linux-ext4 - Re: [PATCH 18/31] libext2fs: Badblocks should handle 48-bit block numbers correctly

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Date:	Wed, 9 Oct 2013 14:57:32 -0700
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 18/31] libext2fs: Badblocks should handle 48-bit block
 numbers correctly

On Tue, Oct 08, 2013 at 12:03:31PM -0400, Theodore Ts'o wrote:
> On Mon, Sep 30, 2013 at 06:28:37PM -0700, Darrick J. Wong wrote:
> > Currently, the badblocks code assumes 32-bit block numbers.  This leads to
> > unfortunate results, because feeding a badblocks file to mke2fs with 64-bit
> > block numbers causes libext2fs to rip off the upper 32 bits of the block number
> > and then assign a truncated block number to the badblocks file.
> > 
> > This is just as well, since the code that writes to the bb inode doesn't know
> > about extents anyway.  Rather than continuing to open-code block map
> > manipulation, simply use existing library functions to truncate the old bb
> > inode, mark all badblocks in use, and then assign them to the badblocks file.
> > We can even use extents now.
> > 
> > (It's arguable that badblocks is a vestigial organ now, but perhaps someone is
> > using it?  I use it to stress-test disk block allocation, but I might just be
> > nutty.)
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> 
> Yeah, I think badblocks is vestigal at this point, and for huge disk
> arrays, almost certainly block replacement will be handed at the LVM,
> storage array, or HDD level.  So it might be better simply to have
> mke2fs throw an error if there is an attempt to hand it a 64-bit block
> number.

Ok.  I'll audit all callers of ext2fs_badblocks_list_add() to make sure they
reject > 2^32 numbers.

--D
> 
> 							- Ted
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