Re: + task_struct-make-journal_info-conditional.patch added to -mm tree

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On Fri, 2009-12-04 at 08:17 +0300, Alexey Dobriyan wrote:
> On Fri, Dec 04, 2009 at 12:58:06PM +0900, Hiroshi Shimamoto wrote:
> > Alexey Dobriyan wrote:
> > > On Thu, Dec 03, 2009 at 02:40:57PM -0800, akpm@linux-foundation.org wrote:
> > >> --- a/include/linux/sched.h~task_struct-make-journal_info-conditional
> > >> +++ a/include/linux/sched.h
> > >> @@ -1452,8 +1452,10 @@ struct task_struct {
> > >>  	gfp_t lockdep_reclaim_gfp;
> > >>  #endif
> > >>  
> > >> +#ifdef CONFIG_FS_JOURNAL_INFO
> > >>  /* journalling filesystem info */
> > >>  	void *journal_info;
> > >> +#endif
> > > 
> > > This will prevent using e.g. ext3 on CONFIG_EXT3_FS=n kernels.
> > 
> > I'm sorry, I'm not sure what you're mentioning.
> 
> With this patch admin must decide in advance if he will ever use ext3.
> EXT3_FS=n kernels won't be able to get ext3 support without reboot
> even as module, because task_struct will be different.
> 
> Which is a regression compared to current state.
> 
> The biggest example of such behaviour is ipv6 module, but it should not
> be spread more.

I agree. If we want to be rid of this then I think we should simply pass
the journal info as a parameter through the relevant filesystems (is
there any reason why we do things this way? I couldn't think of one) and
thus avoid the use of this field in the first place,

Steve.