[PATCH v11 6/9] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages()

Logan Gunthorpe
2022-10-21T17:41:53Z

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@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
---
block/bio.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 439469370b7c..a7abf9b1b66a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1197,6 +1197,7 @@ 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 gup_flags = 0;
ssize_t size, left;
unsigned len, i = 0;
size_t offset, trim;
@@ -1210,6 +1211,9 @@ 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 && blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
+ gup_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
@@ -1217,8 +1221,9 @@ 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(iter, pages,
+ UINT_MAX - bio->bi_iter.bi_size,
+ nr_pages, &offset, gup_flags);
if (unlikely(size <= 0))
return size ? size : -EFAULT;

--
2.30.2