rust_binderfs: fix a dentry leak

Parallel to binderfs patches - 02da8d2 "binderfs_binder_ctl_create():
kill a bogus check" and the bit of b89aa54 "convert binderfs" that
got lost when making 4433d8e "convert rust_binderfs"; the former is
a cleanup, the latter is about marking /binder-control persistent, so that
it would be taken out on umount.

Fixes: 4433d8e ("convert rust_binderfs")
Acked-by: Alice Ryhl <[email protected]>
Acked-by: Christian Brauner <[email protected]>
Signed-off-by: Al Viro <[email protected]>

Author: Al Viro

drivers/android/binder/rust_binderfs.c

@@ -391,12 +391,6 @@ static int binderfs_binder_ctl_create(struct super_block *sb)
 	if (!device)
 		return -ENOMEM;
 
-	/* If we have already created a binder-control node, return. */
-	if (info->control_dentry) {
-		ret = 0;
-		goto out;
-	}
-
 	ret = -ENOMEM;
 	inode = new_inode(sb);
 	if (!inode)
@@ -431,7 +425,8 @@ static int binderfs_binder_ctl_create(struct super_block *sb)
 
 	inode->i_private = device;
 	info->control_dentry = dentry;
-	d_add(dentry, inode);
+	d_make_persistent(dentry, inode);
+	dput(dentry);
 
 	return 0;