LU-2370 ldiskfs: fix procfs access to mb groups.
backporting a fix
95599968d19db175829fb580baa6b68939b320fb
from kernel.org
with additional memory allocation error handling.
Xyratex-bug-id: MRP-757
Change-Id: I33e7daa18c8b74e34bbd1e12120e27ab7be23cf5
Signed-off-by: Alexey Lyashkov <alexey_lyashkov@xyratex.com>
Reviewed-on: http://review.whamcloud.com/4654
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>