This is the case e.g. if JFFS2 partition is full.
see: https://www.mail-archive.com/linux-unionfs@vger.kernel.org/msg00246.html
(a small error in a logmessage was changed and reported upstream)
runtime tested on ar71xx with kernel 3.18.11 and r45772
this paritially fixes#19564
Signed-off-by: Bastian Bittorf <bittorf@bluebottle.com>
Acked-by: Jo-Philipp Wich <jow@openwrt.org>
SVN-Revision: 45833