Re: [PATCH v9 6/8] block: set FOLL_PCI_P2PDMA in bio_map_user_iov()

John Hubbard
2022-09-06T00:54:30Z

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