Date: Thu, 21 Jan 2016 14:38:14 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Andriy Gapon <avg@FreeBSD.org> Cc: Alan Somers <asomers@FreeBSD.org>, "svn-src-head@freebsd.org" <svn-src-head@FreeBSD.org>, "svn-src-all@freebsd.org" <svn-src-all@FreeBSD.org>, "src-committers@freebsd.org" <src-committers@FreeBSD.org> Subject: Re: svn commit: r294329 - in head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs: . sys Message-ID: <20160121113813.GG37895@zxy.spb.ru> In-Reply-To: <56A019A1.4030900@FreeBSD.org> References: <201601191700.u0JH0P6k061610@repo.freebsd.org> <569E6DA0.9010300@pix.net> <CAOtMX2idrWOpWbkYxPFn3yur8w-vgfBryhT4_0yiBvg10sWWRA@mail.gmail.com> <569F516D.80303@FreeBSD.org> <CAOtMX2gs37OnLMXE4zCduZF94%2B5z-TgPW%2Bqg8K8BweauLCRgDQ@mail.gmail.com> <56A019A1.4030900@FreeBSD.org>
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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@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 problems 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 always > welcomed. > > P.S. > I think that the real problem here is that a method of a geom must never drop > topology_lock. In other words, the GEOM management code (like g_xxx() stuff 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)?
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