[Linux] disk_io_counters() broken on Linux kernel 5.5

[jonringer]

Platform

• Linux 5.5
• psutil==5.6.7
• python3.7

Bug description
linux 5.4

$ cat /proc/diskstats
   1       0 ram0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   1       1 ram1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   1       2 ram2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

linux 5.5

$ cat /proc/diskstats
   1       0 ram0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   1       1 ram1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   1       2 ram2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Error
It produces the following:

  File "/nix/store/3zqd997wmhxl1r8dhwjwgczx5rrxg18n-python3.7-psutil-5.6.7/lib/python3.7/site-packages/psutil/__init__.py", line 2168, in disk_io_counters
    rawdict = _psplatform.disk_io_counters(**kwargs)
  File "/nix/store/3zqd997wmhxl1r8dhwjwgczx5rrxg18n-python3.7-psutil-5.6.7/lib/python3.7/site-packages/psutil/_pslinux.py", line 1125, in disk_io_counters
    for entry in gen:
  File "/nix/store/3zqd997wmhxl1r8dhwjwgczx5rrxg18n-python3.7-psutil-5.6.7/lib/python3.7/site-packages/psutil/_pslinux.py", line 1098, in read_procfs
    raise ValueError("not sure how to interpret line %r" % line)
ValueError: not sure how to interpret line '   1       0 ram0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0\n'

Additional context:
according to: https://www.kernel.org/doc/Documentation/ABI/testing/procfs-diskstats
they added two new fields:

		Kernel 5.5+ appends two more fields for flush requests:

		19 - flush requests completed successfully
		20 - time spent flushing

[logan2611]

Was just about to come here and write this bug report, lol.
Can confirm I am also having this issue on kernel 5.5.3, psutil 5.6.7 and python 3.8.1

[jonringer]

actually, this looks to be resolved by 2e0952e I was about to make a PR.

They just need to cut a new release