ext4: add tracepoint in punching hole

This patch adds a tracepoint in ext4_punch_hole.

CC: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -3567,6 +3567,8 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 		return -EOPNOTSUPP;
 	}
 
+	trace_ext4_punch_hole(inode, offset, length);
+
 	return ext4_ext_punch_hole(file, offset, length);
 }
 

include/trace/events/ext4.h

@@ -1324,6 +1324,31 @@ TRACE_EVENT(ext4_fallocate_exit,
 		  __entry->ret)
 );
 
+TRACE_EVENT(ext4_punch_hole,
+	TP_PROTO(struct inode *inode, loff_t offset, loff_t len),
+
+	TP_ARGS(inode, offset, len),
+
+	TP_STRUCT__entry(
+		__field(	dev_t,	dev			)
+		__field(	ino_t,	ino			)
+		__field(	loff_t,	offset			)
+		__field(	loff_t, len			)
+	),
+
+	TP_fast_assign(
+		__entry->dev	= inode->i_sb->s_dev;
+		__entry->ino	= inode->i_ino;
+		__entry->offset	= offset;
+		__entry->len	= len;
+	),
+
+	TP_printk("dev %d,%d ino %lu offset %lld len %lld",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  (unsigned long) __entry->ino,
+		  __entry->offset, __entry->len)
+);
+
 TRACE_EVENT(ext4_unlink_enter,
 	TP_PROTO(struct inode *parent, struct dentry *dentry),