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Subject: Re: [PATCH] blk-mq: fix is_flush_rq
To:     Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc:     linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        John Garry <john.garry@huawei.com>,
        "Blank-Burian, Markus, Dr." <blankburian@uni-muenster.de>,
        Yufen Yu <yuyufen@huawei.com>
References: <20210818010925.607383-1-ming.lei@redhat.com>
From:   Bart Van Assche <bvanassche@acm.org>
Message-ID: <ef0681f8-5862-e340-b9e6-ebce5cfa3c2c@acm.org>
Date:   Tue, 17 Aug 2021 20:02:58 -0700
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On 8/17/21 6:09 PM, Ming Lei wrote:
> +bool is_flush_rq(struct request *rq)
> +{
> +	return rq->end_io == flush_end_io;
> +}

My understanding is that calling is_flush_rq() is only safe if the
caller guarantees that the request refcount >= 1. How about adding a
comment that explains this?

Thanks,

Bart.