[PATCH 09/11] mm: memcontrol: constify the swap accounting helpers

[Tal Zussman]

mem_cgroup_get_nr_swap_pages(), mem_cgroup_get_folio_swap_margin(), and
mem_cgroup_swap_full() only read swap counters and limits. Constify
them.

Remove externs from function declarations while at it.

Signed-off-by: Tal Zussman <tz2294@xxxxxxxxxxxx>
---
 include/linux/swap.h | 12 ++++++------
 mm/memcontrol.c      |  6 +++---
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index a72ecf12c00d..a64b5d37bf36 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -510,9 +510,9 @@ static inline void mem_cgroup_uncharge_swap(unsigned short id, unsigned int nr_p
 	__mem_cgroup_uncharge_swap(id, nr_pages);
 }
 
-long mem_cgroup_get_folio_swap_margin(struct folio *folio);
-extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
-extern bool mem_cgroup_swap_full(struct folio *folio);
+long mem_cgroup_get_folio_swap_margin(const struct folio *folio);
+long mem_cgroup_get_nr_swap_pages(const struct mem_cgroup *memcg);
+bool mem_cgroup_swap_full(const struct folio *folio);
 #else
 static inline int mem_cgroup_try_charge_swap(struct folio *folio)
 {
@@ -524,17 +524,17 @@ static inline void mem_cgroup_uncharge_swap(unsigned short id,
 {
 }
 
-static inline long mem_cgroup_get_folio_swap_margin(struct folio *folio)
+static inline long mem_cgroup_get_folio_swap_margin(const struct folio *folio)
 {
 	return PAGE_COUNTER_MAX;
 }
 
-static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
+static inline long mem_cgroup_get_nr_swap_pages(const struct mem_cgroup *memcg)
 {
 	return get_nr_swap_pages();
 }
 
-static inline bool mem_cgroup_swap_full(struct folio *folio)
+static inline bool mem_cgroup_swap_full(const struct folio *folio)
 {
 	return vm_swap_full();
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3d3eadddc130..2b8705a88f6a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5839,7 +5839,7 @@ void __mem_cgroup_uncharge_swap(unsigned short id, unsigned int nr_pages)
 	rcu_read_unlock();
 }
 
-long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
+long mem_cgroup_get_nr_swap_pages(const struct mem_cgroup *memcg)
 {
 	long nr_swap_pages = get_nr_swap_pages();
 
@@ -5855,7 +5855,7 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
  *
  * Return: Remaining chargeable pages in the folio's memcg hierarchy.
  */
-long mem_cgroup_get_folio_swap_margin(struct folio *folio)
+long mem_cgroup_get_folio_swap_margin(const struct folio *folio)
 {
 	struct mem_cgroup *memcg;
 	long margin;
@@ -5872,7 +5872,7 @@ long mem_cgroup_get_folio_swap_margin(struct folio *folio)
 	return margin;
 }
 
-bool mem_cgroup_swap_full(struct folio *folio)
+bool mem_cgroup_swap_full(const struct folio *folio)
 {
 	struct mem_cgroup *memcg;
 	bool ret = false;

-- 
2.39.5