f2fs: fix wrong value of tracepoint parameter

In f2fs_lookup(), we should set @err correctly before printing it
in tracepoint.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/namei.c

@@ -504,6 +504,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 			err = PTR_ERR(page);
 			goto out;
 		}
+		err = -ENOENT;
 		goto out_splice;
 	}
 
@@ -549,7 +550,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 #endif
 	new = d_splice_alias(inode, dentry);
 	err = PTR_ERR_OR_ZERO(new);
-	trace_f2fs_lookup_end(dir, dentry, ino, err);
+	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
 	return new;
 out_iput:
 	iput(inode);