zfs mount -l -a is failing to mount datasets where the encryption root is another dataset

[Davis-A]

System information

Type	Version/Name
Distribution Name	Debian
Distribution Version	Buster/10
Linux Kernel	Debian 5.10.19
Architecture	x86_64
ZFS Version	2.0.4-1
SPL Version	2.0.4-1

Describe the problem you're observing

zfs mount -l -a returns an error when trying to mount datasets where encryptionroot is a parent dataset

Here are my datasets

# zfs list
NAME           USED  AVAIL     REFER   MOUNTPOINT
tank           3.11G  18.7G     3.10G  /tank
tank/slot2     192K  4.00G      192K   /slot2
tank/slot4     192K  4.00G      192K   /slot4

The encryption setup; tank is encrypted and the child datasets slot2 and slot4 inherit its encryption, example here (note: this was run before loading the key)

# zfs get all tank/slot2 | grep "key\|encryption\|pass"
tank/slot2  encryption            aes-256-gcm            -
tank/slot2  keylocation           none                   default
tank/slot2  keyformat             passphrase             -
tank/slot2  encryptionroot        tank                   -
tank/slot2  keystatus             unavailable            -

What happens when i run zfs mount -l -a

# zfs mount -l -a
Key load error: Keys must be loaded for encryption root of 'tank/slot2' (tank).
Key load error: Keys must be loaded for encryption root of 'tank/slot4' (tank).

tank mounts and running zfs mount -a again (with our without -l) the child datasets mount.

Perhaps some kind of race between loading the key/mounting the tank and then trying to mount the child datasets?

Describe how to reproduce the problem

Create a pool where encryption is set at pool creation time eg

  -O encryption=on \
  -O keylocation=file:///etc/zfs.key \
  -O keyformat=passphrase \

Then create child datasets
EDIT: You also have to set the child dataset mountpoints so they are no longer below their encryption root

zfs create -o mountpoint=/foo tank/foo
zfs create -o mountpoint=/bar tank/bar

Bounce the machine then run zfs mount -l -a

[nabijaczleweli]

Can't reproduce this on 2.0.3 nor 2.0.4:

truncate -s 40G /tmp/test
dd if=/dev/urandom of=/tmp/k bs=128 count=1 status=none
zpool create -O encryption=on -O keylocation=file:///tmp/k -O keyformat=passphrase test /tmp/test
zfs create test/a
zfs create test/b
zfs umount test
zfs unload-key test
zfs mount -la

all succeed

[Davis-A]

Ok, i tried to reproduce this from scratch breaking each aspect of my pool setup apart. The key part is the dataset mount points must not be under their encryption root. Try this

truncate -s 40G /tmp/test
dd if=/dev/urandom of=/tmp/k bs=128 count=1 status=none
zpool create -O encryption=on -O keylocation=file:///tmp/k -O keyformat=passphrase test /tmp/test
zfs create -o mountpoint=/a test/a
zfs create -o mountpoint=/b test/b
zfs umount test
zfs unload-key test
zfs mount -la

[nabijaczleweli]

You're right, that does do it! Fix was easy enough, can you try #11875?

[Davis-A]

Yep that works. Thanks!