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MDLog.cc
1438 lines (1207 loc) · 43.1 KB
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MDLog.cc
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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#include "MDSRank.h"
#include "MDLog.h"
#include "MDCache.h"
#include "LogEvent.h"
#include "MDSContext.h"
#include "osdc/Journaler.h"
#include "mds/JournalPointer.h"
#include "common/entity_name.h"
#include "common/perf_counters.h"
#include "common/Cond.h"
#include "events/ESubtreeMap.h"
#include "common/config.h"
#include "common/errno.h"
#include "include/assert.h"
#define dout_subsys ceph_subsys_mds
#undef DOUT_COND
#define DOUT_COND(cct, l) l<=cct->_conf->debug_mds || l <= cct->_conf->debug_mds_log
#undef dout_prefix
#define dout_prefix *_dout << "mds." << mds->get_nodeid() << ".log "
// cons/des
MDLog::~MDLog()
{
if (journaler) { delete journaler; journaler = 0; }
if (logger) {
g_ceph_context->get_perfcounters_collection()->remove(logger);
delete logger;
logger = 0;
}
}
void MDLog::create_logger()
{
PerfCountersBuilder plb(g_ceph_context, "mds_log", l_mdl_first, l_mdl_last);
plb.add_u64_counter(l_mdl_evadd, "evadd",
"Events submitted", "subm");
plb.add_u64_counter(l_mdl_evex, "evex", "Total expired events");
plb.add_u64_counter(l_mdl_evtrm, "evtrm", "Trimmed events");
plb.add_u64(l_mdl_ev, "ev",
"Events", "evts");
plb.add_u64(l_mdl_evexg, "evexg", "Expiring events");
plb.add_u64(l_mdl_evexd, "evexd", "Current expired events");
plb.add_u64_counter(l_mdl_segadd, "segadd", "Segments added");
plb.add_u64_counter(l_mdl_segex, "segex", "Total expired segments");
plb.add_u64_counter(l_mdl_segtrm, "segtrm", "Trimmed segments");
plb.add_u64(l_mdl_seg, "seg",
"Segments", "segs");
plb.add_u64(l_mdl_segexg, "segexg", "Expiring segments");
plb.add_u64(l_mdl_segexd, "segexd", "Current expired segments");
plb.add_u64(l_mdl_expos, "expos", "Journaler xpire position");
plb.add_u64(l_mdl_wrpos, "wrpos", "Journaler write position");
plb.add_u64(l_mdl_rdpos, "rdpos", "Journaler read position");
plb.add_u64(l_mdl_jlat, "jlat", "Journaler flush latency");
plb.add_u64_counter(l_mdl_replay, "replay", "Events replayed");
// logger
logger = plb.create_perf_counters();
g_ceph_context->get_perfcounters_collection()->add(logger);
}
void MDLog::set_write_iohint(unsigned iohint_flags)
{
journaler->set_write_iohint(iohint_flags);
}
class C_MDL_WriteError : public MDSIOContextBase {
protected:
MDLog *mdlog;
MDSRank *get_mds() {return mdlog->mds;}
void finish(int r) {
MDSRank *mds = get_mds();
// assume journal is reliable, so don't choose action based on
// g_conf->mds_action_on_write_error.
if (r == -EBLACKLISTED) {
derr << "we have been blacklisted (fenced), respawning..." << dendl;
mds->respawn();
} else {
derr << "unhandled error " << cpp_strerror(r) << ", shutting down..." << dendl;
// Although it's possible that this could be something transient,
// it's severe and scary, so disable this rank until an administrator
// intervenes.
mds->clog->error() << "Unhandled journal write error on MDS rank " <<
mds->get_nodeid() << ": " << cpp_strerror(r) << ", shutting down.";
mds->damaged();
assert(0); // damaged should never return
}
}
public:
explicit C_MDL_WriteError(MDLog *m) : mdlog(m) {}
};
void MDLog::write_head(MDSInternalContextBase *c)
{
C_OnFinisher *fin = NULL;
if (c != NULL) {
fin = new C_OnFinisher(new C_IO_Wrapper(mds, c), mds->finisher);
}
journaler->write_head(fin);
}
uint64_t MDLog::get_read_pos()
{
return journaler->get_read_pos();
}
uint64_t MDLog::get_write_pos()
{
return journaler->get_write_pos();
}
uint64_t MDLog::get_safe_pos()
{
return journaler->get_write_safe_pos();
}
void MDLog::create(MDSInternalContextBase *c)
{
dout(5) << "create empty log" << dendl;
C_GatherBuilder gather(g_ceph_context);
// This requires an OnFinisher wrapper because Journaler will call back the completion for write_head inside its own lock
// XXX but should maybe that be handled inside Journaler?
