如果再conf 文件中指定了data_dir 参数，则在该路径中获取
如果conf 文件中没有指定：
In V8 filestore is used by default.. no need for extra setup...
If user runnig odoo has home set to /opt/odoo , then default filestore location is:
/opt/odoo/.local/share/Odoo/filestore/database_name
参考:
https://www.odoo.com/zh_CN/forum/help-1/ir-attachment-location-for-v8-45571