func (iamOS *IAMObjectStore) rlock() *iamCache {
	iamOS.RLock()
	return iamOS.iamCache
}

func (iamOS *IAMObjectStore) runlock() {
	iamOS.RUnlock()
}

func (iamOS *IAMObjectStore) lock() *iamCache {
	iamOS.Lock()
	return iamOS.iamCache
}

func (iamOS *IAMObjectStore) unlock() {
	iamOS.Unlock()
}

func (iamOS *IAMObjectStore) getUsersSysType() UsersSysType {
	return iamOS.usersSysType
}

func (s *xlStorage) WalkDir(ctx context.Context, opts WalkDirOptions, wr io.Writer) (err error) {
	legacyFS := s.fsType != xfs && s.fsType != ext4

	s.RLock()
	legacy := s.formatLegacy
	s.RUnlock()

	// Verify if volume is valid and it exists.
	volumeDir, err := s.getVolDir(opts.Bucket)
	if err != nil {
		return err
	}

	if !skipAccessChecks(opts.Bucket) {
		// Stat a volume entry.

						mu.Lock()
						results[i] = info
						mu.Unlock()
					}
				}()
				// Start scanner. Blocks until done.
				err := erObj.nsScanner(ctx, allBuckets, wantCycle, updates, healScanMode)
				if err != nil {
					scannerLogIf(ctx, err)
					mu.Lock()
					if firstErr == nil {
						firstErr = err
					}
					// Cancel remaining...
					cancel()
					mu.Unlock()
					return
				}

	t.lastDayMu.Lock()
	defer t.lastDayMu.Unlock()

	if _, ok := t.lastDayStats[tier]; !ok {
		t.lastDayStats[tier] = &lastDayTierStats{}
	}
	t.lastDayStats[tier].addStats(ts)
}

func (t *transitionState) getDailyAllTierStats() DailyAllTierStats {
	t.lastDayMu.RLock()
	defer t.lastDayMu.RUnlock()

	res := make(DailyAllTierStats, len(t.lastDayStats))

	bootstrapTraceMsg("IAM initialization started")
	globalServerConfigMu.RLock()
	s := globalServerConfig
	globalServerConfigMu.RUnlock()

	sys.Lock()
	sys.iamRefreshInterval = iamRefreshInterval
	sys.Unlock()

	r := rand.New(rand.NewSource(time.Now().UnixNano()))

	var (
		openidInit bool
		ldapInit   bool
		authNInit  bool
		authZInit  bool
	)

		// - xl.meta metadata is still verified for quorum under lock()
		//   however writing the response doesn't need to serialize
		//   concurrent writers
		unlockOnDefer = true
		nsUnlocker = func() { lock.RUnlock(lkctx) }
	}

	fi, metaArr, onlineDisks, err := er.getObjectFileInfo(ctx, bucket, object, opts, true)
	if err != nil {
		return nil, toObjectErr(err, bucket, object)
	}

call <i>n</i> of <code>l.Unlock()</code> is synchronized before call <i>m</i> of <code>l.Lock()</code> returns.
</p>

<p>
This program:
</p>

<pre>
var l sync.Mutex
var a string

func f() {
	a = "hello, world"
	l.Unlock()
}

func main() {
	l.Lock()
	go f()
	l.Lock()
	print(a)
}
</pre>

	}

	ctx = plkctx.Context()
	defer partIDLock.Unlock(plkctx)

	// Read lock for upload id, only held while reading the upload metadata.
	uploadIDRLock := er.NewNSLock(bucket, pathJoin(object, uploadID))
	rlkctx, err := uploadIDRLock.GetRLock(ctx, globalOperationTimeout)
	if err != nil {
		return PartInfo{}, err
	}
	ctx = rlkctx.Context()
	defer uploadIDRLock.RUnlock(rlkctx)

	for {
		// Grab current values
		d.mu.RLock()
		minWait, maxWait := d.minSleep, d.maxSleep
		factor := d.factor
		cycle := d.cycle
		d.mu.RUnlock()
		// Don't sleep for really small amount of time
		wantSleep := time.Duration(float64(base) * factor)
		if wantSleep <= minWait {
			return
		}
		if maxWait > 0 && wantSleep > maxWait {

)

func getStorageViaEndpoint(endpoint Endpoint) StorageAPI {
	globalLocalDrivesMu.RLock()
	defer globalLocalDrivesMu.RUnlock()
	if len(globalLocalSetDrives) == 0 {
		return globalLocalDrivesMap[endpoint.String()]
	}
	return globalLocalSetDrives[endpoint.PoolIdx][endpoint.SetIdx][endpoint.DiskIdx]
}