gather.set_finisher(new C_OnFinisher(new C_IO_Wrapper(mds, c), mds->finisher));
// The inode of the default Journaler we will create
ino = MDS_INO_LOG_OFFSET + mds->get_nodeid();
// Instantiate Journaler and start async write to RADOS
assert(journaler == NULL);
journaler = new Journaler(ino, mds->mdsmap->get_metadata_pool(), CEPH_FS_ONDISK_MAGIC, mds->objecter,
logger, l_mdl_jlat,
&mds->timer,
mds->finisher);
assert(journaler->is_readonly());
journaler->set_write_error_handler(new C_MDL_WriteError(this));
journaler->set_writeable();
journaler->create(&mds->mdcache->default_log_layout, g_conf->mds_journal_format);
journaler->write_head(gather.new_sub());
// Async write JournalPointer to RADOS
JournalPointer jp(mds->get_nodeid(), mds->mdsmap->get_metadata_pool());
jp.front = ino;
jp.back = 0;
jp.save(mds->objecter, gather.new_sub());
gather.activate();
logger->set(l_mdl_expos, journaler->get_expire_pos());
logger->set(l_mdl_wrpos, journaler->get_write_pos());
submit_thread.create("md_submit");
}
void MDLog::open(MDSInternalContextBase *c)
{
dout(5) << "open discovering log bounds" << dendl;
assert(!recovery_thread.is_started());
recovery_thread.set_completion(c);
recovery_thread.create("md_recov_open");
submit_thread.create("md_submit");
// either append() or replay() will follow.
}
/**
* Final part of reopen() procedure, after recovery_thread
* has done its thing we call append()
*/
class C_ReopenComplete : public MDSInternalContext {
MDLog *mdlog;
MDSInternalContextBase *on_complete;
public:
C_ReopenComplete(MDLog *mdlog_, MDSInternalContextBase *on_complete_) : MDSInternalContext(mdlog_->mds), mdlog(mdlog_), on_complete(on_complete_) {}
void finish(int r) {
mdlog->append();
on_complete->complete(r);
}
};
/**
* Given that open() has been called in the past, go through the journal
* recovery procedure again, potentially reformatting the journal if it
* was in an old format.
*/
void MDLog::reopen(MDSInternalContextBase *c)
{
dout(5) << "reopen" << dendl;
// Because we will call append() at the completion of this, check that we have already
// read the whole journal.
assert(journaler != NULL);
assert(journaler->get_read_pos() == journaler->get_write_pos());
delete journaler;
journaler = NULL;
// recovery_thread was started at some point in the past. Although
// it has called it's completion if we made it back here, it might
// still not have been cleaned up: join it.
recovery_thread.join();
recovery_thread.set_completion(new C_ReopenComplete(this, c));
recovery_thread.create("md_recov_reopen");
}
void MDLog::append()
{
dout(5) << "append positioning at end and marking writeable" << dendl;
journaler->set_read_pos(journaler->get_write_pos());
journaler->set_expire_pos(journaler->get_write_pos());
journaler->set_writeable();
logger->set(l_mdl_expos, journaler->get_write_pos());
}
// -------------------------------------------------
void MDLog::_start_entry(LogEvent *e)
{
assert(submit_mutex.is_locked_by_me());
assert(cur_event == NULL);
cur_event = e;
event_seq++;
EMetaBlob *metablob = e->get_metablob();
if (metablob) {
metablob->event_seq = event_seq;
metablob->last_subtree_map = get_last_segment_seq();
}
}
void MDLog::cancel_entry(LogEvent *le)
{
assert(le == cur_event);
cur_event = NULL;
delete le;
}
void MDLog::_submit_entry(LogEvent *le, MDSInternalContextBase *c)
{
assert(submit_mutex.is_locked_by_me());
assert(!mds->is_any_replay());
assert(!capped);
assert(le == cur_event);
cur_event = NULL;
if (!g_conf->mds_log) {
// hack: log is disabled.
