From patchwork Wed Sep 13 11:10:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13382851 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 44A77EDEC45 for ; Wed, 13 Sep 2023 11:11:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240242AbjIMLLo (ORCPT ); Wed, 13 Sep 2023 07:11:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240001AbjIMLLb (ORCPT ); Wed, 13 Sep 2023 07:11:31 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 38F70212C; Wed, 13 Sep 2023 04:11:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=gAQpn3abjr3bCkTLiF8aPyoqkxGk9OOm0IM5g63D6eE=; b=NdBTKNAaKwHERWBpvD3UHGHfWf zb1yuh/XGcMfDzj1uLx+u6lD7qnepKXrpO/pZmptTHoHtwVpXIcZshX4OUVEMjv7TFo69PbppmJ2S rlnKrkO75331r1G0LrzPr74Ld8r5vKU+AwChAsIjk83zQKmZMBIc84YOIDUSjkv5ZJvuC/IOK+E12 WpSRWG3djGVWDuKbehP3xIldJ/rcOSFsLliI85QDerGS8G2MUpKUaT8chV07JMkBU1+2CEJsmDyZe wUX0ytw7XTGMjsPQ73ZLJ7fI2JwOsX3VvP93iP4mMmit4r7MmaYr4cQY0nPPcL0S7f0OQ64t+qePR HbqcSKpA==; Received: from [190.210.221.22] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qgNls-005i4Y-1y; Wed, 13 Sep 2023 11:11:01 +0000 From: Christoph Hellwig To: Christian Brauner , Al Viro Cc: Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Fenghua Yu , Reinette Chatre , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Dennis Dalessandro , Tejun Heo , Trond Myklebust , Anna Schumaker , Kees Cook , Damien Le Moal , Naohiro Aota , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org, linux-hardening@vger.kernel.org, cgroups@vger.kernel.org Subject: [PATCH 11/19] fs: add new shutdown_sb and free_sb methods Date: Wed, 13 Sep 2023 08:10:05 -0300 Message-Id: <20230913111013.77623-12-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230913111013.77623-1-hch@lst.de> References: <20230913111013.77623-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Currently super_blocks are shut down using the ->kill_sb method, which must call generic_shutdown_super, but allows the file system to add extra work before or after the call to generic_shutdown_super. File systems tend to get rather confused by this, so add an alternative shutdown sequence where generic_shutdown_super is called by the core code, and there are extra ->shutdown_sb and ->free_sb hooks before and after it. To remove the amount of boilerplate code ->shutdown_sb is only called if the super has finished initialization and ->d_root is set. Signed-off-by: Christoph Hellwig --- Documentation/filesystems/locking.rst | 4 ++++ Documentation/filesystems/vfs.rst | 12 ++++++++++++ fs/super.c | 9 +++++++-- include/linux/fs.h | 2 ++ 4 files changed, 25 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index 7be2900806c853..c33e2f03ed1f69 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -220,7 +220,9 @@ prototypes:: struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); + void (*shutdown_sb) (struct super_block *); void (*kill_sb) (struct super_block *); + void (*free_sb) (struct super_block *); locking rules: @@ -228,7 +230,9 @@ locking rules: ops may block ======= ========= mount yes +shutdown_sb yes kill_sb yes +free_sb yes ======= ========= ->mount() returns ERR_PTR or the root dentry; its superblock should be locked diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index 99acc2e9867391..1a7c6926c31f34 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -119,7 +119,9 @@ members are defined: const struct fs_parameter_spec *parameters; struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); + void (*shutdown_sb) (struct super_block *); void (*kill_sb) (struct super_block *); + void (*free_sb) (struct super_block *); struct module *owner; struct file_system_type * next; struct hlist_head fs_supers; @@ -155,10 +157,20 @@ members are defined: the method to call when a new instance of this filesystem should be mounted +``shutdown_sb`` + Cleanup after a super_block has reached a zero active count, and before + the VFS level cleanup happens. Typical picks all fs-specific objects + (if any) that need destruction out of superblock and releases them. + Note: dentries and inodes are normally taken care of and do not need + specific handling unless they are pinned by kernel users. + ``kill_sb`` the method to call when an instance of this filesystem should be shut down +``free_sb`` + Free file system specific resources like sb->s_fs_info that are + still needed while inodes are freed during umount. ``owner`` for internal VFS use: you should initialize this to THIS_MODULE diff --git a/fs/super.c b/fs/super.c index 5c685b4944c2d6..8e173eccc8c113 100644 --- a/fs/super.c +++ b/fs/super.c @@ -480,10 +480,15 @@ void deactivate_locked_super(struct super_block *s) unregister_shrinker(&s->s_shrink); - if (fs->kill_sb) + if (fs->kill_sb) { fs->kill_sb(s); - else + } else { + if (fs->shutdown_sb) + fs->shutdown_sb(s); generic_shutdown_super(s); + if (fs->free_sb) + fs->free_sb(s); + } kill_super_notify(s); diff --git a/include/linux/fs.h b/include/linux/fs.h index 31b6b235b36efa..12fff7df3cc46b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2341,6 +2341,8 @@ struct file_system_type { struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); void (*kill_sb) (struct super_block *); + void (*shutdown_sb)(struct super_block *sb); + void (*free_sb)(struct super_block *sb); struct module *owner; struct file_system_type * next; struct hlist_head fs_supers;