[libvirt PATCH 6/7] qemu_snapshot: correctly load the saved memory state file

[Pavel Hrdina]

Original code assumed that the memory state file is only migration
stream but it has additional metadata stored by libvirt. To correctly
load the memory state file we need to reuse code that is used when
restoring domain from saved image.

Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
---
 src/qemu/qemu_snapshot.c | 78 ++++++++++++++++++++++++----------------
 1 file changed, 47 insertions(+), 31 deletions(-)

diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c
index ff85d56572..869b46a9a8 100644
--- a/src/qemu/qemu_snapshot.c
+++ b/src/qemu/qemu_snapshot.c
@@ -2004,6 +2004,21 @@ qemuSnapshotRevertWriteMetadata(virDomainObj *vm,
 }
 
 
+typedef struct _qemuSnapshotRevertMemoryData {
+    int fd;
+    char *path;
+    virQEMUSaveData *data;
+} qemuSnapshotRevertMemoryData;
+
+static void
+qemuSnapshotClearRevertMemoryData(qemuSnapshotRevertMemoryData *memdata)
+{
+    VIR_FORCE_CLOSE(memdata->fd);
+    virQEMUSaveDataFree(memdata->data);
+}
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC(qemuSnapshotRevertMemoryData, qemuSnapshotClearRevertMemoryData);
+
+
 /**
  * qemuSnapshotRevertExternalPrepare:
  * @vm: domain object
@@ -2011,15 +2026,13 @@ qemuSnapshotRevertWriteMetadata(virDomainObj *vm,
  * @snap: snapshot object we are reverting to
  * @config: live domain definition
  * @inactiveConfig: offline domain definition
- * memsnapFD: pointer to store memory state file FD or NULL
- * memsnapPath: pointer to store memory state file path or NULL
+ * @memdata: struct with data to load memory state
  *
  * Prepare new temporary snapshot definition @tmpsnapdef that will
  * be used while creating new overlay files after reverting to snapshot
  * @snap. In case we are reverting to snapshot with memory state it will
- * open it and pass FD via @memsnapFD and path to the file via
- * @memsnapPath, caller is responsible for freeing both @memsnapFD and
- * memsnapPath.
+ * open it and store necessary data in @memdata. Caller is responsible
+ * to clear the data by using qemuSnapshotClearRevertMemoryData().
  *
  * Returns 0 in success, -1 on error.
  */
@@ -2029,8 +2042,7 @@ qemuSnapshotRevertExternalPrepare(virDomainObj *vm,
                                   virDomainMomentObj *snap,
                                   virDomainDef *config,
                                   virDomainDef *inactiveConfig,
-                                  int *memsnapFD,
-                                  char **memsnapPath)
+                                  qemuSnapshotRevertMemoryData *memdata)
 {
     size_t i;
     bool active = virDomainObjIsActive(vm);
@@ -2065,12 +2077,21 @@ qemuSnapshotRevertExternalPrepare(virDomainObj *vm,
             return -1;
     }
 
-    if (memsnapFD && memsnapPath && snapdef->memorysnapshotfile) {
+    if (memdata && snapdef->memorysnapshotfile) {
         virQEMUDriver *driver = ((qemuDomainObjPrivate *) vm->privateData)->driver;
-        g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
+        g_autoptr(virDomainDef) savedef = NULL;
 
-        *memsnapPath = snapdef->memorysnapshotfile;
-        *memsnapFD = qemuDomainOpenFile(cfg, NULL, *memsnapPath, O_RDONLY, NULL);
+        memdata->path = snapdef->memorysnapshotfile;
+        memdata->fd = qemuSaveImageOpen(driver, NULL, memdata->path,
+                                        &savedef, &memdata->data,
+                                        false, NULL,
+                                        false, false);
+
+        if (memdata->fd < 0)
+            return -1;
+
+        if (!virDomainDefCheckABIStability(savedef, domdef, driver->xmlopt))
+            return -1;
     }
 
     return 0;
@@ -2254,13 +2275,13 @@ qemuSnapshotRevertActive(virDomainObj *vm,
     virObjectEvent *event = NULL;
     virObjectEvent *event2 = NULL;
     virDomainMomentObj *loadSnap = NULL;
-    VIR_AUTOCLOSE memsnapFD = -1;
-    char *memsnapPath = NULL;
     int detail;
     bool defined = false;
     qemuDomainSaveCookie *cookie = (qemuDomainSaveCookie *) snapdef->cookie;
     int rc;
     g_autoptr(virDomainSnapshotDef) tmpsnapdef = NULL;
+    g_auto(qemuSnapshotRevertMemoryData) memdata = { -1, NULL, NULL };
+    bool started = false;
 
     start_flags |= VIR_QEMU_PROCESS_START_PAUSED;
 
@@ -2284,7 +2305,7 @@ qemuSnapshotRevertActive(virDomainObj *vm,
 
         if (qemuSnapshotRevertExternalPrepare(vm, tmpsnapdef, snap,
                                               *config, *inactiveConfig,
-                                              &memsnapFD, &memsnapPath) < 0) {
+                                              &memdata) < 0) {
             return -1;
         }
     } else {
@@ -2298,28 +2319,24 @@ qemuSnapshotRevertActive(virDomainObj *vm,
 
     virDomainObjAssignDef(vm, config, true, NULL);
 
-    /* No cookie means libvirt which saved the domain was too old to
-     * mess up the CPU definitions.
-     */
-    if (cookie &&
-        qemuDomainFixupCPUs(vm, &cookie->cpu) < 0)
+    if (qemuSaveImageStartProcess(snapshot->domain->conn, driver, vm,
+                                  &memdata.fd, memdata.path, loadSnap,
+                                  memdata.data ? &memdata.data->header : NULL,
+                                  cookie, VIR_ASYNC_JOB_SNAPSHOT, start_flags,
+                                  "from-snapshot", &started) < 0) {
+        if (started) {
+            qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED,
+                            VIR_ASYNC_JOB_SNAPSHOT,
+                            VIR_QEMU_PROCESS_STOP_MIGRATED);
+        }
         return -1;
+    }
 
-    rc = qemuProcessStart(snapshot->domain->conn, driver, vm,
-                          cookie ? cookie->cpu : NULL,
-                          VIR_ASYNC_JOB_SNAPSHOT, NULL, memsnapFD,
-                          memsnapPath, loadSnap,
-                          VIR_NETDEV_VPORT_PROFILE_OP_CREATE,
-                          start_flags);
-    virDomainAuditStart(vm, "from-snapshot", rc >= 0);
     detail = VIR_DOMAIN_EVENT_STARTED_FROM_SNAPSHOT;
     event = virDomainEventLifecycleNewFromObj(vm,
                                      VIR_DOMAIN_EVENT_STARTED,
                                      detail);
     virObjectEventStateQueue(driver->domainEventState, event);
-    if (rc < 0)
-        return -1;
-
 
     if (virDomainSnapshotIsExternal(snap)) {
         if (qemuSnapshotRevertExternalActive(vm, tmpsnapdef) < 0)
@@ -2427,8 +2444,7 @@ qemuSnapshotRevertInactive(virDomainObj *vm,
             return -1;
 
         if (qemuSnapshotRevertExternalPrepare(vm, tmpsnapdef, snap,
-                                              NULL, *inactiveConfig,
-                                              NULL, NULL) < 0) {
+                                              NULL, *inactiveConfig, NULL) < 0) {
             return -1;
         }
 
-- 
2.41.0