From 716c46178ab6e32195f71261cc7b4fa00c13a40a Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Fri, 15 Jun 2018 09:12:01 +0200
Subject: [PATCH] qemu: Add field to store QOM path of a disk in private data
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When using -blockdev you need to use the qom path to refer to the disk
fronends. Add means for storing the path and getting it after restart.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_domain.c                    | 27 +++++++++++++++++++++++
 src/qemu/qemu_domain.h                    |  2 ++
 tests/qemustatusxml2xmldata/modern-in.xml |  3 +++
 3 files changed, 32 insertions(+)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 6e51f590cd..4ea12c3fd7 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1065,6 +1065,7 @@ qemuDomainDiskPrivateDispose(void *obj)
 
     VIR_FREE(priv->blockJobError);
     virStorageSourceFree(priv->migrSource);
+    VIR_FREE(priv->qomName);
 }
 
 static virClassPtr qemuDomainStorageSourcePrivateClass;
@@ -2123,6 +2124,30 @@ qemuStorageSourcePrivateDataFormat(virStorageSourcePtr src,
 }
 
 
+static int
+qemuDomainDiskPrivateParse(xmlXPathContextPtr ctxt,
+                           virDomainDiskDefPtr disk)
+{
+    qemuDomainDiskPrivatePtr priv = QEMU_DOMAIN_DISK_PRIVATE(disk);
+
+    priv->qomName = virXPathString("string(./qom/@name)", ctxt);
+
+    return 0;
+}
+
+
+static int
+qemuDomainDiskPrivateFormat(virDomainDiskDefPtr disk,
+                            virBufferPtr buf)
+{
+    qemuDomainDiskPrivatePtr priv = QEMU_DOMAIN_DISK_PRIVATE(disk);
+
+    virBufferEscapeString(buf, "<qom name='%s'/>\n", priv->qomName);
+
+    return 0;
+}
+
+
 static void
 qemuDomainObjPrivateXMLFormatVcpus(virBufferPtr buf,
                                    virDomainDefPtr def)
@@ -2973,6 +2998,8 @@ virDomainXMLPrivateDataCallbacks virQEMUDriverPrivateDataCallbacks = {
     .alloc = qemuDomainObjPrivateAlloc,
     .free = qemuDomainObjPrivateFree,
     .diskNew = qemuDomainDiskPrivateNew,
+    .diskParse = qemuDomainDiskPrivateParse,
+    .diskFormat = qemuDomainDiskPrivateFormat,
     .vcpuNew = qemuDomainVcpuPrivateNew,
     .chrSourceNew = qemuDomainChrSourcePrivateNew,
     .vsockNew = qemuDomainVsockPrivateNew,
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 5dcbdfbbe1..2afc6b454a 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -396,6 +396,8 @@ struct _qemuDomainDiskPrivate {
     /* information about the device */
     bool tray; /* device has tray */
     bool removable; /* device media can be removed/changed */
+
+    char *qomName; /* QOM path of the disk (also refers to the block backend) */
 };
 
 # define QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(src) \
diff --git a/tests/qemustatusxml2xmldata/modern-in.xml b/tests/qemustatusxml2xmldata/modern-in.xml
index c9f5c4e76a..24e9fd9f6d 100644
--- a/tests/qemustatusxml2xmldata/modern-in.xml
+++ b/tests/qemustatusxml2xmldata/modern-in.xml
@@ -333,6 +333,9 @@
         <target dev='vdb' bus='virtio'/>
         <alias name='virtio-disk1'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
+        <privateData>
+          <qom name='virtio-disk1/virtio-backend'/>
+        </privateData>
       </disk>
       <disk type='file' device='cdrom'>
         <driver name='qemu' type='raw'/>