if (c) {
c->complete(0);
}
return;
}
// let the event register itself in the segment
assert(!segments.empty());
LogSegment *ls = segments.rbegin()->second;
ls->num_events++;
le->_segment = ls;
le->update_segment();
le->set_stamp(ceph_clock_now(g_ceph_context));
pending_events[ls->seq].push_back(PendingEvent(le, c));
num_events++;
if (logger) {
logger->inc(l_mdl_evadd);
logger->set(l_mdl_ev, num_events);
}
unflushed++;
uint64_t period = journaler->get_layout_period();
// start a new segment?
if (le->get_type() == EVENT_SUBTREEMAP ||
(le->get_type() == EVENT_IMPORTFINISH && mds->is_resolve())) {
// avoid infinite loop when ESubtreeMap is very large.
// do not insert ESubtreeMap among EImportFinish events that finish
// disambiguate imports. Because the ESubtreeMap reflects the subtree
// state when all EImportFinish events are replayed.
} else if (ls->end/period != ls->offset/period ||
ls->num_events >= g_conf->mds_log_events_per_segment) {
dout(10) << "submit_entry also starting new segment: last = "
<< ls->seq << "/" << ls->offset << ", event seq = " << event_seq << dendl;
_start_new_segment();
} else if (g_conf->mds_debug_subtrees &&
le->get_type() != EVENT_SUBTREEMAP_TEST) {
// debug: journal this every time to catch subtree replay bugs.
// use a different event id so it doesn't get interpreted as a
// LogSegment boundary on replay.
LogEvent *sle = mds->mdcache->create_subtree_map();
sle->set_type(EVENT_SUBTREEMAP_TEST);
_submit_entry(sle, NULL);
}
}
/**
* Invoked on the flush after each entry submitted
*/
class C_MDL_Flushed : public MDSIOContextBase {
protected:
MDLog *mdlog;
MDSRank *get_mds() {return mdlog->mds;}
uint64_t flushed_to;
MDSInternalContextBase *wrapped;
void finish(int r) {
if (wrapped) {
wrapped->complete(r);
}
mdlog->submit_mutex.Lock();
assert(mdlog->safe_pos <= flushed_to);
mdlog->safe_pos = flushed_to;
mdlog->submit_mutex.Unlock();
}
public:
C_MDL_Flushed(MDLog *m, uint64_t ft, MDSInternalContextBase *w)
: mdlog(m), flushed_to(ft), wrapped(w) {}
};
void MDLog::_submit_thread()
{
dout(10) << "_submit_thread start" << dendl;
submit_mutex.Lock();
while (!mds->is_daemon_stopping()) {
if (g_conf->mds_log_pause) {
submit_cond.Wait(submit_mutex);
continue;
}
map<uint64_t,list<PendingEvent> >::iterator it = pending_events.begin();
if (it == pending_events.end()) {
submit_cond.Wait(submit_mutex);
continue;
}
if (it->second.empty()) {
pending_events.erase(it);
continue;
}
PendingEvent data = it->second.front();
it->second.pop_front();
submit_mutex.Unlock();
if (data.le) {
LogEvent *le = data.le;
LogSegment *ls = le->_segment;
// encode it, with event type
bufferlist bl;
le->encode_with_header(bl, mds->mdsmap->get_up_features());
uint64_t write_pos = journaler->get_write_pos();
le->set_start_off(write_pos);
if (le->get_type() == EVENT_SUBTREEMAP)
ls->offset = write_pos;
dout(5) << "_submit_thread " << write_pos << "~" << bl.length()
<< " : " << *le << dendl;
// journal it.
const uint64_t new_write_pos = journaler->append_entry(bl); // bl is destroyed.
ls->end = new_write_pos;
journaler->wait_for_flush(new C_MDL_Flushed(
this, new_write_pos, data.fin));
if (data.flush)
journaler->flush();
if (logger)
logger->set(l_mdl_wrpos, ls->end);
delete le;
} else {
journaler->wait_for_flush(new C_MDL_Flushed(
this, journaler->get_write_pos(), data.fin));
if (data.flush)
journaler->flush();
}
submit_mutex.Lock();
if (data.flush)
unflushed = 0;
else if (data.le)
unflushed++;
}
submit_mutex.Unlock();
}
void MDLog::wait_for_safe(MDSInternalContextBase *c)
{
if (!g_conf->mds_log) {
// hack: bypass.
