From patchwork Mon Jun 20 13:49:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12887636 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 231F3C433EF for ; Mon, 20 Jun 2022 14:35:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241969AbiFTOfW (ORCPT ); Mon, 20 Jun 2022 10:35:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245099AbiFTOeM (ORCPT ); Mon, 20 Jun 2022 10:34:12 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC81938B6 for ; Mon, 20 Jun 2022 06:50:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A8C45B80B95 for ; Mon, 20 Jun 2022 13:50:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77435C341C0; Mon, 20 Jun 2022 13:50:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655733007; bh=WBo2KDi3tcjgyyBk/6HvvPlktRUrhHSQLUOeSEPBtWc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ckz2K/f7JAT/lwX6SPEOgVqv2oFS6FhN8YBfH4v93y/YJfQJKKUQ0l+jlXLqxqxLz Dx5IXF44GRF/rcHY8CdigWMwARMQHEz02TP2XZp3+LC37LwpQKuM7cfFTwqLpAalcp xDlbtYoo+hfaoKPQwsXwHI3PztVlA8n+A3HljS1p1B38ysLCBqliO4IPqqVeLR9PUy CPfQ5qxAz3WKFsjoisZaxtoCoWAyzLxIwSeJ1mju8U+wipk/ytnRdyZRTRU9+1B6F1 AUEcyQ+TZZY3rUaj7splHajt9mOiZMfditzm4JkxAFk87aZSPyuxITdAB3x+c2huWO eFlfF6VE9Vk1A== From: Christian Brauner To: Christoph Hellwig , linux-fsdevel@vger.kernel.org, Seth Forshee Cc: Christian Brauner , Aleksa Sarai , Linus Torvalds , Al Viro Subject: [PATCH 3/8] fs: use mount types in iattr Date: Mon, 20 Jun 2022 15:49:42 +0200 Message-Id: <20220620134947.2772863-4-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220620134947.2772863-1-brauner@kernel.org> References: <20220620134947.2772863-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3102; h=from:subject; bh=WBo2KDi3tcjgyyBk/6HvvPlktRUrhHSQLUOeSEPBtWc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSRtqHqT73fI/rnhXI9fXnvXM/dbHrM8p/1xsvtqn+VaaRfN eI5nd5SyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAEzk83OG/6GBF6406U98dPQa35Jg7v nqb8x2lFe4OGfoKGbz3+BVnMLw350x4xp/dfPBY6sOHrmdxbLPKmjG209sTl227VO2Pbs7gxMA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add ia_mnt{g,u}id members of type kmnt{g,u}id_t to struct iattr. We use an anonymous union (similar to what we do in struct file) around ia_{g,u}id and ia_mnt{g,u}id. At the end of this series ia_{g,u}id and ia_mnt{g,u}id will always contain the same value independent of whether struct iattr is initialized from an idmapped mount. This is a change from how this is done today. Wrapping this in a anonymous unions has a few advantages. It allows us to avoid needlessly increasing struct iattr. Since the types for ia_{g,u}id and ia_mnt{g,u}id are structures with overlapping/identical members they are covered by 6.5.2.3/6 of the C standard and it is safe to initialize and access them. Filesystems that raise FS_ALLOW_IDMAP and thus support idmapped mounts will have to use ia_mnt{g,u}id and the associated helpers. And will be ported at the end of this series. They will immediately benefit from the type safe new helpers. Filesystems that do not support FS_ALLOW_IDMAP can continue to use ia_{g,u}id for now. The aim is to convert every filesystem to always use ia_mnt{g,u}id and thus ultimately remove the ia_{g,u}id members. Cc: Seth Forshee Cc: Christoph Hellwig Cc: Aleksa Sarai Cc: Linus Torvalds Cc: Al Viro CC: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner (Microsoft) --- include/linux/fs.h | 18 ++++++++++++++++-- include/linux/mnt_idmapping.h | 5 +++++ 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 8724a31b95e5..0da6c0481dbd 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -221,8 +221,22 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, struct iattr { unsigned int ia_valid; umode_t ia_mode; - kuid_t ia_uid; - kgid_t ia_gid; + /* + * The two anonymous unions wrap structures with the same member. + * + * Filesystems raising FS_ALLOW_IDMAP need to use ia_mnt{g,u}id which + * are a dedicated type requiring the filesystem to use the dedicated + * helpers. Other filesystem can continue to use ia_{g,u}id until they + * have been ported. + */ + union { + kuid_t ia_uid; + kmntuid_t ia_mntuid; + }; + union { + kgid_t ia_gid; + kmntgid_t ia_mntgid; + }; loff_t ia_size; struct timespec64 ia_atime; struct timespec64 ia_mtime; diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h index 8dbaef494e02..8f555c746cf4 100644 --- a/include/linux/mnt_idmapping.h +++ b/include/linux/mnt_idmapping.h @@ -21,6 +21,11 @@ typedef struct { gid_t val; } kmntgid_t; +static_assert(sizeof(kmntuid_t) == sizeof(kuid_t)); +static_assert(sizeof(kmntgid_t) == sizeof(kgid_t)); +static_assert(offsetof(kmntuid_t, val) == offsetof(kuid_t, val)); +static_assert(offsetof(kmntgid_t, val) == offsetof(kgid_t, val)); + #ifdef CONFIG_MULTIUSER static inline uid_t __kmntuid_val(kmntuid_t uid) {