I was compiling the bug report, when I found out that on my host:
$ df -h
df: /mnt/dati: Resource temporarily unavailable
df: /mnt/dati_for_internal: Resource temporarily unavailable
df: /mnt/monitoring_for_internal: Resource temporarily unavailable
Filesystem Size Used Avail Use% Mounted on
tmpfs 1.6G 2.2M 1.6G 1% /run
<…>
Even though the content is actually accessible on the host (!!!)
It’s a bug in the linux kernel, not in LXD:
Last message as of few hours ago claims 5.15.0-104-generic fixes the issue and will be released soon.
Sorry for the noise!