afs: Trace afs_server usage

Add a tracepoint (afs_server) to track the afs_server object usage count.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 32 insertions, 7 deletions

diff --git a/fs/afs/server.c b/fs/afs/server.c
index 52c170b59cfd..b69571bb9d37 100644
--- a/fs/afs/server.c
+++ b/fs/afs/server.c
@@ -17,6 +17,7 @@
 
 static unsigned afs_server_gc_delay = 10;	/* Server record timeout in seconds */
 static unsigned afs_server_update_delay = 30;	/* Time till VLDB recheck in secs */
+static atomic_t afs_server_debug_id;
 
 static void afs_inc_servers_outstanding(struct afs_net *net)
 {
@@ -51,7 +52,7 @@ struct afs_server *afs_find_server(struct afs_net *net,
 
 	do {
 		if (server)
-			afs_put_server(net, server);
+			afs_put_server(net, server, afs_server_trace_put_find_rsq);
 		server = NULL;
 		read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
 
@@ -116,7 +117,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
 		 * changes.
 		 */
 		if (server)
-			afs_put_server(net, server);
+			afs_put_server(net, server, afs_server_trace_put_uuid_rsq);
 		server = NULL;
 
 		read_seqbegin_or_lock(&net->fs_lock, &seq);
@@ -131,7 +132,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
 			} else if (diff > 0) {
 				p = p->rb_right;
 			} else {
-				afs_get_server(server);
+				afs_get_server(server, afs_server_trace_get_by_uuid);
 				break;
 			}
 
@@ -202,7 +203,7 @@ static struct afs_server *afs_install_server(struct afs_net *net,
 	ret = 0;
 
 exists:
-	afs_get_server(server);
+	afs_get_server(server, afs_server_trace_get_install);
 	write_sequnlock(&net->fs_lock);
 	return server;
 }
@@ -223,6 +224,7 @@ static struct afs_server *afs_alloc_server(struct afs_net *net,
 		goto enomem;
 
 	atomic_set(&server->usage, 1);
+	server->debug_id = atomic_inc_return(&afs_server_debug_id);
 	RCU_INIT_POINTER(server->addresses, alist);
 	server->addr_version = alist->version;
 	server->uuid = *uuid;
@@ -234,6 +236,7 @@ static struct afs_server *afs_alloc_server(struct afs_net *net,
 	spin_lock_init(&server->probe_lock);
 
 	afs_inc_servers_outstanding(net);
+	trace_afs_server(server, 1, afs_server_trace_alloc);
 	_leave(" = %p", server);
 	return server;
 
@@ -329,9 +332,22 @@ void afs_servers_timer(struct timer_list *timer)
 }
 
 /*
+ * Get a reference on a server object.
+ */
+struct afs_server *afs_get_server(struct afs_server *server,
+				  enum afs_server_trace reason)
+{
+	unsigned int u = atomic_inc_return(&server->usage);
+
+	trace_afs_server(server, u, reason);
+	return server;
+}
+
+/*
  * Release a reference on a server record.
  */
-void afs_put_server(struct afs_net *net, struct afs_server *server)
+void afs_put_server(struct afs_net *net, struct afs_server *server,
+		    enum afs_server_trace reason)
 {
 	unsigned int usage;
 
@@ -342,7 +358,7 @@ void afs_put_server(struct afs_net *net, struct afs_server *server)
 
 	usage = atomic_dec_return(&server->usage);
 
-	_enter("{%u}", usage);
+	trace_afs_server(server, usage, reason);
 
 	if (likely(usage > 0))
 		return;
@@ -354,6 +370,8 @@ static void afs_server_rcu(struct rcu_head *rcu)
 {
 	struct afs_server *server = container_of(rcu, struct afs_server, rcu);
 
+	trace_afs_server(server, atomic_read(&server->usage),
+			 afs_server_trace_free);
 	afs_put_addrlist(rcu_access_pointer(server->addresses));
 	kfree(server);
 }
@@ -369,7 +387,9 @@ static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
 		.index	= alist->preferred,
 		.error	= 0,
 	};
-	_enter("%p", server);
+
+	trace_afs_server(server, atomic_read(&server->usage),
+			 afs_server_trace_give_up_cb);
 
 	if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
 		afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
@@ -377,6 +397,8 @@ static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
 	wait_var_event(&server->probe_outstanding,
 		       atomic_read(&server->probe_outstanding) == 0);
 
+	trace_afs_server(server, atomic_read(&server->usage),
+			 afs_server_trace_destroy);
 	call_rcu(&server->rcu, afs_server_rcu);
 	afs_dec_servers_outstanding(net);
 }
@@ -396,6 +418,7 @@ static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
 		write_seqlock(&net->fs_lock);
 		usage = 1;
 		deleted = atomic_try_cmpxchg(&server->usage, &usage, 0);
+		trace_afs_server(server, usage, afs_server_trace_gc);
 		if (deleted) {
 			rb_erase(&server->uuid_rb, &net->fs_servers);
 			hlist_del_rcu(&server->proc_link);
@@ -518,6 +541,8 @@ static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct a
 
 	_enter("");
 
+	trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_update);
+
 	alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key,
 				    &server->uuid);
 	if (IS_ERR(alist)) {