[libvirt] [PATCH variant2 v2 7/7] qemu: Fix snapshot redefine vs. domain state bug

[Eric Blake]

The existing qemu snapshot code has a slight bug: if the domain
is currently pmsuspended, you can't use the _REDEFINE flag even
though the current domain state should have no bearing on being
able to recreate metadata state; and conversely, you can use the
_REDEFINE flag to create snapshot metadata claiming to be
pmsuspended as a bypass to the normal restrictions that you can't
create an original qemu snapshot in that state (the restriction
against pmsuspend is specific to qemu, rather than part of the
driver-agnostic snapshot_conf code).

Fix this by checking the snapshot state (when redefining) instead
of the domain state (which is a subset of snapshot states).

Fixes the second problem mentioned in https://bugzilla.redhat.com/1680304

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/qemu/qemu_driver.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 06bc1893ad..18acdd9816 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15674,7 +15674,9 @@ qemuDomainSnapshotCreateActiveExternal(virQEMUDriverPtr driver,


 /* Validate that a snapshot object does not violate any qemu-specific
- * constraints. */
+ * constraints. @state is virDomainState if flags implies creation, or
+ * virDomainSnapshotState if flags includes _REDEFINE (the latter
+ * enum is a superset of the former). */
 static int
 qemuDomainSnapshotValidate(virDomainSnapshotDefPtr def, int state,
                            unsigned int flags)
@@ -15808,7 +15810,8 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
                                                 parse_flags)))
         goto cleanup;

-    if (qemuDomainSnapshotValidate(def, vm->state.state, flags) < 0)
+    if (qemuDomainSnapshotValidate(def, redefine ? def->state : vm->state.state,
+                                   flags) < 0)
         goto cleanup;

     /* reject the VIR_DOMAIN_SNAPSHOT_CREATE_LIVE flag where not supported */
-- 
2.20.1