c->complete(0);
return;
}
submit_mutex.Lock();
bool no_pending = true;
if (!pending_events.empty()) {
pending_events.rbegin()->second.push_back(PendingEvent(NULL, c));
no_pending = false;
submit_cond.Signal();
}
submit_mutex.Unlock();
if (no_pending && c)
journaler->wait_for_flush(new C_IO_Wrapper(mds, c));
}
void MDLog::flush()
{
submit_mutex.Lock();
bool do_flush = unflushed > 0;
unflushed = 0;
if (!pending_events.empty()) {
pending_events.rbegin()->second.push_back(PendingEvent(NULL, NULL, true));
do_flush = false;
submit_cond.Signal();
}
submit_mutex.Unlock();
if (do_flush)
journaler->flush();
}
void MDLog::kick_submitter()
{
Mutex::Locker l(submit_mutex);
submit_cond.Signal();
}
void MDLog::cap()
{
dout(5) << "cap" << dendl;
capped = true;
}
void MDLog::shutdown()
{
assert(mds->mds_lock.is_locked_by_me());
dout(5) << "shutdown" << dendl;
if (submit_thread.is_started()) {
assert(mds->is_daemon_stopping());
if (submit_thread.am_self()) {
// Called suicide from the thread: trust it to do no work after
// returning from suicide, and subsequently respect mds->is_daemon_stopping()
// and fall out of its loop.
} else {
mds->mds_lock.Unlock();
// Because MDS::stopping is true, it's safe to drop mds_lock: nobody else
// picking it up will do anything with it.
submit_mutex.Lock();
submit_cond.Signal();
submit_mutex.Unlock();
mds->mds_lock.Lock();
submit_thread.join();
}
}
// Replay thread can be stuck inside e.g. Journaler::wait_for_readable,
// so we need to shutdown the journaler first.
if (journaler) {
journaler->shutdown();
}
if (replay_thread.is_started() && !replay_thread.am_self()) {
mds->mds_lock.Unlock();
replay_thread.join();
mds->mds_lock.Lock();
}
if (recovery_thread.is_started() && !recovery_thread.am_self()) {
mds->mds_lock.Unlock();
recovery_thread.join();
mds->mds_lock.Lock();
}
}
// -----------------------------
// segments
void MDLog::_start_new_segment()
{
_prepare_new_segment();
_journal_segment_subtree_map(NULL);
}
void MDLog::_prepare_new_segment()
{
assert(submit_mutex.is_locked_by_me());
uint64_t seq = event_seq + 1;
dout(7) << __func__ << " seq " << seq << dendl;
segments[seq] = new LogSegment(seq);
logger->inc(l_mdl_segadd);
logger->set(l_mdl_seg, segments.size());
// Adjust to next stray dir
dout(10) << "Advancing to next stray directory on mds " << mds->get_nodeid()
<< dendl;
mds->mdcache->advance_stray();
}
void MDLog::_journal_segment_subtree_map(MDSInternalContextBase *onsync)
{
assert(submit_mutex.is_locked_by_me());
dout(7) << __func__ << dendl;
ESubtreeMap *sle = mds->mdcache->create_subtree_map();
sle->event_seq = get_last_segment_seq();
_submit_entry(sle, onsync);
}
void MDLog::trim(int m)
{
unsigned max_segments = g_conf->mds_log_max_segments;
int max_events = g_conf->mds_log_max_events;
if (m >= 0)
max_events = m;
if (mds->mdcache->is_readonly()) {
dout(10) << "trim, ignoring read-only FS" << dendl;
return;
}
// Clamp max_events to not be smaller than events per segment
if (max_events > 0 && max_events <= g_conf->mds_log_events_per_segment) {
max_events = g_conf->mds_log_events_per_segment + 1;
}
submit_mutex.Lock();
// trim!
