blk-integrity: enable p2p source and destination

Set the extraction flags to allow p2p pages for the metadata buffer if
the block device allows it. Similar to data payloads, ensure the bio
does not use merging if we see a p2p page.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: keithbusch

block/bio-integrity.c

@@ -230,7 +230,8 @@ static int bio_integrity_init_user(struct bio *bio, struct bio_vec *bvec,
 }
 
 static unsigned int bvec_from_pages(struct bio_vec *bvec, struct page **pages,
-				    int nr_vecs, ssize_t bytes, ssize_t offset)
+				    int nr_vecs, ssize_t bytes, ssize_t offset,
+				    bool *is_p2p)
 {
 	unsigned int nr_bvecs = 0;
 	int i, j;
@@ -251,6 +252,9 @@ static unsigned int bvec_from_pages(struct bio_vec *bvec, struct page **pages,
 			bytes -= next;
 		}
 
+		if (is_pci_p2pdma_page(pages[i]))
+			*is_p2p = true;
+
 		bvec_set_page(&bvec[nr_bvecs], pages[i], size, offset);
 		offset = 0;
 		nr_bvecs++;
@@ -264,10 +268,11 @@ int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter)
 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 	struct page *stack_pages[UIO_FASTIOV], **pages = stack_pages;
 	struct bio_vec stack_vec[UIO_FASTIOV], *bvec = stack_vec;
+	iov_iter_extraction_t extraction_flags = 0;
 	size_t offset, bytes = iter->count;
+	bool copy, is_p2p = false;
 	unsigned int nr_bvecs;
 	int ret, nr_vecs;
-	bool copy;
 
 	if (bio_integrity(bio))
 		return -EINVAL;
@@ -286,15 +291,23 @@ int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter)
 
 	copy = iov_iter_alignment(iter) &
 			blk_lim_dma_alignment_and_pad(&q->limits);
-	ret = iov_iter_extract_pages(iter, &pages, bytes, nr_vecs, 0, &offset);
+
+	if (blk_queue_pci_p2pdma(q))
+		extraction_flags |= ITER_ALLOW_P2PDMA;
+
+	ret = iov_iter_extract_pages(iter, &pages, bytes, nr_vecs,
+					extraction_flags, &offset);
 	if (unlikely(ret < 0))
 		goto free_bvec;
 
-	nr_bvecs = bvec_from_pages(bvec, pages, nr_vecs, bytes, offset);
+	nr_bvecs = bvec_from_pages(bvec, pages, nr_vecs, bytes, offset,
+				   &is_p2p);
 	if (pages != stack_pages)
 		kvfree(pages);
 	if (nr_bvecs > queue_max_integrity_segments(q))
 		copy = true;
+	if (is_p2p)
+		bio->bi_opf |= REQ_NOMERGE;
 
 	if (copy)
 		ret = bio_integrity_copy_user(bio, bvec, nr_bvecs, bytes);