ceph/src/librbd/object_map/SnapshotRemoveRequest.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_REMOVE_REQUEST_H
   5 #define CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_REMOVE_REQUEST_H
   6
   7 #include "include/int_types.h"
   8 #include "include/buffer.h"
   9 #include "common/bit_vector.hpp"
  10 #include "librbd/AsyncRequest.h"
  11
  12 namespace librbd {
  13 namespace object_map {
  14
  15 class SnapshotRemoveRequest : public AsyncRequest<> {
  16 public:
  17   /**
  18    * Snapshot rollback goes through the following state machine:
  19    *
  20    * @verbatim
  21    *
  22    * <start> -----------> STATE_LOAD_MAP ----\
  23    *    .                      *             |
  24    *    .                      * (error)     |
  25    *    . (invalid object map) v             |
  26    *    . . . > STATE_INVALIDATE_NEXT_MAP    |
  27    *    .                      |             |
  28    *    .                      |             |
  29    *    . (fast diff disabled) v             v
  30    *    . . . . . . . . . . > STATE_REMOVE_MAP
  31    *                                 |
  32    *                                 v
  33    *                             <finish>
  34    *
  35    * @endverbatim
  36    *
  37    * The _LOAD_MAP state is skipped if the fast diff feature is disabled.
  38    * If the fast diff feature is enabled and the snapshot is flagged as
  39    * invalid, the next snapshot / HEAD object mapis flagged as invalid;
  40    * otherwise, the state machine proceeds to remove the object map.
  41    */
  42   enum State {
  43     STATE_LOAD_MAP,
  44     STATE_REMOVE_SNAPSHOT,
  45     STATE_INVALIDATE_NEXT_MAP,
  46     STATE_REMOVE_MAP
  47   };
  48
  49   SnapshotRemoveRequest(ImageCtx &image_ctx, ceph::BitVector<2> *object_map,
  50                         uint64_t snap_id, Context *on_finish)
  51     : AsyncRequest(image_ctx, on_finish), m_object_map(*object_map),
  52       m_snap_id(snap_id), m_next_snap_id(CEPH_NOSNAP) {
  53   }
  54
  55   void send() override;
  56
  57 protected:
  58   bool should_complete(int r) override;
  59
  60   int filter_return_code(int r) const override {
  61     if ((m_state == STATE_LOAD_MAP || m_state == STATE_REMOVE_MAP) &&
  62         r == -ENOENT) {
  63       return 0;
  64     }
  65     return r;
  66   }
  67
  68 private:
  69   State m_state;
  70   ceph::BitVector<2> &m_object_map;
  71   uint64_t m_snap_id;
  72   uint64_t m_next_snap_id;
  73
  74   ceph::BitVector<2> m_snap_object_map;
  75   bufferlist m_out_bl;
  76
  77   void send_load_map();
  78   void send_remove_snapshot();
  79   void send_invalidate_next_map();
  80   void send_remove_map();
  81
  82   void compute_next_snap_id();
  83   void update_object_map();
  84 };
  85
  86 } // namespace object_map
  87 } // namespace librbd
  88
  89 #endif // CEPH_LIBRBD_OBJECT_MAP_SNAPSHOT_REMOVE_REQUEST_H