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[libvirt] [PATCH]: Add a flag to let live migration be persistent



As pointed out by Łukasz Mierzwa <l mierzwa gmail com>, it would be nice if
there was an option to automatically make a domain persistent on the destination
during a live migration.  The attached patch adds this simple capability.  Note
that this has to be applied on top of my previous secure migration patch,
otherwise you'll have conflicts.

Signed-off-by: Chris Lalancette <clalance redhat com>
diff --git a/include/libvirt/libvirt.h b/include/libvirt/libvirt.h
index 195a6ee..72a7b21 100644
--- a/include/libvirt/libvirt.h
+++ b/include/libvirt/libvirt.h
@@ -320,6 +320,7 @@ typedef virDomainInterfaceStatsStruct *virDomainInterfaceStatsPtr;
 typedef enum {
   VIR_MIGRATE_LIVE              = 1, /* live migration */
   VIR_MIGRATE_SECURE            = 2, /* secure migration */
+  VIR_MIGRATE_PERSISTENT        = 4, /* persistent the VM on the destination */
 } virDomainMigrateFlags;
 
 /* Domain migration. */
diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index 688d13e..1103c73 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -320,6 +320,7 @@ typedef virDomainInterfaceStatsStruct *virDomainInterfaceStatsPtr;
 typedef enum {
   VIR_MIGRATE_LIVE              = 1, /* live migration */
   VIR_MIGRATE_SECURE            = 2, /* secure migration */
+  VIR_MIGRATE_PERSISTENT        = 4, /* persistent the VM on the destination */
 } virDomainMigrateFlags;
 
 /* Domain migration. */
diff --git a/src/libvirt.c b/src/libvirt.c
index 90e9c1b..942d014 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -2660,8 +2660,10 @@ error:
  * host given by dconn (a connection to the destination host).
  *
  * Flags may be one of more of the following:
- *   VIR_MIGRATE_LIVE   Attempt a live migration.
- *   VIR_MIGRATE_SECURE Attempt to do a secure migration
+ *   VIR_MIGRATE_LIVE        Attempt a live migration.
+ *   VIR_MIGRATE_SECURE      Attempt to do a secure migration
+ *   VIR_MIGRATE_PERSISTENT  If the migration is successful, persist the domain
+ *                           XML on the destination host.
  *
  * If a hypervisor supports renaming domains during migration,
  * then you may set the dname parameter to the new name (otherwise
diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index 8747eb1..c77be7a 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -5264,6 +5264,7 @@ qemudDomainMigrateFinish2 (virConnectPtr dconn,
     virDomainEventPtr event = NULL;
     char *info = NULL;
     struct secure_mig *secureMigData;
+    int newVM = 1;
 
     qemuDriverLock(driver);
     vm = virDomainFindByName(&driver->domains, dname);
@@ -5291,6 +5292,32 @@ qemudDomainMigrateFinish2 (virConnectPtr dconn,
      * object, but if no, clean up the empty qemu process.
      */
     if (retcode == 0) {
+        if (flags & VIR_MIGRATE_PERSISTENT) {
+            if (vm->persistent)
+                newVM = 0;
+            vm->persistent = 1;
+
+            if (virDomainSaveConfig(dconn, driver->configDir, vm->def) < 0) {
+                /* Hmpf.  Migration was successful, but making it persistent
+                 * was not.  If we report successful, then when this domain
+                 * shuts down, management tools are in for a surprise.  On the
+                 * other hand, if we report failure, then the management tools
+                 * might try to restart the domain on the source side, even
+                 * though the domain is actually running on the destination.
+                 * Return a NULL dom pointer, and hope that this is a rare
+                 * situation and management tools are smart.
+                 */
+                vm = NULL;
+                goto cleanup;
+            }
+
+            event = virDomainEventNewFromObj(vm,
+                                             VIR_DOMAIN_EVENT_DEFINED,
+                                             newVM ?
+                                             VIR_DOMAIN_EVENT_DEFINED_ADDED :
+                                             VIR_DOMAIN_EVENT_DEFINED_UPDATED);
+
+        }
         dom = virGetDomain (dconn, vm->def->name, vm->def->uuid);
         VIR_FREE(info);
         vm->state = VIR_DOMAIN_RUNNING;
diff --git a/src/virsh.c b/src/virsh.c
index cd31633..20dc472 100644
--- a/src/virsh.c
+++ b/src/virsh.c
@@ -2321,6 +2321,7 @@ static const vshCmdInfo info_migrate[] = {
 static const vshCmdOptDef opts_migrate[] = {
     {"live", VSH_OT_BOOL, 0, gettext_noop("live migration")},
     {"secure", VSH_OT_BOOL, 0, gettext_noop("secure migration")},
+    {"persistent", VSH_OT_BOOL, 0, gettext_noop("persist VM on destination")},
     {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, gettext_noop("domain name, id or uuid")},
     {"desturi", VSH_OT_DATA, VSH_OFLAG_REQ, gettext_noop("connection URI of the destination host")},
     {"migrateuri", VSH_OT_DATA, 0, gettext_noop("migration URI, usually can be omitted")},
@@ -2361,6 +2362,9 @@ cmdMigrate (vshControl *ctl, const vshCmd *cmd)
     if (vshCommandOptBool (cmd, "secure"))
         flags |= VIR_MIGRATE_SECURE;
 
+    if (vshCommandOptBool (cmd, "persistent"))
+        flags |= VIR_MIGRATE_PERSISTENT;
+
     /* Temporarily connect to the destination host. */
     dconn = virConnectOpenAuth (desturi, virConnectAuthPtrDefault, 0);
     if (!dconn) goto done;

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