如何可靠识别Linux系统下对应QNAP前置USB口的/sys/device设备

大多数QNAP NAS的正面配有一个“复制”按钮，旁边是一个USB-A接口。按下该按钮会复制插入旁边USB接口的硬盘内容。我想为Linux开发该功能，但无法找到可靠的方法确定/sys/devices下哪个设备对应该前置USB接口。在我的设备上，插入该接口的USB3硬盘会显示在/sys/devices/.../usb2/2-4/2-4:1.0路径下，而USB2闪存盘则显示在/sys/devices/.../usb1/1-4/1-4:1.0路径下。

我曾以为通过/sys/devices/.../physical_location可以解决问题，但该接口对USB2和USB3设备上报的位置信息不一致：USB3设备的信息为{"horizontal_position": "left", "vertical_position": "lower", "panel": "left"}，USB2设备则为{"horizontal_position": "center", "vertical_position": "lower", "panel": "left"}。

既然QNAP的系统可以实现该功能，那必然存在匹配该USB接口与对应存储设备的方法，但我搜索多日仍未找到。

补充说明 #

为准确说明，以下是各场景下的lsusb -tv输出：

前置USB口插入USB2设备时输出 #

# lsusb -tv
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 2537:1081 Norelsys 
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 4: Dev 4, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 090c:1000 Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) Flash Drive

前置USB口插入USB3设备时输出 #

# lsusb -tv
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 2537:1081 Norelsys 
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
    |__ Port 4: Dev 20, If 0, Class=Mass Storage, Driver=uas, 5000M
        ID 04e8:61b5 Samsung Electronics Co., Ltd M3 Portable Hard Drive 2TB
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub

其他测试场景 #

1. 后置两个接口分别插入USB2和USB3设备，前置接口无设备：

# lsusb -tv
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 2537:1081 Norelsys 
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
    |__ Port 3: Dev 21, If 0, Class=Mass Storage, Driver=uas, 5000M
        ID 04e8:61b5 Samsung Electronics Co., Ltd M3 Portable Hard Drive 2TB
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 090c:1000 Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) Flash Drive

2. 与上述情况相同，但两个设备互换，前置接口仍无设备：

# lsusb -tv 
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 2537:1081 Norelsys 
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
    |__ Port 2: Dev 22, If 0, Class=Mass Storage, Driver=uas, 5000M
        ID 04e8:61b5 Samsung Electronics Co., Ltd M3 Portable Hard Drive 2TB
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 3: Dev 6, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 090c:1000 Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) Flash Drive

3. 3个USB-A接口均插入USB2设备：

# lsusb -tv
/:  Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/2p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 2, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 2537:1081 Norelsys 
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
    ID 1d6b:0003 Linux Foundation 3.0 root hub
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 480M
    ID 1d6b:0002 Linux Foundation 2.0 root hub
    |__ Port 2: Dev 12, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 058f:6387 Alcor Micro Corp. Flash Drive
    |__ Port 3: Dev 11, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 058f:6387 Alcor Micro Corp. Flash Drive
    |__ Port 4: Dev 10, If 0, Class=Mass Storage, Driver=usb-storage, 480M
        ID 090c:1000 Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) Flash Drive

当设备为USB2类型时，始终使用Bus 01.Port 1，这无法帮助我区分设备是插入前置还是后置接口。另外注意Bus 03.Port 1似乎是承载QNAP系统的内部存储。

内容的提问来源于stack exchange，提问作者Augier