linux-ext4 - Re: [PATCH 1/2] ext4: Remove arbitrary block value in __es_remove

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Message-ID: <20140417161944.GJ18591@thunk.org>
Date:	Thu, 17 Apr 2014 12:19:44 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Lukas Czerner <lczerner@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2] ext4: Remove arbitrary block value in
 __es_remove_extent()

On Tue, Apr 15, 2014 at 08:08:21PM +0200, Lukas Czerner wrote:
> In __es_remove_extent() we're storing seemingly arbitrary value
> 0x7FDEADBEEF into block variable. I assume that the reason is just to
> initialize the variable before the use because the actual value does not
> matter at this point.
> 
> Just remove the arbitrary value and initialized block variable to zero
> which is much less suspicious.

The whole point was for the value to be suspicious.  That way, if
there is a bug, and we try to use that value, it is a large enough
value that for most storage devices, we will get an I/O error (because
the disk isn't that big :-) referencing that block value, and we'll
have a bit of a hint where that suspicious value might have come from.

       	      	     	   		   - Ted
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