svn commit: r344569 - in head/cddl/contrib/opensolaris: cmd/zfs lib/libzfs/common

Rodney W. Grimes freebsd at
Tue Feb 26 16:59:52 UTC 2019

> On Tue, Feb 26, 2019 at 10:14 AM Cy Schubert <Cy.Schubert at>
> wrote:
> > On February 26, 2019 7:48:27 AM PST, Cy Schubert <
> > Cy.Schubert at> wrote:
> > >On February 26, 2019 12:18:35 AM PST, Baptiste Daroussin
> > ><bapt at> wrote:
> >
> [trimming the unneeded pile of commit body]
> > >This broke my systems, many filesystems fail to mount causing nullfs
> > >late mounts to fail. No details now until tonight.
> > >
> > >Suggest we back this out until it is properly tested.
> >
> > Nested zfs filesystems seem not to be handled properly or possibly not
> > supported any more. This explains my mail gateway also not mounting all
> > filesystems in /home. It was odd that dovecot stopped working.
> >
> > The symptom of the problem is zfs mount -a no longer mounts all
> > filesystems. Zfs mount fails saying the filesystem is already mounted. The
> > workaround is to zfs umount each affected zfs dataset by hand and zfs mount
> > it by hand.
> >
> > Generally this has screwed up sites that have hundreds (in my case 122)
> > zfs datasets. The work around might be to script testing each mount,
> > unmounting and remounting if necessary.
> >
> > I'm being sarcastic about creating an rc script to clean this up. This
> > needs to be backed out and tested properly before being committed.
> >
> >
> I don't know what you mean by "nested zfs filesystems" -- do you mean a
> zpool within a zvol?
> That has been unsupported for a long time, IIRC.  And
That had better not be unsupported, that is the prefered technology
for all of the virtualization stuff, bhyve, virtualbox, qemu, etc.

I think by nested zfs it sounds like he is talking about datasets
inside of other datasets just from reading "all filesystems in /home"

> I'm not sure what else "nested filesystems" would be, since having (e.g.)
> separate zfs filesystems for /usr and /usr/ports is so common that surely
> it has already been tested...

It might be when the intervening dataset is marked canmount=off?
Though that should fail for the /usr /usr/foo case, as usr is normally
marked this way.  Maybe some other special case.

> -Ben
Rod Grimes                                                 rgrimes at

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