revert "memcg: enhance memcg iterator to support predicates"

Revert commit de57780dc659 ("memcg: enhance memcg iterator to support
predicates")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 43 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 60e95872da29..ef2b9bd7fafa 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -53,23 +53,6 @@ struct mem_cgroup_reclaim_cookie {
         unsigned int generation;
 };
 
-enum mem_cgroup_filter_t {
-        VISIT,          /* visit current node */
-        SKIP,           /* skip the current node and continue traversal */
-        SKIP_TREE,      /* skip the whole subtree and continue traversal */
-};
-
-/*
- * mem_cgroup_filter_t predicate might instruct mem_cgroup_iter_cond how to
- * iterate through the hierarchy tree. Each tree element is checked by the
- * predicate before it is returned by the iterator. If a filter returns
- * SKIP or SKIP_TREE then the iterator code continues traversal (with the
- * next node down the hierarchy or the next node that doesn't belong under the
- * memcg's subtree).
- */
-typedef enum mem_cgroup_filter_t
-(*mem_cgroup_iter_filter)(struct mem_cgroup *memcg, struct mem_cgroup *root);
-
 #ifdef CONFIG_MEMCG
 /*
  * All "charge" functions with gfp_mask should use GFP_KERNEL or
@@ -137,18 +120,9 @@ mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
 extern void mem_cgroup_end_migration(struct mem_cgroup *memcg,
         struct page *oldpage, struct page *newpage, bool migration_ok);
 
-struct mem_cgroup *mem_cgroup_iter_cond(struct mem_cgroup *root,
-                                   struct mem_cgroup *prev,
-                                   struct mem_cgroup_reclaim_cookie *reclaim,
-                                   mem_cgroup_iter_filter cond);
-
-static inline struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
-                                   struct mem_cgroup *prev,
-                                   struct mem_cgroup_reclaim_cookie *reclaim)
-{
-        return mem_cgroup_iter_cond(root, prev, reclaim, NULL);
-}
-
+struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
+                                   struct mem_cgroup *,
+                                   struct mem_cgroup_reclaim_cookie *);
 void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
 
 /*
@@ -260,8 +234,7 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
         mem_cgroup_update_page_stat(page, idx, -1);
 }
 
-enum mem_cgroup_filter_t
-mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
+bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
                 struct mem_cgroup *root);
 
 void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
@@ -376,15 +349,6 @@ static inline void mem_cgroup_end_migration(struct mem_cgroup *memcg,
                 struct page *oldpage, struct page *newpage, bool migration_ok)
 {
 }
-static inline struct mem_cgroup *
-mem_cgroup_iter_cond(struct mem_cgroup *root,
-                struct mem_cgroup *prev,
-                struct mem_cgroup_reclaim_cookie *reclaim,
-                mem_cgroup_iter_filter cond)
-{
-        /* first call must return non-NULL, second return NULL */
-        return (struct mem_cgroup *)(unsigned long)!prev;
-}
 
 static inline struct mem_cgroup *
 mem_cgroup_iter(struct mem_cgroup *root,
@@ -471,11 +435,10 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
 }
 
 static inline
-enum mem_cgroup_filter_t
-mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
+bool mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
                 struct mem_cgroup *root)
 {
-        return VISIT;
+        return false;
 }
 
 static inline void mem_cgroup_split_huge_fixup(struct page *head)