Date: Tue, 15 Dec 2009 23:02:50 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: Christian Kujau <lists@nerdbynature.de>
Cc: Heinz Diehl <htd@fancy-poultry.org>, LKML <linux-kernel@vger.kernel.org>,
       martin.petersen@oracle.com
Subject: Re: todays git regression (2.6.32-04008.g3ff6a46): lot of device
	mapper warnings
Message-ID: <20091215220249.GG28252@kernel.dk>
References: <200912091049.12604.borntraeger@de.ibm.com> <20091209212516.GA6206@fancy-poultry.org> <20091209214501.GC8742@kernel.dk> <20091209220749.GD8742@kernel.dk> <alpine.DEB.2.01.0912151354350.3483@bogon.housecafe.de>
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On Tue, Dec 15 2009, Christian Kujau wrote:
> On Wed, 9 Dec 2009 at 23:07, Jens Axboe wrote:
> > Does this work?
> > 
> [...]
> > +#if 0
> >  	if (offset &&
> >  	    (offset & (b->discard_granularity - 1)) != b->discard_alignment) {
> >  		t->discard_misaligned = 1;
> >  		ret = -1;
> >  	}
> > +#endif
> 
> I can't tell: is this a purely cosmetical change or is it dangerous to run 
> my DM devices without that patch? I'm trying to track mainline -git but 
> the patch hasn't made into the tree yet, so I always have to manually
> apply the patch - or can I just ignore the warning?

You can ignore it, it wont harm the functionality or data integrity. The
code "failure" will always trigger, since the default settings are 0.
Thus:

(offset & (b->discard_granularity - 1)) != b->discard_alignment

will always be true.

I'll revert the bad commit tomorrow so that -rc1 wont be affected, at
least.

-- 
Jens Axboe

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