Re: [PATCH v4 04/12] auto-fs: rename d_count field of dentry to d_refcount

[Thomas Gleixner <tglx@linutronix.de>]

On Thu, 4 Jul 2013, Linus Torvalds wrote:

> On Thu, Jul 4, 2013 at 7:47 AM, Waiman Long <waiman.long@hp.com> wrote:
> >
> > I could change patch 3 so that I keep the d_count name, but #define
> > d_refcount to d_count. In that way, I can do piece-meal changes without
> > breaking the build. Alternatively, I could collapse patches 3-11 into a
> > single big patch which will be harder to review.
> 
> Since there are many fewer d_count users than there are d_lock users,
> I think collapsing things is the right thing to do.
> 
> That said, I think Al is right that for all those filesystem uses, we
> might actually be much better off with a helper function looking at
> d_count, with no macros etc, since they are purely about reading the
> count.
> 
> So maybe the right thing to do is to add a
> 
>    static inline int d_count(struct dentry *dentry) { return dentry->d_count; }
> 
> helper function *first*, and just say "filesystems should never access
> d_count directly", and make the few filesystem users use this helper
> function first. That way we can do that as independent commits to
> prepare for the switch-over.
> 
> Then when the switch-over happens, we just change "d_count" in that
> helper function, and it has no filesystem impact at all.
> 
> But fs/dcache.c and fs/namei.c that actually really know about and
> modify d_count would not use that helper function. It would purely be
> about isolating filesystems from these kinds of internal
> implementation issues: fs/cache.c and fs/namei.c are all *about* those
> internal issues, so they shouldn't be isolated..

And all of this can sanely be done with coccinelle. Julia will
certainly help to get the scripts right.

Thanks,

	tglx