what on earth is blkid doing?

[Tom Horsley]

Over in the discussion about disk labeling, the blkid tool was
mentioned. I ran it (no args), and it showed the label on
all my partitions, including the /dev/dvd device, which doesn't
have a DVD in it. The label it showed me was the last DVD I did
have in it a few days ago, and I've rebooted several times since
then. Where the heck is this coming from? Does the DVD drive
itself store that? (I probably haven't powered off the system
since that DVD was in there, so I suppose the drive might be
the one stashing it). Another thing to be paranoid about! The
NSA can keep track of which movies you last watched by remotely
querying your DVD drives! :-).