[libvirt PATCH] qemu_snapshot: fix detection if non-leaf snapshot isn't in active chain

The condition was completely wrong. As per the comment for function virDomainMomentIsAncestor() it checks that the first argument is descendant of the second argument. Consider the following snapshot tree for VM: s1 | +- s2 | | | +- s3 | +- s4 | +- s5 (current) When deleting s2 with the original code we checked if virDomainMomentIsAncestor(s2, s5) which would return false basically for any snapshot as s5 is leaf snapshot so no children. When deleting s2 with fixed code we check if virDomainMomentIsAncestor(s5, s2) which still returns false but when deleting s4 it will correctly return true. Resolves: https://issues.redhat.com/browse/RHEL-23212 Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- src/qemu/qemu_snapshot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c index 73ff533827..af5f995b0d 100644 --- a/src/qemu/qemu_snapshot.c +++ b/src/qemu/qemu_snapshot.c @@ -3815,7 +3815,7 @@ qemuSnapshotDeleteValidate(virDomainObj *vm, } if (snap != current && snap->nchildren != 0 && - virDomainMomentIsAncestor(snap, current)) { + !virDomainMomentIsAncestor(current, snap)) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", _("deletion of non-leaf external snapshot that is not in active chain is not supported")); return -1; -- 2.43.0

On Tue, Jan 30, 2024 at 13:15:50 +0100, Pavel Hrdina wrote:
The condition was completely wrong. As per the comment for function virDomainMomentIsAncestor() it checks that the first argument is descendant of the second argument.
Consider the following snapshot tree for VM:
s1 | +- s2 | | | +- s3 | +- s4 | +- s5 (current)
When deleting s2 with the original code we checked if virDomainMomentIsAncestor(s2, s5) which would return false basically for any snapshot as s5 is leaf snapshot so no children.
When deleting s2 with fixed code we check if virDomainMomentIsAncestor(s5, s2) which still returns false but when deleting s4 it will correctly return true.
Resolves: https://issues.redhat.com/browse/RHEL-23212 Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- src/qemu/qemu_snapshot.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Please add the currently-wrong error message into the commit message. Reviewed-by: Peter Krempa <pkrempa@redhat.com>
participants (2)
-
Pavel Hrdina
-
Peter Krempa