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Date:   Fri, 19 Nov 2021 14:56:43 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Muchun Song <songmuchun@bytedance.com>, adobriyan@gmail.com,
        gladkov.alexey@gmail.com, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2] fs: proc: store PDE()->data into inode->i_private
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On Thu, 18 Nov 2021 23:23:39 -0800 Christoph Hellwig <hch@infradead.org> wrote:

> On Fri, Nov 19, 2021 at 12:11:04PM +0800, Muchun Song wrote:
> > +
> > +/*
> > + * Obtain the private data passed by user through proc_create_data() or
> > + * related.
> > + */
> > +static inline void *pde_data(const struct inode *inode)
> > +{
> > +	return inode->i_private;
> > +}
> > +
> > +#define PDE_DATA(i)	pde_data(i)
> 
> What is the point of pde_data?

It's a regular old C function, hence should be in lower case.

I assume the upper case thing is a holdover from when it was
implemented as a macro.

>  If we really think changing to lower
> case is worth it (I don't think so, using upper case for getting at
> private data is a common idiom in file systems),

It is?  How odd.

I find the upper-case thing to be actively misleading.  It's mildly
surprising to discover that it's actually a plain old C function.

> we can just do that
> scripted in one go.

Yes, I'd like to see a followup patch which converts the current
PDE_DATA() callsites.