From a801f0e79b94645de82524a4ba0e8f927da0ecc1 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Tue, 27 Mar 2018 11:11:26 +0200
Subject: [PATCH] qemu: domain: Move initialization of disk cachemode for
 <shareable> disks

The qemu command line generator code set disk caching of shareable disks
to 'none' when formatting the command line silently. Move this code to a
common place when preparing the domain definition for startup so that it
does not have to be duplicated.

The new test case shows that the actual cache mode will now be recorded
in the live XML definition.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 src/qemu/qemu_command.c                               |  2 --
 src/qemu/qemu_domain.c                                | 11 +++++++++++
 tests/qemuxml2startupxmloutdata/disk-drive-shared.xml |  2 +-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index be70c22332..bbd3cd0a7d 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1804,8 +1804,6 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
     if (disk->cachemode) {
         virBufferAsprintf(&opt, ",cache=%s",
                           qemuDiskCacheV2TypeToString(disk->cachemode));
-    } else if (disk->src->shared && !disk->src->readonly) {
-        virBufferAddLit(&opt, ",cache=none");
     }
 
     if (disk->copy_on_read) {
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 827df4a5cc..9d1c33b54a 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -11891,11 +11891,22 @@ qemuDomainPrepareDiskSourceChain(virDomainDiskDefPtr disk,
 }
 
 
+static void
+qemuDomainPrepareDiskCachemode(virDomainDiskDefPtr disk)
+{
+    if (disk->cachemode == VIR_DOMAIN_DISK_CACHE_DEFAULT &&
+        disk->src->shared && !disk->src->readonly)
+        disk->cachemode = VIR_DOMAIN_DISK_CACHE_DISABLE;
+}
+
+
 int
 qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk,
                             qemuDomainObjPrivatePtr priv,
                             virQEMUDriverConfigPtr cfg)
 {
+    qemuDomainPrepareDiskCachemode(disk);
+
     if (qemuDomainPrepareDiskSourceTLS(disk->src, cfg) < 0)
         return -1;
 
diff --git a/tests/qemuxml2startupxmloutdata/disk-drive-shared.xml b/tests/qemuxml2startupxmloutdata/disk-drive-shared.xml
index f4d2871ae7..60b7eca788 100644
--- a/tests/qemuxml2startupxmloutdata/disk-drive-shared.xml
+++ b/tests/qemuxml2startupxmloutdata/disk-drive-shared.xml
@@ -15,7 +15,7 @@
   <devices>
     <emulator>/usr/bin/qemu-system-i686</emulator>
     <disk type='block' device='disk'>
-      <driver name='qemu' type='raw'/>
+      <driver name='qemu' type='raw' cache='none'/>
       <source dev='/dev/HostVG/QEMUGuest1'/>
       <target dev='hda' bus='ide'/>
       <shareable/>