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Date: Fri, 4 Dec 2009 08:17:29 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: linux-kernel@vger.kernel.org, mm-commits@vger.kernel.org,
       chris.mason@oracle.com, konishi.ryusuke@lab.ntt.co.jp,
       swhiteho@redhat.com, tytso@mit.edu
Subject: Re: + task_struct-make-journal_info-conditional.patch added to -mm
 tree
Message-ID: <20091204051729.GA3927@x200>
References: <200912032240.nB3Mevae027408@imap1.linux-foundation.org>
 <20091204021444.GA8392@x200>
 <4B1888CE.8000406@ct.jp.nec.com>
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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.
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