How to close a LUKS mounted image-file without ' Device ... is still in use' - need to wait maybe 15 minutes

[Alex R. Berg]

I'm running unraid 6.12.4.
This is likely not unRaid specific, but I don't know.

TLDR: I can mount a LUKS drive but sometimes when on luksClose it won't close, but so far waiting 15 minutes helps.

I tried creating a LUKS encrypted file using this guide:

https://blog.tian.it/create-encrypted-luks-sparse-file/

When I unmount the mounted filesystem and then try to close the LUKS using

```
umount /cryptoarchive/stuff
cryptsetup luksClose "/dev/mapper/stuff"
```

then I get the following error:

```
Device /dev/mapper/stuff.img is still in use.
```

Running `df` I can see the unmount worked, and also the `umount` didn't fail. `lsof` shows me that the loop-device file is (of cause) still in use, but no files on the mounted dir `/cryptoarchive/stuff` is shown .

Once after waiting an hour or so, I tried remounting and then umounting immediately afterwards, and that one time luksClose succeeded. I have shared the mount point via samba, but as mentioned umount works.

I have attached my mount and unmount scripts.


Thx, Alex

 

 

luks-unmount.sh

luks-mount.sh

Edited December 10, 2023 by Alex R. Berg