From: Mingming Cao <cmm@us.ibm.com>
Subject: Re: [patch 1/2] add init_ext4_proc() stub for when CONFIG_PROC_FS
	is not set
Date: Tue, 09 Oct 2007 10:03:06 -0700
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References: <20071009055033.145153755@au1.ibm.com>
	 <20071009061101.666614585@au1.ibm.com>
	 <1191947487.12131.33.camel@dyn9047017100.beaverton.ibm.com>
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Cc: markn@au1.ibm.com, ext4 <linux-ext4@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Amit K. Arora" <aarora@linux.vnet.ibm.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Badari Pulavarty <pbadari@gmail.com>
In-Reply-To: <1191947487.12131.33.camel@dyn9047017100.beaverton.ibm.com>
Sender: linux-ext4-owner@vger.kernel.org

On Tue, 2007-10-09 at 09:31 -0700, Badari Pulavarty wrote:
> On Tue, 2007-10-09 at 15:50 +1000, markn@au1.ibm.com wrote:
> > plain text document attachment (ext4-add-init_ext4_proc-stub.patch)
> > init_ext4_fs() calls init_ext4_proc() so we need a stub init_ext4_proc()
> > for the case that CONFIG_PROC_FS is not set.
> > Without the stub we get a build error:
> > 
> > fs/ext4/mballoc.c: In function 'init_ext4_proc':
> > fs/ext4/mballoc.c:2837: error: 'proc_root_fs' undeclared (first use in this function)
> > fs/ext4/mballoc.c:2837: error: (Each undeclared identifier is reported only once
> > fs/ext4/mballoc.c:2837: error: for each function it appears in.)
> > 
> > Add a stub init_ext4_proc() function that does nothing but return 0
> > 
> > Signed-off-by: Mark Nelson <markn@au1.ibm.com>
> > ---
> >  fs/ext4/mballoc.c |    7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > Index: ext4/fs/ext4/mballoc.c
> > ===================================================================
> > --- ext4.orig/fs/ext4/mballoc.c
> > +++ ext4/fs/ext4/mballoc.c
> > @@ -2825,6 +2825,7 @@ static int ext4_mb_destroy_per_dev_proc(
> >  	return 0;
> >  }
> >  
> > +#ifdef CONFIG_PROC_FS
> >  int __init init_ext4_proc(void)
> >  {
> >  	ext4_pspace_cachep =
> > @@ -2840,6 +2841,12 @@ int __init init_ext4_proc(void)
> >  
> >  	return 0;
> >  }
> > +#else
> > +int __init init_ext4_proc(void)
> > +{
> > +	return 0;
> > +}
> > +#endif
> >  
> >  void exit_ext4_proc(void)
> >  {
> 
> Nope. I don't think we can do this :(
> 
> For example, we need to create ext4_pspace_cachep kmem cache 
> for the pre-allocation to work. We can't ifdef it out.
> 
> Mingming/Amit, can you take a look at this ? It looks like
> we NEED procfs support to make mballoc work. If so, we need
> to add it to the dependency.
> 
> 

I guess our testing did not catch this up because we have CONFIG_PROC_FS
enabled all the time. mballoc needs procfs for exporting some stats info
and tunable paramenters to optimize/customize multiple allocation.

We could select CONFIG_PROC_FS at kconfig when ext4dev is enabled.

Mingming