block: introduce blk_rq_is_passthrough

This can be used to check for fs vs non-fs requests and basically
removes all knowledge of BLOCK_PC specific from the block layer,
as well as preparing for removing the cmd_type field in struct request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index cbc0c5f..c611412 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -5539,8 +5539,8 @@
 	 * Retries always go down the normal I/O path.
 	 */
 	if (likely(cmd->retries == 0 &&
-		cmd->request->cmd_type == REQ_TYPE_FS &&
-		h->acciopath_status)) {
+			!blk_rq_is_passthrough(cmd->request) &&
+			h->acciopath_status)) {
 		rc = hpsa_ioaccel_submit(h, c, cmd, scsi3addr);
 		if (rc == 0)
 			return 0;