filemap_flush_range
ret = filemap_flush_range(mapping, offset, endbyte);
int filemap_flush_range(struct address_space *mapping, loff_t start,
filemap_flush_range(mapping, iocb->ki_pos - count,
filemap_flush_range(mapping, offset, endbyte);
EXPORT_SYMBOL_GPL(filemap_flush_range);
return filemap_flush_range(mapping, 0, LLONG_MAX);