udev not creating device file for cloned zvol

[ghost]

System information

Type	Version/Name
Distribution Name	Debian
Distribution Version	Bullseye
Linux Kernel	5.7.6
Architecture	x86_64
ZFS Version	0.8.4
SPL Version	0.8.4

Describe the problem you're observing

I have an encrypted zvol pool_name/base and a snapshot of it pool_name/base@snapshot.
When a zvol clone pool_name/clone is created from the snapshot, udev creates a device file /dev/zvol/pool_name/clone(symlink to /dev/zdX).
However, this does not seem to survive an export. When the zfs pool is re-imported, device file is only created for the base zvol, not the clone.

Describe how to reproduce the problem

zpool create pool_name backing_device
zpool import pool_name
zfs create -V 1G -o encryption=on,keylocation=file:///path_to_encryption_key pool_name/base
zfs snapshot pool_name/base@snapshot
zfs clone pool_name/base@snapshot pool_name/clone
By now /dev/zvol/pool_name/clone should show up.

zfs export pool_name
We would expect that after the re-import, /dev/zvol/pool_name/clone would appear again. However, only pool_name/base is under /dev/zvol/
zpool import -l pool_name

Side note:

• There seems to be a certain degree randomness in its behaviour. Sometimes (but rarely) /dev/zvol/pool_name/clone does show up.
• In reality, I have multiple zvol clones based off the snapshot. There have been cases when only some of these zvol clones appear under /dev/zvol
• When /dev/zvol/pool_name/clone is not created, neither is /dev/zdX, so it doesn't seem like a problem with udev configuration.

Include any warning/errors/backtraces from the system logs

Not sure which file contains the log for zfs.

[danielfullmer]

I am encountering the same issue as well. This appears to be an issue with combining encryption with zvol clones. Running the instructions for reproducing above will work fine if encryption is not enabled, but fail if encryption is enabled.

(As mentioned in the original issue, I don't think this is an issue with udev, since even the /sys/block/zd[0-9]* device doesn't show up at all.)

System information

Type	Version/Name
Distribution Name	NixOS
Distribution Version	21.11.20210628.b809a63
Linux Kernel	5.4.127
Architecture	x86_64
ZFS Version	2.1.0-rc7
SPL Version	2.1.0-rc7

[stale]

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