xfstests xfs/293 failure with current xfstests

[Ross Zwisler]

It looks like the current version of xfsprogs (v4.3.0) has an inconsistency
between its documentation and implementation that is making the xfstest
xfs/293 fail:

./check xfs/293
FSTYP         -- xfs (debug)
PLATFORM      -- Linux/x86_64 lorwyn 4.5.0-rc1
MKFS_OPTIONS  -- -f -bsize=4096 /dev/pmem0p2
MOUNT_OPTIONS -- -o dax -o context=system_u:object_r:nfs_t:s0 /dev/pmem0p2 /mnt/xfstests_scratch

xfs/293	 - output mismatch (see /root/xfstests/results//xfs/293.out.bad)
    --- tests/xfs/293.out	2015-10-02 10:19:36.836796097 -0600
    +++ /root/xfstests/results//xfs/293.out.bad	2016-01-29 10:41:25.530512911 -0700
    @@ -1,2 +1,4 @@
     QA output created by 293
     Silence is golden
    +help not documented in the xfs_io manpage
    +zero not documented in the xfs_io manpage
    ...
    (Run 'diff -u tests/xfs/293.out /root/xfstests/results//xfs/293.out.bad'  to see the entire diff)
Ran: xfs/293
Failures: xfs/293
Failed 1 of 1 tests

"help" and "zero" are indeed options in xfs_io, but aren't listed in the man
page.

Thanks,
- Ross