mount: /dev/ada0p1: Device busy Busy with what?

[Per olof Ljungmark]

I have apart from the boot drives a SATA disk for storage. Usually I
would mount it with
mount /dev/ada0p1 /archive
but as my last reboot into
FreeBSD 9.1-STABLE #0 r252369
I cannot mount the disk, I get
mount: /dev/ada0p1: Device busy

Well, busy with what?

fuser -m /dev/ada0p1
/dev/ada0p1:

I REALLY need to acces trhis UFS formatted drive, how can I convice it
that everything is ok and it's not really busy with anything?

Could anyone please help to sort this please?

TIA

//per