[PATCH v2] Mount /tmp as tmpfs in test-container and run utime tests in it

[Arjun Shankar]

Hi Adhemerval,

> Sorry, I still think we should not gloss over buggy filesystems.
> I really want this tests to be tested on multiple different filesystem
> and check if the interface is really working as intended.  There is no
> point in providing y2038 interfaces that might be broken when used
> on different FS that is actually used in the wild.

Testing various filesystems is certainly of value when done
systematically. The issues I see right now are:

In its present state, this test can fail even though there is no known
glibc bug in the functionality it tests. This makes the test flaky
when it comes to verifying glibc functionality itself.

In the future, this test could also fail because of a glibc regression.
At that point someone used to running the test and seeing it fail
often in the past could disregard the failure, or the filesystem bug
could mask a glibc regression, thus causing us to miss catching the
glibc regression. So this test is also flaky when it comes to catching
a potential regression.

A test that doesn't always pass when the glibc interface under test is
actually working well and doesn't always clearly identify a regression
because it is masked by a well known bug in some other component is a
test that has potential for improvement.

The way I understand it, this is a unit test of a glibc interface. The
goal of unit testing is to isolate each part of the program and show
that the individual parts are correct. In that spirit, I feel that
running this test in isolation from the filesystem has value and is an
improvement over its present state.

The XFS bug is well known. I feel that the value to this community
from consistently verifying glibc functionality is higher than the
value of reminding ourselves of a well known bug in another component.

I hope this makes a convincing argument, but irrespective of whether
you approve of this patch or the direction it takes: thank you for the
time you have taken to respond to these patches.

Cheers,
Arjun