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Date:   Fri, 15 Sep 2023 14:40:07 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Daniel Gomez <da.gomez@samsung.com>
Cc:     "minchan@kernel.org" <minchan@kernel.org>,
        "senozhatsky@chromium.org" <senozhatsky@chromium.org>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
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        "mcgrof@kernel.org" <mcgrof@kernel.org>,
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        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "gost.dev@samsung.com" <gost.dev@samsung.com>,
        Pankaj Raghav <p.raghav@samsung.com>
Subject: Re: [PATCH 1/6] filemap: make the folio order calculation shareable
Message-ID: <ZQRet4w5VSbvKvKB@casper.infradead.org>
References: <20230915095042.1320180-1-da.gomez@samsung.com>
 <CGME20230915095124eucas1p1eb0e0ef883f6316cf14c349404a51150@eucas1p1.samsung.com>
 <20230915095042.1320180-2-da.gomez@samsung.com>
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On Fri, Sep 15, 2023 at 09:51:23AM +0000, Daniel Gomez wrote:
> To make the code that clamps the folio order in the __filemap_get_folio
> routine reusable to others, move and merge it to the fgf_set_order
> new subroutine (mapping_size_order), so when mapping the size at a
> given index, the order calculated is already valid and ready to be
> used when order is retrieved from fgp_flags with FGF_GET_ORDER.
> 
> Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
> ---
>  fs/iomap/buffered-io.c  |  6 ++++--
>  include/linux/pagemap.h | 42 ++++++++++++++++++++++++++++++++++++-----
>  mm/filemap.c            |  8 --------
>  3 files changed, 41 insertions(+), 15 deletions(-)

That seems like a lot of extra code to add in order to avoid copying
six lines of code and one comment into the shmem code.

It's not wrong, but it seems like a bad tradeoff to me.