LU-3157 llite: A not locked mutex can be unlocked.

In case of memory pressure a not locked mutex can be unlocked
in function ll_file_open(). This is not allowed and subsequent
behavior is not defined.

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I21368247cac23038f9b995e9de328f9286909731
Reviewed-on: http://review.whamcloud.com/6028
Reviewed-by: John Hammond <johnlockwoodhammond@gmail.com>
Reviewed-by: Nikitas Angelinas <nikitas_angelinas@xyratex.com>
Tested-by: Hudson
Reviewed-by: Sebastien Buisson <sebastien.buisson@bull.net>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
LU-3283 llite: check ll_prep_md_op_data() using IS_ERR()

In ll_file_ioctl() and ll_swap_layouts() check the result of
ll_prep_md_op_data() using IS_ERR().

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Ib916635559863cd7a8aee3c88bb1d2bb2e7921b8
Reviewed-on: http://review.whamcloud.com/6275
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>