diff --git a/block/blk-core.c b/block/blk-core.c
index 29bcfac..859879d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -132,6 +132,7 @@
 	INIT_HLIST_NODE(&rq->hash);
 	RB_CLEAR_NODE(&rq->rb_node);
 	rq->cmd = rq->__cmd;
+	rq->cmd_len = BLK_MAX_CDB;
 	rq->tag = -1;
 	rq->ref_count = 1;
 }
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 73d7860..b32ff44 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -643,7 +643,7 @@
 	if (blk_pc_request(rq)) {
 		what |= BLK_TC_ACT(BLK_TC_PC);
 		__blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
-				sizeof(rq->cmd), rq->cmd);
+				rq->cmd_len, rq->cmd);
 	} else  {
 		what |= BLK_TC_ACT(BLK_TC_FS);
 		__blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,