docs: filesystems: vfs: actualize struct file_system_type description

struct file_system_type

-----------------------

This describes the filesystem.  As of kernel 2.6.39, the following

This describes the filesystem.  The following

members are defined:

.. code-block:: c

	struct file_system_type {

		const char *name;

		int fs_flags;

		int (*init_fs_context)(struct fs_context *);

		const struct fs_parameter_spec *parameters;

		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 list_head fs_supers;

		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 invalidate_lock_key;

		struct lock_class_key i_mutex_dir_key;

	};

``name``

``fs_flags``

	various flags (i.e. FS_REQUIRES_DEV, FS_NO_DCACHE, etc.)

``init_fs_context``

	Initializes 'struct fs_context' ->ops and ->fs_private fields with

	filesystem-specific data.

``parameters``

	Pointer to the array of filesystem parameters descriptors

	'struct fs_parameter_spec'.

	More info in Documentation/filesystems/mount_api.rst.

``mount``

	the method to call when a new instance of this filesystem should

	be mounted

``next``

	for internal VFS use: you should initialize this to NULL

  s_lock_key, s_umount_key: lockdep-specific

``fs_supers``

	for internal VFS use: hlist of filesystem instances (superblocks)

  s_lock_key, s_umount_key, s_vfs_rename_key, s_writers_key,

  i_lock_key, i_mutex_key, invalidate_lock_key, i_mutex_dir_key: lockdep-specific

The mount() method has the following arguments: