[PATCH v7 18/21] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages()

Logan Gunthorpe
2022-06-15T16:13:15Z

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>
---
block/bio.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index a402a4760457..0d152da8938d 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1180,6 +1180,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
struct page **pages = (struct page **)bv;
bool same_page = false;
+ unsigned int flags = 0;
ssize_t size, left;
unsigned len, i;
size_t offset;
@@ -1192,7 +1193,12 @@ 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);

- size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+ if (bio->bi_bdev && bio->bi_bdev->bd_disk &&
+ blk_queue_pci_p2pdma(bio->bi_bdev->bd_disk->queue))
+ flags |= FOLL_PCI_P2PDMA;
+
+ size = iov_iter_get_pages_flags(iter, pages, LONG_MAX, nr_pages,
+ &offset, flags);
if (unlikely(size <= 0))
return size ? size : -EFAULT;

--
2.30.2