Date: Wed, 27 Feb 2019 05:24:36 -0800 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: Cy Schubert <Cy.Schubert@cschubert.com>, Baptiste Daroussin <bapt@FreeBSD.org>, src-committers <src-committers@FreeBSD.org>, svn-src-head@FreeBSD.org, Jack Halford <jack@gandi.net> Subject: Re: svn commit: r344569 - in head/cddl/contrib/opensolaris: cmd/zfs lib/libzfs/common Message-ID: <201902271324.x1RDOaVf016848@slippy.cwsent.com> In-Reply-To: Message from Andriy Gapon <avg@FreeBSD.org> of "Wed, 27 Feb 2019 15:10:00 %2B0200." <19c0f590-4327-d2c8-4660-bd9f5df12b50@FreeBSD.org>
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In message <19c0f590-4327-d2c8-4660-bd9f5df12b50@FreeBSD.org>, Andriy Gapon wri tes: > On 27/02/2019 15:04, Cy Schubert wrote: > > In message <0563e72c-c9e3-a476-ce43-d4a67c454508@FreeBSD.org>, Andriy > > Gapon wri > > tes: > >> On 26/02/2019 22:58, Cy Schubert wrote: > >>> I was talking about nested datasets, i.e. tank/freebsd/git/current and > >>> tank/freebsd/git/ports are four levels deep. > >> > >> We usually don't call them "nested". In fact, I don't think that we call > the > >> m > >> anything special because having N levels deep datasets (N > 1) is just a c > omm > >> on > >> thing. We may call them subordinate or child datasets when mentioning a > >> relation to a parent dataset. > >> > >>> In my case the ports > >>> dataset was mounted while the current dataset was not, though zfs > >>> believed it was. unmounting the current dataset and remounting it, zfs > >>> umount .../current; zfs mount .../current worked around the issue. > >> > >> Are you sure that it was not mounted? > > > > Yes. > > > >> Have you checked that by looking at mount output? > > > > Yes > > > >> I suspect that it was mounted, just not where you expected and its mount p > ath > >> was covered by another filesystem. > > > > If you read my original email > > Apologies, I failed to read your original email when I first saw it. > I pressed Page Down a few times but was still seeing only a quoted text, so I > gave up. That was my fault but given I was using an email client on my phone, removing the quoted text would have taken forever. Usually in that circumstance I wait until I get to a real keyboard before firing off an email. > > > a zfs umount followed by a zfs mount for > > each affected filesystem worked around the problem. zfs properties > > showed that each and every filesystem was mounted. mount(1) and df(1) > > confirmed they were not. Furthermore nullfs mounts with the late > > attribute failed to mount because their underlying zfs datasets were > > not mounted -- this is what clued me into the problem in the first > > place, a FreeBSD system dropping into single user at boot. And, no, > > fstab on that machine had not been changed for months, them machine > > failed to boot. So, no, I was not mistaken. I was rather displeased > > because I had to try to fix the problem using ssh on a phone to a > > machine connected to a console server. > > > >> > >> E.g., lets consider this hypothetical case. > >> I have two same level datasets tank/freebsd/src and tank/freebsd/sys where > >> tank/freebsd/src is mounted at /usr/src and tank/freebsd/sys is mounted at > >> /usr/src/sys (a child directory of /usr/src). > >> If tank/freebsd/src is mounted first, then everything is okay, tank/freebs > d/s > >> ys > >> would be mounted on top of sys directory in tank/freebsd/src. > >> If, however, tank/freebsd/sys is mounted first (assuming that path /usr/sr > c/s > >> ys > >> exists in a root filesystem), then mounting tank/freebsd/src would simply > hid > >> e > >> tank/freebsd/sys "below" it as /usr/src/sys would be sys directory in > >> tank/freebsd/src. > >> > >> I guess that this is a kind of problem that could be introduced with paral > lel > >> mounting. And I guess that this is a kind of problem that you might actua > lly > >> have. But it's just a guess. > > > > No. I had not mistakenly mounted the datasets elsewhere, mistakenly > > deleted them or mistakenly changed their mount attributes. It was a > > real, not imagined, regression fixed by the patch posted near the end > > of the email thread. > > Okay. Great that it is fixed and sorry for my noise. NP. I'm glad it's fixed too. -- Cheers, Cy Schubert <Cy.Schubert@cschubert.com> FreeBSD UNIX: <cy@FreeBSD.org> Web: http://www.FreeBSD.org The need of the many outweighs the greed of the few.
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