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

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Date: Wed, 14 Feb 2024 18:49:49 +0000
From: Matthew Wilcox <willy@...radead.org>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
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 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.

> +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.