8:12 a.m.
On Fri, Aug 28, 2020 at 10:08:31 -0400, Masayoshi Mizuma wrote:
From: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com>
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(a)jp.fujitsu.com>
---
src/qemu/qemu_snapshot.c | 134 ++++++++++++++++++++++++++++++++++++++
src/qemu/qemu_snapshot.h | 8 +++
src/util/virstoragefile.h | 2 +
3 files changed, 144 insertions(+)
diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c
index d310e6ff02..5c61d19f26 100644
--- a/src/qemu/qemu_snapshot.c
+++ b/src/qemu/qemu_snapshot.c
@@ -2265,3 +2265,137 @@ qemuSnapshotDelete(virDomainObjPtr vm,
cleanup:
return ret;
}
+
+static int
+qemuTransientDiskPrepareOne(virQEMUDriverPtr driver,
This should be named with a qemuSnapshot... prefix:
qemuSnapshotDiskTransientPrepareOne for example.
+ virDomainObjPtr vm,
+ qemuSnapshotDiskDataPtr data,
+ virHashTablePtr blockNamedNodeData,
+ int asyncJob,
+ virJSONValuePtr actions)
+{
+ int rc = -1;
+ virStorageSourcePtr dest;
You can use g_autoptr here.
+ virStorageSourcePtr src = data->disk->src;
+ qemuDomainObjPrivatePtr priv = vm->privateData;
+ g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(priv->driver);
+
+ if (!strlen(src->path))
This will not work as expected. You must make sure that the source disk
is VIR_STORAGE_TYPE_FILE. presence of src->path does not guarantee it.
Also you can use virStorageSourceIsEmpty() here if you want to skip
empty cdroms, but transient cdrom/readonly disks should be rejected in
the config validator beforehand.
+ return rc;
Please always return constants right away. (rc is a constant at this
point).
> +
> + if (!(dest = virStorageSourceNew()))
+ return rc;
> +
> + dest->path = g_strdup_printf("%s.TRANSIENT", src->path);
> +
> + if (virFileExists(dest->path)) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + _("Transient disk '%s' for '%s'
exists"),
> + dest->path, src->path);
> + goto cleanup;
> + }
> +
> + dest->type = VIR_STORAGE_TYPE_FILE;
> + dest->format = VIR_STORAGE_FILE_QCOW2;
> + data->src = dest;
> +
> + if (qemuSnapshotDiskPrepareOne(driver, vm, cfg, data->disk,
> + NULL, data, blockNamedNodeData,
Create a virDomainSnapshotDiskDefPtr with the correct data from above
and pass it in here, rather than working around the addition to the data
structure.
+ false, true, asyncJob,
actions) < 0)
+ goto cleanup;
+
+ rc = 0;
+ cleanup:
+ if (rc < 0)
+ g_free(dest->path);
+
+ return rc;
+}
+
+static int
+qemuWaitTransaction(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ int asyncJob,
+ virJSONValuePtr *actions)
This function isn't IMO necessary.
+{
+ qemuDomainObjPrivatePtr priv = vm->privateData;
+
+ if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
+ return -1;
+
+ if (qemuMonitorTransaction(priv->mon, actions) < 0)
+ return -1;
+
+ if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ return -1;
+
+ rturn 0;
+}
+
+int
+qemuTransientCreatetDisk(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ int asyncJob)
+{
+ size_t i;
+ int rc = -1;
+ size_t ndata = 0;
+ qemuSnapshotDiskDataPtr data = NULL;
+ g_autoptr(virJSONValue) actions = NULL;
+ qemuDomainObjPrivatePtr priv = vm->privateData;
+ g_autoptr(virHashTable) blockNamedNodeData = NULL;
+ bool blockdev = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV);
Imo it will be better to factor out the common parts from this and
qemuSnapshotCreateDiskActive and then just use the disjunct logic in
this function.
> +
> + if (!blockdev)
+ return rc;
This breaks startup of VMs with pre-blockdev qemu as it returns -1 here
directly when blockdev is not supported.
> + if (VIR_ALLOC_N(data, vm->def->ndisks) < 0)
+ return rc;
> +
> + if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, asyncJob)))
> + goto cleanup;
> +
> + if (!(actions = virJSONValueNewArray()))
> + goto cleanup;
> +
> + for (i = 0; i < vm->def->ndisks; i++) {
> + virDomainDiskDefPtr disk = vm->def->disks[i];
> +
> + if (disk->src->readonly)
> + continue;
This transient+readonly should be a hard error and validated in the
config validator rather than here.
+
+ if (disk->transient) {
+ data[ndata].disk = disk;
+ if (qemuTransientDiskPrepareOne(driver, vm, &data[ndata],
blockNamedNodeData,
+ asyncJob, actions) < 0)
misaligned code.
+ goto cleanup;
+ ndata++;
+ }
+ }
+
+ if (qemuWaitTransaction(driver, vm, asyncJob, &actions) < 0)
+ goto cleanup;
+
+ for (i = 0; i < ndata; i++) {
+ qemuSnapshotDiskDataPtr dd = &data[i];
+
+ qemuSnapshotDiskUpdateSource(driver, vm, dd, blockdev);
+ dd->disk->src->transientEstablished = true;
+ }
These both can be factored out and shared with the snapshot code.
+
+ VIR_FREE(data);
+ rc = 0;
+ cleanup:
+ qemuSnapshotDiskCleanup(data, vm->def->ndisks, driver, vm, asyncJob);
+
+ return rc;
+}
+
+void
+qemuTransientRemoveDisk(virDomainDiskDefPtr disk)
This doesn't belong into this helper file. Removal of the snapshot
images is not related to snapshots.
+{
+ if (disk->src->transientEstablished) {
+ VIR_DEBUG("unlink transient disk: %s", disk->src->path);
+ unlink(disk->src->path);
+ }
+}
diff --git a/src/qemu/qemu_snapshot.h b/src/qemu/qemu_snapshot.h
index 8b3ebe87b1..aecb1762d2 100644
--- a/src/qemu/qemu_snapshot.h
+++ b/src/qemu/qemu_snapshot.h
@@ -53,3 +53,11 @@ int
qemuSnapshotDelete(virDomainObjPtr vm,
virDomainSnapshotPtr snapshot,
unsigned int flags);
+
+int
+qemuTransientCreatetDisk(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ int asyncJob);
+
+void
+qemuTransientRemoveDisk(virDomainDiskDefPtr disk);
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index f73b3ee005..fd42d017f3 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -383,6 +383,8 @@ 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;
+
+ bool transientEstablished;
The deep copy function is not updated with this new member. Also you
should document this variable.
};
G_DEFINE_AUTOPTR_CLEANUP_FUNC(virStorageSource, virObjectUnref);
--
2.27.0