On Sat, 2005-01-29 at 03:35, Oleg Nesterov wrote:
> > This patch introduces make_ahead_window() function for
> > simplification of page_cache_readahead.
>
> If you will count this patch acceptable, I'll rediff it against
> next mm iteration.
>
> For your convenience here is the code with the patch applied.
>
> int make_ahead_window(mapping, filp, ra, int force)
> {
> int block, ret;
>
> ra->ahead_size = get_next_ra_size(ra);
> ra->ahead_start = ra->start + ra->size;
>
> block = force || (ra->prev_page >= ra->ahead_start);
> ret = blockable_page_cache_readahead(mapping, filp,
> ra->ahead_start, ra->ahead_size, ra, block);
>
> if (!ret && !force) {
As steve pointed out this should be :
if ( !ret && ! block ) {
> ra->ahead_start = 0;
> ra->ahead_size = 0;
> }
>
> return ret;
> }
>
> unsigned long page_cache_readahead(mapping, ra, filp, offset, req_size)
> {
> unsigned long max, newsize = req_size;
> int sequential = (offset == ra->prev_page + 1);
>
> if (offset == ra->prev_page && req_size == 1 && ra->size != 0)
> goto out;
> ra->prev_page = offset;
> max = get_max_readahead(ra);
> newsize = min(req_size, max);
>
> if (newsize == 0 || (ra->flags & RA_FLAG_INCACHE)) {
> newsize = 1;
At this point prev_page has to be updated:
ra->prev_page = offset;
> goto out;
> }
>
> ra->prev_page += newsize - 1;
>
> if ((ra->size == 0 && offset == 0) ||
> (ra->size == -1 && sequential)) {
> ra->size = get_init_ra_size(newsize, max);
> ra->start = offset;
> if (!blockable_page_cache_readahead(mapping, filp, offset,
> ra->size, ra, 1))
> goto out;
>
> if (req_size >= max)
> make_ahead_window(mapping, filp, ra, 1);
>
> goto out;
> }
>
> if (!sequential || (ra->size == 0)) {
> ra_off(ra);
> blockable_page_cache_readahead(mapping, filp, offset, newsize,
> ra, 1);
> goto out;
> }
>
>
> if (ra->ahead_start == 0) {
> if (!make_ahead_window(mapping, filp, ra, 0))
> goto out;
> }
>
> if (ra->prev_page >= ra->ahead_start) {
> ra->start = ra->ahead_start;
> ra->size = ra->ahead_size;
> make_ahead_window(mapping, filp, ra, 0);
> }
> out:
> return newsize;
> }
Otherwise this code looks much cleaner and correct. Can you send me a
updated patch. I will run it through my test harness.
RP
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