From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47072) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VMhPW-0005BQ-3Z for qemu-devel@nongnu.org; Thu, 19 Sep 2013 12:49:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VMhPN-0007uK-Dp for qemu-devel@nongnu.org; Thu, 19 Sep 2013 12:48:58 -0400 Received: from mail-ye0-x22f.google.com ([2607:f8b0:4002:c04::22f]:49123) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VMhPN-0007uF-9B for qemu-devel@nongnu.org; Thu, 19 Sep 2013 12:48:49 -0400 Received: by mail-ye0-f175.google.com with SMTP id q8so3534819yen.34 for ; Thu, 19 Sep 2013 09:48:48 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Thu, 19 Sep 2013 18:48:52 +0200 Message-Id: <1379609334-20811-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 0/2] Serious bugs in the handling of writeback caching List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, rusty@au1.ibm.com, stefanha@redhat.com The first bug is simply that in 1.6.0 the default was changed by mistake to cache=unsafe. This affects all block drivers. It is fixed in the first patch. The second is that Linux guests that support the CONFIG_WCE option were mistaken into thinking that caching was writethrough, and thus did not send any flush. The bug is in QEMU, and is fixed by the second patch. Paolo Bonzini (2): blockdev: do not default cache.no-flush to true virtio-blk: do not relay a previous driver's WCE configuration to the current blockdev.c | 2 +- hw/block/virtio-blk.c | 8 ++++++-- include/hw/virtio/virtio-blk.h | 1 + 3 files changed, 8 insertions(+), 3 deletions(-) -- 1.8.3.1