ceph/src/librbd/io/CopyupRequest.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_IO_COPYUP_REQUEST_H
   5 #define CEPH_LIBRBD_IO_COPYUP_REQUEST_H
   6
   7 #include "librbd/AsyncOperation.h"
   8 #include "include/int_types.h"
   9 #include "include/rados/librados.hpp"
  10 #include "include/buffer.h"
  11 #include "librbd/io/Types.h"
  12
  13 #include <string>
  14 #include <vector>
  15 #include <atomic>
  16
  17 namespace librbd {
  18
  19 struct ImageCtx;
  20
  21 namespace io {
  22
  23 struct AioCompletion;
  24 template <typename I> class ObjectRequest;
  25
  26 class CopyupRequest {
  27 public:
  28   CopyupRequest(ImageCtx *ictx, const std::string &oid, uint64_t objectno,
  29                 Extents &&image_extents);
  30   ~CopyupRequest();
  31
  32   void append_request(ObjectRequest<ImageCtx> *req);
  33
  34   void send();
  35
  36   void complete(int r);
  37
  38 private:
  39   /**
  40    * Copyup requests go through the following state machine to read from the
  41    * parent image, update the object map, and copyup the object:
  42    *
  43    *
  44    * @verbatim
  45    *
  46    *              <start>
  47    *                 |
  48    *                 v
  49    *    . . .STATE_READ_FROM_PARENT. . .
  50    *    . .          |                 .
  51    *    . .          v                 .
  52    *    . .  STATE_OBJECT_MAP_HEAD     v (copy on read /
  53    *    . .          |                 .  no HEAD rev. update)
  54    *    v v          v                 .
  55    *    . .    STATE_OBJECT_MAP. . . . .
  56    *    . .          |
  57    *    . .          v
  58    *    . . . . > STATE_COPYUP
  59    *    .            |
  60    *    .            v
  61    *    . . . . > <finish>
  62    *
  63    * @endverbatim
  64    *
  65    * The _OBJECT_MAP state is skipped if the object map isn't enabled or if
  66    * an object map update isn't required. The _COPYUP state is skipped if
  67    * no data was read from the parent *and* there are no additional ops.
  68    */
  69   enum State {
  70     STATE_READ_FROM_PARENT,
  71     STATE_OBJECT_MAP_HEAD, // only update the HEAD revision
  72     STATE_OBJECT_MAP,      // update HEAD+snaps (if any)
  73     STATE_COPYUP
  74   };
  75
  76   ImageCtx *m_ictx;
  77   std::string m_oid;
  78   uint64_t m_object_no;
  79   Extents m_image_extents;
  80   State m_state;
  81   ceph::bufferlist m_copyup_data;
  82   std::vector<ObjectRequest<ImageCtx> *> m_pending_requests;
  83   std::atomic<unsigned> m_pending_copyups { 0 };
  84
  85   AsyncOperation m_async_op;
  86
  87   std::vector<uint64_t> m_snap_ids;
  88   librados::IoCtx m_data_ctx; // for empty SnapContext
  89
  90   void complete_requests(int r);
  91
  92   bool should_complete(int r);
  93
  94   void remove_from_list();
  95
  96   bool send_object_map_head();
  97   bool send_object_map();
  98   bool send_copyup();
  99   bool is_copyup_required();
 100 };
 101
 102 } // namespace io
 103 } // namespace librbd
 104
 105 #endif // CEPH_LIBRBD_IO_COPYUP_REQUEST_H