Re: [PATCH] libata, freezer: avoid block device removal while systemis frozen

[Ming Lei]

On Mon, Dec 16, 2013 at 8:45 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> Hello,
>
> On Mon, Dec 16, 2013 at 08:12:07PM +0800, Ming Lei wrote:
>> Looks we should guarantee that I/O queue is emptied before system sleep,
>> otherwise it may be a bug, since battery may be drained up to cause
>> data loss or block devices may be disconnected during sleep.
>
> It's a bit beside the point as that's what journaling is for.  Power
> loss during suspend isn't all that different from power loss while
> suspended.  Also, the filesystems are already synced before entering
> suspend, so it shouldn't be an issue.  However, that doesn't guarantee
> there aren't no pending bdi work items.  We *hope* to control the

You mean there are still some write I/O scheduled after processes are
frozen? by unfreezable kernel threads?

> sources with freezer but there's no guarantee about the coverage and
> no way to verify that either.

Thanks,
-- 
Ming Lei
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