1 files changed, 74 insertions, 0 deletions
diff --git a/src/librbd/object_map/SnapshotRollbackRequest.h b/src/librbd/object_map/SnapshotRollbackRequest.h
new file mode 100644
index 000000000..e26b1e0a3
--- /dev/null
+++ b/src/librbd/object_map/SnapshotRollbackRequest.h
@@ -0,0 +1,74 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#ifndef CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H
+#define CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H
+
+#include "include/int_types.h"
+#include "librbd/object_map/Request.h"
+
+class Context;
+
+namespace librbd {
+
+class ImageCtx;
+
+namespace object_map {
+
+class SnapshotRollbackRequest : public Request {
+public:
+  /**
+   * Snapshot rollback goes through the following state machine:
+   *
+   * @verbatim
+   *
+   * <start>
+   *    |
+   *    v           (error)
+   * STATE_READ_MAP * * * * > STATE_INVALIDATE_MAP
+   *    |                         |
+   *    v                         v
+   * STATE_WRITE_MAP -------> <finish>
+   *
+   * @endverbatim
+   *
+   * If an error occurs within the READ_MAP state, the associated snapshot's
+   * object map will be flagged as invalid.  Otherwise, an error from any state
+   * will result in the HEAD object map being flagged as invalid via the base
+   * class.
+   */
+  enum State {
+    STATE_READ_MAP,
+    STATE_INVALIDATE_MAP,
+    STATE_WRITE_MAP
+  };
+
+  SnapshotRollbackRequest(ImageCtx &image_ctx, uint64_t snap_id,
+                          Context *on_finish)
+    : Request(image_ctx, CEPH_NOSNAP, on_finish),
+      m_snap_id(snap_id), m_ret_val(0) {
+    ceph_assert(snap_id != CEPH_NOSNAP);
+  }
+
+  void send() override;
+
+protected:
+  bool should_complete(int r) override;
+
+private:
+  State m_state = STATE_READ_MAP;
+  uint64_t m_snap_id;
+  int m_ret_val;
+
+  bufferlist m_read_bl;
+
+  void send_read_map();
+  void send_invalidate_map();
+  void send_write_map();
+
+};
+
+} // namespace object_map
+} // namespace librbd
+
+#endif // CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H