linux-ext4 - Re: [PATCH v2] ext4: add checks of block references for non-extent inodes

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Message-ID: <20090328011054.GA2155@mit.edu>
Date:	Fri, 27 Mar 2009 21:10:54 -0400
From:	Theodore Tso <tytso@....edu>
To:	Thiemo Nagel <thiemo.nagel@...tum.de>
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2] ext4: add checks of block references for non-extent
	inodes

On Fri, Mar 20, 2009 at 03:15:56PM +0100, Thiemo Nagel wrote:
> Dear Ted,
>
> I'm sending an improved patch as I've come to the conclusion that the  
> previous patch is too lenient in two ways:
> * off-by-one in the check of the upper block limit
> * it shouldn't stop when encountering a reference to block number zero  
> because, if I'm not mistaken, references behind it still might be  
> accessed in sparse files / when seeking behind the end of a file.

Note: this patch has a rather fatal flaw; it doens't check to make
sure that file is a regular file or directory first.  If you have a
fast symlink, ext4_iget() will blow up since it's a non-extent file,
but the i_blocks[] will contain an ASCII string.

I'll fix up your patch to deal add the appropriate checking.

          	    	       	       	   - Ted
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