From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [GIT PULL] for-2.6.32/bug-fixes Date: Wed, 18 May 2011 16:03:41 +0100 Message-ID: <4DD3FBED0200007800041E8E@vpn.id2.novell.com> References: <4DD373C0020000780007014D@vpn.id2.novell.com> <20110518132442.GB3238@dumpdata.com> <4DD3F4670200007800041E55@vpn.id2.novell.com> <20110518145644.GA4556@dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20110518145644.GA4556@dumpdata.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Konrad Rzeszutek Wilk Cc: jeremy@goop.org, xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org >>> On 18.05.11 at 16:56, Konrad Rzeszutek Wilk = wrote: > On Wed, May 18, 2011 at 03:31:35PM +0100, Jan Beulich wrote: >> >>> On 18.05.11 at 15:24, Konrad Rzeszutek Wilk = wrote: >> >> >Well, req->ns_segments =3D 0, so nseg is zero, which means all >> >> >of those for loops never get executed. >> >>=20 >> >> This you say is the case for the request you saw the failure with, = or >> >> *all* barrier requests? In the latter case, what do you conclude = this >> >=20 >> > Good question. It was the first barrier request sent when guest tried = to >> > mount the filesystem. I will instrument the code to see what the = other >> > barriers contained when they were sent. >>=20 >> That wouldn't tell you anything if they're all empty, as there's = nothing >> preventing other guests (including other guest OSes) to still send >> non-empty ones - after all the protocol allows for this. >=20 > Aha! That is what you been trying to tell me. I will make a patch to = make > sure to not overwrite the req->sector_number blindly. What other guest = OSes Or use the patch I proposed? > use barriers? I looked at Solaris (it uses 'feature-flush-cache'), = NetBSD > ('feature-flush-cache') and Linux ('feature-barrier' and now in 2.6.40 > 'feature-flush-cache'). >=20 > The GPLV Windows drivers have no barrier implementation - do you know if > the Novell ones are using barriers? No, I don't. Jan