tmpfs breakage in 5.99.53?

[Julio Merino <jmmv%julipedia.org@localhost>]

Hello,

After upgrading my amd64 box from 5.99.52 to 5.99.53, the tests in 
tests/atf/test-programs/expect_test have started to fail as follows:

expect_test (1/1): 6 test cases
    expect_death: Failed: atf-check failed; see the output of the test 
for details
    expect_exit: Failed: atf-check failed; see the output of the test 
for details
    expect_fail: Passed.
    expect_pass: Passed.
    expect_signal: Failed: atf-check failed; see the output of the test 
for details
    expect_timeout: Failed: atf-check failed; see the output of the 
test for details

Upon further inspection, it seems like some writes are not reaching the 
disk.  The tests above open a new file, write the test result into it (a 
single text line) and immediately afterwards close the file.  Looking at 
these files after they have been created, they are empty.  Adding a 
sync() call between the write and the close makes the write reach the disk.

The breakage seems to be tmpfs-related.  The tests above fail because my 
/tmp is tmpfs, and atf-run uses /tmp by default for the test work 
directories.

The following should reproduce the problem:

# mount -t tmpfs tmpfs /tmp
# cd /usr/tests/atf/test-programs
# atf-run expect_test | atf-report

Or, if you want something more fine-grained:

# mount -t tmpfs tmpfs /foo/bar
# /usr/tests/atf/test-programs/c_helpers -r /not/in/tmpfs/result \
  expect_exit_but_pass
# /usr/tests/atf/test-programs/c_helpers -r /foo/bar/result \
  expect_exit_but_pass
# cat /foo/bar/result

/not/in/tmpfs/result will have some contents, but /foo/bar/result will not.

Any ideas?

Thanks.