[libvirt] [PATCHv3 37/43] snapshot: add flag for requesting disk snapshot

[Eric Blake]

Prior to this patch, <domainsnapshot>/<disks> was ignored.  This
changes it to be an error unless an explicit disk snapshot is
requested (a future patch may relax things if it turns out to
be useful to have a <disks> specification alongside a system
checkpoint).

* include/libvirt/libvirt.h.in
(VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY): New flag.
* src/libvirt.c (virDomainSnapshotCreateXML): Document it.
* src/esx/esx_driver.c (esxDomainSnapshotCreateXML): Disk
snapshots not supported yet.
* src/vbox/vbox_tmpl.c (vboxDomainSnapshotCreateXML): Likewise.
* src/qemu/qemu_driver.c (qemuDomainSnapshotCreateXML): Likewise.
---
 include/libvirt/libvirt.h.in |    2 ++
 src/esx/esx_driver.c         |    6 ++++++
 src/libvirt.c                |    6 ++++++
 src/qemu/qemu_driver.c       |    6 ++++++
 src/vbox/vbox_tmpl.c         |    6 ++++++
 5 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index c62577d..440af92 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -2574,6 +2574,8 @@ typedef virDomainSnapshot *virDomainSnapshotPtr;
 typedef enum {
     VIR_DOMAIN_SNAPSHOT_CREATE_HALT = (1 << 0), /* Stop running guest after
                                                    snapshot is complete */
+    VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY = (1 << 1), /* disk snapshot, not
+                                                        system checkpoint */
 } virDomainSnapshotCreateFlags;

 /* Take a snapshot of the current VM state */
diff --git a/src/esx/esx_driver.c b/src/esx/esx_driver.c
index 8fbbe8a..14b58c9 100644
--- a/src/esx/esx_driver.c
+++ b/src/esx/esx_driver.c
@@ -4229,6 +4229,12 @@ esxDomainSnapshotCreateXML(virDomainPtr domain, const char *xmlDesc,
         return NULL;
     }

+    if (def->ndisks) {
+        ESX_ERROR(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                  _("disk snapshots not supported yet"));
+        return NULL;
+    }
+
     if (esxVI_LookupVirtualMachineByUuidAndPrepareForTask
           (priv->primary, domain->uuid, NULL, &virtualMachine,
            priv->parsedUri->autoAnswer) < 0 ||
diff --git a/src/libvirt.c b/src/libvirt.c
index ffd27bc..c0a17bb 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -15482,6 +15482,12 @@ error:
  * it was active before; otherwise, a running domain will still be
  * running after the snapshot.  This flag is invalid on transient domains.
  *
+ * If @flags includes VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY, then the
+ * snapshot will be limited to the disks described in @xmlDesc, and no
+ * VM state will be saved.  For an active guest, the disk image may be
+ * inconsistent (as if power had been pulled), and specifying this
+ * with the VIR_DOMAIN_SNAPSHOT_CREATE_HALT flag risks data loss.
+ *
  * Returns an (opaque) virDomainSnapshotPtr on success, NULL on failure.
  */
 virDomainSnapshotPtr
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e60d508..aeb8ad9 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -8717,6 +8717,12 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
     if (!qemuDomainSnapshotIsAllowed(vm))
         goto cleanup;

+    if (def->ndisks) {
+        qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                        _("disk snapshots not supported yet"));
+        goto cleanup;
+    }
+
     if (!(snap = virDomainSnapshotAssignDef(&vm->snapshots, def)))
         goto cleanup;
     def = NULL;
diff --git a/src/vbox/vbox_tmpl.c b/src/vbox/vbox_tmpl.c
index 0dd5efa..1715432 100644
--- a/src/vbox/vbox_tmpl.c
+++ b/src/vbox/vbox_tmpl.c
@@ -5664,6 +5664,12 @@ vboxDomainSnapshotCreateXML(virDomainPtr dom,
     if (!(def = virDomainSnapshotDefParseString(xmlDesc, 1, NULL, 0, 0)))
         goto cleanup;

+    if (def->ndisks) {
+        vboxError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                  _("disk snapshots not supported yet"));
+        goto cleanup;
+    }
+
     vboxIIDFromUUID(&domiid, dom->uuid);
     rc = VBOX_OBJECT_GET_MACHINE(domiid.value, &machine);
     if (NS_FAILED(rc)) {
-- 
1.7.4.4