Re: [PATCH 1/2] mm,fs: introduce helpers around i_mmap_mutex

[Davidlohr Bueso <davidlohr@hp.com>]

On Thu, 2013-10-03 at 13:58 -0700, Andrew Morton wrote:
> On Wed,  2 Oct 2013 13:17:45 -0700 Davidlohr Bueso <davidlohr@hp.com> wrote:
> 
> > Various parts of the kernel acquire and release this mutex,
> > so add i_mmap_lock_write() and immap_unlock_write() helper
> > functions that will encapsulate this logic. The next patch
> > will make use of these.
> > 
> > ...
> >
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -478,6 +478,16 @@ struct block_device {
> >  
> >  int mapping_tagged(struct address_space *mapping, int tag);
> >  
> > +static inline void i_mmap_lock_write(struct address_space *mapping)
> > +{
> > +	mutex_lock(&mapping->i_mmap_mutex);
> > +}
> 
> I don't understand the thinking behind the "_write".  There is no
> "_read" and all callsites use "_write", so why not call it
> i_mmap_lock()?
> 
> I *assume* the answer is "so we can later convert some sites to a new
> i_mmap_lock_read()".  If so, the changelog should have discussed this. 
> If not, still confused.
> 

Yes, that's exactly right. I'll resend with an updated changelog.

Thanks,
Davidlohr


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