老师，我的用户头像是存在的，但无法显示？

<div class="form-group">
    <label for="input_face">
        <span class="glyphicon glyphicon-picture"></span>
        &nbsp;{{form.face.label}}
    </label>
    {{form.face}}
    {% if user.face %}
    <img src="{{url_for('static',filename='uploads/users/'+user.face)}}" style="width:100px"
         class="img-responsive img-rounded">
    {% else %}
    <img data-src="holder.js/100x100" class="img-responsive img-rounded">
    {% endif %}
</div>

#会员资料修改
@home.route('/user',methods=['GET','POST'])
@user_login_req
def user():
    form=UserdetailForm()
    user=User.query.get(int(session['user_id']))
    form.face.validators=[]
    if request.method=='GET':
        form.name.data=user.name
        form.email.data = user.email
        form.phone.data = user.phone
        form.info.data = user.info
    if form.validate_on_submit():
        data=form.data
        file_face=secure_filename(form.face.data.filename)
        if not os.path.exists(app.config['FC_DIR']):
            os.makedirs(app.config['FC_DIR'])
            os.chmod(app.config['FC_DIR'],'rw')
        user.face=change_filename(file_face)
        form.face.data.save(app.config['FC_DIR']+user.face)
        name_count=User.query.filter_by(name=data['name']).count()
        if name_count==1 and data['name']!=user.name:
            flash('昵称已存在！','err')
            return redirect(url_for('home.user'))

        email_count = User.query.filter_by(email=data['email']).count()
        if email_count == 1 and data['email'] != user.email:
            flash('邮箱已存在！', 'err')
            return redirect(url_for('home.user'))

        phone_count = User.query.filter_by(phone=data['phone']).count()
        if phone_count == 1 and data['phone'] != user.phone:
            flash('手机号码已存在！', 'err')
            return redirect(url_for('home.user'))
        user.name = data['name']
        user.email = data['email']
        user.phone = data['phone']
        user.info=data['info']
        db.session.add(user)
        db.session.commit()
        flash('修改成功', 'ok')
        return redirect(url_for('home.user'))
    return render_template('home/user.html',form=form,user=user)