From 3b2b7fd01ac7817ceefbbccfb6073abbda5321ea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ernesto=20A=2E=20Fern=C3=A1ndez?= <ernesto@corellium.com>
Date: Tue, 11 May 2021 22:24:23 -0300
Subject: [PATCH] Get rid of query cache
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Back when he first tried this out, Stan mentioned that using the slab
cache for queries doesn't actually improve performance. It seems that I
somehow made a mistake and pushed his test changes anyway, so revert
them now.

Signed-off-by: Ernesto A. Fernández <ernesto@corellium.com>
---
 apfs.h  |  4 ----
 btree.c |  6 +++---
 super.c | 44 +-------------------------------------------
 3 files changed, 4 insertions(+), 50 deletions(-)

diff --git a/apfs.h b/apfs.h
index 355fe16..96d7c63 100644
--- a/apfs.h
+++ b/apfs.h
@@ -494,10 +494,6 @@ static inline u32 apfs_query_storage(struct apfs_query *query)
 	BUG();
 }
 
-/* super.c */
-struct apfs_query *apfs_alloc_query_item(void);
-void apfs_free_query_item(struct apfs_query *qi);
-
 /*
  * Extent record data in memory
  */
diff --git a/btree.c b/btree.c
index 6f6e1ca..9e22950 100644
--- a/btree.c
+++ b/btree.c
@@ -185,7 +185,7 @@ struct apfs_query *apfs_alloc_query(struct apfs_node *node,
 {
 	struct apfs_query *query;
 
-	query = apfs_alloc_query_item();
+	query = kmalloc(sizeof(*query), GFP_KERNEL);
 	if (!query)
 		return NULL;
 
@@ -216,7 +216,7 @@ void apfs_free_query(struct super_block *sb, struct apfs_query *query)
 		struct apfs_query *parent = query->parent;
 
 		apfs_node_put(query->node);
-		apfs_free_query_item(query);
+		kfree(query);
 		query = parent;
 	}
 }
@@ -342,7 +342,7 @@ next_node:
 
 	/*
 	 * Remember the parent node and index in case the search needs
-	 * to be continued later.  TODO: allocate queries from a cache?
+	 * to be continued later.
 	 */
 	*query = apfs_alloc_query(node, *query);
 	apfs_node_put(node);
diff --git a/super.c b/super.c
index 0c71cab..7cc2d61 100644
--- a/super.c
+++ b/super.c
@@ -650,40 +650,6 @@ static void destroy_inodecache(void)
 	kmem_cache_destroy(apfs_inode_cachep);
 }
 
-static struct kmem_cache *apfs_query_cachep;
-
-static int __init init_querycache(void)
-{
-	apfs_query_cachep = kmem_cache_create("apfs_query_cache",
-					     sizeof(struct apfs_query),
-					     0, (SLAB_RECLAIM_ACCOUNT|
-						SLAB_MEM_SPREAD|SLAB_ACCOUNT),
-					     NULL);
-	if (apfs_query_cachep == NULL)
-		return -ENOMEM;
-	return 0;
-}
-
-struct apfs_query *apfs_alloc_query_item(void)
-{
-	struct apfs_query *qi;
-	qi = kmem_cache_alloc(apfs_query_cachep, GFP_KERNEL);
-	if(!qi)
-		return NULL;
-	memset(qi, 0, sizeof(struct apfs_query));
-	return qi;
-}
-
-void apfs_free_query_item(struct apfs_query *qi)
-{
-	kmem_cache_free(apfs_query_cachep, qi);
-}
-
-static void destroy_querycache(void)
-{
-	kmem_cache_destroy(apfs_query_cachep);
-}
-
 /**
  * apfs_count_used_blocks - Count the blocks in use across all volumes
  * @sb:		filesystem superblock
@@ -1269,23 +1235,15 @@ static int __init init_apfs_fs(void)
 	err = init_inodecache();
 	if (err)
 		return err;
-	err = init_querycache();
-	if (err) {
-		destroy_inodecache();
-		return err;
-	}
 	err = register_filesystem(&apfs_fs_type);
-	if (err) {
-		destroy_querycache();
+	if (err)
 		destroy_inodecache();
-	}
 	return err;
 }
 
 static void __exit exit_apfs_fs(void)
 {
 	unregister_filesystem(&apfs_fs_type);
-	destroy_querycache();
 	destroy_inodecache();
 }