From mboxrd@z Thu Jan 1 00:00:00 1970 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 1A534C001DE for ; Mon, 31 Jul 2023 16:33:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229570AbjGaQdR (ORCPT ); Mon, 31 Jul 2023 12:33:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233413AbjGaQdA (ORCPT ); Mon, 31 Jul 2023 12:33:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EE7FE3; Mon, 31 Jul 2023 09:32:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 145B0611FA; Mon, 31 Jul 2023 16:32:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79433C433C7; Mon, 31 Jul 2023 16:32:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690821178; bh=9i8LJI+T4uoH41XWGczyor+SrktGj/4ZSTLsUYWT9LM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t+wY7zG0+STpq+BUQ5RxzgSL1jfWTCHHd/N3iuued8C2cRbltXGEyZkooxZdi2la0 SEZA+u/yDM7Tk3DbloF2FjbB5kHd2YWfRyJQwCI0y1//gGowS7ZKrYRk/yJG3FnTO/ qJ6cB9FcKYCZDE2B2YmYM/qkENr6dEUiSBCbZsnI4zYRdtgztODsiZarWRnQcQQuuM DpTgPHjj3XbYJWok8O2qXQlhQlTu44sQEHFcHNrLHO5Zefvlpr8tmSwVzQ4PmgRRHT pYawqEMg5o5UHeAZjliaNOrU7lMz0gWwXACIZpnfwRLgQ7bYaaVoRsmTgUKAFfkqWQ sgd+9A5sXrOVg== Date: Mon, 31 Jul 2023 18:32:52 +0200 From: Christian Brauner To: Christoph Hellwig , Gao Xiang Cc: syzbot , chao@kernel.org, huyue2@coolpad.com, jack@suse.cz, jefflexu@linux.alibaba.com, linkinjeon@kernel.org, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, sj1557.seo@samsung.com, syzkaller-bugs@googlegroups.com, xiang@kernel.org Subject: Re: [syzbot] [erofs?] [fat?] WARNING in erofs_kill_sb Message-ID: <20230731-flugbereit-wohnlage-78acdf95ab7e@brauner> References: <000000000000f43cab0601c3c902@google.com> <20230731093744.GA1788@lst.de> <9b57e5f7-62b6-fd65-4dac-a71c9dc08abc@linux.alibaba.com> <20230731111622.GA3511@lst.de> <20230731-augapfel-penibel-196c3453f809@brauner> <20230731-unbeirrbar-kochen-761422d57ffc@brauner> <20230731135325.GB6016@lst.de> <20230731-deswegen-chatten-4ff6c45563ad@brauner> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230731-deswegen-chatten-4ff6c45563ad@brauner> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jul 31, 2023 at 03:57:57PM +0200, Christian Brauner wrote: > On Mon, Jul 31, 2023 at 03:53:25PM +0200, Christoph Hellwig wrote: > > On Mon, Jul 31, 2023 at 03:22:28PM +0200, Christian Brauner wrote: > > > Uh, no. I vasty underestimated how sensitive that change would be. Plus > > > arguably ->kill_sb() really should be callable once the sb is visible. > > > > > > Are you looking into this or do you want me to, Christoph? > > > > I'm planning to look into it, but I won't get to it before tomorrow. > > Ok, let me go through the callsites and make sure that all callers are > safe. I think we should just continue calling deactivate_locked_super() > exactly the way we do right now but remove shenanigans like the one we > have in erofs_kill_sb(). The only filesystem that did implicitly rely on fill_super() having been called was indeed - sorry to single it out - erofs. Everyone else doesn't have that sort of dependency afaict. fs/erofs/super.c: return get_tree_bdev(fc, erofs_fc_fill_super); => ->kill_sb() has requirement that ->fill_super() has been called. So I went and looked at all users of (1) get_tree_bdev() -> new mount api (2) mount_bdev -> old mount api which are the two functions that were changed in Jan's and Christoph's patch. I'm listing the results below. One thing to note is that only 40% (10 out of the 26 I looked at) of block based filesystems reliant on higher-level fs/super.c helpers directly (e.g., that excludes btrfs) have converted to the new mount api. In any case, Gao, can you remove that dependency of erofs_kill_sb() on erofs_fill_super(), please? Once that hits upstream the syzbot report will go away. fs/exfat/super.c: return get_tree_bdev(fc, exfat_fill_super); fs/ntfs3/super.c: return get_tree_bdev(fc, ntfs_fill_super); fs/squashfs/super.c: return get_tree_bdev(fc, squashfs_fill_super); fs/ext4/super.c: return get_tree_bdev(fc, ext4_fill_super); fs/xfs/xfs_super.c: return get_tree_bdev(fc, xfs_fs_fill_super); fs/adfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, adfs_fill_super); fs/befs/linuxvfs.c: return mount_bdev(fs_type, flags, dev_name, data, befs_fill_super); fs/bfs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, bfs_fill_super); fs/ext2/super.c: return mount_bdev(fs_type, flags, dev_name, data, ext2_fill_super); fs/fat/namei_msdos.c: return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super); fs/fat/namei_vfat.c: return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super); fs/freevxfs/vxfs_super.c: return mount_bdev(fs_type, flags, dev_name, data, vxfs_fill_super); fs/hfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, hfs_fill_super); fs/hfsplus/super.c: return mount_bdev(fs_type, flags, dev_name, data, hfsplus_fill_super); fs/hpfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, hpfs_fill_super); fs/isofs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super); fs/jfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, jfs_fill_super); fs/minix/inode.c: return mount_bdev(fs_type, flags, dev_name, data, minix_fill_super); fs/ntfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, ntfs_fill_super); fs/ocfs2/super.c: return mount_bdev(fs_type, flags, dev_name, data, ocfs2_fill_super); fs/omfs/inode.c: return mount_bdev(fs_type, flags, dev_name, data, omfs_fill_super); fs/qnx6/inode.c: return mount_bdev(fs_type, flags, dev_name, data, qnx6_fill_super); fs/sysv/super.c: return mount_bdev(fs_type, flags, dev_name, data, sysv_fill_super); fs/udf/super.c: return mount_bdev(fs_type, flags, dev_name, data, udf_fill_super); fs/ufs/super.c: return mount_bdev(fs_type, flags, dev_name, data, ufs_fill_super); => no custom ->kill_sb() method. fs/cramfs/inode.c: ret = get_tree_bdev(fc, cramfs_blkdev_fill_super); fs/fuse/inode.c: err = get_tree_bdev(fsc, fuse_fill_super); fs/gfs2/ops_fstype.c: error = get_tree_bdev(fc, gfs2_fill_super); fs/romfs/super.c: ret = get_tree_bdev(fc, romfs_fill_super); fs/affs/super.c: return mount_bdev(fs_type, flags, dev_name, data, affs_fill_super); fs/efs/super.c: return mount_bdev(fs_type, flags, dev_name, data, efs_fill_super); fs/f2fs/super.c: return mount_bdev(fs_type, flags, dev_name, data, f2fs_fill_super); fs/qnx4/inode.c: return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super); fs/reiserfs/super.c: return mount_bdev(fs_type, flags, dev_name, data, reiserfs_fill_super); fs/zonefs/super.c: return mount_bdev(fs_type, flags, dev_name, data, zonefs_fill_super); => ->kill_sb() has no requirement that ->fill_super() has been called.