rbd: don't treat CEPH_OSD_OP_DELETE as extent op

CEPH_OSD_OP_DELETE is not an extent op, stop treating it as such.  This
sneaked in with discard patches - it's one of the three osd ops (the
other two are CEPH_OSD_OP_TRUNCATE and CEPH_OSD_OP_ZERO) that discard
is implemented with.
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>

drivers/block/rbd.c

@@ -2370,8 +2370,12 @@ static void rbd_img_obj_request_fill(struct rbd_obj_request *obj_request,
 		opcode = CEPH_OSD_OP_READ;
 	}
 
-	osd_req_op_extent_init(osd_request, num_ops, opcode, offset, length,
-				0, 0);
+	if (opcode == CEPH_OSD_OP_DELETE)
+		osd_req_op_init(osd_request, num_ops, opcode);
+	else
+		osd_req_op_extent_init(osd_request, num_ops, opcode,
+				       offset, length, 0, 0);
+
 	if (obj_request->type == OBJ_REQUEST_BIO)
 		osd_req_op_extent_osd_data_bio(osd_request, num_ops,
 					obj_request->bio_list, length);