SG_GET_ACCESS_COUNT 0x2289.  This ioctl() yields the access count maintained by the mid level for this SCSI device. This number is incremented by each open() call done by the upper level SCSI drivers (i.e. sd, sr, st and sg) and decremented by those drivers' release(). [A driver's release() corresponds to the last close() on a file descriptor, or is supplied by the kernel when a process is aborted.] Each SCSI device has a separate access count.