dout(10) << "trim "
<< segments.size() << " / " << max_segments << " segments, "
<< num_events << " / " << max_events << " events"
<< ", " << expiring_segments.size() << " (" << expiring_events << ") expiring"
<< ", " << expired_segments.size() << " (" << expired_events << ") expired"
<< dendl;
if (segments.empty()) {
submit_mutex.Unlock();
return;
}
// hack: only trim for a few seconds at a time
utime_t stop = ceph_clock_now(g_ceph_context);
stop += 2.0;
map<uint64_t,LogSegment*>::iterator p = segments.begin();
while (p != segments.end() &&
((max_events >= 0 &&
num_events - expiring_events - expired_events > max_events) ||
(segments.size() - expiring_segments.size() - expired_segments.size() > max_segments))) {
if (stop < ceph_clock_now(g_ceph_context))
break;
int num_expiring_segments = (int)expiring_segments.size();
if (num_expiring_segments >= g_conf->mds_log_max_expiring)
break;
int op_prio = CEPH_MSG_PRIO_LOW +
(CEPH_MSG_PRIO_HIGH - CEPH_MSG_PRIO_LOW) *
num_expiring_segments / g_conf->mds_log_max_expiring;
// look at first segment
LogSegment *ls = p->second;
assert(ls);
++p;
if (pending_events.count(ls->seq) ||
ls->end > safe_pos) {
dout(5) << "trim segment " << ls->seq << "/" << ls->offset << ", not fully flushed yet, safe "
<< journaler->get_write_safe_pos() << " < end " << ls->end << dendl;
break;
}
if (expiring_segments.count(ls)) {
dout(5) << "trim already expiring segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
} else if (expired_segments.count(ls)) {
dout(5) << "trim already expired segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
} else {
assert(expiring_segments.count(ls) == 0);
expiring_segments.insert(ls);
expiring_events += ls->num_events;
submit_mutex.Unlock();
uint64_t last_seq = ls->seq;
try_expire(ls, op_prio);
submit_mutex.Lock();
p = segments.lower_bound(last_seq + 1);
}
}
// discard expired segments and unlock submit_mutex
_trim_expired_segments();
}
class C_MaybeExpiredSegment : public MDSInternalContext {
MDLog *mdlog;
LogSegment *ls;
int op_prio;
public:
C_MaybeExpiredSegment(MDLog *mdl, LogSegment *s, int p) :
MDSInternalContext(mdl->mds), mdlog(mdl), ls(s), op_prio(p) {}
void finish(int res) {
if (res < 0)
mdlog->mds->handle_write_error(res);
mdlog->_maybe_expired(ls, op_prio);
}
};
/**
* Like MDLog::trim, but instead of trimming to max_segments, trim all but the latest
* segment.
*/
int MDLog::trim_all()
{
submit_mutex.Lock();
dout(10) << __func__ << ": "
<< segments.size()
<< "/" << expiring_segments.size()
<< "/" << expired_segments.size() << dendl;
uint64_t last_seq = 0;
if (!segments.empty())
last_seq = get_last_segment_seq();
map<uint64_t,LogSegment*>::iterator p = segments.begin();
while (p != segments.end() &&
p->first < last_seq && p->second->end <= safe_pos) {
LogSegment *ls = p->second;
++p;
// Caller should have flushed journaler before calling this
if (pending_events.count(ls->seq)) {
dout(5) << __func__ << ": segment " << ls->seq << " has pending events" << dendl;
submit_mutex.Unlock();
return -EAGAIN;
}
if (expiring_segments.count(ls)) {
dout(5) << "trim already expiring segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
} else if (expired_segments.count(ls)) {
dout(5) << "trim already expired segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
} else {
assert(expiring_segments.count(ls) == 0);
expiring_segments.insert(ls);
expiring_events += ls->num_events;
submit_mutex.Unlock();
uint64_t next_seq = ls->seq + 1;
try_expire(ls, CEPH_MSG_PRIO_DEFAULT);
submit_mutex.Lock();
p = segments.lower_bound(next_seq);
}
}
_trim_expired_segments();
return 0;
}
void MDLog::try_expire(LogSegment *ls, int op_prio)
{
MDSGatherBuilder gather_bld(g_ceph_context);
ls->try_to_expire(mds, gather_bld, op_prio);
if (gather_bld.has_subs()) {
dout(5) << "try_expire expiring segment " << ls->seq << "/" << ls->offset << dendl;
gather_bld.set_finisher(new C_MaybeExpiredSegment(this, ls, op_prio));
gather_bld.activate();
} else {
dout(10) << "try_expire expired segment " << ls->seq << "/" << ls->offset << dendl;
submit_mutex.Lock();
assert(expiring_segments.count(ls));
expiring_segments.erase(ls);
expiring_events -= ls->num_events;
_expired(ls);
submit_mutex.Unlock();
}
logger->set(l_mdl_segexg, expiring_segments.size());
logger->set(l_mdl_evexg, expiring_events);
}
void MDLog::_maybe_expired(LogSegment *ls, int op_prio)
{
if (mds->mdcache->is_readonly()) {
dout(10) << "_maybe_expired, ignoring read-only FS" << dendl;
return;
}
dout(10) << "_maybe_expired segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
try_expire(ls, op_prio);
}
void MDLog::_trim_expired_segments()
{
assert(submit_mutex.is_locked_by_me());
// trim expired segments?
