qemu: snapshot: inactive external snapshot can't work after libvirtd restart

When create inactive external snapshot, after update disk definitions,
virDomainSaveConfig is needed, if not after restart libvirtd the new snapshot
file definitions in xml will be lost.

Reproduce steps:

1. prepare a shut off guest
$ virsh domstate rhel7 && virsh domblklist rhel7
shut off

Target     Source
------------------------------------------------
vda        /var/lib/libvirt/images/rhel7.img

2. create external disk snapshot
$ virsh snapshot-create rhel7 --disk-only && virsh domblklist rhel7
Domain snapshot 1417882967 created
Target     Source
------------------------------------------------
vda        /var/lib/libvirt/images/rhel7.1417882967

3. restart libvirtd then check guest source file
$ service  libvirtd restart && virsh domblklist rhel7
Redirecting to /bin/systemctl restart  libvirtd.service
Target     Source
------------------------------------------------
vda        /var/lib/libvirt/images/rhel7.img

This was first reported by Eric Blake
http://www.redhat.com/archives/libvir-list/2014-December/msg00369.html

Signed-off-by: Shanzhi Yu <shyu@redhat.com>

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 89cb33d28a145d4b59cc1a220a313ced43905fc6..c02de0a2cde035843529fff1ec86f0163ee1aeb7 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12799,6 +12799,9 @@ qemuDomainSnapshotCreateInactiveExternal(virQEMUDriverPtr driver,
                 goto cleanup;
             }
             defdisk->src->format = snapdisk->src->format;
+
+            if (virDomainSaveConfig(cfg->configDir, vm->def) < 0)
+                goto cleanup;
         }
     }