vfs: add a flags argument to user_path_parent

...so we can pass in LOOKUP_REVAL. For now, nothing does yet.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2175,15 +2175,19 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
  *     path-walking is complete.
  */
 static struct filename *
-user_path_parent(int dfd, const char __user *path, struct nameidata *nd)
+user_path_parent(int dfd, const char __user *path, struct nameidata *nd,
+		 unsigned int flags)
 {
 	struct filename *s = getname(path);
 	int error;
 
+	/* only LOOKUP_REVAL is allowed in extra flags */
+	flags &= LOOKUP_REVAL;
+
 	if (IS_ERR(s))
 		return s;
 
-	error = filename_lookup(dfd, s, LOOKUP_PARENT, nd);
+	error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd);
 	if (error) {
 		putname(s);
 		return ERR_PTR(error);
@@ -3336,7 +3340,7 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	struct dentry *dentry;
 	struct nameidata nd;
 
-	name = user_path_parent(dfd, pathname, &nd);
+	name = user_path_parent(dfd, pathname, &nd, 0);
 	if (IS_ERR(name))
 		return PTR_ERR(name);
 
@@ -3432,7 +3436,7 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 	struct nameidata nd;
 	struct inode *inode = NULL;
 
-	name = user_path_parent(dfd, pathname, &nd);
+	name = user_path_parent(dfd, pathname, &nd, 0);
 	if (IS_ERR(name))
 		return PTR_ERR(name);
 
@@ -3827,13 +3831,13 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
 	struct filename *to;
 	int error;
 
-	from = user_path_parent(olddfd, oldname, &oldnd);
+	from = user_path_parent(olddfd, oldname, &oldnd, 0);
 	if (IS_ERR(from)) {
 		error = PTR_ERR(from);
 		goto exit;
 	}
 
-	to = user_path_parent(newdfd, newname, &newnd);
+	to = user_path_parent(newdfd, newname, &newnd, 0);
 	if (IS_ERR(to)) {
 		error = PTR_ERR(to);
 		goto exit1;