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To: Yamagi Burmeister <lists@yamagi.org>
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Date: Sun, 29 Jan 2012 00:09:59 -0800
From: Kirk McKusick <mckusick@mckusick.com>
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Cc: antonio.trindade@gmail.com, freebsd-fs@freebsd.org
Subject: Re: kernel: panic: softdep_sync_buf: Unknown type jnewblk 
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> Date: Fri, 27 Jan 2012 09:39:34 +0100
> From: Yamagi Burmeister <lists@yamagi.org>
> To: freebsd@jdc.parodius.com
> Cc: antonio.trindade@gmail.com, freebsd-fs@freebsd.org, dougb@freebsd.org,
>         freebsd-stable@freebsd.org
> Subject: Re: kernel: panic: softdep_sync_buf: Unknown type jnewblk
> 
> Hi :)
> 
> On Thu, 26 Jan 2012 17:54:30 -0800
> Jeremy Chadwick <freebsd@jdc.parodius.com> wrote:
> 
> > I'll also point out, though the OP isn't using snapshots, that it's
> > confirmed use of snapshots on SU+J can result in a full filesystem hang.
> > Confirmation is from Kirk McKusick (author of SU and designer of SU+J):
> >
> > http://lists.freebsd.org/pipermail/freebsd-fs/2012-January/013429.html
> >
> > Something really needs to be done about this combination of problems.
> >
> > Since SU+J is the default choice for all UFS filesystems on 9.0-RELEASE,
> > the only solution I can think of is to send a massive announcement to
> > relevant mailing lists, AND put something on the freebsd.org home page
> > about these issues.
> 
> The problem was analyzed but no immediate solution found. Therefor
> snapshots on filesystems with SU+J (but not SU alone) were disabled
> by Kirk McKusick in SVN r230250. The MFC to 9-STABLE has still to
> be done. Maybe this fix is a candidate for an errata notice / patch,
> distributed by freebsd-update?

With revision 230725 I have MFC'ed to 9 the above change to disable
snapshots when running SU+J. Hopefully Jeff and I will manage to get
a fix for snapshots so as to be able to run them reliably with SU+J.
The above change is not relevant to 8 or earlier systems, so this MFC
will not be applied to them.

	Kirk McKusick