ext4: add tracepoint for ext4_forget()

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 554c679..13de1dd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -89,6 +89,7 @@
 
 	might_sleep();
 
+	trace_ext4_forget(inode, is_metadata, blocknr);
 	BUFFER_TRACE(bh, "enter");
 
 	jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "