util: storage: Store backing chain index in virStorageSource

The backing store indexes were not bound to the storage sources in any
way. To allow us to bind a given alias to a given storage source we need
to save the index in virStorageSource. The backing store ids are now
generated when detecting the backing chain.

Since we don't re-detect the backing chain after snapshots, the
numbering needs to be fixed there.

src/conf/domain_conf.c

@@ -8281,6 +8281,7 @@ virDomainDiskBackingStoreParse(xmlXPathContextPtr ctxt,
     xmlNodePtr source;
     char *type = NULL;
     char *format = NULL;
+    char *idx = NULL;
     int ret = -1;
 
     if (!(ctxt->node = virXPathNode("./backingStore[*]", ctxt))) {
@@ -8291,6 +8292,13 @@ virDomainDiskBackingStoreParse(xmlXPathContextPtr ctxt,
     if (VIR_ALLOC(backingStore) < 0)
         goto cleanup;
 
+    if (!(flags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
+        (idx = virXMLPropString(ctxt->node, "index")) &&
+        virStrToLong_uip(idx, NULL, 10, &backingStore->id) < 0) {
+        virReportError(VIR_ERR_XML_ERROR, _("invalid disk index '%s'"), idx);
+        goto cleanup;
+    }
+
     if (!(type = virXMLPropString(ctxt->node, "type"))) {
         virReportError(VIR_ERR_XML_ERROR, "%s",
                        _("missing disk backing store type"));
@@ -21910,8 +21918,7 @@ virDomainDiskSourceFormat(virBufferPtr buf,
 static int
 virDomainDiskBackingStoreFormat(virBufferPtr buf,
                                 virStorageSourcePtr backingStore,
-                                const char *backingStoreRaw,
-                                unsigned int idx)
+                                const char *backingStoreRaw)
 {
     const char *type;
     const char *format;
@@ -21938,8 +21945,10 @@ virDomainDiskBackingStoreFormat(virBufferPtr buf,
         return -1;
     }
 
-    virBufferAsprintf(buf, "<backingStore type='%s' index='%u'>\n",
-                      type, idx);
+    virBufferAsprintf(buf, "<backingStore type='%s'", type);
+    if (backingStore->id != 0)
+        virBufferAsprintf(buf, " index='%u'", backingStore->id);
+    virBufferAddLit(buf, ">\n");
     virBufferAdjustIndent(buf, 2);
 
     virBufferAsprintf(buf, "<format type='%s'/>\n", format);
@@ -21947,8 +21956,7 @@ virDomainDiskBackingStoreFormat(virBufferPtr buf,
     if (virDomainDiskSourceFormatInternal(buf, backingStore, 0, 0, true) < 0 ||
         virDomainDiskBackingStoreFormat(buf,
                                         backingStore->backingStore,
-                                        backingStore->backingStoreRaw,
-                                        idx + 1) < 0)
+                                        backingStore->backingStoreRaw) < 0)
         return -1;
 
     virBufferAdjustIndent(buf, -2);
@@ -22084,7 +22092,7 @@ virDomainDiskDefFormat(virBufferPtr buf,
      * persistent storage of backing chains is ready. */
     if (!(flags & VIR_DOMAIN_DEF_FORMAT_INACTIVE) &&
         virDomainDiskBackingStoreFormat(buf, def->src->backingStore,
-                                        def->src->backingStoreRaw, 1) < 0)
+                                        def->src->backingStoreRaw) < 0)
         return -1;
 
     virBufferEscapeString(buf, "<backenddomain name='%s'/>\n", def->domain_name);

src/qemu/qemu_driver.c

@@ -14429,6 +14429,17 @@ qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver,
 }
 
 
+static void
+qemuDomainSnapshotUpdateDiskSourcesRenumber(virStorageSourcePtr src)
+{
+    virStorageSourcePtr next;
+    unsigned int idx = 1;
+
+    for (next = src->backingStore; next; next = next->backingStore)
+        next->id = idx++;
+}
+
+
 /**
  * qemuDomainSnapshotUpdateDiskSources:
  * @dd: snapshot disk data object
@@ -14451,6 +14462,9 @@ qemuDomainSnapshotUpdateDiskSources(qemuDomainSnapshotDiskDataPtr dd,
     VIR_STEAL_PTR(dd->src->backingStore, dd->disk->src);
     VIR_STEAL_PTR(dd->disk->src, dd->src);
 
+    /* fix numbering of disks */
+    qemuDomainSnapshotUpdateDiskSourcesRenumber(dd->disk->src);
+
     if (dd->persistdisk) {
         VIR_STEAL_PTR(dd->persistsrc->backingStore, dd->persistdisk->src);
         VIR_STEAL_PTR(dd->persistdisk->src, dd->persistsrc);

src/storage/storage_source.c

@@ -396,7 +396,8 @@ virStorageFileGetMetadataRecurse(virStorageSourcePtr src,
                                  uid_t uid, gid_t gid,
                                  bool allow_probe,
                                  bool report_broken,
-                                 virHashTablePtr cycle)
+                                 virHashTablePtr cycle,
+                                 unsigned int depth)
 {
     int ret = -1;
     const char *uniqueName;
@@ -474,7 +475,7 @@ virStorageFileGetMetadataRecurse(virStorageSourcePtr src,
     if ((ret = virStorageFileGetMetadataRecurse(backingStore, parent,
                                                 uid, gid,
                                                 allow_probe, report_broken,
-                                                cycle)) < 0) {
+                                                cycle, depth + 1)) < 0) {
         if (report_broken)
             goto cleanup;
 
@@ -489,6 +490,8 @@ virStorageFileGetMetadataRecurse(virStorageSourcePtr src,
     ret = 0;
 
  cleanup:
+    if (src->backingStore)
+        src->backingStore->id = depth;
     VIR_FREE(buf);
     virStorageFileDeinit(src);
     virStorageSourceFree(backingStore);
@@ -543,7 +546,7 @@ virStorageFileGetMetadata(virStorageSourcePtr src,
     }
 
     ret = virStorageFileGetMetadataRecurse(src, src, uid, gid,
-                                           allow_probe, report_broken, cycle);
+                                           allow_probe, report_broken, cycle, 1);
 
     virHashFree(cycle);
     return ret;

src/util/virstoragefile.c

@@ -2030,6 +2030,7 @@ virStorageSourceCopy(const virStorageSource *src,
     if (VIR_ALLOC(ret) < 0)
         return NULL;
 
+    ret->id = src->id;
     ret->type = src->type;
     ret->protocol = src->protocol;
     ret->format = src->format;

src/util/virstoragefile.h

@@ -227,6 +227,7 @@ typedef virStorageSource *virStorageSourcePtr;
  * IMPORTANT: When adding fields to this struct it's also necessary to add
  * appropriate code to the virStorageSourceCopy deep copy function */
 struct _virStorageSource {
+    unsigned int id; /* backing chain identifier, 0 is unset */
     int type; /* virStorageType */
     char *path;
     int protocol; /* virStorageNetProtocol */