util: storage: Add helper for determining whether a backing chain requires PR

With blockdev support we will need to introspect whether any of the
backing chain members requires PR rather just one of them. Add a helper
and reuse it in virDomainDefHasManagedPR.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/conf/domain_conf.c

@@ -29946,7 +29946,7 @@ virDomainDefHasManagedPR(const virDomainDef *def)
     size_t i;
 
     for (i = 0; i < def->ndisks; i++) {
-        if (virStoragePRDefIsManaged(def->disks[i]->src->pr))
+        if (virStorageSourceChainHasManagedPR(def->disks[i]->src))
             return true;
     }
 

src/libvirt_private.syms

@@ -2815,6 +2815,7 @@ virStoragePRDefIsEqual;
 virStoragePRDefIsManaged;
 virStoragePRDefParseXML;
 virStorageSourceBackingStoreClear;
+virStorageSourceChainHasManagedPR;
 virStorageSourceClear;
 virStorageSourceCopy;
 virStorageSourceFindByNodeName;

src/util/virstoragefile.c

@@ -2025,6 +2025,20 @@ virStoragePRDefIsManaged(virStoragePRDefPtr prd)
 }
 
 
+bool
+virStorageSourceChainHasManagedPR(virStorageSourcePtr src)
+{
+    virStorageSourcePtr n;
+
+    for (n = src; virStorageSourceIsBacking(n); n = n->backingStore) {
+        if (virStoragePRDefIsManaged(src->pr))
+            return true;
+    }
+
+    return false;
+}
+
+
 virSecurityDeviceLabelDefPtr
 virStorageSourceGetSecurityLabelDef(virStorageSourcePtr src,
                                     const char *model)

src/util/virstoragefile.h

@@ -400,6 +400,9 @@ bool virStoragePRDefIsEqual(virStoragePRDefPtr a,
                             virStoragePRDefPtr b);
 bool virStoragePRDefIsManaged(virStoragePRDefPtr prd);
 
+bool
+virStorageSourceChainHasManagedPR(virStorageSourcePtr src);
+
 virSecurityDeviceLabelDefPtr
 virStorageSourceGetSecurityLabelDef(virStorageSourcePtr src,
                                     const char *model);