vfs: do_last(): make ENOENT exit RCU safe

This will allow this code to be used in RCU mode.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2361,8 +2361,10 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 	BUG_ON(nd->flags & LOOKUP_RCU);
 	inode = path->dentry->d_inode;
 	error = -ENOENT;
-	if (!inode)
-		goto exit_dput;
+	if (!inode) {
+		path_to_nameidata(path, nd);
+		goto exit;
+	}
 
 	if (should_follow_link(inode, !symlink_ok)) {
 		if (nd->flags & LOOKUP_RCU) {