The error code in gfs2_rs_alloc() is set to ENOMEM when error
but never be used, instead, gfs2_rs_alloc() always return 0.
Fix to return 'error'.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>