vfs address_space

struct address_space {
    struct inode        *host;        /* owner: inode, block_device */
    struct radix_tree_root    page_tree;    /* radix tree of all pages */
    spinlock_t        tree_lock;    /* and lock protecting it */
    unsigned int        i_mmap_writable;/* count VM_SHARED mappings */
    struct prio_tree_root    i_mmap;        /* tree of private and shared mappings */
    struct list_head    i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
    spinlock_t        i_mmap_lock;    /* protect tree, count, list */
    unsigned int        truncate_count;    /* Cover race condition with truncate */
    unsigned long        nrpages;    /* number of total pages */
    pgoff_t            writeback_index;/* writeback starts here */
    const struct address_space_operations *a_ops;    /* methods */
    unsigned long        flags;        /* error bits/gfp mask */
    struct backing_dev_info *backing_dev_info; /* device readahead, etc */
    spinlock_t        private_lock;    /* for use by the address_space */
    struct list_head    private_list;    /* ditto */
    struct address_space    *assoc_mapping;    /* ditto */
} __attribute__((aligned(sizeof(long))));

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

    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 long);
    int (*releasepage) (struct page *, gfp_t);
    ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
            loff_t offset, unsigned long nr_segs);
    int (*get_xip_mem)(struct address_space *, pgoff_t, int,
                        void **, unsigned long *);
    /* migrate the contents of a page to the specified target */
    int (*migratepage) (struct address_space *,
            struct page *, struct page *);
    int (*launder_page) (struct page *);
    int (*is_partially_uptodate) (struct page *, read_descriptor_t *,
                    unsigned long);
    int (*error_remove_page)(struct address_space *, struct page *);
};