linux-kernel - Re: [PATCH 3/6] iomap: Use __set_page_dirty

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Message-ID: <YMmfQNjExNs3cuyq@kroah.com>
Date:   Wed, 16 Jun 2021 08:50:40 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Al Viro <viro@...iv.linux.org.uk>,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] iomap: Use __set_page_dirty_nobuffers

On Tue, Jun 15, 2021 at 07:13:16PM +0100, Matthew Wilcox wrote:
> On Tue, Jun 15, 2021 at 07:34:53PM +0200, Christoph Hellwig wrote:
> > On Tue, Jun 15, 2021 at 06:32:37PM +0100, Matthew Wilcox wrote:
> > > On Tue, Jun 15, 2021 at 07:19:59PM +0200, Greg Kroah-Hartman wrote:
> > > > On Tue, Jun 15, 2021 at 05:23:39PM +0100, Matthew Wilcox (Oracle) wrote:
> > > > Using __ functions in structures in different modules feels odd to me.
> > > > Why not just have iomap_set_page_dirty be a #define to this function now
> > > > if you want to do this?
> > > > 
> > > > Or take the __ off of the function name?
> > > > 
> > > > Anyway, logic here is fine, but feels odd.
> > > 
> > > heh, that was how I did it the first time.  Then I thought that it was
> > > better to follow Christoph's patch:
> > > 
> > >  static const struct address_space_operations adfs_aops = {
> > > +       .set_page_dirty = __set_page_dirty_buffers,
> > > (etc)
> > 
> > Eventually everything around set_page_dirty should be changed to operate
> > on folios, and that will be a good time to come up with a sane
> > naming scheme without introducing extra churn.
> 
> The way it currently looks in my tree ...
> 
> set_page_dirty(page) is a thin wrapper that calls folio_mark_dirty(folio).
> folio_mark_dirty() calls a_ops->dirty_folio(mapping, folio) (which
> 	returns bool).
> __set_page_dirty_nobuffers() becomes filemap_dirty_folio()
> __set_page_dirty_buffers() becomes block_dirty_folio()
> __set_page_dirty_no_writeback() becomes dirty_folio_no_writeback()
> 
> Now I look at it, maybe that last should be nowb_dirty_folio().

Not to be a pain, but you are mixing "folio" at the front and back of
the api name?  We messed up in the driver core with this for some things
(get_device() being one), I would recommend just sticking with one
naming scheme now as you are getting to pick what you want to use.

So perhaps for the above:
	folio_mark_dirty()
	folio_dirty_no_writeback()
	folio_dirty_filemap()
	folio_dirty_block()

much like "set_page" is used today?

Anyway, just bikeshedding, it's your code, your choice :)

thanks for doing this work overall.

greg k-h