linux-kernel - Re: [PATCH] filemap: remove obsolete comment in lock

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Date:   Mon, 4 Apr 2022 16:32:34 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     akpm@...ux-foundation.org, dhowells@...hat.com,
        william.kucharski@...cle.com, vbabka@...e.cz,
        kirill.shutemov@...ux.intel.com, hannes@...xchg.org,
        agruenba@...hat.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] filemap: remove obsolete comment in lock_page

On Sat, Apr 02, 2022 at 02:22:18PM +0800, Miaohe Lin wrote:
> lock_page needs the caller to have a reference on the page->mapping inode
> due to sync_page. Also lock_page_nosync is introduced which does not do a
> sync_page via commit db37648cd6ce ("[PATCH] mm: non syncing lock_page()").
> But commit 7eaceaccab5f ("block: remove per-queue plugging") kills off the
> old plugging along with aops->sync_page() and lock_page_nosync. So there
> is no need to have a reference on the page->mapping inode when calling
> lock_page anymore. Remove this obsolete and confusing comment.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>

Thanks.  I'll fix up the changelog (some of the tenses are a little
strange) and take this through my pagecache tree.

>  include/linux/pagemap.h | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 993994cd943a..8dfe8e49c427 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -908,9 +908,6 @@ static inline void folio_lock(struct folio *folio)
>  		__folio_lock(folio);
>  }
>  
> -/*
> - * lock_page may only be called if we have the page's inode pinned.
> - */
>  static inline void lock_page(struct page *page)
>  {
>  	struct folio *folio;
> -- 
> 2.23.0
>