int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
			      unsigned int len)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head bh;
	unsigned int shift;
	u64 lblock, lblock_stop, size;
	u64 end_of_file;

	if (!len)
		return 0;

	if (gfs2_is_stuffed(ip)) {
		if (offset + len >
		    sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
			return 1;
		return 0;
	}

	shift = sdp->sd_sb.sb_bsize_shift;
	BUG_ON(gfs2_is_dir(ip));
	end_of_file = (i_size_read(&ip->i_inode) + sdp->sd_sb.sb_bsize - 1) >> shift;
	lblock = offset >> shift;
	lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
	if (lblock_stop > end_of_file)
		return 1;

	size = (lblock_stop - lblock) << shift;
	do {
		bh.b_state = 0;
		bh.b_size = size;
		gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
		if (!buffer_mapped(&bh))
			return 1;
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);

	return 0;
}
int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
			      unsigned int len)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head bh;
	unsigned int shift;
	u64 lblock, lblock_stop, size;
	u64 end_of_file;

	if (!len)
		return 0;

	if (gfs2_is_stuffed(ip)) {
		if (offset + len >
		    sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
			return 1;
		return 0;
	}

	shift = sdp->sd_sb.sb_bsize_shift;
	BUG_ON(gfs2_is_dir(ip));
	end_of_file = (i_size_read(&ip->i_inode) + sdp->sd_sb.sb_bsize - 1) >> shift;
	lblock = offset >> shift;
	lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
	if (lblock_stop > end_of_file)
		return 1;

	size = (lblock_stop - lblock) << shift;
	do {
		bh.b_state = 0;
		bh.b_size = size;
		gfs2_block_map(&ip->i_inode, lblock, &bh, 0);
		if (!buffer_mapped(&bh))
			return 1;
		size -= bh.b_size;
		lblock += (bh.b_size >> ip->i_inode.i_blkbits);
	} while(size > 0);

	return 0;
}