[Solved] Can't unmount; resource busy

[Hegabo]

I have two HDDs connected to my Archer C7 V2 running 18.06.01. Each disk has only 1 NTFS partition, mounted on boot by rc.local

ntfs-3g /dev/sda1 /HP -o rw,sync
ntfs-3g /dev/sdb1 /WD -o rw,sync

One of the disks is used for miniDLNA.

I could unmount the disk that's not used for miniDLNA using umount. However, or the disk that's used for miniDLNA, I don't seem to be able to unmount it, even after stopping miniDLNA.

root@C7:~# service minidlna stop
root@C7:~#
root@C7:~# umount /dev/sda1
umount: can't unmount /HP: Resource busy

[vgaetera]

service samba stop

opkg update
opkg install lsof
lsof +D /HP /WD

[Hegabo]

Works! It appears it was the Samba. Thanks @vgaetera