Hi, Both 2.6.38 and older kernels do not update the CD-ROM block device inode's size after media change. If one process holds a file descriptor to the device across media change, then all other processes on the system will read the outdated size when they use lseek(2) even if they opened the device after media change. The reason for this is that although the sysfs size attribute is up-to-date, the inode size is never updated by the sr driver or the universal cdrom driver. Here is an example. There is a medium inserted: $ cat /sys/block/sr0/size 7656192 Now let's start a process that keeps the file descriptor open: $ python 1>>> import os 1>>> fd = os.open('/dev/sr0', os.O_RDONLY | os.O_NONBLOCK) 1>>> os.lseek(fd, 0, 2) / 512 7656192 Now change the medium and check what sysfs says after hald/udisks has polled: $ cat /sys/block/sr0/size 15120512 Okay, the size has been updated in sysfs. The python process still has a file descriptor to the device open. Let's start a new process and see what lseek(2) says: $ python 2>>> import os 2>>> fd = os.open('/dev/sr0', os.O_RDONLY | os.O_NONBLOCK) 2>>> os.lseek(fd, 0, 2) / 512 7656192 2>>> os.close(fd) Still the old value because the inode size has not been updated. Close the file descriptor in the original process so there are no more references and then reopen it: 1>>> os.close(fd) 1>>> fd = os.open('/dev/sr0', os.O_RDONLY | os.O_NONBLOCK) 1>>> os.lseek(fd, 0, 2) / 512 15120512 Now we get the new value. I would like to add a check_disk_size_change() call to sr.c. Is there a reason to keep the existing behavior? Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html