ext4: add tracepoint in punching hole

This patch adds a tracepoint in ext4_punch_hole.

CC: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 93a7e84..5abf89c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3567,6 +3567,8 @@
 		return -EOPNOTSUPP;
 	}
 
+	trace_ext4_punch_hole(inode, offset, length);
+
 	return ext4_ext_punch_hole(file, offset, length);
 }