[PATCH 2/2] bio-integrity: create multi-page bvecs in bio_integrity_add_page()

[Jinyoung Choi]

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@xxxxxx>
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>

Fixes: 783b94bd9250 ("nvme-pci: do not build a scatterlist to map metadata")
Signed-off-by: Jinyoung Choi <j-young.choi@xxxxxxxxxxx>
---
 block/bio-integrity.c | 50 ++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 045553a164e0..ae054c6a06cb 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -123,21 +123,38 @@ 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++;
-
+	bip->bip_iter.bi_size += len;
 	return len;
 }
 EXPORT_SYMBOL(bio_integrity_add_page);
@@ -244,7 +261,6 @@ bool bio_integrity_prep(struct bio *bio)
 	}
 
 	bip->bip_flags |= BIP_BLOCK_INTEGRITY;
-	bip->bip_iter.bi_size = len;
 	bip_set_seed(bip, bio->bi_iter.bi_sector);
 
 	if (bi->flags & BLK_INTEGRITY_IP_CHECKSUM)
@@ -252,27 +268,18 @@ bool bio_integrity_prep(struct bio *bio)
 
 	/* Map it */
 	offset = offset_in_page(buf);
-	for (i = 0 ; i < nr_pages ; i++) {
-		int ret;
+	for (i = 0; i < nr_pages && len > 0; i++) {
 		bytes = PAGE_SIZE - offset;
 
-		if (len <= 0)
-			break;
-
 		if (bytes > len)
 			bytes = len;
 
-		ret = bio_integrity_add_page(bio, virt_to_page(buf),
-					     bytes, offset);
-
-		if (ret == 0) {
+		if (bio_integrity_add_page(bio, virt_to_page(buf),
+					   bytes, offset) < bytes) {
 			printk(KERN_ERR "could not attach integrity payload\n");
 			goto err_end_io;
 		}
 
-		if (ret < bytes)
-			break;
-
 		buf += bytes;
 		len -= bytes;
 		offset = 0;
@@ -291,7 +298,6 @@ bool bio_integrity_prep(struct bio *bio)
 	bio->bi_status = BLK_STS_RESOURCE;
 	bio_endio(bio);
 	return false;
-
 }
 EXPORT_SYMBOL(bio_integrity_prep);
 
-- 
2.34.1