address_space

include/linux/fs.h

struct address_space {
	struct inode		*host;
	struct xarray		i_pages;
	gfp_t			gfp_mask;
	atomic_t		i_mmap_writable;
#ifdef CONFIG_READ_ONLY_THP_FOR_FS
	/* number of thp, only for non-shmem files */
	atomic_t		nr_thps;
#endif
	struct rb_root_cached	i_mmap;
	struct rw_semaphore	i_mmap_rwsem;
	unsigned long		nrpages;
	unsigned long		nrexceptional;
	pgoff_t			writeback_index;
	const struct address_space_operations *a_ops;
	unsigned long		flags;
	errseq_t		wb_err;
	spinlock_t		private_lock;
	struct list_head	private_list;
	void			*private_data;
} __attribute__((aligned(sizeof(long)))) __randomize_layout;

* address_space 객체는 파일마다 1개만 생긴다.

 

include/linux/fs.h

struct address_space_operations {
	int (*writepage)(struct page *page, struct writeback_control *wbc);
	int (*readpage)(struct file *, struct page *);

	/* Write back some dirty pages from this mapping. */
	int (*writepages)(struct address_space *, struct writeback_control *);

	/* Set a page dirty.  Return true if this dirtied it */
	int (*set_page_dirty)(struct page *page);

	/*
	 * Reads in the requested pages. Unlike ->readpage(), this is
	 * PURELY used for read-ahead!.
	 */
	int (*readpages)(struct file *filp, struct address_space *mapping,
			struct list_head *pages, unsigned nr_pages);

	int (*write_begin)(struct file *, struct address_space *mapping,
				loff_t pos, unsigned len, unsigned flags,
				struct page **pagep, void **fsdata);
	int (*write_end)(struct file *, struct address_space *mapping,
				loff_t pos, unsigned len, unsigned copied,
				struct page *page, void *fsdata);

	/* Unfortunately this kludge is needed for FIBMAP. Don't use it */
	sector_t (*bmap)(struct address_space *, sector_t);
	void (*invalidatepage) (struct page *, unsigned int, unsigned int);
	int (*releasepage) (struct page *, gfp_t);
	void (*freepage)(struct page *);
	ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
	/*
	 * migrate the contents of a page to the specified target. If
	 * migrate_mode is MIGRATE_ASYNC, it must not block.
	 */
	int (*migratepage) (struct address_space *,
			struct page *, struct page *, enum migrate_mode);
	bool (*isolate_page)(struct page *, isolate_mode_t);
	void (*putback_page)(struct page *);
	int (*launder_page) (struct page *);
	int (*is_partially_uptodate) (struct page *, unsigned long,
					unsigned long);
	void (*is_dirty_writeback) (struct page *, bool *, bool *);
	int (*error_remove_page)(struct address_space *, struct page *);

	/* swapfile support */
	int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
				sector_t *span);
	void (*swap_deactivate)(struct file *file);
};