> 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) {
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;
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;
}
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