bool trimmed = false;
while (!segments.empty()) {
LogSegment *ls = segments.begin()->second;
if (!expired_segments.count(ls)) {
dout(10) << "_trim_expired_segments waiting for " << ls->seq << "/" << ls->offset
<< " to expire" << dendl;
break;
}
dout(10) << "_trim_expired_segments trimming expired "
<< ls->seq << "/0x" << std::hex << ls->offset << std::dec << dendl;
expired_events -= ls->num_events;
expired_segments.erase(ls);
num_events -= ls->num_events;
// this was the oldest segment, adjust expire pos
if (journaler->get_expire_pos() < ls->end) {
journaler->set_expire_pos(ls->end);
}
logger->set(l_mdl_expos, ls->offset);
logger->inc(l_mdl_segtrm);
logger->inc(l_mdl_evtrm, ls->num_events);
segments.erase(ls->seq);
delete ls;
trimmed = true;
}
submit_mutex.Unlock();
if (trimmed)
journaler->write_head(0);
}
void MDLog::trim_expired_segments()
{
submit_mutex.Lock();
_trim_expired_segments();
}
void MDLog::_expired(LogSegment *ls)
{
assert(submit_mutex.is_locked_by_me());
dout(5) << "_expired segment " << ls->seq << "/" << ls->offset
<< ", " << ls->num_events << " events" << dendl;
if (!capped && ls == peek_current_segment()) {
dout(5) << "_expired not expiring " << ls->seq << "/" << ls->offset
<< ", last one and !capped" << dendl;
} else {
// expired.
expired_segments.insert(ls);
expired_events += ls->num_events;
// Trigger all waiters
for (std::list<MDSInternalContextBase*>::iterator i = ls->expiry_waiters.begin();
i != ls->expiry_waiters.end(); ++i) {
(*i)->complete(0);
}
ls->expiry_waiters.clear();
logger->inc(l_mdl_evex, ls->num_events);
logger->inc(l_mdl_segex);
}
logger->set(l_mdl_ev, num_events);
logger->set(l_mdl_evexd, expired_events);
logger->set(l_mdl_seg, segments.size());
logger->set(l_mdl_segexd, expired_segments.size());
}
void MDLog::replay(MDSInternalContextBase *c)
{
assert(journaler->is_active());
assert(journaler->is_readonly());
// empty?
if (journaler->get_read_pos() == journaler->get_write_pos()) {
dout(10) << "replay - journal empty, done." << dendl;
if (c) {
c->complete(0);
}
return;
}
// add waiter
if (c)
waitfor_replay.push_back(c);
// go!
dout(10) << "replay start, from " << journaler->get_read_pos()
<< " to " << journaler->get_write_pos() << dendl;
assert(num_events == 0 || already_replayed);
if (already_replayed) {
// Ensure previous instance of ReplayThread is joined before
// we create another one
replay_thread.join();
}
already_replayed = true;
replay_thread.create("md_log_replay");
}
/**
* Resolve the JournalPointer object to a journal file, and
* instantiate a Journaler object. This may re-write the journal
* if the journal in RADOS appears to be in an old format.
*
* This is a separate thread because of the way it is initialized from inside
* the mds lock, which is also the global objecter lock -- rather than split
* it up into hard-to-read async operations linked up by contexts,
*
* When this function completes, the `journaler` attribute will be set to
* a Journaler instance using the latest available serialization format.
