!5696 NFS: Fix an Oopsable condition in __nfs_pageio_add_request()

Merge Pull Request from: @ci-robot 
 
PR sync from: ZhaoLong Wang <wangzhaolong1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/GUUN3DUMW6T7C4QO2YMJ5QSG3645E7XH/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9BHTI 
 
Link:https://gitee.com/openeuler/kernel/pulls/5696

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>