root@ubuntu:/# mount /boot
mount: /dev/sdb1 already mounted or /boot busy
mount: according to mtab, /dev/sdb1 is already mounted on /boot
root@ubuntu:/# fsck -f /dev/sdb1
fsck from util-linux 2.20.1
e2fsck 1.42.9 (4-Feb-2014)
/dev/sdb1 is mounted.
e2fsck: Cannot continue, aborting.