Re: [PATCH next] ext4: Fix diagnostic printf formats

[Theodore Tso]

On Fri, Mar 27, 2026 at 04:12:38PM +0200, Andy Shevchenko wrote:
> > > I'm not sure how your patch helps with all that, but apparently the
> > > printed data has to be NUL-terminated, otherwise I have no idea how
> > > it was ever working without crashes.
> > 
> > I noticed that as well.
> > I suspect it way have worked for the person that wrote it because the
> > name strings all happened to be NUL terminated.
> > There is certainly likely to be a '\0' before you 'fall off' mapped
> > memory and crash - so maybe they just ignored the extra characters.
> > 
> > Clearly the other option is to delete it all.
> 
> I would go for the history of the change and if it's old enough and not
> mentioned in any Documentation or not-so-old email thread, kill all that
> for good. But better to hear the ext4 maintainers first.

This is code that can only be manually enabled by adding a

#define DX_DEBUG

to the sources; it's not anything that users can configure using
Kconfig.  It *has* been used relatively recently, when developers
added support for three level htree directories.  I'm not sure why
they didn't run into the NULL termination issue, but since it is handy
to have the debugging code for developers' use, my preference would be
to keep the code and fix it up the problems.

   	    	     	    - Ted