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Subject: Re: ubifs: sync() causes writes even if nothing is changed
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Matthieu CASTET <matthieu.castet@parrot.com>
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Date: Thu, 21 Oct 2010 21:43:29 +0300
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Cc: linux-mtd <linux-mtd@lists.infradead.org>,
	Adrian Hunter <adrian.hunter@nokia.com>
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On Thu, 2010-10-21 at 19:04 +0200, Matthieu CASTET wrote:
> Hi,
> 
> Artem Bityutskiy a écrit :
> > On Thu, 2010-10-21 at 10:23 +0200, Sebastian Andrzej Siewior wrote:
> >> Artem Bityutskiy wrote:
> >>>> From a quick glance at the ubifs code, this might come out of the
> >>>> garbage collector that is triggered on every sync() and writes
> >>>> something even if nothing has changed.
> > 
> > Yeah, the UBIFS must be writing the commit start and commit end nodes,
> > and then erasing the previous log LEB (all this is done in log.c). As
> > soon as I have time I'll look at this, I really do not have time right
> > now. And there is Matthiew's problem which is actually quite big, but
> > for some reasons affects only him :-)
> It could be interesting to know which nand flash are tested.
> 
> On our boards ST 256MB chip work fine, but micron flash got unstable 
> page problem (sorry I don't have the model number ATM).
> 
> And it is getting worse, new SLC flash can now get up to 4 bits error 
> per 512.

It would be great if you sent me a board where unstable pages are easy
to reproduce.

-- 
Best Regards,
Artem Bityutskiy (Битюцкий Артём)