When IOCB_FLAG_RESFD flag is set and iocb->aio_resfd is incorrect,
statement 'goto out_put_req' is executed. At label 'out_put_req',
aio_put_req(..) is called, which requires 'req->ki_filp' set.

Signed-off-by: Yan Zheng<yanzheng@21cn.com>
Cc: Zach Brown <zach.brown@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>