linux-kernel - [PATCH v9 5/8] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get

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Date:   Thu, 25 Aug 2022 09:24:22 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-mm@...ck.org
Cc:     Christoph Hellwig <hch@....de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@...il.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Stephen Bates <sbates@...thlin.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v9 5/8] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages()

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 O_DIRECT path in iomap based filesystems
and direct to block devices.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 block/bio.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 969607bc1f4d..ca09d79a0683 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1200,6 +1200,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
 	struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
 	struct page **pages = (struct page **)bv;
+	unsigned int flags = 0;
 	ssize_t size, left;
 	unsigned len, i = 0;
 	size_t offset, trim;
@@ -1213,6 +1214,10 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
 	pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
 
+	if (bio->bi_bdev && bio->bi_bdev->bd_disk &&
+	    blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
+		flags |= FOLL_PCI_P2PDMA;
+
 	/*
 	 * Each segment in the iov is required to be a block size multiple.
 	 * However, we may not be able to get the entire segment if it spans
@@ -1220,8 +1225,9 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	 * result to ensure the bio's total size is correct. The remainder of
 	 * the iov data will be picked up in the next bio iteration.
 	 */
-	size = iov_iter_get_pages2(iter, pages, UINT_MAX - bio->bi_iter.bi_size,
-				  nr_pages, &offset);
+	size = iov_iter_get_pages_flags(iter, pages,
+					UINT_MAX - bio->bi_iter.bi_size,
+					nr_pages, &offset, flags);
 	if (unlikely(size <= 0))
 		return size ? size : -EFAULT;
 
-- 
2.30.2