What is the history of CONFIG_EXT{2,3}_CHECK?

[Theodore Ts'o]

On Mon, Oct 31, 2005 at 02:25:03PM -0700, Andreas Dilger wrote:
> On Oct 31, 2005  01:13 +0100, Adrian Bunk wrote:
> > Can anyone tell me the history of CONFIG_EXT{2,3}_CHECK?
> > 
> > There is code for a "check" option for mount if these options are 
> > enabled, but there's no way to enable them.
> 
> These are expensive debugging options, which walk the inode/block bitmaps
> for getting the group inode/block usage instead of using the group
> summary data.  Not used very often but I suspect occasionally useful for
> developers mucking with ext[23] internals.  Since it is developer-only
> code it needs to be enabled with #define CONFIG_EXT[23]_CHECK in a
> header or compile option.

It's basically a stripped down version of e2fsck pass #5, though.  Is
there any reason why this needs to be in the kernel?  If it would be
useful I could easily make a userspace implementation of these checks.

						- Ted