On Wed, Aug 24, 2011 at 09:22:24AM -0600, Eric Blake wrote:
> A future patch will make it impossible to remove a domain if it
> would leave behind any libvirt-tracked metadata about snapshots,
> since stale metadata interferes with a new domain by the same name.
> But requiring snaphot contents to be deleted before removing a
> domain is harsh; with qemu, qemu-img can still make use of the
> contents after the libvirt domain is gone. Therefore, we need
> an option to get rid of libvirt tracking information, but not
> the actual contents. For hypervisors that do not track any
> metadata in libvirt, the implementation is trivial; all remaining
> hypervisors (really, just qemu) will be dealt with separately.
>
> * include/libvirt/libvirt.h.in
> (VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY): New flag.
> * src/libvirt.c (virDomainSnapshotDelete): Document it.
> * src/esx/esx_driver.c (esxDomainSnapshotDelete): Trivially
> supported when there is no libvirt metadata.
> * src/vbox/vbox_tmpl.c (vboxDomainSnapshotDelete): Likewise.
> ---
> include/libvirt/libvirt.h.in | 3 ++-
> src/esx/esx_driver.c | 10 +++++++++-
> src/libvirt.c | 10 +++++++---
> src/vbox/vbox_tmpl.c | 10 +++++++++-
> 4 files changed, 27 insertions(+), 6 deletions(-)
>
> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index a625479..eae0a10 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -2579,7 +2579,8 @@ int virDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
>
> /* Delete a snapshot */
> typedef enum {
> - VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN = (1 << 0),
> + VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN = (1 << 0), /* Also delete children */
> + VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY = (1 << 1), /* Delete just metadata */
> } virDomainSnapshotDeleteFlags;
>
> int virDomainSnapshotDelete(virDomainSnapshotPtr snapshot,
> diff --git a/src/esx/esx_driver.c b/src/esx/esx_driver.c
> index c097651..beeafbd 100644
> --- a/src/esx/esx_driver.c
> +++ b/src/esx/esx_driver.c
> @@ -4543,7 +4543,8 @@ esxDomainSnapshotDelete(virDomainSnapshotPtr snapshot, unsigned int flags)
> esxVI_TaskInfoState taskInfoState;
> char *taskInfoErrorMessage = NULL;
>
> - virCheckFlags(VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN, -1);
> + virCheckFlags(VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN |
> + VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY, -1);
>
> if (esxVI_EnsureSession(priv->primary) < 0) {
> return -1;
> @@ -4561,6 +4562,13 @@ esxDomainSnapshotDelete(virDomainSnapshotPtr snapshot, unsigned int flags)
> goto cleanup;
> }
>
> + /* ESX snapshots do not require any libvirt metadata, making this
> + * flag trivial once we know we have a valid snapshot. */
> + if (flags & VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY) {
> + result = 0;
> + goto cleanup;
> + }
> +
> if (esxVI_RemoveSnapshot_Task(priv->primary, snapshotTree->snapshot,
> removeChildren, &task) < 0 ||
> esxVI_WaitForTaskCompletion(priv->primary, task, snapshot->domain->uuid,
> diff --git a/src/libvirt.c b/src/libvirt.c
> index a1197e0..a80c140 100644
> --- a/src/libvirt.c
> +++ b/src/libvirt.c
> @@ -15798,14 +15798,18 @@ error:
> /**
> * virDomainSnapshotDelete:
> * @snapshot: a domain snapshot object
> - * @flags: flag parameters
> + * @flags: bitwise-or of supported virDomainSnapshotDeleteFlags
> *
> * Delete the snapshot.
> *
> * If @flags is 0, then just this snapshot is deleted, and changes from
> * this snapshot are automatically merged into children snapshots. If
> - * flags is VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN, then this snapshot
> - * and any children snapshots are deleted.
> + * @flags includes VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN, then this snapshot
> + * and any children snapshots are deleted. If @flags includes
> + * VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY, then any snapshot metadata
> + * tracked by libvirt is removed while keeping the snapshot contents
> + * intact; if a hypervisor does not require any libvirt metadata to
> + * track snapshots, then this flag is silently ignored.
> *
> * Returns 0 if the snapshot was successfully deleted, -1 on error.
> */
> diff --git a/src/vbox/vbox_tmpl.c b/src/vbox/vbox_tmpl.c
> index 822e899..8de2bae 100644
> --- a/src/vbox/vbox_tmpl.c
> +++ b/src/vbox/vbox_tmpl.c
> @@ -6361,7 +6361,8 @@ vboxDomainSnapshotDelete(virDomainSnapshotPtr snapshot,
> PRUint32 state;
> nsresult rc;
>
> - virCheckFlags(VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN, -1);
> + virCheckFlags(VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN |
> + VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY, -1);
>
> vboxIIDFromUUID(&domiid, dom->uuid);
> rc = VBOX_OBJECT_GET_MACHINE(domiid.value, &machine);
> @@ -6382,6 +6383,13 @@ vboxDomainSnapshotDelete(virDomainSnapshotPtr snapshot,
> goto cleanup;
> }
>
> + /* VBOX snapshots do not require any libvirt metadata, making this
> + * flag trivial once we know we have a valid snapshot. */
> + if (flags & VIR_DOMAIN_SNAPSHOT_DELETE_METADATA_ONLY) {
> + ret = 0;
> + goto cleanup;
> + }
> +
> if (state >= MachineState_FirstOnline
> && state <= MachineState_LastOnline) {
> vboxError(VIR_ERR_OPERATION_INVALID, "%s",
ACK
Daniel
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