f2fs: add f2fs_drop_inode tracepoint

Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -624,6 +624,7 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 
 static int f2fs_drop_inode(struct inode *inode)
 {
+	int ret;
 	/*
 	 * This is to avoid a deadlock condition like below.
 	 * writeback_single_inode(inode)
@@ -656,10 +657,12 @@ static int f2fs_drop_inode(struct inode *inode)
 			spin_lock(&inode->i_lock);
 			atomic_dec(&inode->i_count);
 		}
+		trace_f2fs_drop_inode(inode, 0);
 		return 0;
 	}
-
-	return generic_drop_inode(inode);
+	ret = generic_drop_inode(inode);
+	trace_f2fs_drop_inode(inode, ret);
+	return ret;
 }
 
 int f2fs_inode_dirtied(struct inode *inode, bool sync)

include/trace/events/f2fs.h

@@ -315,6 +315,13 @@ DEFINE_EVENT(f2fs__inode_exit, f2fs_unlink_exit,
 	TP_ARGS(inode, ret)
 );
 
+DEFINE_EVENT(f2fs__inode_exit, f2fs_drop_inode,
+
+	TP_PROTO(struct inode *inode, int ret),
+
+	TP_ARGS(inode, ret)
+);
+
 DEFINE_EVENT(f2fs__inode, f2fs_truncate,
 
 	TP_PROTO(struct inode *inode),