qemuDomainBlockCommit: Handle bitmaps on start of commit

On start of the commit job, we need to disable any active bitmap in the
base. Use qemuBlockBitmapsHandleCommitStart to calculate which and call
the appropriate QMP APIs. We use blockdev-reopen to make the 'base'
writable to disable the bitmaps.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_driver.c

@@ -18399,6 +18399,8 @@ qemuDomainBlockCommit(virDomainPtr dom,
     const char *nodebase = NULL;
     bool persistjob = false;
     bool blockdev = false;
+    g_autoptr(virJSONValue) bitmapDisableActions = NULL;
+    VIR_AUTOSTRINGLIST bitmapDisableList = NULL;
 
     virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW |
                   VIR_DOMAIN_BLOCK_COMMIT_ACTIVE |
@@ -18555,8 +18557,29 @@ qemuDomainBlockCommit(virDomainPtr dom,
             goto endjob;
     }
 
+    if (blockdev &&
+        virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN)) {
+        g_autoptr(virHashTable) blockNamedNodeData = NULL;
+        if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, QEMU_ASYNC_JOB_NONE)))
+            goto endjob;
+
+        if (qemuBlockBitmapsHandleCommitStart(topSource, baseSource,
+                                              blockNamedNodeData,
+                                              &bitmapDisableActions,
+                                              &bitmapDisableList) < 0)
+            goto endjob;
+
+        /* if we don't have terminator on 'base' we can't reopen it */
+        if (bitmapDisableActions && !baseSource->backingStore) {
+            virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
+                           _("can't handle bitmaps on unterminated backing image '%s'"),
+                           base);
+            goto endjob;
+        }
+    }
+
     if (!(job = qemuBlockJobDiskNewCommit(vm, disk, top_parent, topSource,
-                                          baseSource, NULL,
+                                          baseSource, &bitmapDisableList,
                                           flags & VIR_DOMAIN_BLOCK_COMMIT_DELETE,
                                           flags)))
         goto endjob;
@@ -18578,6 +18601,24 @@ qemuDomainBlockCommit(virDomainPtr dom,
         if (!backingPath && top_parent &&
             !(backingPath = qemuBlockGetBackingStoreString(baseSource)))
             goto endjob;
+
+        if (bitmapDisableActions) {
+            int rc;
+
+            if (qemuBlockReopenReadWrite(vm, baseSource, QEMU_ASYNC_JOB_NONE) < 0)
+                goto endjob;
+
+            qemuDomainObjEnterMonitor(driver, vm);
+            rc = qemuMonitorTransaction(priv->mon, &bitmapDisableActions);
+            if (qemuDomainObjExitMonitor(driver, vm) < 0)
+                goto endjob;
+
+            if (qemuBlockReopenReadOnly(vm, baseSource, QEMU_ASYNC_JOB_NONE) < 0)
+                goto endjob;
+
+            if (rc < 0)
+                goto endjob;
+        }
     } else {
         device = job->name;
     }