defer l.mutex.Unlock()
	var locksHeld int64
	if locksHeld, reply = l.lockMap[args.Resources[0]]; !reply { // No lock is held on the given name
		return false, fmt.Errorf("RUnlock attempted on an unlocked entity: %s", args.Resources[0])
	}
	if reply = locksHeld != WriteLock; !reply { // A write-lock is held, cannot release a read lock
		return false, fmt.Errorf("RUnlock attempted on a write locked entity: %s", args.Resources[0])
	}

	defer m.respMu.Unlock()
	if m.closed {
		return errors.New("mux client closed")
	}
	return m.sendLocked(msg)
}

// sendLocked the message. msg.Seq and msg.MuxID will be set.
// m.respMu must be held.
func (m *muxClient) sendLocked(msg message) error {
	dst := GetByteBufferCap(msg.Msgsize())
	msg.Seq = m.SendSeq
	msg.MuxID = m.MuxID
	msg.Flags |= m.BaseFlags
	if debugPrint {

// Assumes that c.Lock is held by caller.
func (c *iamCache) buildUserGroupMemberships() {
	for group, gi := range c.iamGroupsMap {
		c.updateGroupMembershipsMap(group, &gi)
	}
}

// updateGroupMembershipsMap - updates the memberships map for a
// group. IMPORTANT: Assumes c.Lock() is held by caller.
func (c *iamCache) updateGroupMembershipsMap(group string, gi *GroupInfo) {

	defer l.mutex.Unlock()
	var lri []lockRequesterInfo

	resource := args.Resources[0]
	if lri, reply = l.lockMap[resource]; !reply {
		// No lock is held on the given name
		return true, nil
	}
	if isWriteLock(lri) {
		// A write-lock is held, cannot release a read lock
		return false, fmt.Errorf("RUnlock attempted on a write locked entity: %s", resource)
	}
	l.removeEntry(resource, args, &lri)

	if data.Size() < -1 {
		bugLogIf(ctx, errInvalidArgument, logger.ErrorKind)
		return pi, toObjectErr(errInvalidArgument)
	}

	// 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
	}

	for !releaseAll(ctx, dm.clnt, tolerance, owner, &locks, isReadLock, restClnts, dm.Names...) {
		time.Sleep(time.Duration(dm.rng.Float64() * float64(dm.lockRetryMinInterval)))
	}
}

// RUnlock releases a read lock held on dm.
//
// It is a run-time error if dm is not locked on entry to RUnlock.
func (dm *DRWMutex) RUnlock(ctx context.Context) {
	dm.m.Lock()
	dm.cancelRefresh()
	dm.m.Unlock()

	// Initialize a new ticker with 1 minute between each ticks.
	lkTimer := time.NewTimer(lockMaintenanceInterval)
	// Stop the timer upon returning.
	defer lkTimer.Stop()

	for {
		// Verifies every minute for locks held more than 2 minutes.
		select {
		case <-ctx.Done():
			return
		case <-lkTimer.C:
			globalLockServer.expireOldLocks(lockValidityDuration)

			// Reset the timer for next cycle.