From 319a4830bb9c8b1be052ed1bcdec61d825eac351 Mon Sep 17 00:00:00 2001
From: Juan Quintela <quintela@redhat.com>
Date: Tue, 21 Jul 2009 22:27:15 +0200
Subject: [PATCH 10/16] change qcow2 default cache mode to none

Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-Id: <2fde8ebf99cd62c084c378d287fe3324e83de12c.1248207932.git.quintela@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Bugzilla: 512837
Message-Id: <31a92212c1ecff51ba68bb4442b588b8ef756753.1248095798.git.quintela@redhat.com>
Acked-by: "Daniel P. Berrange" <berrange@redhat.com>
Acked-by: Dor Laor <dlaor@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
---
 qemu/block-qcow2.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/qemu/block-qcow2.c b/qemu/block-qcow2.c
index 3e111ad..3e57ddf 100644
--- a/qemu/block-qcow2.c
+++ b/qemu/block-qcow2.c
@@ -274,12 +274,9 @@ static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
     QCowHeader header;
     uint64_t ext_end;
 
-    /* Performance is terrible right now with cache=writethrough due mainly
-     * to reference count updates.  If the user does not explicitly specify
-     * a caching type, force to writeback caching.
-     */
+    /* We default to NO CACHE if nothing is defined */
     if ((flags & BDRV_O_CACHE_DEF)) {
-        flags |= BDRV_O_CACHE_WB;
+        flags |= BDRV_O_NOCACHE;
         flags &= ~BDRV_O_CACHE_DEF;
     }
     ret = bdrv_file_open(&s->hd, filename, flags);
-- 
1.6.3.rc4.29.g8146