*/
void MDLog::_recovery_thread(MDSInternalContextBase *completion)
{
assert(journaler == NULL);
if (g_conf->mds_journal_format > JOURNAL_FORMAT_MAX) {
dout(0) << "Configuration value for mds_journal_format is out of bounds, max is "
<< JOURNAL_FORMAT_MAX << dendl;
// Oh dear, something unreadable in the store for this rank: require
// operator intervention.
mds->damaged();
assert(0); // damaged should not return
}
// First, read the pointer object.
// If the pointer object is not present, then create it with
// front = default ino and back = null
JournalPointer jp(mds->get_nodeid(), mds->mdsmap->get_metadata_pool());
int const read_result = jp.load(mds->objecter);
if (read_result == -ENOENT) {
inodeno_t const default_log_ino = MDS_INO_LOG_OFFSET + mds->get_nodeid();
jp.front = default_log_ino;
int write_result = jp.save(mds->objecter);
// Nothing graceful we can do for this
assert(write_result >= 0);
} else if (read_result != 0) {
mds->clog->error() << "failed to read JournalPointer: " << read_result
<< " (" << cpp_strerror(read_result) << ")";
mds->damaged_unlocked();
assert(0); // Should be unreachable because damaged() calls respawn()
}
// If the back pointer is non-null, that means that a journal
// rewrite failed part way through. Erase the back journal
// to clean up.
if (jp.back) {
if (mds->is_standby_replay()) {
dout(1) << "Journal " << jp.front << " is being rewritten, "
<< "cannot replay in standby until an active MDS completes rewrite" << dendl;
Mutex::Locker l(mds->mds_lock);
if (mds->is_daemon_stopping()) {
return;
}
completion->complete(-EAGAIN);
return;
}
dout(1) << "Erasing journal " << jp.back << dendl;
C_SaferCond erase_waiter;
Journaler back(jp.back, mds->mdsmap->get_metadata_pool(), CEPH_FS_ONDISK_MAGIC,
mds->objecter, logger, l_mdl_jlat, &mds->timer, mds->finisher);
// Read all about this journal (header + extents)
C_SaferCond recover_wait;
back.recover(&recover_wait);
int recovery_result = recover_wait.wait();
if (recovery_result != 0) {
// Journaler.recover succeeds if no journal objects are present: an error
// means something worse like a corrupt header, which we can't handle here.
mds->clog->error() << "Error recovering journal " << jp.front << ": "
<< cpp_strerror(recovery_result);
mds->damaged_unlocked();
assert(recovery_result == 0); // Unreachable because damaged() calls respawn()
}
// We could read journal, so we can erase it.
back.erase(&erase_waiter);
int erase_result = erase_waiter.wait();
// If we are successful, or find no data, we can update the JournalPointer to
// reflect that the back journal is gone.
if (erase_result != 0 && erase_result != -ENOENT) {
derr << "Failed to erase journal " << jp.back << ": " << cpp_strerror(erase_result) << dendl;
} else {
dout(1) << "Successfully erased journal, updating journal pointer" << dendl;
jp.back = 0;
int write_result = jp.save(mds->objecter);
// Nothing graceful we can do for this
assert(write_result >= 0);
}
}
/* Read the header from the front journal */
Journaler *front_journal = new Journaler(jp.front, mds->mdsmap->get_metadata_pool(),
CEPH_FS_ONDISK_MAGIC, mds->objecter, logger, l_mdl_jlat, &mds->timer, mds->finisher);
// Assign to ::journaler so that we can be aborted by ::shutdown while
// waiting for journaler recovery
{
Mutex::Locker l(mds->mds_lock);
journaler = front_journal;
}
C_SaferCond recover_wait;
front_journal->recover(&recover_wait);
dout(4) << "Waiting for journal " << jp.front << " to recover..." << dendl;
int recovery_result = recover_wait.wait();
dout(4) << "Journal " << jp.front << " recovered." << dendl;
if (recovery_result != 0) {
mds->clog->error() << "Error recovering journal " << jp.front << ": "
<< cpp_strerror(recovery_result);
mds->damaged_unlocked();
assert(recovery_result == 0); // Unreachable because damaged() calls respawn()
}
/* Check whether the front journal format is acceptable or needs re-write */
if (front_journal->get_stream_format() > JOURNAL_FORMAT_MAX) {
dout(0) << "Journal " << jp.front << " is in unknown format " << front_journal->get_stream_format()
<< ", does this MDS daemon require upgrade?" << dendl;
{
Mutex::Locker l(mds->mds_lock);