canmount=noauto prevents unmounting when child filesystems have canmount=on #18250
Description
System information
| Type | Version/Name |
|---|---|
| Distribution Name | OpenSUSE Tumbleweed |
| Distribution Version | 20260212 |
| Kernel Version | 6.18.9 |
| Architecture | x86_64 |
| OpenZFS Version | 2.4.0 |
Describe the problem you're observing
canmount=noauto prevents unmounting when child filesystems have canmount=on
Describe how to reproduce the problem
zfs create -o canmount=noauto zroot/dummy
zfs create -p zroot/dummy/var/log
zfs mount zroot/dummy
creates and mounts zroot/dummy (canmount=noauto) and child filesystems zroot/dummy/var and zroot/dummy/var/log (both canmount=on) , but it appears impossible to unmount them.
zfs unmount -a, zfs unmount zroot/dummy, zfs unmount zroot/dummy/var, and zfs unmount zroot/dummy/var/log all fail to unmount them (as shown by zfs mount) and return error message
cannot unmount '/mnt2/var/log': no such pool or dataset