From: Matthew Wilcox <willy@infradead.org>
Date: Tue, 12 Feb 2019 13:35:25 +0000 (-0500)
Subject: vmscan: Convert shrinker_idr to XArray
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e622bfaa91195c606c1da304a16c5ff2988d6d4f;p=users%2Fwilly%2Fxarray.git

vmscan: Convert shrinker_idr to XArray

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index dbdc46a84f63..83d1d33a60dc 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -192,29 +192,29 @@ static DECLARE_RWSEM(shrinker_rwsem);
  */
 #define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
 
-static DEFINE_IDR(shrinker_idr);
+static DEFINE_XARRAY_ALLOC(memcg_shrinkers);
 static int shrinker_nr_max;
 
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 {
-	int id, ret = -ENOMEM;
+	int ret;
 
 	down_write(&shrinker_rwsem);
 	/* This may call shrinker, so it must use down_read_trylock() */
-	id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
-	if (id < 0)
+	ret = xa_alloc(&memcg_shrinkers, &shrinker->id, SHRINKER_REGISTERING,
+			xa_limit_31b, GFP_KERNEL);
+	if (ret < 0)
 		goto unlock;
 
-	if (id >= shrinker_nr_max) {
-		if (memcg_expand_shrinker_maps(id)) {
-			idr_remove(&shrinker_idr, id);
+	if (shrinker->id >= shrinker_nr_max) {
+		if (memcg_expand_shrinker_maps(shrinker->id)) {
+			xa_erase(&memcg_shrinkers, shrinker->id);
+			ret = -ENOMEM;
 			goto unlock;
 		}
 
-		shrinker_nr_max = id + 1;
+		shrinker_nr_max = shrinker->id + 1;
 	}
-	shrinker->id = id;
-	ret = 0;
 unlock:
 	up_write(&shrinker_rwsem);
 	return ret;
@@ -226,9 +226,7 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
 
 	BUG_ON(id < 0);
 
-	down_write(&shrinker_rwsem);
-	idr_remove(&shrinker_idr, id);
-	up_write(&shrinker_rwsem);
+	xa_erase(&memcg_shrinkers, id);
 }
 #else /* CONFIG_MEMCG_KMEM */
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
@@ -429,7 +427,7 @@ void register_shrinker_prepared(struct shrinker *shrinker)
 	list_add_tail(&shrinker->list, &shrinker_list);
 #ifdef CONFIG_MEMCG_KMEM
 	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
-		idr_replace(&shrinker_idr, shrinker, shrinker->id);
+		xa_store(&memcg_shrinkers, shrinker->id, shrinker, GFP_KERNEL);
 #endif
 	up_write(&shrinker_rwsem);
 }
@@ -621,7 +619,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
 		};
 		struct shrinker *shrinker;
 
-		shrinker = idr_find(&shrinker_idr, i);
+		shrinker = xa_load(&memcg_shrinkers, i);
 		if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) {
 			if (!shrinker)
 				clear_bit(i, map->map);