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Date:   Wed, 13 May 2020 14:00:23 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        John Garry <john.garry@huawei.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Hannes Reinecke <hare@suse.com>,
        Christoph Hellwig <hch@lst.de>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH V11 08/12] block: add blk_end_flush_machinery
Message-ID: <20200513120023.GD6297@lst.de>
References: <20200513034803.1844579-1-ming.lei@redhat.com> <20200513034803.1844579-9-ming.lei@redhat.com>
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> +		struct list_head *flush_list)
> +{
> +	struct block_device *bdev;
> +	struct request *rq;
> +	int error = -ENXIO;
> +
> +	if (list_empty(flush_list))
> +		return;
> +
> +	rq = list_first_entry(flush_list, struct request, queuelist);

> +	/* Send flush via one active hctx so we can move on */
> +	bdev = bdget_disk(rq->rq_disk, 0);
> +	if (bdev) {
> +		error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
> +		bdput(bdev);
> +	}

As mentioned before:  please don't add pointless bdget calls, as we
don't even need the block_device.  Just open code the trivial bits of
blkdev_issue_flushblkdev_issue_flush that are needed.