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Sender: Tejun Heo <htejun@gmail.com>
Date: Thu, 30 May 2024 08:33:46 -1000
From: Tejun Heo <tj@kernel.org>
To: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: willy@infradead.org, akpm@linux-foundation.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 8/8] writeback: factor out balance_wb_limits to remove
 repeated code
Message-ID: <ZljGiunxmVAlW6EE@slm.duckdns.org>
References: <20240514125254.142203-1-shikemeng@huaweicloud.com>
 <20240514125254.142203-9-shikemeng@huaweicloud.com>
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In-Reply-To: <20240514125254.142203-9-shikemeng@huaweicloud.com>

Hello,

On Tue, May 14, 2024 at 08:52:54PM +0800, Kemeng Shi wrote:
> +static void balance_wb_limits(struct dirty_throttle_control *dtc,
> +			      bool strictlimit)
> +{
> +	wb_dirty_freerun(dtc, strictlimit);
> +	if (dtc->freerun)
> +		return;
> +
> +	wb_dirty_exceeded(dtc, strictlimit);
> +	wb_position_ratio(dtc);
> +}
..
> @@ -1869,12 +1880,9 @@ static int balance_dirty_pages(struct bdi_writeback *wb,
>  		 * Calculate global domain's pos_ratio and select the
>  		 * global dtc by default.
>  		 */
> -		wb_dirty_freerun(gdtc, strictlimit);
> +		balance_wb_limits(gdtc, strictlimit);
>  		if (gdtc->freerun)
>  			goto free_running;
> -
> -		wb_dirty_exceeded(gdtc, strictlimit);
> -		wb_position_ratio(gdtc);
>  		sdtc = gdtc;

Isn't this a bit nasty? The helper skips updating states because it knows
the caller is not going to use them? I'm not sure the slight code reduction
justifies the added subtlety.

Thanks.

-- 
tejun