linux-kernel - Re: [PATCH v11 09/33] mm: Add folio_try_get

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Message-ID: <YMhH99XFlaoxKUae@infradead.org>
Date:   Tue, 15 Jun 2021 07:25:59 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Vlastimil Babka <vbabka@...e.cz>,
        William Kucharski <william.kucharski@...cle.com>
Subject: Re: [PATCH v11 09/33] mm: Add folio_try_get_rcu()

On Mon, Jun 14, 2021 at 09:14:11PM +0100, Matthew Wilcox (Oracle) wrote:
> This is the equivalent of page_cache_get_speculative().  Also add
> folio_ref_try_add_rcu (the equivalent of page_cache_add_speculative)
> and folio_get_unless_zero() (the equivalent of get_page_unless_zero()).
> 
> The new kernel-doc attempts to explain from the user's point of view
> when to use folio_try_get_rcu() and when to use folio_get_unless_zero(),
> because there seems to be some confusion currently between the users of
> page_cache_get_speculative() and get_page_unless_zero().
> 
> Reimplement page_cache_add_speculative() and page_cache_get_speculative()
> as wrappers around the folio equivalents, but leave get_page_unless_zero()
> alone for now.  This commit reduces text size by 3 bytes due to slightly
> different register allocation & instruction selections.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> Reviewed-by: William Kucharski <william.kucharski@...cle.com>

Looks good:

Reviewed-by: Christoph Hellwig <hch@....de>