[PATCH 08/33] readahead: common macros

Wu Fengguang
2006-05-24T11:19:31Z

[-- Attachment #1: readahead-common-macros.patch --]
[-- Type: text/plain, Size: 1649 bytes --]

Define some common used macros for the read-ahead logics.

Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---

mm/readahead.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)

--- linux-2.6.17-rc4-mm3.orig/mm/readahead.c
+++ linux-2.6.17-rc4-mm3/mm/readahead.c
@@ -5,6 +5,8 @@
*
* 09Apr2002 akpm@zip.com.au
* Initial version.
+ * 21May2006 Wu Fengguang <wfg@mail.ustc.edu.cn>
+ * Adaptive read-ahead framework.
*/

#include <linux/kernel.h>
@@ -14,6 +16,14 @@
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
+#include <linux/writeback.h>
+#include <linux/nfsd/const.h>
+
+#define PAGES_BYTE(size) (((size) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT)
+#define PAGES_KB(size) PAGES_BYTE((size)*1024)
+
+#define next_page(pg) (list_entry((pg)->lru.prev, struct page, lru))
+#define prev_page(pg) (list_entry((pg)->lru.next, struct page, lru))

void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
{
@@ -21,7 +31,7 @@ void default_unplug_io_fn(struct backing
EXPORT_SYMBOL(default_unplug_io_fn);

struct backing_dev_info default_backing_dev_info = {
- .ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE,
+ .ra_pages = PAGES_KB(VM_MAX_READAHEAD),
.state = 0,
.capabilities = BDI_CAP_MAP_COPY,
.unplug_io_fn = default_unplug_io_fn,
@@ -50,7 +60,7 @@ static inline unsigned long get_max_read

static inline unsigned long get_min_readahead(struct file_ra_state *ra)
{
- return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
+ return PAGES_KB(VM_MIN_READAHEAD);
}

static inline void reset_ahead_window(struct file_ra_state *ra)

--