From b028739e4fce3d1b8e1ac5009f2e2def2f53f2e2 Mon Sep 17 00:00:00 2001
Message-Id: <b028739e4fce3d1b8e1ac5009f2e2def2f53f2e2@dist-git>
From: Eric Blake <eblake@redhat.com>
Date: Tue, 28 Oct 2014 08:21:17 -0600
Subject: [PATCH] qemu: forbid snapshot-delete --children-only on external
 snapshot

https://bugzilla.redhat.com/show_bug.cgi?id=956506 documents that
given a domain where an internal snapshot parent has an external
snapshot child, we lacked a safety check when trying to use the
--children-only option to snapshot-delete:

$ virsh start dom
$ virsh snapshot-create-as dom internal
$ virsh snapshot-create-as dom external --disk-only
$ virsh snapshot-delete dom external
error: Failed to delete snapshot external
error: unsupported configuration: deletion of 1 external disk snapshots not supported yet
$ virsh snapshot-delete dom internal --children
error: Failed to delete snapshot internal
error: unsupported configuration: deletion of 1 external disk snapshots not supported yet
$ virsh snapshot-delete dom internal --children-only
Domain snapshot internal children deleted

While I'd still like to see patches that actually do proper external
snapshot deletion, we should at least fix the inconsistency in the
meantime.  With this patch:

$ virsh snapshot-delete dom internal --children-only
error: Failed to delete snapshot internal
error: unsupported configuration: deletion of 1 external disk snapshots not supported yet

* src/qemu/qemu_driver.c (qemuDomainSnapshotDelete): Fix condition.

Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit 2086a9905aac877d1618f96c7eea8e3d6a01fd9a)
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_driver.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 3c1d2f5..88a1895 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -14612,7 +14612,8 @@ qemuDomainSnapshotDelete(virDomainSnapshotPtr snapshot,
         if (!(flags & VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN_ONLY) &&
             virDomainSnapshotIsExternal(snap))
             external++;
-        if (flags & VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN)
+        if (flags & (VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN |
+                     VIR_DOMAIN_SNAPSHOT_DELETE_CHILDREN_ONLY))
             virDomainSnapshotForEachDescendant(snap,
                                                qemuDomainSnapshotCountExternal,
                                                &external);
-- 
2.1.3