Comment 7 for bug 1270228

There is one commit that is not yet in 3.13.0-4 but has a very suspicious comment in the commit:

commit d1969a84dd6a44d375aa82bba7d6c38713a429c3
Author: Hugh Dickins <email address hidden>
Date: Thu Jan 16 15:26:48 2014 -0800

    percpu_counter: unbreak __percpu_counter_add()

    Commit 74e72f894d56 ("lib/percpu_counter.c: fix __percpu_counter_add()")
    looked very plausible, but its arithmetic was badly wrong: obvious once
    you see the fix, but maddening to get there from the weird tmpfs ENOSPCs

That would explain why there is ENOSPC reported without du agreeing when counting the usage.