how to implement prepare_write, commit_write for ubifs

[Ivan Chan]

Hi all,

I am porting UBIFS/UBI to 2.6.4 kernel, however, 2.6.4 kernel requires
prepare_write, commit_write in address_space_operations (defined in
include/linux/fs.h),
but it is no longer exists in 2.6.2x kernel.

How can I rewrite these function for 2.6.4 kernel?

In 2.6.2x, there is similar function write_begin, and write_end, but
the API requires
struct address_space *mapping,  struct page **pagep, void **fsdata,

Is that possible and how to provide this argument in 2.6.4 kernel?

Regards,
Ivan

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

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

    /* Set a page dirty */
    int (*set_page_dirty)(struct page *page);

    int (*readpages)(struct file *filp, struct address_space *mapping,
            struct list_head *pages, unsigned nr_pages);

    /*
     * ext3 requires that a successful prepare_write() call be followed
     * by a commit_write() call - they must be balanced
     */
    int (*prepare_write)(struct file *, struct page *, unsigned, unsigned);
    int (*commit_write)(struct file *, struct page *, unsigned, unsigned);
    /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
    sector_t (*bmap)(struct address_space *, sector_t);
    int (*invalidatepage) (struct page *, unsigned long);
    int (*releasepage) (struct page *, int);
    int (*direct_IO)(int, struct kiocb *, const struct iovec *iov,
            loff_t offset, unsigned long nr_segs);
};

2.6.2x

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);
};