ocfs2: use list_for_each_entry() instead of list_for_each()

[dan.carpenter@oracle.com: fix up some NULL dereference bugs]
Signed-off-by: Dong Fang <yp.fangdong@gmail.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jeff Liu <jeff.liu@oracle.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>