Re: [PATCH 04/33] readahead: page flag PG_readahead

Andrew Morton
2006-05-25T16:23:46Z

Wu Fengguang <wfg@mail.ustc.edu.cn> wrote:
>
> An new page flag PG_readahead is introduced as a look-ahead mark, which
> reminds the caller to give the adaptive read-ahead logic a chance to do
> read-ahead ahead of time for I/O pipelining.
>
> It roughly corresponds to `ahead_start' of the stock read-ahead logic.
>

This isn't a very revealing description of what this flag does.

> +#define __SetPageReadahead(page) __set_bit(PG_readahead, &(page)->flags)

uh-oh. This is extremly risky. Needs extensive justification, please.