Comment 4 for bug 1236041

A bit more googling shows that this change was actually not suitable for inclusion in kernels versions prior to 3.8.0:
http://oss.sgi.com/archives/xfs/2013-02/msg00201.html

...which is why it had been reverted in 3.7.9, after it was added by mistake in a previous 3.7.x version:
https://lkml.org/lkml/2013/2/15/638

Hope this helps.