From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37525) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YpzQQ-0004XC-Ds for qemu-devel@nongnu.org; Wed, 06 May 2015 09:31:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YpzQK-000636-4x for qemu-devel@nongnu.org; Wed, 06 May 2015 09:31:46 -0400 Message-ID: <554A17B7.5010304@redhat.com> Date: Wed, 06 May 2015 15:31:35 +0200 From: Max Reitz MIME-Version: 1.0 References: <1430911774-19006-1-git-send-email-kwolf@redhat.com> In-Reply-To: <1430911774-19006-1-git-send-email-kwolf@redhat.com> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] qcow2: Flush pending discards before allocating cluster List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org On 06.05.2015 13:29, Kevin Wolf wrote: > Before a freed cluster can be reused, pending discards for this cluster > must be processed. > > The original assumption was that this was not a problem because discards > are only cached during discard/write zeroes operations, which are > synchronous so that no concurrent write requests can cause cluster > allocations. > > However, the discard/write zeroes operation itself can allocate a new L2 > table (and it has to in order to put zero flags there), so make sure we > can cope with the situation. > > This fixes https://bugs.launchpad.net/bugs/1349972. > > Signed-off-by: Kevin Wolf > --- > block/qcow2-refcount.c | 5 +++++ > 1 file changed, 5 insertions(+) Reviewed-by: Max Reitz