test max hw sectors for REQ_PC commands

index 6fd9121..bfcd501 100644
@@ -1322,9 +1322,15 @@ static inline int ll_new_hw_segment(requ
 static int ll_back_merge_fn(request_queue_t *q, struct request *req, 
 			    struct bio *bio)
 {
+	unsigned short max_sectors;
 	int len;
 
-	if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
+	if (unlikely(blk_pc_request(req)))
+		max_sectors = q->max_hw_sectors;
+	else
+		max_sectors = q->max_sectors;
+
+	if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
 		req->flags |= REQ_NOMERGE;
 		if (req == q->last_merge)
 			q->last_merge = NULL;

@@ -1354,9 +1360,16 @@ static int ll_back_merge_fn(request_queu
 static int ll_front_merge_fn(request_queue_t *q, struct request *req, 
 			     struct bio *bio)
 {
+	unsigned short max_sectors;
 	int len;
 
-	if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
+	if (unlikely(blk_pc_request(req)))
+		max_sectors = q->max_hw_sectors;
+	else
+		max_sectors = q->max_sectors;
+
+
+	if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
 		req->flags |= REQ_NOMERGE;
 		if (req == q->last_merge)
 			q->last_merge = NULL;

index 99cb09f..6248f3a 100644
@@ -461,6 +461,7 @@ int scsi_execute_async(struct scsi_devic
 	req = blk_get_request(sdev->request_queue, write, gfp);
 	if (!req)
 		goto free_sense;
+	req->flags |= REQ_BLOCK_PC | REQ_QUIET;
 
 	if (use_sg)
 		err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);

@@ -476,7 +477,6 @@ int scsi_execute_async(struct scsi_devic
 	req->sense_len = 0;
 	req->timeout = timeout;
 	req->retries = retries;
-	req->flags |= REQ_BLOCK_PC | REQ_QUIET;
 	req->end_io_data = sioc;
 
 	sioc->data = privdata;