BLK_IO_TRACE_MAGIC   42 block/blktrace.c 		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
BLK_IO_TRACE_MAGIC  161 block/blktrace.c 		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;