[PATCH 1/2] mm/vmstat: add helpers to get vmstat item names for each enum type

[Konstantin Khlebnikov <khlebnikov@yandex-team.ru>]

Statistics in vmstat is combined from counters with different structure,
but names for them are merged into one array.

This patch adds trivial helpers to get name for each item:

const char *zone_stat_name(enum zone_stat_item item);
const char *numa_stat_name(enum numa_stat_item item);
const char *node_stat_name(enum node_stat_item item);
const char *writeback_stat_name(enum writeback_stat_item item);
const char *vm_event_name(enum vm_event_item item);


Names for enum writeback_stat_item are folded in the middle of
vmstat_text so this patch moves declaration into header to calculate
offset of following items.


Also this patch reuses piece of node stat names for lru list names:

const char *lru_list_name(enum lru_list lru);

This returns common lru list names: "inactive_anon", "active_anon",
"inactive_file", "active_file", "unevictable".

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 drivers/base/node.c    |    9 +++------
 include/linux/vmstat.h |   50 ++++++++++++++++++++++++++++++++++++++++++++++++
 mm/vmstat.c            |   27 +++++++++-----------------
 3 files changed, 62 insertions(+), 24 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 296546ffed6c..98a31bafc8a2 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -496,20 +496,17 @@ static ssize_t node_read_vmstat(struct device *dev,
 	int n = 0;
 
 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
-		n += sprintf(buf+n, "%s %lu\n", vmstat_text[i],
+		n += sprintf(buf+n, "%s %lu\n", zone_stat_name(i),
 			     sum_zone_node_page_state(nid, i));
 
 #ifdef CONFIG_NUMA
 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
-		n += sprintf(buf+n, "%s %lu\n",
-			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
+		n += sprintf(buf+n, "%s %lu\n", numa_stat_name(i),
 			     sum_zone_numa_state(nid, i));
 #endif
 
 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
-		n += sprintf(buf+n, "%s %lu\n",
-			     vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
-			     NR_VM_NUMA_STAT_ITEMS],
+		n += sprintf(buf+n, "%s %lu\n", node_stat_name(i),
 			     node_page_state(pgdat, i));
 
 	return n;
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index bdeda4b079fe..b995d8b680c2 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -31,6 +31,12 @@ struct reclaim_stat {
 	unsigned nr_unmap_fail;
 };
 
+enum writeback_stat_item {
+	NR_DIRTY_THRESHOLD,
+	NR_DIRTY_BG_THRESHOLD,
+	NR_VM_WRITEBACK_STAT_ITEMS,
+};
+
 #ifdef CONFIG_VM_EVENT_COUNTERS
 /*
  * Light weight per cpu counter implementation.
@@ -381,4 +387,48 @@ static inline void __mod_zone_freepage_state(struct zone *zone, int nr_pages,
 
 extern const char * const vmstat_text[];
 
+static inline const char *zone_stat_name(enum zone_stat_item item)
+{
+	return vmstat_text[item];
+}
+
+#ifdef CONFIG_NUMA
+static inline const char *numa_stat_name(enum numa_stat_item item)
+{
+	return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
+			   item];
+}
+#endif /* CONFIG_NUMA */
+
+static inline const char *node_stat_name(enum node_stat_item item)
+{
+	return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
+			   NR_VM_NUMA_STAT_ITEMS +
+			   item];
+}
+
+static inline const char *lru_list_name(enum lru_list lru)
+{
+	return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
+}
+
+static inline const char *writeback_stat_name(enum writeback_stat_item item)
+{
+	return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
+			   NR_VM_NUMA_STAT_ITEMS +
+			   NR_VM_NODE_STAT_ITEMS +
+			   item];
+}
+
+#ifdef CONFIG_VM_EVENT_COUNTERS
+static inline const char *vm_event_name(enum vm_event_item item)
+{
+	return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
+			   NR_VM_NUMA_STAT_ITEMS +
+			   NR_VM_NODE_STAT_ITEMS +
+			   NR_VM_WRITEBACK_STAT_ITEMS +
+			   item];
+}
+#endif /* CONFIG_VM_EVENT_COUNTERS */
+
 #endif /* _LINUX_VMSTAT_H */
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6afc892a148a..590aeca27cab 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1134,7 +1134,7 @@ const char * const vmstat_text[] = {
 	"numa_other",
 #endif
 
-	/* Node-based counters */
+	/* enum node_stat_item counters */
 	"nr_inactive_anon",
 	"nr_active_anon",
 	"nr_inactive_file",
@@ -1547,10 +1547,8 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 	if (is_zone_first_populated(pgdat, zone)) {
 		seq_printf(m, "\n  per-node stats");
 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
-			seq_printf(m, "\n      %-12s %lu",
-				vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
-				NR_VM_NUMA_STAT_ITEMS],
-				node_page_state(pgdat, i));
+			seq_printf(m, "\n      %-12s %lu", node_stat_name(i),
+				   node_page_state(pgdat, i));
 		}
 	}
 	seq_printf(m,
@@ -1583,14 +1581,13 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 	}
 
 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
-		seq_printf(m, "\n      %-12s %lu", vmstat_text[i],
-				zone_page_state(zone, i));
+		seq_printf(m, "\n      %-12s %lu", zone_stat_name(i),
+			   zone_page_state(zone, i));
 
 #ifdef CONFIG_NUMA
 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
-		seq_printf(m, "\n      %-12s %lu",
-				vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
-				zone_numa_state_snapshot(zone, i));
+		seq_printf(m, "\n      %-12s %lu", numa_stat_name(i),
+			   zone_numa_state_snapshot(zone, i));
 #endif
 
 	seq_printf(m, "\n  pagesets");
@@ -1641,12 +1638,6 @@ static const struct seq_operations zoneinfo_op = {
 	.show	= zoneinfo_show,
 };
 
-enum writeback_stat_item {
-	NR_DIRTY_THRESHOLD,
-	NR_DIRTY_BG_THRESHOLD,
-	NR_VM_WRITEBACK_STAT_ITEMS,
-};
-
 static void *vmstat_start(struct seq_file *m, loff_t *pos)
 {
 	unsigned long *v;
@@ -1764,7 +1755,7 @@ int vmstat_refresh(struct ctl_table *table, int write,
 		val = atomic_long_read(&vm_zone_stat[i]);
 		if (val < 0) {
 			pr_warn("%s: %s %ld\n",
-				__func__, vmstat_text[i], val);
+				__func__, zone_stat_name(i), val);
 			err = -EINVAL;
 		}
 	}
@@ -1773,7 +1764,7 @@ int vmstat_refresh(struct ctl_table *table, int write,
 		val = atomic_long_read(&vm_numa_stat[i]);
 		if (val < 0) {
 			pr_warn("%s: %s %ld\n",
-				__func__, vmstat_text[i + NR_VM_ZONE_STAT_ITEMS], val);
+				__func__, numa_stat_name(i), val);
 			err = -EINVAL;
 		}
 	}