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Date:   Mon, 28 Jan 2019 07:57:52 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     John Garry <john.garry@huawei.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        "chenxiang (M)" <chenxiang66@hisilicon.com>,
        jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
        linuxarm@huawei.com, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, axboe@kernel.dk,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [PATCH] block: set rq->cmd_flags with bio->opf instead of
 data->cmd_flags when bio is not Null
Message-ID: <20190128155752.GA29076@infradead.org>
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 <20190128140716.GA18162@infradead.org>
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On Mon, Jan 28, 2019 at 03:36:58PM +0000, John Garry wrote:
> As I understood, the problem is the scenario of calling
> blk_mq_make_request()->bio_integrity_prep() where we then allocate a bio
> integrity payload in calling bio_integrity_alloc().
> 
> In this case, bio_integrity_alloc() sets bio->bi_opf |= REQ_INTEGRITY, which
> is no longer consistent with data.cmd_flags.

I don't see how that could happen:

static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
	...

	if (!bio_integrity_prep(bio))
		return BLK_QC_T_NONE;

	...

	data.cmd_flags = bio->bi_opf;
        rq = blk_mq_get_request(q, bio, &data);