qemu_blockjob: Remove secdriver metadata for whole backing chain on job completion

Turns out, block mirror is not the only job a disk can have. It
can also do commits of one layer into the other. Or possibly some
other tricks too. Problem is that while we set seclabels on given
layers of backing chain when the job is starting (via
qemuDomainStorageSourceAccessAllow()) we don't restore them when
job finishes. This leaves XATTRs set and corresponding images
unusable.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
ACKed-by: NPeter Krempa <pkrempa@redhat.com>

src/qemu/qemu_blockjob.c

@@ -664,9 +664,9 @@ qemuBlockJobEventProcessLegacyCompleted(virQEMUDriverPtr driver,
         virObjectUnref(disk->src);
         disk->src = disk->mirror;
     } else {
-        if (disk->mirror) {
-            virStorageSourcePtr n;
+        virStorageSourcePtr n;
 
+        if (disk->mirror) {
             virDomainLockImageDetach(driver->lockManager, vm, disk->mirror);
 
             /* Ideally, we would restore seclabels on the backing chain here
@@ -684,6 +684,16 @@ qemuBlockJobEventProcessLegacyCompleted(virQEMUDriverPtr driver,
 
             virObjectUnref(disk->mirror);
         }
+
+        for (n = disk->src; virStorageSourceIsBacking(n); n = n->backingStore) {
+            if (qemuSecurityMoveImageMetadata(driver, vm, n, NULL) < 0) {
+                VIR_WARN("Unable to remove disk metadata on "
+                         "vm %s from %s (disk target %s)",
+                         vm->def->name,
+                         NULLSTR(n->path),
+                         disk->dst);
+            }
+        }
     }
 
     /* Recompute the cached backing chain to match our