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Date:   Thu, 15 Dec 2022 18:45:09 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Chao Yu <chao@kernel.org>
Cc:     "Vishal Moola (Oracle)" <vishal.moola@gmail.com>,
        linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, linux-mm@kvack.org,
        fengnanchang@gmail.com, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH] f2fs: Convert f2fs_write_cache_pages() to use
 filemap_get_folios_tag()
Message-ID: <Y5trNfldXrM4FIyU@casper.infradead.org>
References: <0a95ba7b-9335-ce03-0f47-5d9f4cce988f@kernel.org>
 <20221212191317.9730-1-vishal.moola@gmail.com>
 <6770f692-490e-34fc-46f8-4f65aa071f58@kernel.org>
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On Thu, Dec 15, 2022 at 09:48:41AM +0800, Chao Yu wrote:
> On 2022/12/13 3:13, Vishal Moola (Oracle) wrote:
> > +add_more:
> > +			pages[nr_pages] = folio_page(folio,idx);
> > +			folio_ref_inc(folio);
> 
> It looks if CONFIG_LRU_GEN is not set, folio_ref_inc() does nothing. For those
> folios recorded in pages array, we need to call folio_get() here to add one more
> reference on each of them?

static inline void folio_get(struct folio *folio)
{
        VM_BUG_ON_FOLIO(folio_ref_zero_or_close_to_overflow(folio), folio);
        folio_ref_inc(folio);
}

That said, folio_ref_inct() is very much MM-internal and filesystems
should be using folio_get(), so please make that modification in the
next revision, Vishal.