qemu: block: Explicitly specify backingStore when creating format layer props

Pass in backing store explicitly to qemuBlockStorageSourceGetBlockdevProps
and fix the callers.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_block.c

@@ -1396,15 +1396,16 @@ qemuBlockStorageSourceGetBlockdevFormatProps(virStorageSourcePtr src)
  * qemuBlockStorageSourceGetBlockdevProps:
  *
  * @src: storage source to format
+ * @backingStore: a storage source to use as backing of @src
  *
  * Formats @src into a JSON object which can be used with blockdev-add or
  * -blockdev. The formatted object contains both the storage and format layer
  * in nested form including link to the backing chain layer if necessary.
  */
 virJSONValuePtr
-qemuBlockStorageSourceGetBlockdevProps(virStorageSourcePtr src)
+qemuBlockStorageSourceGetBlockdevProps(virStorageSourcePtr src,
+                                       virStorageSourcePtr backingStore)
 {
-    virStorageSourcePtr backingStore = src->backingStore;
     VIR_AUTOPTR(virJSONValue) props = NULL;
 
     if (!(props = qemuBlockStorageSourceGetBlockdevFormatProps(src)))
@@ -1484,7 +1485,8 @@ qemuBlockStorageSourceAttachPrepareBlockdev(virStorageSourcePtr src,
     if (VIR_ALLOC(data) < 0)
         return NULL;
 
-    if (!(data->formatProps = qemuBlockStorageSourceGetBlockdevProps(src)) ||
+    if (!(data->formatProps = qemuBlockStorageSourceGetBlockdevProps(src,
+                                                                     src->backingStore)) ||
         !(data->storageProps = qemuBlockStorageSourceGetBackendProps(src, false,
                                                                      false,
                                                                      autoreadonly)))

src/qemu/qemu_block.h

@@ -66,7 +66,8 @@ virURIPtr
 qemuBlockStorageSourceGetURI(virStorageSourcePtr src);
 
 virJSONValuePtr
-qemuBlockStorageSourceGetBlockdevProps(virStorageSourcePtr src);
+qemuBlockStorageSourceGetBlockdevProps(virStorageSourcePtr src,
+                                       virStorageSourcePtr backingStore);
 
 virJSONValuePtr
 qemuBlockStorageGetCopyOnReadProps(virDomainDiskDefPtr disk);

tests/qemublocktest.c

@@ -226,7 +226,7 @@ testQemuDiskXMLToProps(const void *opaque)
         if (qemuDomainPrepareDiskSourceData(disk, n, NULL, data->qemuCaps) < 0)
             goto cleanup;
 
-        if (!(formatProps = qemuBlockStorageSourceGetBlockdevProps(n)) ||
+        if (!(formatProps = qemuBlockStorageSourceGetBlockdevProps(n, n->backingStore)) ||
             !(storageSrcOnlyProps = qemuBlockStorageSourceGetBackendProps(n, false, true, true)) ||
             !(storageProps = qemuBlockStorageSourceGetBackendProps(n, false, false, true))) {
             if (!data->fail) {