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Date: Wed, 23 Apr 2025 08:58:51 -0600
From: Keith Busch <kbusch@kernel.org>
To: Leon Romanovsky <leon@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>,
	Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
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	Leon Romanovsky <leonro@nvidia.com>
Subject: Re: [PATCH v9 23/24] nvme-pci: convert to blk_rq_dma_map
Message-ID: <aAkAKyr4fbd5sLCH@kbusch-mbp.dhcp.thefacebook.com>
References: <cover.1745394536.git.leon@kernel.org>
 <7c5c5267cba2c03f6650444d4879ba0d13004584.1745394536.git.leon@kernel.org>
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In-Reply-To: <7c5c5267cba2c03f6650444d4879ba0d13004584.1745394536.git.leon@kernel.org>

On Wed, Apr 23, 2025 at 11:13:14AM +0300, Leon Romanovsky wrote:
> +static bool nvme_try_setup_sgl_simple(struct nvme_dev *dev, struct request *req,
> +				      struct nvme_rw_command *cmnd,
> +				      struct blk_dma_iter *iter)
> +{
> +	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
> +	struct bio_vec bv = req_bvec(req);
> +
> +	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && (req->cmd_flags & REQ_P2PDMA))
> +		return false;
> +
> +	if ((bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) + bv.bv_len >
> +			NVME_CTRL_PAGE_SIZE * 2)
> +		return false;

We don't need this check for SGLs. If we have a single segment, we can
put it in a single SG element no matter how large it is.