and how could it be done in a way that doesn't require a seperate
function like this?
Is this anything to do with what's on my mind as a database guy? I've
heard that things like RAID and LVM have difficulty providing write
barriers.
I want to be confident that, at EVERY level of the stack, I can put a
barrier in that guarantees that everything written by user-space BEFORE
the barrier is handled before anything written AFTER the barrier. That
way, I can be confident that, after a problem, I know whether I can
safely roll the log forward or back.
Cheers,
Wol
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