From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
Here is the implementation of transient option for qcow2 and raw format
disk. This gets available <transient/> directive in domain xml file
like as:
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/var/lib/libvirt/images/guest.qcow2'/>
<target dev='vda' bus='virtio'/>
<transient/>
</disk>
When the qemu command line options are built, a new qcow2 image is
created with backing qcow2 by using blockdev-snapshot command.
The backing image is the qcow2 file which is set as <source>.
The filename of the new qcow2 image is original-source-file.TRANSIENT.
Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
---
src/qemu/qemu_snapshot.c | 103 +++++++++++++++++++++++++++++++++++---
src/qemu/qemu_snapshot.h | 5 ++
src/util/virstoragefile.c | 2 +
src/util/virstoragefile.h | 4 ++
4 files changed, 107 insertions(+), 7 deletions(-)
diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c
index 1e8ea80b22..67fdc488e0 100644
--- a/src/qemu/qemu_snapshot.c
+++ b/src/qemu/qemu_snapshot.c
@@ -1158,7 +1158,8 @@ qemuSnapshotCreateDiskActive(virQEMUDriverPtr driver,
virHashTablePtr blockNamedNodeData,
unsigned int flags,
virQEMUDriverConfigPtr cfg,
- qemuDomainAsyncJob asyncJob)
+ qemuDomainAsyncJob asyncJob,
+ bool domSave)
{
qemuDomainObjPrivatePtr priv = vm->privateData;
g_autoptr(virJSONValue) actions = NULL;
@@ -1201,17 +1202,26 @@ qemuSnapshotCreateDiskActive(virQEMUDriverPtr driver,
virDomainAuditDisk(vm, dd->disk->src, dd->src, "snapshot", rc >= 0);
- if (rc == 0)
+ if (rc == 0) {
qemuSnapshotDiskUpdateSource(driver, vm, dd, blockdev);
+
+ if (dd->disk->transient) {
+ /* Mark the transient working is completed to make sure we can */
+ /* remove the transient disk when the guest is shutdown. */
+ dd->disk->src->transientEstablished = true;
+ }
+ }
}
if (rc < 0)
goto cleanup;
- if (virDomainObjSave(vm, driver->xmlopt, cfg->stateDir) < 0 ||
- (vm->newDef && virDomainDefSave(vm->newDef, driver->xmlopt,
- cfg->configDir) < 0))
- goto cleanup;
+ if (domSave) {
+ if (virDomainObjSave(vm, driver->xmlopt, cfg->stateDir) < 0 ||
+ (vm->newDef && virDomainDefSave(vm->newDef, driver->xmlopt,
+ cfg->configDir) < 0))
+ goto cleanup;
+ }
ret = 0;
@@ -1349,7 +1359,7 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
if ((ret = qemuSnapshotCreateDiskActive(driver, vm, snap,
blockNamedNodeData, flags, cfg,
- QEMU_ASYNC_JOB_SNAPSHOT)) < 0)
+ QEMU_ASYNC_JOB_SNAPSHOT, true)) < 0)
goto cleanup;
/* the snapshot is complete now */
@@ -2264,3 +2274,82 @@ qemuSnapshotDelete(virDomainObjPtr vm,
cleanup:
return ret;
}
+
+
+static int
+qemuSnapshotSetupTransientDisk(virDomainSnapshotDiskDefPtr def,
+ virStorageSourcePtr src)
+{
+ g_autoptr(virStorageSource) trans = NULL;
+
+ if (!(trans = virStorageSourceNew()))
+ return -1;
+
+ trans->path = g_strdup_printf("%s.TRANSIENT", src->path);
+ if (virFileExists(trans->path)) {
+ virReportError(VIR_ERR_INVALID_ARG,
+ _("Transient disk '%s' for '%s' exists"),
+ trans->path, src->path);
+ return -1;
+ }
+
+ trans->type = VIR_STORAGE_TYPE_FILE;
+ trans->format = VIR_STORAGE_FILE_QCOW2;
+
+ def->src = g_steal_pointer(&trans);
+
+ return 0;
+}
+
+
+int
+qemuSnapshotCreateTransientDisk(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ int asyncJob)
+{
+ int rc;
+ size_t i;
+ virDomainMomentObjPtr snap = NULL;
+ g_autoptr(virDomainSnapshotDef) snapdef = NULL;
+ g_autoptr(virHashTable) blockNamedNodeData = NULL;
+ qemuDomainObjPrivatePtr priv = vm->privateData;
+ g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(priv->driver);
+
+ if (!(snapdef = virDomainSnapshotDefNew()))
+ return -1;
+
+ snapdef->parent.name = g_strdup_printf("transient");
+
+ snapdef->ndisks = vm->def->ndisks;
+ if (VIR_ALLOC_N(snapdef->disks, snapdef->ndisks) < 0)
+ return -1;
+
+ for (i = 0; i < vm->def->ndisks; i++) {
+ virDomainDiskDefPtr disk = vm->def->disks[i];
+ virDomainSnapshotDiskDefPtr snapdisk = &(snapdef->disks[i]);
+
+ if (disk->transient) {
+ if ((rc = qemuSnapshotSetupTransientDisk(snapdisk, disk->src)) < 0)
+ return -1;
+
+ } else {
+ snapdisk->snapshot = VIR_DOMAIN_SNAPSHOT_LOCATION_NONE;
+ }
+ }
+
+ if (!(snap = virDomainSnapshotAssignDef(vm->snapshots, snapdef)))
+ return -1;
+
+ if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, asyncJob)))
+ goto cleanup;
+
+ /* The last argument domSave is false here because transient disk config */
+ /* is volatile so we don't need to save it. */
+ rc = qemuSnapshotCreateDiskActive(driver, vm, snap, blockNamedNodeData,
+ 0, cfg, asyncJob, false);
+
+ cleanup:
+ virDomainSnapshotObjListRemove(vm->snapshots, snap);
+
+ return rc;
+}
diff --git a/src/qemu/qemu_snapshot.h b/src/qemu/qemu_snapshot.h
index 8b3ebe87b1..d57ef4b8a4 100644
--- a/src/qemu/qemu_snapshot.h
+++ b/src/qemu/qemu_snapshot.h
@@ -53,3 +53,8 @@ int
qemuSnapshotDelete(virDomainObjPtr vm,
virDomainSnapshotPtr snapshot,
unsigned int flags);
+
+int
+qemuSnapshotCreateTransientDisk(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ int asyncJob);
diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
index 97a346db28..636f27ef09 100644
--- a/src/util/virstoragefile.c
+++ b/src/util/virstoragefile.c
@@ -2456,6 +2456,8 @@ virStorageSourceCopy(const virStorageSource *src,
def->ssh_host_key_check_disabled = src->ssh_host_key_check_disabled;
def->ssh_user = g_strdup(src->ssh_user);
+ def->transientEstablished = src->transientEstablished;
+
return g_steal_pointer(&def);
}
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index 87763cf389..0dc275c11e 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -384,6 +384,10 @@ struct _virStorageSource {
/* these must not be used apart from formatting the output JSON in the qemu driver */
char *ssh_user;
bool ssh_host_key_check_disabled;
+
+ /* set to true if the storage source is setup as a transient disk. */
+ /* The changes to the disk are dropped after the guest machine is shutdown. */
+ bool transientEstablished;
};
G_DEFINE_AUTOPTR_CLEANUP_FUNC(virStorageSource, virObjectUnref);
--
2.27.0
