Re: [PATCH] mm/filemap: add static for function __add_to_page_cache_locked

[Christoph Hellwig]

On Wed, Dec 09, 2020 at 04:51:48PM +0100, Stanislaw Gruszka wrote:
> On Wed, Dec 09, 2020 at 03:08:26PM +0000, Matthew Wilcox wrote:
> > On Wed, Dec 09, 2020 at 03:46:28PM +0100, Stanislaw Gruszka wrote:
> > > At this point of release cycle we should probably go with revert,
> > > but I think the main problem is that BPF and ERROR_INJECTION use
> > > function that is not intended to be used externally. For external users
> > > add_to_page_cache_lru() and add_to_page_cache_locked() are exported
> > > and I think those should be used (see the patch below).
> > 
> > FWIW, I intend to do some consolidation/renaming in this area.  I
> > trust that will not be a problem?
> 
> If it does not break anything, it will be not a problem ;-)
> 
> It's possible that __add_to_page_cache_locked() can be a global symbol
> with add_to_page_cache_lru() + add_to_page_cache_locked() being just
> static/inline wrappers around it.

So what happens to BTF if we change this area entirely?  Your IDs
sound like some kind of ABI to me, which is extremely scary.