Comment 11 for bug 1760173

If you're running zfs tools in a container setting the timeout to 0 will
likely be helpful. The device node will never appear in the containers /dev
since a) it's a tmpfs and b) even if it were a devtmpfs it wouldn't help
since devtmpfs isn't namespaced. (In fact udevd will even ignore any device
event inside an unprivileged container since it's sent with
INVALID_{G,U}ID. I have kernel patches to handle this and a bunch of other
quirks that are up for merging.) For unpriv containers any device that you
somehow create by talking to /dev/zfs (e.g. by having LXD create a device
node for the container) will never show up in the container. It will always
show up in the hosts devtmpfs.

On the host setting it to 0 should also not have a negative effect since
the modprobe should a) cause devtmpfs to create the device node *before*
sending a uevent and b) zfs userspace will likely wait for udevd to settle
aka setup symlinks and persistent device naming. The timeout logic only
makes sense for old udevd implementations that do create device nodes and
might do so in a delayed manner. But better to test.