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Date:   Mon, 5 Sep 2022 17:54:13 -0700
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Subject: Re: [PATCH v9 6/8] block: set FOLL_PCI_P2PDMA in bio_map_user_iov()
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To:     Logan Gunthorpe <logang@deltatee.com>,
        linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-mm@kvack.org
Cc:     Christoph Hellwig <hch@lst.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Don Dutile <ddutile@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Minturn Dave B <dave.b.minturn@intel.com>,
        Jason Ekstrand <jason@jlekstrand.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Xiong Jianxin <jianxin.xiong@intel.com>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Martin Oliveira <martin.oliveira@eideticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@gmail.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Stephen Bates <sbates@raithlin.com>
References: <20220825152425.6296-1-logang@deltatee.com>
 <20220825152425.6296-7-logang@deltatee.com>
From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20220825152425.6296-7-logang@deltatee.com>
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On 8/25/22 08:24, Logan Gunthorpe wrote:
> When a bio's queue supports PCI P2PDMA, set FOLL_PCI_P2PDMA for
> iov_iter_get_pages_flags(). This allows PCI P2PDMA pages to be
> passed from userspace and enables the NVMe passthru requests to
> use P2PDMA pages.
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
>  block/blk-map.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/block/blk-map.c b/block/blk-map.c
> index 7196a6b64c80..1378f49ca5ca 100644
> --- a/block/blk-map.c
> +++ b/block/blk-map.c
> @@ -236,6 +236,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
>  {
>  	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
>  	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
> +	unsigned int flags = 0;

A small thing, but I'd also like to name that one gup_flags, instead of flags.

>  	struct bio *bio;
>  	int ret;
>  	int j;
> @@ -248,13 +249,17 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
>  		return -ENOMEM;
>  	bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
>  
> +	if (blk_queue_pci_p2pdma(rq->q))
> +		flags |= FOLL_PCI_P2PDMA;
> +
>  	while (iov_iter_count(iter)) {
>  		struct page **pages;
>  		ssize_t bytes;
>  		size_t offs, added = 0;
>  		int npages;
>  
> -		bytes = iov_iter_get_pages_alloc2(iter, &pages, LONG_MAX, &offs);
> +		bytes = iov_iter_get_pages_alloc_flags(iter, &pages, LONG_MAX,
> +						       &offs, flags);
>  		if (unlikely(bytes <= 0)) {
>  			ret = bytes ? bytes : -EFAULT;
>  			goto out_unmap;

Looks good, please feel free to add:

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,

-- 
John Hubbard
NVIDIA