Re: OpenZFS support merged: problem mounting ZFS within JAILs

On Mon, 24 Aug 2020 19:38:53 -0700
Matthew Macy <mmacy_at_freebsd.org> wrote:

> r364746 merged OpenZFS support in to HEAD.
>
> The change should be transparent unless you want to use new features.
> I caution against 'zpool upgrade' for the next few weeks.
>
> https://svnweb.freebsd.org/base?view=revision&revision=364746
>
> If you encounter problems please report them to me, Ryan Moeller, and
> -current. _______________________________________________
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Hello.

We just upgraded several boxes running CURRENT to r365325. These systems are
running customized kernels with ZFS statically compiled in. the host's OS is
derived from "make buildworld buildkernel" in /usr/src.

Jails on that hosts are maintained vi /etc/jail.conf, but system is installed
by misusage of ezjail. So far the environemnt.

One of the jails is a dedicated poudriere jail using ZFS. This worked so far.
Every pool this specific jail or any other jail is mounting is located below

POOL/ezjail

therefore we consider

enforce_statfs= "1";

in /etc/jail.conf as sufficient. After updating all /etc/default/ and
/etc/rc.d of those poudriere-jails with ZFS everything should be inline
regarding new requests for OpenZFS .

But now enforce_statfs= "1"; isn't sufficient anymore, the jais fail to startup
with a mount error complaining about insufficient access rights. The problem
partially disappear by setting enforce_statfs= "0";, but this isn't what we
want and personally I consider it a risk. But furthermore, several ZFS datasets
prior to the upgrade successfully being exported from the hosts pools and mount
from withing the jail are now invisible within the jail.

According to /usr/src/UPDATING, tag 20200824, the features of the ZFS pools of
the main hosts have been left untouched so far, no feature upgrade has been
performed.

Some hints would be nice.

Kind regards,

oh