ubifs: ubifs_link: Fix wrong name len calculating when UBIFS is encrypted补丁分析

UBIFS加密场景做硬链接，目录下新增的目录项长度计算有误，应该是加密后的长度（但实际是加密前的），导致更新的dir size有误。当把dir下所有目录项清空后，dir size变成负数，造成文件系统不一致

复现方法：
```
1. 加密方式挂载UBIFS到/root/temp
2. 
[root@localhost ~]# TMP=/root/temp
[root@localhost ~]# touch $TMP/file
[root@localhost ~]#  mkdir $TMP/dir
[root@localhost ~]#  stat $TMP/dir
  File: /root/temp/dir
  Size: 160             Blocks: 0          IO Block: 4096   directory
Device: 29h/41d Inode: 68          Links: 2
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2024-05-29 14:48:01.000000000 +0800
Modify: 2024-05-29 14:48:01.000000000 +0800
Change: 2024-05-29 14:48:01.000000000 +0800
 Birth: -
[root@localhost ~]#  for i in $(seq 1 8)
>  do
>    ln $TMP/file $TMP/dir/$i
>    unlink $TMP/dir/$i
>  done
[root@localhost ~]#  stat $TMP/dir
  File: /root/temp/dir
  Size: -96      #注意这里size变成负数       Blocks: 0          IO Block: 4096   directory
Device: 29h/41d Inode: 68          Links: 2
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2024-05-29 14:48:01.000000000 +0800
Modify: 2024-05-29 14:48:01.000000000 +0800
Change: 2024-05-29 14:48:01.000000000 +0800
 Birth: -

```

合入修复补丁后复现
```
[root@localhost ~]#  stat $TMP/dir
  File: /root/temp/dir
  Size: 160          # size是ino node size，代表目录为空，没有溢出   Blocks: 0          IO Block: 4096   directory
Device: 29h/41d Inode: 68          Links: 2
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2024-05-29 14:52:15.000000000 +0800
Modify: 2024-05-29 14:52:15.000000000 +0800
Change: 2024-05-29 14:52:15.000000000 +0800
 Birth: -
```

GVP openEuler/kernel

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GVPopenEuler/kernel

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