HBitmap *copy_bitmap;
 } BackupBlockJob;
 
+static const BlockJobDriver backup_job_driver;
+
 /* See if in-flight requests overlap and wait for them to complete */
 static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
                                                        int64_t start,
     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
     int64_t len;
 
-    assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
+    assert(block_job_driver(job) == &backup_job_driver);
 
     if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
         error_setg(errp, "The backup job only supports block checkpoint in"
     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
     int64_t start, end;
 
-    assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
+    assert(block_job_driver(job) == &backup_job_driver);
 
     start = QEMU_ALIGN_DOWN(offset, backup_job->cluster_size);
     end = QEMU_ALIGN_UP(offset + bytes, backup_job->cluster_size);
     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
     int64_t start, end;
 
-    assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP);
+    assert(block_job_driver(job) == &backup_job_driver);
 
     start = QEMU_ALIGN_DOWN(offset, backup_job->cluster_size);
     end = QEMU_ALIGN_UP(offset + bytes, backup_job->cluster_size);
 
     return job->co;
 }
 
+const BlockJobDriver *block_job_driver(BlockJob *job)
+{
+    return job->driver;
+}
+
 /**
  * All jobs must allow a pause point before entering their job proper. This
  * ensures that jobs can be paused prior to being started, then resumed later.