[PATCH] NUMA: Add zone_to_nid function

There are many places where we need to determine the node of a zone.
Currently we use a difficult to read sequence of pointer dereferencing.
Put that into an inline function and use throughout VM.  Maybe we can find
a way to optimize the lookup in the future.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 7 insertions, 8 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3aceadce1a76..7c7d03dbf73d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -72,7 +72,7 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
         struct zone **z;
 
         for (z = zonelist->zones; *z; z++) {
-                nid = (*z)->zone_pgdat->node_id;
+                nid = zone_to_nid(*z);
                 if (cpuset_zone_allowed(*z, GFP_HIGHUSER) &&
                     !list_empty(&hugepage_freelists[nid]))
                         break;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8002e1faccda..38f89650bc84 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -487,7 +487,7 @@ static void get_zonemask(struct mempolicy *p, nodemask_t *nodes)
         switch (p->policy) {
         case MPOL_BIND:
                 for (i = 0; p->v.zonelist->zones[i]; i++)
-                        node_set(p->v.zonelist->zones[i]->zone_pgdat->node_id,
+                        node_set(zone_to_nid(p->v.zonelist->zones[i]),
                                 *nodes);
                 break;
         case MPOL_DEFAULT:
@@ -1145,7 +1145,7 @@ unsigned slab_node(struct mempolicy *policy)
                  * Follow bind policy behavior and start allocation at the
                  * first node.
                  */
-                return policy->v.zonelist->zones[0]->zone_pgdat->node_id;
+                return zone_to_nid(policy->v.zonelist->zones[0]);
 
         case MPOL_PREFERRED:
                 if (policy->v.preferred_node >= 0)
@@ -1649,7 +1649,7 @@ void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask)
 
                 nodes_clear(nodes);
                 for (z = pol->v.zonelist->zones; *z; z++)
-                        node_set((*z)->zone_pgdat->node_id, nodes);
+                        node_set(zone_to_nid(*z), nodes);
                 nodes_remap(tmp, nodes, *mpolmask, *newmask);
                 nodes = tmp;
 
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f1c0ef1fd21f..bada3d03119f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -177,8 +177,7 @@ static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask)
 
         for (z = zonelist->zones; *z; z++)
                 if (cpuset_zone_allowed(*z, gfp_mask))
-                        node_clear((*z)->zone_pgdat->node_id,
-                                        nodes);
+                        node_clear(zone_to_nid(*z), nodes);
                 else
                         return CONSTRAINT_CPUSET;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cf913bdd433e..51070b6d593f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1217,7 +1217,7 @@ unsigned int nr_free_pagecache_pages(void)
 #ifdef CONFIG_NUMA
 static void show_node(struct zone *zone)
 {
-        printk("Node %d ", zone->zone_pgdat->node_id);
+        printk("Node %ld ", zone_to_nid(zone));
 }
 #else
 #define show_node(zone) do { } while (0)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b950f193816e..87779dda4ec6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1661,7 +1661,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
          * over remote processors and spread off node memory allocations
          * as wide as possible.
          */
-        node_id = zone->zone_pgdat->node_id;
+        node_id = zone_to_nid(zone);
         mask = node_to_cpumask(node_id);
         if (!cpus_empty(mask) && node_id != numa_node_id())
                 return 0;