MOD: surface filesystem device error #2918

[PamelaMei-SAP]

To provide contribution on issue: #2918

Adding new label of "device_error" to surface error in node_filesystem_device_error.
Tests have been done for below scenarios, could you please help review and share your suggestion? Thanks.

Scenario-1: No device error
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 83276 0 83276 0 0 1786k 0 --:--:-- --:--:-- --:--:-- 1807k node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="",fstype="nfs4",mountpoint="/test_nfs"} 0

Scenario-2: mountpoint timeout
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 83312 0 83312 0 0 3053k 0 --:--:-- --:--:-- --:--:-- 3129k node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="mountpoint timeout",fstype="nfs4",mountpoint="/test_nfs"} 1

Scenario-3: error from statfs() e.g. permission denied
curl http://localhost:9100/metrics | grep node_filesystem_device_error | grep 100.70.222.247 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 83208 0 83208 0 0 2943k 0 --:--:-- --:--:-- --:--:-- 3009k node_filesystem_device_error{device="100.70.222.247:/share_5618cf05_5d99_44b6_a90d_8c2797929dbb",device_error="permission denied",fstype="nfs4",mountpoint="/test_nfs"} 1

[PamelaMei-SAP]

circleci failed in gofmt, re-submit later.

[SuperQ]

Please do not open and close PRs like this. It spams out system.

You do not need to create new PRs to update the commits.