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From: Christoph Hellwig <hch@lst.de>
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Subject: Re: [PATCH v8 23/24] nvme-pci: convert to blk_rq_dma_map
Message-ID: <20250422050050.GB28077@lst.de>
References: <cover.1744825142.git.leon@kernel.org> <f06a04098cb14e1051bddec8a7bdebe1c384d983.1744825142.git.leon@kernel.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

> +	dma_len = min_t(u32, length, NVME_CTRL_PAGE_SIZE - (dma_addr & (NVME_CTRL_PAGE_SIZE - 1)));

And overly long line slipped in here during one of the rebases.

> +		/*
> +		 * We are in this mode as IOVA path wasn't taken and DMA length
> +		 * is morethan two sectors. In such case, mapping was perfoormed
> +		 * per-NVME_CTRL_PAGE_SIZE, so unmap accordingly.
> +		 */

Where does this comment come from?  Lots of spelling errors, and I
also don't understand what it is talking about as setors are entirely
irrelevant here.

> +	if (!blk_rq_dma_unmap(req, dev->dev, &iod->dma_state, iod->total_len)) {
> +		if (iod->cmd.common.flags & NVME_CMD_SGL_METABUF)
> +			nvme_free_sgls(dev, req);

With the addition of metadata SGL support this also needs to check
NVME_CMD_SGL_METASEG.

The commit message should also really mentioned that someone
significantly altered the patch for merging with latest upstream,
as I as the nominal author can't recognize some of that code.

> +	unsigned int entries = req->nr_integrity_segments;
>  	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
>  
> +	if (!blk_rq_dma_unmap(req, dev->dev, &iod->dma_meta_state,
> +			      iod->total_meta_len)) {
> +		if (entries == 1) {
> +			dma_unmap_page(dev->dev, iod->meta_dma,
> +				       rq_integrity_vec(req).bv_len,
> +				       rq_dma_dir(req));
> +			return;
>  		}
>  	}
>  
> +	dma_pool_free(dev->prp_small_pool, iod->meta_list, iod->meta_dma);

This now doesn't unmap for entries > 1 in the non-IOVA case.