dm-cache: fix warnings about duplicate slab caches

The commit 4c39529663b9 adds a warning about duplicate cache names if
CONFIG_DEBUG_VM is selected. These warnings are triggered by the dm-cache
code.

The dm-cache code allocates a slab cache for each device. This commit
changes it to allocate just one slab cache in the module init function.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 4c39529663b9 ("slab: Warn on duplicate cache names when DEBUG_VM=y")

1 files changed, 6 insertions, 19 deletions

diff --git a/drivers/md/dm-cache-background-tracker.c b/drivers/md/dm-cache-background-tracker.c
index 9c5308298cf1..f3051bd7d2df 100644
--- a/drivers/md/dm-cache-background-tracker.c
+++ b/drivers/md/dm-cache-background-tracker.c
@@ -11,12 +11,6 @@
 
 #define DM_MSG_PREFIX "dm-background-tracker"
 
-struct bt_work {
-	struct list_head list;
-	struct rb_node node;
-	struct policy_work work;
-};
-
 struct background_tracker {
 	unsigned int max_work;
 	atomic_t pending_promotes;
@@ -26,10 +20,10 @@ struct background_tracker {
 	struct list_head issued;
 	struct list_head queued;
 	struct rb_root pending;
-
-	struct kmem_cache *work_cache;
 };
 
+struct kmem_cache *btracker_work_cache = NULL;
+
 struct background_tracker *btracker_create(unsigned int max_work)
 {
 	struct background_tracker *b = kmalloc(sizeof(*b), GFP_KERNEL);
@@ -48,12 +42,6 @@ struct background_tracker *btracker_create(unsigned int max_work)
 	INIT_LIST_HEAD(&b->queued);
 
 	b->pending = RB_ROOT;
-	b->work_cache = KMEM_CACHE(bt_work, 0);
-	if (!b->work_cache) {
-		DMERR("couldn't create mempool for background work items");
-		kfree(b);
-		b = NULL;
-	}
 
 	return b;
 }
@@ -66,10 +54,9 @@ void btracker_destroy(struct background_tracker *b)
 	BUG_ON(!list_empty(&b->issued));
 	list_for_each_entry_safe (w, tmp, &b->queued, list) {
 		list_del(&w->list);
-		kmem_cache_free(b->work_cache, w);
+		kmem_cache_free(btracker_work_cache, w);
 	}
 
-	kmem_cache_destroy(b->work_cache);
 	kfree(b);
 }
 EXPORT_SYMBOL_GPL(btracker_destroy);
@@ -180,7 +167,7 @@ static struct bt_work *alloc_work(struct background_tracker *b)
 	if (max_work_reached(b))
 		return NULL;
 
-	return kmem_cache_alloc(b->work_cache, GFP_NOWAIT);
+	return kmem_cache_alloc(btracker_work_cache, GFP_NOWAIT);
 }
 
 int btracker_queue(struct background_tracker *b,
@@ -203,7 +190,7 @@ int btracker_queue(struct background_tracker *b,
 		 * There was a race, we'll just ignore this second
 		 * bit of work for the same oblock.
 		 */
-		kmem_cache_free(b->work_cache, w);
+		kmem_cache_free(btracker_work_cache, w);
 		return -EINVAL;
 	}
 
@@ -244,7 +231,7 @@ void btracker_complete(struct background_tracker *b,
 	update_stats(b, &w->work, -1);
 	rb_erase(&w->node, &b->pending);
 	list_del(&w->list);
-	kmem_cache_free(b->work_cache, w);
+	kmem_cache_free(btracker_work_cache, w);
 }
 EXPORT_SYMBOL_GPL(btracker_complete);