crush: merge working data and scratch

Much like Arlo Guthrie, I decided that one big pile is better than two
little piles.

Reflects ceph.git commit 95c2df6c7e0b22d2ea9d91db500cf8b9441c73ba.

Signed-off-by: Ilya Dryomov <[e-mail]>

include/linux/ceph/osdmap.h

···
 	 * the list of osds that store+replicate them. */
 	struct crush_map *crush;
 
-	struct mutex crush_scratch_mutex;
-	int crush_scratch_ary[CEPH_PG_MAX_SIZE * 3];
+	struct mutex crush_workspace_mutex;
 	void *crush_workspace;
 };
 

include/linux/crush/mapper.h

···
 			 int ruleno,
 			 int x, int *result, int result_max,
 			 const __u32 *weights, int weight_max,
-			 void *cwin, int *scratch);
+			 void *cwin);
+
+/*
+ * Returns the exact amount of workspace that will need to be used
+ * for a given combination of crush_map and result_max. The caller can
+ * then allocate this much on its own, either on the stack, in a
+ * per-thread long-lived buffer, or however it likes.
+ */
+static inline size_t crush_work_size(const struct crush_map *map,
+				     int result_max)
+{
+	return map->working_size + result_max * 3 * sizeof(__u32);
+}
 
 void crush_init_workspace(const struct crush_map *map, void *v);
 

net/ceph/crush/mapper.c

···
  * @result_max: maximum result size
  * @weight: weight vector (for map leaves)
  * @weight_max: size of weight vector
- * @cwin: pointer to at least map->working_size bytes of memory
- * @scratch: scratch vector for private use; must be >= 3 * result_max
+ * @cwin: pointer to at least crush_work_size() bytes of memory
  */
 int crush_do_rule(const struct crush_map *map,
 		  int ruleno, int x, int *result, int result_max,
 		  const __u32 *weight, int weight_max,
-		  void *cwin, int *scratch)
+		  void *cwin)
 {
 	int result_len;
 	struct crush_work *cw = cwin;
-	int *a = scratch;
-	int *b = scratch + result_max;
-	int *c = scratch + result_max*2;
+	int *a = cwin + map->working_size;
+	int *b = a + result_max;
+	int *c = b + result_max;
+	int *w = a;
+	int *o = b;
 	int recurse_to_leaf;
-	int *w;
 	int wsize = 0;
-	int *o;
 	int osize;
 	int *tmp;
 	const struct crush_rule *rule;
···
 
 	rule = map->rules[ruleno];
 	result_len = 0;
-	w = a;
-	o = b;
 
 	for (step = 0; step < rule->len; step++) {
 		int firstn = 0;

net/ceph/osdmap.c

···
 	map->pool_max = -1;
 	map->pg_temp = RB_ROOT;
 	map->primary_temp = RB_ROOT;
-	mutex_init(&map->crush_scratch_mutex);
+	mutex_init(&map->crush_workspace_mutex);
 
 	return map;
 }
···
 static int osdmap_set_crush(struct ceph_osdmap *map, struct crush_map *crush)
 {
 	void *workspace;
+	size_t work_size;
 
 	if (IS_ERR(crush))
 		return PTR_ERR(crush);
 
-	workspace = kmalloc(crush->working_size, GFP_NOIO);
+	work_size = crush_work_size(crush, CEPH_PG_MAX_SIZE);
+	dout("%s work_size %zu bytes\n", __func__, work_size);
+	workspace = kmalloc(work_size, GFP_NOIO);
 	if (!workspace) {
 		crush_destroy(crush);
 		return -ENOMEM;
···
 
 	BUG_ON(result_max > CEPH_PG_MAX_SIZE);
 
-	mutex_lock(&map->crush_scratch_mutex);
+	mutex_lock(&map->crush_workspace_mutex);
 	r = crush_do_rule(map->crush, ruleno, x, result, result_max,
-			  weight, weight_max, map->crush_workspace,
-			  map->crush_scratch_ary);
-	mutex_unlock(&map->crush_scratch_mutex);
+			  weight, weight_max, map->crush_workspace);
+	mutex_unlock(&map->crush_workspace_mutex);
 
 	return r;
 }