[FS] Implement block_page_mkwrite.

	return 0;

}

/*

 * block_page_mkwrite() is not allowed to change the file size as it gets

 * called from a page fault handler when a page is first dirtied. Hence we must

 * be careful to check for EOF conditions here. We set the page up correctly

 * for a written page which means we get ENOSPC checking when writing into

 * holes and correct delalloc and unwritten extent mapping on filesystems that

 * support these features.

 *

 * We are not allowed to take the i_mutex here so we have to play games to

 * protect against truncate races as the page could now be beyond EOF.  Because

 * vmtruncate() writes the inode size before removing pages, once we have the

 * page lock we can determine safely if the page is beyond EOF. If it is not

 * beyond EOF, then the page is guaranteed safe against truncation until we

 * unlock the page.

 */

int

block_page_mkwrite(struct vm_area_struct *vma, struct page *page,

		   get_block_t get_block)

{

	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;

	unsigned long end;

	loff_t size;

	int ret = -EINVAL;

	lock_page(page);

	size = i_size_read(inode);

	if ((page->mapping != inode->i_mapping) ||

	    ((page->index << PAGE_CACHE_SHIFT) > size)) {

		/* page got truncated out from underneath us */

		goto out_unlock;

	}

	/* page is wholly or partially inside EOF */

	if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)

		end = size & ~PAGE_CACHE_MASK;

	else

		end = PAGE_CACHE_SIZE;

	ret = block_prepare_write(page, 0, end, get_block);

	if (!ret)

		ret = block_commit_write(page, 0, end);

out_unlock:

	unlock_page(page);

	return ret;

}

/*

 * nobh_prepare_write()'s prereads are special: the buffer_heads are freed

EXPORT_SYMBOL(__wait_on_buffer);

EXPORT_SYMBOL(block_commit_write);

EXPORT_SYMBOL(block_prepare_write);

EXPORT_SYMBOL(block_page_mkwrite);

EXPORT_SYMBOL(block_read_full_page);

EXPORT_SYMBOL(block_sync_page);

EXPORT_SYMBOL(block_truncate_page);

int generic_cont_expand(struct inode *inode, loff_t size);

int generic_cont_expand_simple(struct inode *inode, loff_t size);

int block_commit_write(struct page *page, unsigned from, unsigned to);

int block_page_mkwrite(struct vm_area_struct *vma, struct page *page,

				get_block_t get_block);

void block_sync_page(struct page *);

sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);

int generic_commit_write(struct file *, struct page *, unsigned, unsigned);