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Date: Mon, 12 May 2025 07:17:22 +0200
From: Christoph Hellwig <hch@lst.de>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: hch@lst.de, xni@redhat.com, colyli@kernel.org, agk@redhat.com,
	snitzer@kernel.org, mpatocka@redhat.com, song@kernel.org,
	yukuai3@huawei.com, linux-kernel@vger.kernel.org,
	dm-devel@lists.linux.dev, linux-raid@vger.kernel.org,
	yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com
Subject: Re: [PATCH RFC md-6.16 v3 15/19] md/md-llbitmap: implement APIs to
 dirty bits and clear bits
Message-ID: <20250512051722.GA1667@lst.de>
References: <20250512011927.2809400-1-yukuai1@huaweicloud.com> <20250512011927.2809400-16-yukuai1@huaweicloud.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Mon, May 12, 2025 at 09:19:23AM +0800, Yu Kuai wrote:
> +static void llbitmap_unplug(struct mddev *mddev, bool sync)
> +{
> +	DECLARE_COMPLETION_ONSTACK(done);
> +	struct llbitmap *llbitmap = mddev->bitmap;
> +	struct llbitmap_unplug_work unplug_work = {
> +		.llbitmap = llbitmap,
> +		.done = &done,
> +	};
> +
> +	if (!llbitmap_dirty(llbitmap))
> +		return;
> +
> +	INIT_WORK_ONSTACK(&unplug_work.work, llbitmap_unplug_fn);
> +	queue_work(md_llbitmap_unplug_wq, &unplug_work.work);
> +	wait_for_completion(&done);
> +	destroy_work_on_stack(&unplug_work.work);

Why is this deferring the work to a workqueue, but then synchronously
waits on it?