1 files changed, 9 insertions, 36 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 7d4af6cea2a6..798f0f03b62b 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -508,10 +508,6 @@ void kernfs_put(struct kernfs_node *kn)
 	struct kernfs_node *parent;
 	struct kernfs_root *root;
 
-	/*
-	 * kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_ino
-	 * depends on this to filter reused stale node
-	 */
 	if (!kn || !atomic_dec_and_test(&kn->count))
 		return;
 	root = kernfs_root(kn);
@@ -646,11 +642,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 	kn->id.ino = ret;
 	kn->id.generation = gen;
 
-	/*
-	 * set ino first. This RELEASE is paired with atomic_inc_not_zero in
-	 * kernfs_find_and_get_node_by_ino
-	 */
-	atomic_set_release(&kn->count, 1);
+	atomic_set(&kn->count, 1);
 	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
 	RB_CLEAR_NODE(&kn->rb);
 
@@ -716,38 +708,19 @@ struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
 {
 	struct kernfs_node *kn;
 
-	rcu_read_lock();
+	spin_lock(&kernfs_idr_lock);
+
 	kn = idr_find(&root->ino_idr, ino);
 	if (!kn)
-		goto out;
+		goto err_unlock;
 
-	/*
-	 * Since kernfs_node is freed in RCU, it's possible an old node for ino
-	 * is freed, but reused before RCU grace period. But a freed node (see
-	 * kernfs_put) or an incompletedly initialized node (see
-	 * __kernfs_new_node) should have 'count' 0. We can use this fact to
-	 * filter out such node.
-	 */
-	if (!atomic_inc_not_zero(&kn->count)) {
-		kn = NULL;
-		goto out;
-	}
-
-	/*
-	 * The node could be a new node or a reused node. If it's a new node,
-	 * we are ok. If it's reused because of RCU (because of
-	 * SLAB_TYPESAFE_BY_RCU), the __kernfs_new_node always sets its 'ino'
-	 * before 'count'. So if 'count' is uptodate, 'ino' should be uptodate,
-	 * hence we can use 'ino' to filter stale node.
-	 */
-	if (kn->id.ino != ino)
-		goto out;
-	rcu_read_unlock();
+	if (unlikely(!atomic_inc_not_zero(&kn->count)))
+		goto err_unlock;
 
+	spin_unlock(&kernfs_idr_lock);
 	return kn;
-out:
-	rcu_read_unlock();
-	kernfs_put(kn);
+err_unlock:
+	spin_unlock(&kernfs_idr_lock);
 	return NULL;
 }