From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:39311) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkw29-0005UN-1v for qemu-devel@nongnu.org; Tue, 18 Dec 2012 07:12:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tkw27-0007dv-Iv for qemu-devel@nongnu.org; Tue, 18 Dec 2012 07:12:29 -0500 Received: from isrv.corpit.ru ([86.62.121.231]:34110) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tkw27-0007d5-Bh for qemu-devel@nongnu.org; Tue, 18 Dec 2012 07:12:27 -0500 Message-ID: <50D05DA0.7010306@msgid.tls.msk.ru> Date: Tue, 18 Dec 2012 16:12:16 +0400 From: Michael Tokarev MIME-Version: 1.0 References: <1339767219-24297-1-git-send-email-kwolf@redhat.com> <201212121510.06575.hahn@univention.de> <50C8B6E2.9080306@redhat.com> <201212181046.42577.hahn@univention.de> In-Reply-To: <201212181046.42577.hahn@univention.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [BUG] qemu-1.1.2 [FIXED-BY] qcow2: Fix avail_sectors in cluster allocation code List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philipp Hahn Cc: Kevin Wolf , qemu-devel@nongnu.org On 18.12.2012 13:46, Philipp Hahn wrote: > I think I found your missing link: > After filling in "QCowL2Meta *m", that request ist queued: > QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight); > do prevent double allocating the same cluster for overlapping requests, which > is checked in do_alloc_cluster_offset(). > > I guess that since the sector count was wrong, the overlap detection didn't > work and the two concurrent write requests to the same cluster overwrote each > other. Meh. And I already closed the debian bugreport... :) But thank you Philipp for your excellent work on the matter! /mjt