On top of "readahead: cleanup blockable_page_cache_readahead()",
see http://marc.theaimsgroup.com/?l=linux-kernel&m=110927049500942
Currently page_cache_readahead() treats ra->size == 0 (first read)
and ra->size == -1 (ra_off was called) separately, but does exactly
the same in both cases.
With this patch we may assume that the reading starts in 'ra_off()'
state, so we don't need to consider the first read as a special case.
Signed-off-by: Oleg Nesterov <[EMAIL PROTECTED]>
--- 2.6.11/mm/readahead.c~ 2005-02-04 21:33:40.000000000 +0300
+++ 2.6.11/mm/readahead.c 2005-02-04 21:33:57.000000000 +0300
@@ -55,7 +55,7 @@ static inline void ra_off(struct file_ra
{
ra->start = 0;
ra->flags = 0;
- ra->size = -1;
+ ra->size = 0;
ra->ahead_start = 0;
ra->ahead_size = 0;
return;
@@ -452,7 +452,7 @@ page_cache_readahead(struct address_spac
* perturbing the readahead window expansion logic.
* If size is zero, there is no read ahead window so we need one
*/
- if (offset == ra->prev_page && req_size == 1 && ra->size != 0)
+ if (offset == ra->prev_page && req_size == 1)
goto out;
ra->prev_page = offset;
@@ -471,9 +471,7 @@ page_cache_readahead(struct address_spac
* at start of file, and grow the window fast. Or detect first
* sequential access
*/
- if ((ra->size == 0 && offset == 0) /* first io and start of file */
- || (ra->size == -1 && sequential)) {
- /* First sequential */
+ if (sequential && ra->size == 0) {
ra->size = get_init_ra_size(newsize, max);
ra->start = offset;
if (!blockable_page_cache_readahead(mapping, filp, offset,
@@ -499,7 +497,7 @@ page_cache_readahead(struct address_spac
* partial page reads and first access were handled above,
* so this must be the next page otherwise it is random
*/
- if (!sequential || (ra->size == 0)) {
+ if (!sequential) {
ra_off(ra);
blockable_page_cache_readahead(mapping, filp, offset,
newsize, ra, 1);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
