qemuDomainDiskChainElement{Prepare,Revoke}: manage /dev entry

Again, one missed bit. This time without this commit there is no
/dev entry  in the namespace of the qemu process when doing disk
snapshots or block-copy.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_domain.c

@@ -5090,13 +5090,16 @@ qemuDomainDiskChainElementRevoke(virQEMUDriverPtr driver,
                                  virDomainObjPtr vm,
                                  virStorageSourcePtr elem)
 {
+    if (qemuTeardownImageCgroup(vm, elem) < 0)
+        VIR_WARN("Failed to teardown cgroup for disk path %s",
+                 NULLSTR(elem->path));
+
     if (virSecurityManagerRestoreImageLabel(driver->securityManager,
                                             vm->def, elem) < 0)
         VIR_WARN("Unable to restore security label on %s", NULLSTR(elem->path));
 
-    if (qemuTeardownImageCgroup(vm, elem) < 0)
-        VIR_WARN("Failed to teardown cgroup for disk path %s",
-                 NULLSTR(elem->path));
+    if (qemuDomainNamespaceTeardownDisk(driver, vm, elem) < 0)
+        VIR_WARN("Unable to remove /dev entry for %s", NULLSTR(elem->path));
 
     if (virDomainLockImageDetach(driver->lockManager, vm, elem) < 0)
         VIR_WARN("Unable to release lock on %s", NULLSTR(elem->path));
@@ -5126,6 +5129,9 @@ qemuDomainDiskChainElementPrepare(virQEMUDriverPtr driver,
     if (virDomainLockImageAttach(driver->lockManager, cfg->uri, vm, elem) < 0)
         goto cleanup;
 
+    if (qemuDomainNamespaceSetupDisk(driver, vm, elem) < 0)
+        goto cleanup;
+
     if (qemuSetupImageCgroup(vm, elem) < 0)
         goto cleanup;