看看umount2:

Linux 2.1.116 added the umount2() system call, which, like umount(), unmounts a target, but allows additional flags controlling the behaviour of the operation: MNT_FORCE (since Linux 2.1.116) Force unmount even if busy. (Only for NFS mounts.) MNT_DETACH (since Linux 2.4.11) Perform a lazy unmount: make the mount point unavailable for new accesses, and actually perform the unmount when the mount point ceases to be busy. MNT_EXPIRE (since Linux 2.6.8) Mark the mount point as expired. If a mount point is not currently in use, then an initial call to umount2() with this flag fails with the error EAGAIN, but marks the mount point as expired. The mount point remains expired as long as it isn't accessed by any process. A second umount2() call specifying MNT_EXPIRE unmounts an expired mount point. This flag cannot be specified with either MNT_FORCE or MNT_DETACH. Return Value On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

当您尝试卸载时，请确保您不在已安装的设备中。

当一切正常时，另一个选择是编辑/etc/fstab，添加noauto标志并重新启动机器。设备将不会被安装，当你完成任何操作时，移除标志并重新启动。

sudo fusermount -u -z <mounted path>

注意:不要对路径使用补全，因为这也会冻结终端。

使用exportfs -v检查导出的NFS文件系统。如果发现，使用exportfs -d share:/directory删除。这些不会在fuser/lsof列表中显示，并且会阻止umount成功。

众答:

如果该设备上有一个zfs池，至少当它是一个基于文件的池时，lsof将不会显示使用情况。但你可以简单地跑步

sudo zpool export mypool

然后卸载。