ceph/src/librbd/object_map/SnapshotRollbackRequest.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #ifndef CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H
   5 #define CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H
   6
   7 #include "include/int_types.h"
   8 #include "librbd/object_map/Request.h"
   9
  10 class Context;
  11
  12 namespace librbd {
  13
  14 class ImageCtx;
  15
  16 namespace object_map {
  17
  18 class SnapshotRollbackRequest : public Request {
  19 public:
  20   /**
  21    * Snapshot rollback goes through the following state machine:
  22    *
  23    * @verbatim
  24    *
  25    * <start>
  26    *    |
  27    *    v           (error)
  28    * STATE_READ_MAP * * * * > STATE_INVALIDATE_MAP
  29    *    |                         |
  30    *    v                         v
  31    * STATE_WRITE_MAP -------> <finish>
  32    *
  33    * @endverbatim
  34    *
  35    * If an error occurs within the READ_MAP state, the associated snapshot's
  36    * object map will be flagged as invalid.  Otherwise, an error from any state
  37    * will result in the HEAD object map being flagged as invalid via the base
  38    * class.
  39    */
  40   enum State {
  41     STATE_READ_MAP,
  42     STATE_INVALIDATE_MAP,
  43     STATE_WRITE_MAP
  44   };
  45
  46   SnapshotRollbackRequest(ImageCtx &image_ctx, uint64_t snap_id,
  47                           Context *on_finish)
  48     : Request(image_ctx, CEPH_NOSNAP, on_finish),
  49       m_snap_id(snap_id), m_ret_val(0) {
  50     assert(snap_id != CEPH_NOSNAP);
  51   }
  52
  53   void send() override;
  54
  55 protected:
  56   bool should_complete(int r) override;
  57
  58 private:
  59   State m_state;
  60   uint64_t m_snap_id;
  61   int m_ret_val;
  62
  63   bufferlist m_read_bl;
  64
  65   void send_read_map();
  66   void send_invalidate_map();
  67   void send_write_map();
  68
  69 };
  70
  71 } // namespace object_map
  72 } // namespace librbd
  73
  74 #endif // CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_ROLLBACK_REQUEST_H