mm/vmstat: add helpers to get vmstat item names for each enum type

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".

[khlebnikov@yandex-team.ru: do not use size of vmstat_text as count of /proc/vmstat items]
  Link: http://lkml.kernel.org/r/157152151769.4139.15423465513138349343.stgit@buzz
  Link: https://lore.kernel.org/linux-mm/cd1c42ae-281f-c8a8-70ac-1d01d417b2e1@infradead.org/T/#u
Link: http://lkml.kernel.org/r/157113012325.453.562783073839432766.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 50 insertions, 0 deletions

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 */