On 04/06/2011 12:17 AM, Osier Yang wrote:
Both "qemuDomainStartWithFlags" and "qemuAutostartDomain" try to restore the domain from managedsave'ed image if it exists (by invoking "qemuDomainObjRestore"), but it unlinks the image even if restoring fails, which causes data loss. (This problem exists for "virsh managedsave dom; virsh start dom").
And keeping the saved state will cause data corruption if the user modified his disks and restore the domain second time from the saved state. (Problem exists for "virsh save dom; virsh restore dom").
Based on subsequent conversation on v2, we need v4.
The fix is to: * Don't unlink()s the managed saved state if the restoring fails.
Good
* Remove the saved state if restoring succeeded.
Bad
+++ b/src/qemu/qemu_driver.c @@ -3171,6 +3171,9 @@ qemuDomainRestore(virConnectPtr conn, vm = NULL; }
+ if ((ret == 0) && (unlink(path) < 0)) + VIR_WARN("Failed to remove the saved state %s", path);
Drop this hunk.
+ cleanup: virDomainDefFree(def); VIR_FORCE_CLOSE(fd); @@ -3423,18 +3426,22 @@ static int qemudDomainObjStart(virConnectPtr conn,
/* * If there is a managed saved state restore it instead of starting - * from scratch. In any case the old state is removed. + * from scratch. */ managed_save = qemuDomainManagedSavePath(driver, vm); if ((managed_save) && (virFileExists(managed_save))) {
If managed_save is NULL, then we should be skipping to cleanup (qemuDomainManagedSavePath already reported OOM), rather than silently falling back to normal startup.
ret = qemuDomainObjRestore(conn, driver, vm, managed_save);
- if (unlink(managed_save) < 0) { - VIR_WARN("Failed to remove the managed state %s", managed_save); + if (ret == 0) { + if (unlink(managed_save) < 0) + VIR_WARN("Failed to remove the managed state %s", managed_save); + } else { + qemuReportError(VIR_ERR_INTERNAL_ERROR, + _("Failed to restore from the managed state %s"), + managed_save);
This overwrites the error message from qemuDomainObjRestore, possibly losing useful information. I think you can just drop this else clause.
}
- if (ret == 0) - goto cleanup; + goto cleanup; }
ret = qemuProcessStart(conn, driver, vm, NULL, start_paused, -1, NULL, -- 1.7.4
-- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org