From owner-svn-src-head@freebsd.org Thu Jan 21 11:38:25 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 09140A8BEC0; Thu, 21 Jan 2016 11:38:25 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from zxy.spb.ru (zxy.spb.ru [195.70.199.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id B8B2B1362; Thu, 21 Jan 2016 11:38:24 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from slw by zxy.spb.ru with local (Exim 4.86 (FreeBSD)) (envelope-from ) id 1aMDZ8-000Hol-3k; Thu, 21 Jan 2016 14:38:14 +0300 Date: Thu, 21 Jan 2016 14:38:14 +0300 From: Slawa Olhovchenkov To: Andriy Gapon Cc: Alan Somers , "svn-src-head@freebsd.org" , "svn-src-all@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> References: <201601191700.u0JH0P6k061610@repo.freebsd.org> <569E6DA0.9010300@pix.net> <569F516D.80303@FreeBSD.org> <56A019A1.4030900@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56A019A1.4030900@FreeBSD.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: slw@zxy.spb.ru X-SA-Exim-Scanned: No (on zxy.spb.ru); SAEximRunCond expanded to false X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Jan 2016 11:38:25 -0000 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 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)?