svn commit: r294329 - in head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs: . sys

[Cy Schubert]

In message <20160121113813.GG37895 at zxy.spb.ru>, Slawa Olhovchenkov writes:
> On Thu, Jan 21, 2016 at 01:34:57AM +0200, Andriy Gapon wrote:
> 
> > On 20/01/2016 22:03, Alan Somers wrote:
> > > On Wed, Jan 20, 2016 at 2:20 AM, Andriy Gapon <avg at freebsd.org> wrote:
> > >> On 19/01/2016 19:20, Alan Somers wrote:
> > >>> The thing is, it never really worked in the first place.  Panics and
> > >>> deadlocks are so frequent that I don't think the feature was usable
> > >>> for anybody.
> > >>
> > >> The feature is perfectly usable for me.  I have never run into the probl
> ems that
> > >> you describe.  Why not fix the real bugs that you've run into?
> > > 
> > > Spectra Logic and iXSystems both experienced many problems with this.
> > > The worst is a deadlock that can be triggered simply by pulling a
> > > drive from a redundant pool when there exists a zvol anywhere in the
> > > system (see https://reviews.freebsd.org/D4998 for a quick way to
> > > reproduce).  Fixing it correctly would likely require far more time
> > > than I have available.  I just want the bugs to go away.  See that
> > > same code review for a change to make the feature optional.
> > 
> > I think that we all want all the bugs to go way.  One way to remove bugs is
>  to
> > remove (disable) code that contains bugs.  That way the perfect bug-free
> > software is clearly achievable :-)  Unfortunately, that technique is not al
> ways
> > welcomed.
> > 
> > P.S.
> > I think that the real problem here is that a method of a geom must never dr
> op
> > topology_lock.  In other words, the GEOM management code (like g_xxx() stuf
> f in
> > geom_subr.c) expects that a topology can not change underneath it.  But
> > zvol_geom_access() clearly breaks that contract.
> 
> May be same cause problem with swap on zvol (don't test on latest
> -stable)?

Not related but should be disabled by default through sysctl is vdev on 
USB. OK for a laptop but not a server. 100% hang on shutdown/reboot.


-- 
Cheers,
Cy Schubert <Cy.Schubert at komquats.com> or <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.