[libvirt] [PATCH v2] qemu: Do not unlink managedsave image if restoring fails

[Osier Yang]

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.

The fix is to fail the domain startup if the restoring fails,
but doesn't unlink()s the save state.

v1 - v2:
  * Fails the domain startup and throws error instead of throwing
    a warning.
---
 src/qemu/qemu_driver.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 48fe266..ef4d277 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3423,18 +3423,21 @@ 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))) {
         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);
         }
-
-        if (ret == 0)
-            goto cleanup;
+        goto cleanup;
     }

     ret = qemuProcessStart(conn, driver, vm, NULL, start_paused, -1, NULL,
--
1.7.4