[libvirt] [PATCHv4 46/51] 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 f1b2bf3..0eee6d6 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -2579,6 +2579,8 @@ typedef enum {
                                                           remembering it */
     VIR_DOMAIN_SNAPSHOT_CREATE_HALT        = (1 << 3), /* Stop running guest
                                                           after snapshot */
+    VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY   = (1 << 4), /* 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 1458828..ae189bd 100644
--- a/src/esx/esx_driver.c
+++ b/src/esx/esx_driver.c
@@ -4226,6 +4226,12 @@ 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 0ae6cc2..3cdff36 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -15638,6 +15638,12 @@ error:
  * running after the snapshot.  This flag is invalid on transient domains,
  * and is incompatible with VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE.
  *
+ * 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 c7e195f..19897c6 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -8816,6 +8816,12 @@ 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 cbe34e8..0e4364f 100644
--- a/src/vbox/vbox_tmpl.c
+++ b/src/vbox/vbox_tmpl.c
@@ -5661,6 +5661,12 @@ vboxDomainSnapshotCreateXML(virDomainPtr dom,
     if (!(def = virDomainSnapshotDefParseString(xmlDesc, 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