block: Refuse request/bio merges with gaps in the integrity payload

If a driver sets the block queue virtual boundary mask, it means that
it cannot handle gaps so we must not allow those in the integrity
payload as well.
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>

Fixed up by me to have duplicate integrity merge functions, depending
on whether block integrity is enabled or not. Fixes a compilations
issue with CONFIG_BLK_DEV_INTEGRITY unset.
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-integrity.c

@@ -204,6 +204,9 @@ bool blk_integrity_merge_rq(struct request_queue *q, struct request *req,
 	    q->limits.max_integrity_segments)
 		return false;
 
+	if (integrity_req_gap_back_merge(req, next->bio))
+		return false;
+
 	return true;
 }
 EXPORT_SYMBOL(blk_integrity_merge_rq);

block/blk-merge.c

@@ -440,6 +440,9 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
 {
 	if (req_gap_back_merge(req, bio))
 		return 0;
+	if (blk_integrity_rq(req) &&
+	    integrity_req_gap_back_merge(req, bio))
+		return 0;
 	if (blk_rq_sectors(req) + bio_sectors(bio) >
 	    blk_rq_get_max_sectors(req)) {
 		req->cmd_flags |= REQ_NOMERGE;
@@ -461,6 +464,9 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
 
 	if (req_gap_front_merge(req, bio))
 		return 0;
+	if (blk_integrity_rq(req) &&
+	    integrity_req_gap_front_merge(req, bio))
+		return 0;
 	if (blk_rq_sectors(req) + bio_sectors(bio) >
 	    blk_rq_get_max_sectors(req)) {
 		req->cmd_flags |= REQ_NOMERGE;

include/linux/blkdev.h

@@ -1514,6 +1514,26 @@ queue_max_integrity_segments(struct request_queue *q)
 	return q->limits.max_integrity_segments;
 }
 
+static inline bool integrity_req_gap_back_merge(struct request *req,
+						struct bio *next)
+{
+	struct bio_integrity_payload *bip = bio_integrity(req->bio);
+	struct bio_integrity_payload *bip_next = bio_integrity(next);
+
+	return bvec_gap_to_prev(req->q, &bip->bip_vec[bip->bip_vcnt - 1],
+				bip_next->bip_vec[0].bv_offset);
+}
+
+static inline bool integrity_req_gap_front_merge(struct request *req,
+						 struct bio *bio)
+{
+	struct bio_integrity_payload *bip = bio_integrity(bio);
+	struct bio_integrity_payload *bip_next = bio_integrity(req->bio);
+
+	return bvec_gap_to_prev(req->q, &bip->bip_vec[bip->bip_vcnt - 1],
+				bip_next->bip_vec[0].bv_offset);
+}
+
 #else /* CONFIG_BLK_DEV_INTEGRITY */
 
 struct bio;
@@ -1580,6 +1600,16 @@ static inline bool blk_integrity_is_initialized(struct gendisk *g)
 {
 	return 0;
 }
+static inline bool integrity_req_gap_back_merge(struct request *req,
+						struct bio *next)
+{
+	return false;
+}
+static inline bool integrity_req_gap_front_merge(struct request *req,
+						 struct bio *bio)
+{
+	return false;
+}
 
 #endif /* CONFIG_BLK_DEV_INTEGRITY */