From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E19C1C28E; Fri, 2 Jan 2026 14:36:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767364594; cv=none; b=i5bN6zZ72bs+yt/6abllPl3xGNyThUUG/YISiKPGglFjlBcTW8OrfYTfLJz2MGPCtbNS54ORdKYaqOL1zXSFuj/9wlEVaVLJvmZ1Z9Nqjgj85RZdg1kwIiCdi0GDr7y8vaMNnIc5E2G+GEZmSlPvr5bkVOE+OZguisC314fsgzI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767364594; c=relaxed/simple; bh=BRJskyW4bSDrzfRFjFr9KkoMVvsZwgfeOOmGrr6KHTU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=q+sE3aXI6zvrX7iGZX6UbOBu+848hYQT7TfwfsQwW5jNsXyd87jHrnRqY3NGKlQR3MtEur11h0Hz8hK8s3fpX8qHGshDbsEZKeuiX2mhTX1H2t+ZiYGhj1r+K/AZKze9STo/C2glzJNVe2Kjy7ckA8gJ/ET7Pl833Y/0GZLbgDs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JU5jsHCk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JU5jsHCk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4C45C19421; Fri, 2 Jan 2026 14:36:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767364593; bh=BRJskyW4bSDrzfRFjFr9KkoMVvsZwgfeOOmGrr6KHTU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=JU5jsHCkVp8FqZGwJmv7shCiN/sOMY0sdPxMVjEhCGwd8E6f9ov1bQD9sogGu90mU VsFv+nHy/E7fopyrSrMzexyj9Uvbz25OPIjtB13bP04AoP566H2uLeYCBVSZsvdy0O MN0HHWQJ/NVuE4Knq2/pSHU26ggY9Utlyf3vWh1oB9dFyAHvBfeJCrX822PR3ruRzu 4PvRbDylvkH2oeLAGXHBcBx/V5K4Givoy/Mg43oUQXWrlXCF3PtoT++t+JmhetmXXI 7eMUMZybDuV3lFigZbuNdfL6WtKnSsNlZuuHzYwpSy3kWu30QXJZLKcBs0rFpacbxq 4BDzP5MAMAiAw== From: Christian Brauner Date: Fri, 02 Jan 2026 15:36:22 +0100 Subject: [PATCH 1/3] fs: ensure that internal tmpfs mount gets mount id zero Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260102-work-immutable-rootfs-v1-1-f2073b2d1602@kernel.org> References: <20260102-work-immutable-rootfs-v1-0-f2073b2d1602@kernel.org> In-Reply-To: <20260102-work-immutable-rootfs-v1-0-f2073b2d1602@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Alexander Viro , Jan Kara , Jeff Layton , Amir Goldstein , Lennart Poettering , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , Josef Bacik , Christian Brauner , stable@vger.kernel.org X-Mailer: b4 0.15-dev-a6db3 X-Developer-Signature: v=1; a=openpgp-sha256; l=919; i=brauner@kernel.org; h=from:subject:message-id; bh=BRJskyW4bSDrzfRFjFr9KkoMVvsZwgfeOOmGrr6KHTU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSGX3/zqkE9eZ2xzJc5Yh+WzM9KuVPzWfvBY5N15bxKw bb/ZB/O6yhlYRDjYpAVU2RxaDcJl1vOU7HZKFMDZg4rE8gQBi5OAZjIjC8Mf7jZa67dMTxs/JfF tC7/le9p3VO/oktZ1lwU/hJla+w28RDDfy8/33vNl2cd1tfN/qLC4N58wEyY/feEtay5THMEXuh EswMA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 and the rootfs get mount id one as it always has. Before we actually mount the rootfs we create an internal tmpfs mount which has mount id zero but is never exposed anywhere. Continue that "tradition". Fixes: 7f9bfafc5f49 ("fs: use xarray for old mount id") Cc: Signed-off-by: Christian Brauner --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index c58674a20cad..8b082b1de7f3 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -221,7 +221,7 @@ static int mnt_alloc_id(struct mount *mnt) int res; xa_lock(&mnt_id_xa); - res = __xa_alloc(&mnt_id_xa, &mnt->mnt_id, mnt, XA_LIMIT(1, INT_MAX), GFP_KERNEL); + res = __xa_alloc(&mnt_id_xa, &mnt->mnt_id, mnt, xa_limit_31b, GFP_KERNEL); if (!res) mnt->mnt_id_unique = ++mnt_id_ctr; xa_unlock(&mnt_id_xa); -- 2.47.3