umount

函数名称：vfsmount lock must be held for write

函数原型：static void umount_mnt(struct mount *mnt)

返回类型：void

参数：

类型	参数	名称
struct mount *	mnt

**调用者**
名称	描述
umount_tree	mount_lock must be held* namespace_sem must be held for write
__detach_mounts	__detach_mounts - lazily unmount all mounts on the specified dentry* During unlink, rmdir, and d_drop it is possible to loose the path* to an existing mountpoint, and wind up leaking the mount
SYSCALL_DEFINE2	pivot_root Semantics:* Moves the root file system of the current process to the directory put_old,* makes new_root as the new root file system of the current process, and sets* root/cwd of all processes which had them on the current root to new_root

函数逻辑报告