On Fri, Aug 28, 2020 at 10:08:31 -0400, Masayoshi Mizuma wrote:
From: Masayoshi Mizuma <m.mizuma@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@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