switch debugfs to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 16fc34a..cdea7b5 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -402,7 +402,7 @@
 
 static struct dentry *blk_create_buf_file_callback(const char *filename,
 						   struct dentry *parent,
-						   int mode,
+						   umode_t mode,
 						   struct rchan_buf *buf,
 						   int *is_global)
 {