[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>

9 files changed, 17 insertions, 13 deletions

diff --git a/arch/i386/mm/discontig.c b/arch/i386/mm/discontig.c
index 07c300f93764..fb5d8b747de4 100644
--- a/arch/i386/mm/discontig.c
+++ b/arch/i386/mm/discontig.c
@@ -422,7 +422,7 @@ void __init set_highmem_pages_init(int bad_ppro)
                 zone_end_pfn = zone_start_pfn + zone->spanned_pages;
 
                 printk("Initializing %s for node %d (%08lx:%08lx)\n",
-                                zone->name, zone->zone_pgdat->node_id,
+                                zone->name, zone_to_nid(zone),
                                 zone_start_pfn, zone_end_pfn);
 
                 for (node_pfn = zone_start_pfn; node_pfn < zone_end_pfn; node_pfn++) {
diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index c7329615ef94..25ad28d63e88 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -551,7 +551,7 @@ void show_mem(void)
 
                                 printk("Zone list for zone %d on node %d: ", j, i);
                                 for (k = 0; zl->zones[k] != NULL; k++) 
-                                        printk("[%d/%s] ", zl->zones[k]->zone_pgdat->node_id, zl->zones[k]->name);
+                                        printk("[%d/%s] ", zone_to_nid(zl->zones[k]), zl->zones[k]->name);
                                 printk("\n");
                         }
                 }
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f2018775b995..856f0ee7e84a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -499,12 +499,17 @@ static inline struct zone *page_zone(struct page *page)
         return zone_table[page_zone_id(page)];
 }
 
+static inline unsigned long zone_to_nid(struct zone *zone)
+{
+        return zone->zone_pgdat->node_id;
+}
+
 static inline unsigned long page_to_nid(struct page *page)
 {
         if (FLAGS_HAS_NODE)
                 return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
         else
-                return page_zone(page)->zone_pgdat->node_id;
+                return zone_to_nid(page_zone(page));
 }
 static inline unsigned long page_to_section(struct page *page)
 {
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 76940361273e..cff41511269f 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2245,7 +2245,7 @@ int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)
         int i;
 
         for (i = 0; zl->zones[i]; i++) {
-                int nid = zl->zones[i]->zone_pgdat->node_id;
+                int nid = zone_to_nid(zl->zones[i]);
 
                 if (node_isset(nid, current->mems_allowed))
                         return 1;
@@ -2318,7 +2318,7 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 
         if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
                 return 1;
-        node = z->zone_pgdat->node_id;
+        node = zone_to_nid(z);
         might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
         if (node_isset(node, current->mems_allowed))
                 return 1;
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;