bio-integrity: create multi-page bvecs in bio_integrity_add_page()

In general, the bvec data structure consists of one for physically
continuous pages. But, in the bvec configuration for bip, physically
continuous integrity pages are composed of each bvec.

Allow bio_integrity_add_page() to create multi-page bvecs, just like
the bio payloads. This simplifies adding larger payloads, and fixes
support for non-tiny workloads with nvme, which stopped using
scatterlist for metadata a while ago.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>

Fixes: 783b94bd ("nvme-pci: do not build a scatterlist to map metadata")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Tested-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20230803025202epcms2p82f57cbfe32195da38c776377b55aed59@epcms2p8Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio-integrity.c

@@ -123,17 +123,34 @@ void bio_integrity_free(struct bio *bio)
 int bio_integrity_add_page(struct bio *bio, struct page *page,
 			   unsigned int len, unsigned int offset)
 {
+	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 	struct bio_integrity_payload *bip = bio_integrity(bio);
 
-	if (bip->bip_vcnt >= bip->bip_max_vcnt) {
-		printk(KERN_ERR "%s: bip_vec full\n", __func__);
+	if (((bip->bip_iter.bi_size + len) >> SECTOR_SHIFT) >
+	    queue_max_hw_sectors(q))
 		return 0;
-	}
 
-	if (bip->bip_vcnt &&
-	    bvec_gap_to_prev(&bdev_get_queue(bio->bi_bdev)->limits,
-			     &bip->bip_vec[bip->bip_vcnt - 1], offset))
-		return 0;
+	if (bip->bip_vcnt > 0) {
+		struct bio_vec *bv = &bip->bip_vec[bip->bip_vcnt - 1];
+		bool same_page = false;
+
+		if (bvec_try_merge_hw_page(q, bv, page, len, offset,
+					   &same_page)) {
+			bip->bip_iter.bi_size += len;
+			return len;
+		}
+
+		if (bip->bip_vcnt >=
+		    min(bip->bip_max_vcnt, queue_max_integrity_segments(q)))
+			return 0;
+
+		/*
+		 * If the queue doesn't support SG gaps and adding this segment
+		 * would create a gap, disallow it.
+		 */
+		if (bvec_gap_to_prev(&q->limits, bv, offset))
+			return 0;
+	}
 
 	bvec_set_page(&bip->bip_vec[bip->bip_vcnt], page, len, offset);
 	bip->bip_vcnt++;