VFS之文件系统描述

Linux内核对文件系统类型抽象后的数据结构，每个文件系统都有此类型的一个实例，并且具体 文件系统需要静态定义此类型的对象，然后通过register_filesystem相关接口向系统注册。 或者调用unregister_filesystem()注销。

struct file_system_type {  const char *name;  int fs_flags; #define FS_REQUIRES_DEV  1 #define FS_BINARY_MOUNTDATA 2 #define FS_HAS_SUBTYPE  4 #define FS_USERNS_MOUNT  8 /* Can be mounted by userns root */ #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */  struct dentry *(*mount) (struct file_system_type *, int,          const char *, void *);  void (*kill_sb) (struct super_block *);  struct module *owner;  struct file_system_type * next;  struct hlist_head fs_supers;

 struct lock_class_key s_lock_key;  struct lock_class_key s_umount_key;  struct lock_class_key s_vfs_rename_key;  struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];

 struct lock_class_key i_lock_key;  struct lock_class_key i_mutex_key;  struct lock_class_key i_mutex_dir_key; };