Re: [PATCH 1/2] Btrfs: add leak debug for extent map

[Liu Bo <bo.li.liu@oracle.com>]

On Thu, Jan 10, 2013 at 12:54:26PM +0100, David Sterba wrote:
> On Thu, Jan 10, 2013 at 10:05:39AM +0800, Liu Bo wrote:
> > On Tue, Jan 08, 2013 at 12:07:34PM -0800, Zach Brown wrote:
> > > > This is for detecting extent map leak.
> > > 
> > > Hmm, I guess it's cool to get the allocation-specific decoding which you
> > > don't get from the generic kernel leak tracking?
> > 
> > Thanks for the advice, but what allocation-specific decoding do you refer to?
> > Could you please show me any examples?
> 
> IMHO that there's a leak check that is targeted to one exact problem in
> one subsystem (extent_map in btrfs), does not need to be poked to do a
> scan-for-leaks so the leak can be reported immediatelly and not after
> some time. It makes sense for such a core structure like extent_map.
> Other structures are allocated from a slab so we can at least check for
> leaks upon module unload.

Sorry, I don't get your point, but extent map is allocated from its
slab section as well.

The 'scan-for-leaks' is just for developers' debug purpose, which
can tell us some information about the leaked ones, like refs, type, etc.

I think I'm doing the same thing as leak debug for extent_state/extent_buffer.
We can disable it as default.

thanks,
liubo