tracing: Remove unused trace_event_file dir field

Now that eventfs structure is used to create the events directory via the
eventfs dynamically allocate code, the "dir" field of the trace_event_file
structure is no longer used. Remove it.

Link: https://lkml.kernel.org/r/20230908022001.580400115@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

include/linux/trace_events.h

@@ -650,7 +650,6 @@ struct trace_event_file {
 	struct trace_event_call		*event_call;
 	struct event_filter __rcu	*filter;
 	struct eventfs_file             *ef;
-	struct dentry			*dir;
 	struct trace_array		*tr;
 	struct trace_subsystem_dir	*system;
 	struct list_head		triggers;

kernel/trace/trace_events.c

@@ -992,19 +992,6 @@ static void remove_subsystem(struct trace_subsystem_dir *dir)
 
 static void remove_event_file_dir(struct trace_event_file *file)
 {
-	struct dentry *dir = file->dir;
-	struct dentry *child;
-
-	if (dir) {
-		spin_lock(&dir->d_lock);	/* probably unneeded */
-		list_for_each_entry(child, &dir->d_subdirs, d_child) {
-			if (d_really_is_positive(child))	/* probably unneeded */
-				d_inode(child)->i_private = NULL;
-		}
-		spin_unlock(&dir->d_lock);
-
-		tracefs_remove(dir);
-	}
 	eventfs_remove(file->ef);
 	list_del(&file->list);
 	remove_subsystem(file->system);