linux-kernel - Re: [PATCH v8 03/10] readahead: allocate folios with mapping_min

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Message-ID: <Zoaxv23qdu4T84Sm@casper.infradead.org>
Date: Thu, 4 Jul 2024 15:29:19 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Ryan Roberts <ryan.roberts@....com>
Cc: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>,
	david@...morbit.com, chandan.babu@...cle.com, djwong@...nel.org,
	brauner@...nel.org, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, yang@...amperecomputing.com,
	linux-mm@...ck.org, john.g.garry@...cle.com,
	linux-fsdevel@...r.kernel.org, hare@...e.de, p.raghav@...sung.com,
	mcgrof@...nel.org, gost.dev@...sung.com, cl@...amperecomputing.com,
	linux-xfs@...r.kernel.org, hch@....de, Zi Yan <zi.yan@...t.com>
Subject: Re: [PATCH v8 03/10] readahead: allocate folios with
 mapping_min_order in readahead

On Thu, Jul 04, 2024 at 03:24:10PM +0100, Ryan Roberts wrote:
> > @@ -240,12 +257,13 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
> >  			 * not worth getting one just for that.
> >  			 */
> 
> For the case that the folio is already in the xarray, perhaps its worth
> asserting that the folio is at least min_nrpages?

We'd have to get a reference on the folio to be able to do that safely.
Not worth it.