Re: [PATCH v2 2/7] doc: Correct the description of ->release_folio

[Matthew Wilcox <willy@infradead.org>]

On Sun, Jun 04, 2023 at 10:55:48AM -0700, Darrick J. Wong wrote:
> On Fri, Jun 02, 2023 at 11:24:39PM +0100, Matthew Wilcox (Oracle) wrote:
> > -->release_folio() is called when the kernel is about to try to drop the
> > -buffers from the folio in preparation for freeing it.  It returns false to
> > -indicate that the buffers are (or may be) freeable.  If ->release_folio is
> > -NULL, the kernel assumes that the fs has no private interest in the buffers.
> > +->release_folio() is called when the MM wants to make a change to the
> > +folio that would invalidate the filesystem's private data.  For example,
> > +it may be about to be removed from the address_space or split.  The folio
> > +is locked and not under writeback.  It may be dirty.  The gfp parameter is
> > +not usually used for allocation, but rather to indicate what the filesystem
> > +may do to attempt to free the private data.  The filesystem may
> > +return false to indicate that the folio's private data cannot be freed.
> > +If it returns true, it should have already removed the private data from
> > +the folio.  If a filesystem does not provide a ->release_folio method,
> > +the kernel will call try_to_free_buffers().
> 
> the MM?  Since you changed that above... :)
> 
> With that nit fixed,
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Well, is it the MM?  At this point, the decision is made by
filemap_release_folio(), which is the VFS, in my opinion ;-)

But I'm happy to use "the MM".  Or "the pagecache".