root corrupted

[effemmeffe]

In my dmesg I got this:

[ 10.729779] EXT4-fs (mmcblk0p2): warning: mounting fs with errors, running e2fsck is recommended
[ 11.382713] EXT4-fs (mmcblk0p2): recovery complete
[ 11.385570] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 19.383754] EXT4-fs (sda): warning: mounting unchecked fs, running e2fsck is recommended
[ 19.394781] EXT4-fs (sda): mounted filesystem without journal. Opts: (null)
[ 26.315708] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)

So I run shutdown -rF now, it should run fsck on my sd, correct?
But after the reboot I still get the same errors in dmesg.
Obviously I cannot run fsck on mmcblk0p2 because it's where / is mounted and I can't unmount it.
How can I solve the problem?

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my fstab:
xbian@xbian ~ $ cat /etc/fstab
proc /proc proc defaults 0 0
/dev/mmcblk0p1 /boot vfat defaults 0 2
/dev/mmcblk0p2 / ext4 defaults,noatime 0 1

so /dev/mmcblk0p2 should be checked by fsck