umount: /langanglin: device is busy的解决办法

在umount文件系统时，经常会遇到umount: /langanglin: device is busy这样的问题不能umount，一般情况下是因为有别的进程在访问这个目录。下面说下两种解决方法

一：fuser

[root@lanv langanglin]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 19G 3.3G 15G 19% /
tmpfs 501M 0 501M 0% /dev/shm
/dev/sdb1 1004M 18M 936M 2% /langanglin
[root@lanv langanglin]# pwd
/langanglin

[root@lanv ~]# umount /langanglin/
umount: /langanglin: device is busy
umount: /langanglin: device is busy
[root@lanv ~]# fuser -mk /langanglin/
/langanglin/: 3714c
[root@lanv ~]# umount /langanglin/
[root@lanv ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 19G 3.3G 15G 19% /
tmpfs 501M 0 501M 0% /dev/shm
[root@lanv ~]#

这个方法一般情况下就能解决不能umount的问题，但是也有很多情况下，这个方法不起作用，例如占用这个文件系统的进程是nfs的handle进程。

方法二：umount -l

[root@lanv ~]# mount -t nfs 192.168.238.99:/langanglin/ /langanglin/
[root@lanv ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 19G 3.3G 15G 19% /
tmpfs 501M 0 501M 0% /dev/shm
192.168.238.99:/langanglin/
19G 3.3G 15G 19% /langanglin
[root@lanv ~]# cd /langanglin/
[root@lanv langanglin]# pwd
/langanglin

[root@lanv ~]# service nfs stop
Shutting down NFS mountd: [ OK ]
Shutting down NFS daemon: [ OK ]
Shutting down NFS quotas: [ OK ]
Shutting down NFS services: [ OK ]
[root@lanv ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/sda1              19G  3.3G   15G  19% /tmpfs                 501M     0  501M   0% /dev/shm
df:'/langanglin':Stale NFS file handle

[root@lanv ~]# umount -l /langanglin
[root@lanv ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 19G 3.3G 15G 19% /
tmpfs 501M 0 501M 0% /dev/shm
[root@lanv ~]#

umount -l参数：从文件系统层次结构分离文件系统和清理其所引用的文件系统，文件系统就不会出现busy的情况了。

-l Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all refer-ences to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)