return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
}
-static inline void reset_ahead_window(struct file_ra_state *ra)
-{
- /*
- * ... but preserve ahead_start + ahead_size value,
- * see 'recheck:' label in page_cache_readahead().
- * Note: We never use ->ahead_size as rvalue without
- * checking ->ahead_start != 0 first.
- */
- ra->ahead_size += ra->ahead_start;
- ra->ahead_start = 0;
-}
-
static inline void ra_off(struct file_ra_state *ra)
{
ra->start = 0;
ra->flags = 0;
ra->size = 0;
- reset_ahead_window(ra);
+ ra->ahead_start = 0;
+ ra->ahead_size = 0;
return;
}
{
unsigned long newsize = roundup_pow_of_two(size);
- if (newsize <= max / 32)
- newsize = newsize * 4;
+ if (newsize <= max / 64)
+ newsize = newsize * newsize;
else if (newsize <= max / 4)
- newsize = newsize * 2;
+ newsize = max / 4;
else
newsize = max;
return newsize;
* congestion. The ahead window will any way be closed
* in case we failed due to excessive page cache hits.
*/
- reset_ahead_window(ra);
+ ra->ahead_start = 0;
+ ra->ahead_size = 0;
}
return ret;
* If we get here we are doing sequential IO and this was not the first
* occurence (ie we have an existing window)
*/
+
if (ra->ahead_start == 0) { /* no ahead window yet */
if (!make_ahead_window(mapping, filp, ra, 0))
- goto recheck;
+ goto out;
}
-
/*
* Already have an ahead window, check if we crossed into it.
* If so, shift windows and issue a new ahead window.
ra->start = ra->ahead_start;
ra->size = ra->ahead_size;
make_ahead_window(mapping, filp, ra, 0);
-recheck:
- /* prev_page shouldn't overrun the ahead window */
- ra->prev_page = min(ra->prev_page,
- ra->ahead_start + ra->ahead_size - 1);
}
out:
return ra->prev_page + 1;
}
-EXPORT_SYMBOL_GPL(page_cache_readahead);
/*
* handle_ra_miss() is called when it is known that a page which should have