PHP move_uploaded_file权限被拒绝(权限设置为755)

我试图使用一个简单的HTML输入表单上传用户的照片,但遇到以下错误。我已将上载文件夹的权限设置为755。我尝试了777,这是有效的,但我读到将其设置为777是不建议的,我应该可以使用755?

Warning: move_uploaded_file(uploads/2014_08_21_11_03_14k.jpg) [function.move-uploaded-file]: failed to open stream: Permission denied in /home/yadayada/register.php on line 136
Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move '/tmp/php8KQwyh' to 'uploads/2014_08_21_11_03_14k.jpg' in /home/yadayada/register.php on line 136

这是我的php代码:

$userPhotoUrl = 'uploads/'.date('Y_m_d_H_i_s').$_FILES['photo']['name'];

if (is_uploaded_file($_FILES['photo']['tmp_name'])) {
    if (!move_uploaded_file($_FILES['photo']['tmp_name'], $userPhotoUrl)) {
        // show error message
        return;
    }
} else {
    // show error message
    return;
}