From 462c4b66fa70a93a548c4ad4a1103ac9a32b9faf Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Fri, 31 Mar 2017 15:59:54 +0200
Subject: [PATCH] Introduce and use virDomainDiskEmptySource

Currently, if we want to zero out disk source (e,g, due to
startupPolicy when starting up a domain) we use
virDomainDiskSetSource(disk, NULL). This works well for file
based storage (storage type file, dir, or block). But it doesn't
work at all for other types like volume and network.

So imagine that you have a domain that has a CDROM configured
which source is a volume from an inactive pool. Because it is
startupPolicy='optional', the CDROM is empty when the domain
starts. However, the source element is not cleared out in the
status XML and thus when the daemon restarts and tries to
reconnect to the domain it refreshes the disks (which fails - the
storage pool is still not running) and thus the domain is killed.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/conf/domain_conf.c   | 10 ++++++++++
 src/conf/domain_conf.h   |  1 +
 src/libvirt_private.syms |  1 +
 src/qemu/qemu_domain.c   |  2 +-
 src/qemu/qemu_process.c  |  2 +-
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 01553b5294..80baa090a7 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -1719,6 +1719,16 @@ virDomainDiskSetSource(virDomainDiskDefPtr def, const char *src)
 }
 
 
+void
+virDomainDiskEmptySource(virDomainDiskDefPtr def)
+{
+    virStorageSourcePtr src = def->src;
+
+    virStorageSourceClear(src);
+    src->type = VIR_STORAGE_TYPE_FILE;
+}
+
+
 const char *
 virDomainDiskGetDriver(virDomainDiskDefPtr def)
 {
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 47eaacef3d..26c0e6b887 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2590,6 +2590,7 @@ void virDomainDiskSetType(virDomainDiskDefPtr def, int type);
 const char *virDomainDiskGetSource(virDomainDiskDef const *def);
 int virDomainDiskSetSource(virDomainDiskDefPtr def, const char *src)
     ATTRIBUTE_RETURN_CHECK;
+void virDomainDiskEmptySource(virDomainDiskDefPtr def);
 const char *virDomainDiskGetDriver(virDomainDiskDefPtr def);
 int virDomainDiskSetDriver(virDomainDiskDefPtr def, const char *name)
     ATTRIBUTE_RETURN_CHECK;
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index b551cb86a6..92083e5414 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -299,6 +299,7 @@ virDomainDiskDetectZeroesTypeFromString;
 virDomainDiskDetectZeroesTypeToString;
 virDomainDiskDeviceTypeToString;
 virDomainDiskDiscardTypeToString;
+virDomainDiskEmptySource;
 virDomainDiskErrorPolicyTypeFromString;
 virDomainDiskErrorPolicyTypeToString;
 virDomainDiskFindByBusAndDst;
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 589eb18899..b733505d0b 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -4908,7 +4908,7 @@ qemuDomainCheckRemoveOptionalDisk(virQEMUDriverPtr driver,
         event = virDomainEventDiskChangeNewFromObj(vm, src, NULL,
                                                    disk->info.alias,
                                                    VIR_DOMAIN_EVENT_DISK_CHANGE_MISSING_ON_START);
-        ignore_value(virDomainDiskSetSource(disk, NULL));
+        virDomainDiskEmptySource(disk);
         /* keeping the old startup policy would be invalid for new images */
         disk->startupPolicy = VIR_DOMAIN_STARTUP_POLICY_DEFAULT;
     } else {
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index a20beb13c1..e450d0647e 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -6804,7 +6804,7 @@ qemuProcessRefreshDisks(virQEMUDriverPtr driver,
 
         if (info->removable) {
             if (info->empty)
-                ignore_value(virDomainDiskSetSource(disk, NULL));
+                virDomainDiskEmptySource(disk);
 
             if (info->tray) {
                 if (info->tray_open)