linux-kernel - Re: [RFC v2 01/14] fs: Allow fine-grained control of folio sizes

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Date: Thu, 15 Feb 2024 11:21:58 +0100
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	mcgrof@...nel.org, gost.dev@...sung.com, akpm@...ux-foundation.org, 
	kbusch@...nel.org, djwong@...nel.org, chandan.babu@...cle.com, p.raghav@...sung.com, 
	linux-kernel@...r.kernel.org, hare@...e.de, linux-mm@...ck.org, david@...morbit.com
Subject: Re: [RFC v2 01/14] fs: Allow fine-grained control of folio sizes

On Wed, Feb 14, 2024 at 06:49:49PM +0000, Matthew Wilcox wrote:
> On Tue, Feb 13, 2024 at 10:37:00AM +0100, Pankaj Raghav (Samsung) wrote:
> > +static inline void mapping_set_folio_orders(struct address_space *mapping,
> > +					    unsigned int min, unsigned int max)
> > +{
> > +	if (min == 1)
> > +		min = 2;
> 
> If you order the "support order-1 folios" patch first, you can drop
> these two lines.
> 
Thanks for pointing this out. I actually forgot to update this later in
my series.

The only failure I was noticing for LBS in 8k block sizes (generic/630)
gets fixed by this change as well :) .

> > +static inline unsigned int mapping_min_folio_nrpages(struct address_space *mapping)
> 
> I'm not sure if you need this, but it should return unsigned long, not
> unsigned int.  With 64KiB pages on Arm, a PMD page is 512MiB (order 13)
> and a PUD page will be order 26, which is far too close to 2^32 for
> my comfort.

There were some suggestions from Chinner which might make this function
go away. But in case I need it, I will update it to unsigned long to be
on the safe side.