Does UBI LEB-level access interlock happily with UBIfs access?

[Ricard Wanderlof]

On Sat, 20 Sep 2014, Richard Weinberger wrote:

> On Fri, Sep 19, 2014 at 7:24 PM, Artem Bityutskiy <dedekind1 at gmail.com> wrote:
>> On Fri, 2014-09-19 at 13:17 -0400, Atlant Schmidt wrote:
>>> But as I pointed, this will not force re-read of the volume table LEBs.
>>> To address this, you'd need to do some additional, not very difficult
>>> work.
>>
>> Oh, and this won't make UBI re-read the EC and VID headers, so they may
>> bit-rot too.
>>
>> So indeed it sounds like UBI needs a separate interface for this kind of
>> "scrub all bit-flips" issues. I do not think it is hard to do - all the
>> mechanisms are already implemented, so this would mostly be about
>> inventing good API.
>
> We could implement a trivial knob to trigger such a check in kernel.
> I.e. you trigger the check via an ioctl() or whatever and UBI schedules
> such a read-check for every PEB into the UBI background thread.

During the scanning operation that takes place when a partition is 
attached, doesn't this also trigger a check of all headers, as all the 
data needs to be read as part of the ubiattach process?

Not that that would be a practical solution for many systems where it is 
not practical to detach and re-attach, for instance the partition where 
the root volume is located, as that would in practice require a reboot.

> I'd volunteer to implement this.

I think it would be good if such a forced re-read could be set to happen 
automatically at a specified interval, say by default once a day.

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
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