1 files changed, 36 insertions, 11 deletions

diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index f84194b791d3..137a970c19fb 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -33,8 +33,13 @@ static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
 		} else if (p->vid > volume->vid) {
 			pp = &(*pp)->rb_right;
 		} else {
-			volume = afs_get_volume(p, afs_volume_trace_get_cell_insert);
-			goto found;
+			if (afs_try_get_volume(p, afs_volume_trace_get_cell_insert)) {
+				volume = p;
+				goto found;
+			}
+
+			set_bit(AFS_VOLUME_RM_TREE, &volume->flags);
+			rb_replace_node_rcu(&p->cell_node, &volume->cell_node, &cell->volumes);
 		}
 	}
 
@@ -53,11 +58,12 @@ static void afs_remove_volume_from_cell(struct afs_volume *volume)
 	struct afs_cell *cell = volume->cell;
 
 	if (!hlist_unhashed(&volume->proc_link)) {
-		trace_afs_volume(volume->vid, atomic_read(&volume->usage),
+		trace_afs_volume(volume->vid, refcount_read(&cell->ref),
 				 afs_volume_trace_remove);
 		write_seqlock(&cell->volume_lock);
 		hlist_del_rcu(&volume->proc_link);
-		rb_erase(&volume->cell_node, &cell->volumes);
+		if (!test_and_set_bit(AFS_VOLUME_RM_TREE, &volume->flags))
+			rb_erase(&volume->cell_node, &cell->volumes);
 		write_sequnlock(&cell->volume_lock);
 	}
 }
@@ -88,7 +94,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
 	volume->type_force	= params->force;
 	volume->name_len	= vldb->name_len;
 
-	atomic_set(&volume->usage, 1);
+	refcount_set(&volume->ref, 1);
 	INIT_HLIST_NODE(&volume->proc_link);
 	rwlock_init(&volume->servers_lock);
 	rwlock_init(&volume->cb_v_break_lock);
@@ -229,7 +235,7 @@ static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
 	afs_remove_volume_from_cell(volume);
 	afs_put_serverlist(net, rcu_access_pointer(volume->servers));
 	afs_put_cell(volume->cell, afs_cell_trace_put_vol);
-	trace_afs_volume(volume->vid, atomic_read(&volume->usage),
+	trace_afs_volume(volume->vid, refcount_read(&volume->ref),
 			 afs_volume_trace_free);
 	kfree_rcu(volume, rcu);
 
@@ -237,14 +243,30 @@ static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
 }
 
 /*
+ * Try to get a reference on a volume record.
+ */
+bool afs_try_get_volume(struct afs_volume *volume, enum afs_volume_trace reason)
+{
+	int r;
+
+	if (__refcount_inc_not_zero(&volume->ref, &r)) {
+		trace_afs_volume(volume->vid, r + 1, reason);
+		return true;
+	}
+	return false;
+}
+
+/*
  * Get a reference on a volume record.
  */
 struct afs_volume *afs_get_volume(struct afs_volume *volume,
 				  enum afs_volume_trace reason)
 {
 	if (volume) {
-		int u = atomic_inc_return(&volume->usage);
-		trace_afs_volume(volume->vid, u, reason);
+		int r;
+
+		__refcount_inc(&volume->ref, &r);
+		trace_afs_volume(volume->vid, r + 1, reason);
 	}
 	return volume;
 }
@@ -258,9 +280,12 @@ void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
 {
 	if (volume) {
 		afs_volid_t vid = volume->vid;
-		int u = atomic_dec_return(&volume->usage);
-		trace_afs_volume(vid, u, reason);
-		if (u == 0)
+		bool zero;
+		int r;
+
+		zero = __refcount_dec_and_test(&volume->ref, &r);
+		trace_afs_volume(vid, r - 1, reason);
+		if (zero)
 			afs_destroy_volume(net, volume);
 	}
 }