[libvirt] [PATCH] Recheck disk backing chains after snapshot

[Jiri Denemark]

When a snapshot operation finishes we have to recheck the backing chain
of all disks involved in the snapshot. And we need to do that even if
the operation failed because some of the disks might have changed if
QEMU did not support transactions.

Signed-off-by: Jiri Denemark <jdenemar at redhat.com>
---

Notes:
    - BlockRebase and BlockCommit already recheck the backing chain when we
      get an event about a completed block job (in qemuProcessHandleBlockJob)

 src/qemu/qemu_driver.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 67ba487..492fcc1 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12942,6 +12942,7 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
     bool persist = false;
     bool reuse = (flags & VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT) != 0;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    virErrorPtr orig_err = NULL;
 
     if (!virDomainObjIsActive(vm)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
@@ -13033,6 +13034,17 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
     }
 
  cleanup:
+    /* recheck backing chains of all disks involved in the snapshot */
+    orig_err = virSaveLastError();
+    for (i = 0; i < snap->def->ndisks; i++) {
+        if (snap->def->disks[i].snapshot == VIR_DOMAIN_SNAPSHOT_LOCATION_NONE)
+            continue;
+        qemuDomainDetermineDiskChain(driver, vm, vm->def->disks[i], true);
+    }
+    if (orig_err) {
+        virSetError(orig_err);
+        virFreeError(orig_err);
+    }
 
     if (ret == 0 || !virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_TRANSACTION)) {
         if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0 ||
-- 
1.9.2