Revert "nfs: ensure correct writeback errors are returned on close()"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4T2WV


CVE: NA

--------------------------------

This reverts commit 67dd23f9.

filemap_sample_wb_err() will return 0 if nobody has seen the error yet,
then filemap_check_wb_err() will return the unchanged writeback error.

Reproducer:
        nfs server               |       nfs client
 --------------------------------|----------------------------------------------
 # No space left on server       |
 fallocate -l 100G /server/nospc |
                                 |
                                 | mount -t nfs $nfs_server_ip:/ /mnt
                                 |
                                 | # Expected error: No space left on device
                                 | dd if=/dev/zero of=/mnt/file count=1 ibs=1K
                                 |
                                 | # Release space on mountpoint
                                 | rm /mnt/nospc
                                 |
                                 | # Unexpected error: No space left on device
                                 | dd if=/dev/zero of=/mnt/file count=1 ibs=1K

Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>