btrfsctl -A not returning useful information

Ahmed Kamal
2008-07-18T17:28:40Z

[root@btrfs progs-unstable]# btrfsctl -A /dev/sdb
ioctl returns 0
[root@btrfs progs-unstable]# btrfsctl -A /dev/sdc
ioctl returns 0

/dev/sdb has a btrfs, while /dev/sdc is blank. What's that output
supposed to mean ? Is it a bug ?