ceph/src/mds/JournalPointer.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15
  16 #include "common/debug.h"
  17 #include "common/errno.h"
  18 #include "common/Cond.h"
  19 #include "osdc/Objecter.h"
  20 #include "mds/mdstypes.h"
  21
  22 #include "mds/JournalPointer.h"
  23
  24
  25 #define dout_context g_ceph_context
  26 #define dout_subsys ceph_subsys_journaler
  27 #undef dout_prefix
  28 #define dout_prefix *_dout << objecter->messenger->get_myname() << ".journalpointer "
  29
  30
  31 std::string JournalPointer::get_object_id() const
  32 {
  33   inodeno_t const pointer_ino = MDS_INO_LOG_POINTER_OFFSET + node_id;
  34   char buf[32];
  35   snprintf(buf, sizeof(buf), "%llx.%08llx", (long long unsigned)pointer_ino, (long long unsigned)0);
  36
  37   return std::string(buf);
  38 }
  39
  40
  41 /**
  42  * Blocking read of JournalPointer for this MDS
  43  */
  44 int JournalPointer::load(Objecter *objecter)
  45 {
  46   assert(objecter != NULL);
  47
  48   // Blocking read of data
  49   std::string const object_id = get_object_id();
  50   dout(4) << "Reading journal pointer '" << object_id << "'" << dendl;
  51   bufferlist data;
  52   C_SaferCond waiter;
  53   objecter->read_full(object_t(object_id), object_locator_t(pool_id),
  54       CEPH_NOSNAP, &data, 0, &waiter);
  55   int r = waiter.wait();
  56
  57   // Construct JournalPointer result, null or decoded data
  58   if (r == 0) {
  59     bufferlist::iterator q = data.begin();
  60     try {
  61       decode(q);
  62     } catch (const buffer::error &e) {
  63       return -EINVAL;
  64     }
  65   } else {
  66     dout(1) << "Journal pointer '" << object_id << "' read failed: " << cpp_strerror(r) << dendl;
  67   }
  68   return r;
  69 }
  70
  71
  72 /**
  73  * Blocking write of JournalPointer for this MDS
  74  *
  75  * @return objecter write op status code
  76  */
  77 int JournalPointer::save(Objecter *objecter) const
  78 {
  79   assert(objecter != NULL);
  80   // It is not valid to persist a null pointer
  81   assert(!is_null());
  82
  83   // Serialize JournalPointer object
  84   bufferlist data;
  85   encode(data);
  86
  87   // Write to RADOS and wait for durability
  88   std::string const object_id = get_object_id();
  89   dout(4) << "Writing pointer object '" << object_id << "': 0x"
  90     << std::hex << front << ":0x" << back << std::dec << dendl;
  91
  92   C_SaferCond waiter;
  93   objecter->write_full(object_t(object_id), object_locator_t(pool_id),
  94                        SnapContext(), data,
  95                        ceph::real_clock::now(), 0,
  96                        &waiter);
  97   int write_result = waiter.wait();
  98   if (write_result < 0) {
  99     derr << "Error writing pointer object '" << object_id << "': " << cpp_strerror(write_result) << dendl;
 100   }
 101   return write_result;
 102 }
 103
 104
 105 /**
 106  * Non-blocking variant of save() that assumes objecter lock already held by
 107  * caller
 108  */
 109 void JournalPointer::save(Objecter *objecter, Context *completion) const
 110 {
 111   assert(objecter != NULL);
 112
 113   bufferlist data;
 114   encode(data);
 115
 116   objecter->write_full(object_t(get_object_id()), object_locator_t(pool_id),
 117                        SnapContext(), data,
 118                        ceph::real_clock::now(), 0,
 119                        completion);
 120 }
 121