From: Christoph Lameter <clameter@sgi.com>
Subject: slub: Add function to determine the amount of objects that can reside in a given slab

Add a new function that determines the maximum number of objects that a given slab
can accomodate. At this stage the function always returns the maximum number of objects
since fallback is not available yet.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 mm/slub.c |   31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2008-02-15 11:06:38.237227456 -0800
+++ linux-2.6/mm/slub.c	2008-02-15 11:07:48.669585330 -0800
@@ -315,6 +315,11 @@ static void *slab_address(struct page *p
 	return page->end - PAGE_MAPPING_ANON;
 }
 
+static inline unsigned long slab_objects(struct kmem_cache *s, struct page *page)
+{
+	return s->objects;
+}
+
 static inline int check_valid_pointer(struct kmem_cache *s,
 				struct page *page, const void *object)
 {
@@ -324,8 +329,9 @@ static inline int check_valid_pointer(st
 		return 1;
 
 	base = slab_address(page);
-	if (object < base || object >= base + s->objects * s->size ||
-		(object - base) % s->size) {
+	if (object < base
+		|| object >= base + slab_objects(s, page) * s->size
+		|| (object - base) % s->size) {
 		return 0;
 	}
 
@@ -689,7 +695,7 @@ static int slab_pad_check(struct kmem_ca
 
 	start = slab_address(page);
 	end = start + (PAGE_SIZE << s->order);
-	length = s->objects * s->size;
+	length = slab_objects(s, page) * s->size;
 	remainder = end - (start + length);
 	if (!remainder)
 		return 1;
@@ -769,9 +775,9 @@ static int check_slab(struct kmem_cache 
 		slab_err(s, page, "Not a valid slab page");
 		return 0;
 	}
-	if (page->inuse > s->objects) {
+	if (page->inuse > slab_objects(s, page)) {
 		slab_err(s, page, "inuse %u > max %u",
-			s->name, page->inuse, s->objects);
+			s->name, page->inuse, slab_objects(s, page));
 		return 0;
 	}
 	/* Slab_pad_check fixes things up after itself */
@@ -788,8 +794,9 @@ static int on_freelist(struct kmem_cache
 	int nr = 0;
 	void *fp = page->freelist;
 	void *object = NULL;
+	int objects = slab_objects(s, page);
 
-	while (fp != page->end && nr <= s->objects) {
+	while (fp != page->end && nr <= objects) {
 		if (fp == search)
 			return 1;
 		if (!check_valid_pointer(s, page, fp)) {
@@ -801,7 +808,7 @@ static int on_freelist(struct kmem_cache
 			} else {
 				slab_err(s, page, "Freepointer corrupt");
 				page->freelist = page->end;
-				page->inuse = s->objects;
+				page->inuse = objects;
 				slab_fix(s, "Freelist cleared");
 				return 0;
 			}
@@ -812,10 +819,10 @@ static int on_freelist(struct kmem_cache
 		nr++;
 	}
 
-	if (page->inuse != s->objects - nr) {
+	if (page->inuse != objects - nr) {
 		slab_err(s, page, "Wrong object count. Counter is %d but "
-			"counted were %d", page->inuse, s->objects - nr);
-		page->inuse = s->objects - nr;
+			"counted were %d", page->inuse, objects - nr);
+		page->inuse = objects - nr;
 		slab_fix(s, "Object count adjusted.");
 	}
 	return search == NULL;
@@ -905,7 +912,7 @@ bad:
 		 * as used avoids touching the remaining objects.
 		 */
 		slab_fix(s, "Marking all objects used");
-		page->inuse = s->objects;
+		page->inuse = slab_objects(s, page);
 		page->freelist = page->end;
 	}
 	return 0;
@@ -1535,7 +1542,7 @@ load_freelist:
 
 	object = c->page->freelist;
 	c->freelist = object[c->offset];
-	c->page->inuse = s->objects;
+	c->page->inuse = slab_objects(s, c->page);
 	c->page->freelist = c->page->end;
 	c->node = page_to_nid(c->page);
 unlock_out: