[PATCH 29/35] qemu: Track creation of <transient> disk overlay individually

[Peter Krempa]

In preparation for hotplug of <transient> disks we'll need to track
whether the overlay file was created individually per-disk.

Add 'transientOverlayCreated' to 'struct _qemuDomainDiskPrivate' and
remove 'inhibitDiskTransientDelete' from 'qemuDomainObjPrivate' and
adjust the code for the change.

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/qemu/qemu_domain.c  |  2 --
 src/qemu/qemu_domain.h  |  7 +++----
 src/qemu/qemu_process.c | 33 +++++++++++++++++++--------------
 3 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 10641846b3..c5f994c4a5 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -1880,8 +1880,6 @@ qemuDomainObjPrivateDataClear(qemuDomainObjPrivate *priv)
         g_slist_free_full(g_steal_pointer(&priv->dbusVMStateIds), g_free);

     priv->dbusVMState = false;
-
-    priv->inhibitDiskTransientDelete = false;
 }


diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 4fc1969d9e..9cebf9e426 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -258,10 +258,6 @@ struct _qemuDomainObjPrivate {
     GSList *dbusVMStateIds;
     /* true if -object dbus-vmstate was added */
     bool dbusVMState;
-
-    /* prevent deletion of <transient> disk overlay files between startup and
-     * successful setup of the overlays */
-    bool inhibitDiskTransientDelete;
 };

 #define QEMU_DOMAIN_PRIVATE(vm) \
@@ -292,6 +288,9 @@ struct _qemuDomainDiskPrivate {
     unsigned int effectiveBootindex; /* boot index of the disk based on one
                                         of the two ways we use to select a boot
                                         device */
+
+    bool transientOverlayCreated; /* the overlay image of a transient disk was
+                                     created and the definition was updated */
 };

 #define QEMU_DOMAIN_STORAGE_SOURCE_PRIVATE(src) \
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 7fe051505b..9302180403 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -5709,9 +5709,6 @@ qemuProcessInit(virQEMUDriver *driver,
     if (virDomainObjSetDefTransient(driver->xmlopt, vm, priv->qemuCaps) < 0)
         goto cleanup;

-    /* don't clean up files for <transient> disks until we set them up */
-    priv->inhibitDiskTransientDelete = true;
-
     if (flags & VIR_QEMU_PROCESS_START_PRETEND) {
         if (qemuDomainSetPrivatePaths(driver, vm) < 0) {
             virDomainObjRemoveTransientDef(vm);
@@ -7007,7 +7004,6 @@ static int
 qemuProcessSetupDisksTransientSnapshot(virDomainObj *vm,
                                        qemuDomainAsyncJob asyncJob)
 {
-    qemuDomainObjPrivate *priv = vm->privateData;
     g_autoptr(qemuSnapshotDiskContext) snapctxt = NULL;
     g_autoptr(GHashTable) blockNamedNodeData = NULL;
     size_t i;
@@ -7039,8 +7035,14 @@ qemuProcessSetupDisksTransientSnapshot(virDomainObj *vm,
     if (qemuSnapshotDiskCreate(snapctxt) < 0)
         return -1;

-    /* the overlays are established, so they can be deleted on shutdown */
-    priv->inhibitDiskTransientDelete = false;
+    for (i = 0; i < vm->def->ndisks; i++) {
+        virDomainDiskDef *domdisk = vm->def->disks[i];
+
+        if (!domdisk->transient)
+            continue;
+
+        QEMU_DOMAIN_DISK_PRIVATE(domdisk)->transientOverlayCreated = true;
+    }

     return 0;
 }
@@ -8077,7 +8079,7 @@ void qemuProcessStop(virQEMUDriver *driver,
             /* for now transient disks are forbidden with migration so they
              * can be handled here */
             if (disk->transient &&
-                !priv->inhibitDiskTransientDelete) {
+                QEMU_DOMAIN_DISK_PRIVATE(disk)->transientOverlayCreated) {
                 VIR_DEBUG("Removing transient overlay '%s' of disk '%s'",
                           disk->src->path, disk->dst);
                 if (qemuDomainStorageFileInit(driver, vm, disk->src, NULL) >= 0) {
@@ -8505,10 +8507,6 @@ qemuProcessReconnect(void *opaque)
     if (oldjob.asyncJob == QEMU_ASYNC_JOB_BACKUP && priv->backup)
         priv->backup->apiFlags = oldjob.apiFlags;

-    /* expect that libvirt might have crashed during VM start, so prevent
-     * cleanup of transient disks */
-    priv->inhibitDiskTransientDelete = true;
-
     if (qemuDomainObjBeginJob(driver, obj, QEMU_JOB_MODIFY) < 0)
         goto error;
     jobStarted = true;
@@ -8611,9 +8609,6 @@ qemuProcessReconnect(void *opaque)
         goto error;
     }

-    /* vm startup complete, we can remove transient disks if required */
-    priv->inhibitDiskTransientDelete = false;
-
     /* In case the domain shutdown while we were not running,
      * we need to finish the shutdown process. And we need to do it after
      * we have virQEMUCaps filled in.
@@ -8662,6 +8657,16 @@ qemuProcessReconnect(void *opaque)
     if (qemuProcessRefreshDisks(driver, obj, QEMU_ASYNC_JOB_NONE) < 0)
         goto error;

+    /* At this point we've already checked that the startup of the VM was
+     * completed successfully before, thus that also implies that all transient
+     * disk overlays were created. */
+    for (i = 0; i < obj->def->ndisks; i++) {
+        virDomainDiskDef *disk = obj->def->disks[i];
+
+        if (disk->transient)
+            QEMU_DOMAIN_DISK_PRIVATE(disk)->transientOverlayCreated = true;
+    }
+
     if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV) &&
         qemuBlockNodeNamesDetect(driver, obj, QEMU_ASYNC_JOB_NONE) < 0)
         goto error;
-- 
2.31.1