From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 8839635E93B; Sat, 17 Oct 2026 17:32:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258354; cv=none; b=BzM+WWiFRKTAiiFVgrt44sqL8hydO1kniDn8WslvF6WQ+Q4/fE8Xe0ejL0sxotLcEt14OCWYr0cYqEnd2TBZoWN9hSi5YM94DqAf3zeuf/kDsA1D4VXAs2Vu4S//pz9Lk2Gamssgm43YlXkROws/zbnGOg1zGbpFUU1mGJVdcik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258354; c=relaxed/simple; bh=5jFJy2ooZ4iGn/gDvlpXGNfQT/L3tddfpz7/FuyqbfI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qX+wEjemdNoq8oQaLWSgCIvj/oVeUhk9WxBx0XgbvBB7KrzN4kApGUTkVzxAqWO20TgkLD0kWnez90Rrl+8raJ4Ms5dlBwDJjJhkHP13AOMsZ20slYeoiiK79uLxE5s84n3FdqxwygNTpBSwijsIPOoS0vqJyDjPcDj/GPAEno8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fEusocH+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fEusocH+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A98C91F000C4; Sat, 17 Oct 2026 17:32:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792258353; bh=F00rZ5tClf69s8Kv4nBPkkCES+KyXJBKuzEI7v1pbFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fEusocH+CzJFB3kkl3stuNXXZDBesqElsqliIJZNd2GoMq2CAdEAz3IvB/fHUnQTd A7OCdRt4lP7mZj+bewOeeyh3EfIlXAo4kkzlJ0kegzImLR9C1vmNaAp//LXFaZU1B4 6PPDXtKQANmM8Tx5/QF5oWF0aoq2Q4vIx5kzGPvI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiaming Zhang , Boris Burkov , Johannes Thumshirn , Qu Wenruo , David Sterba , Sasha Levin Subject: [PATCH 6.6 0857/1674] btrfs: reject new transactions if the fs is fully read-only Date: Sat, 17 Oct 2026 17:52:09 +0200 Message-ID: <20261017160453.118564860@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qu Wenruo [ Upstream commit 1972f44c189c8aacde308fa9284e474c1a5cbd9f ] [BUG] There is a bug report where a heavily fuzzed fs is mounted with all rescue mount options, which leads to the following warnings during unmount: BTRFS: Transaction aborted (error -22) Modules linked in: CPU: 0 UID: 0 PID: 9758 Comm: repro.out Not tainted 6.19.0-rc5-00002-gb71e635feefc #7 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:find_free_extent_update_loop fs/btrfs/extent-tree.c:4208 [inline] RIP: 0010:find_free_extent+0x52f0/0x5d20 fs/btrfs/extent-tree.c:4611 Call Trace: btrfs_reserve_extent+0x2cd/0x790 fs/btrfs/extent-tree.c:4705 btrfs_alloc_tree_block+0x1e1/0x10e0 fs/btrfs/extent-tree.c:5157 btrfs_force_cow_block+0x578/0x2410 fs/btrfs/ctree.c:517 btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708 btrfs_search_slot+0xcad/0x2b50 fs/btrfs/ctree.c:2130 btrfs_truncate_inode_items+0x45d/0x2350 fs/btrfs/inode-item.c:499 btrfs_evict_inode+0x923/0xe70 fs/btrfs/inode.c:5628 evict+0x5f4/0xae0 fs/inode.c:837 __dentry_kill+0x209/0x660 fs/dcache.c:670 finish_dput+0xc9/0x480 fs/dcache.c:879 shrink_dcache_for_umount+0xa0/0x170 fs/dcache.c:1661 generic_shutdown_super+0x67/0x2c0 fs/super.c:621 kill_anon_super+0x3b/0x70 fs/super.c:1289 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2127 deactivate_locked_super+0xbc/0x130 fs/super.c:474 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318 task_work_run+0x1d4/0x260 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x694/0x22f0 kernel/exit.c:971 do_group_exit+0x21c/0x2d0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121 x64_sys_call+0x2210/0x2210 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe8/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x44f639 Code: Unable to access opcode bytes at 0x44f60f. RSP: 002b:00007ffc15c4e088 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00000000004c32f0 RCX: 000000000044f639 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001 RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004c32f0 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 Since rescue mount options will mark the full fs read-only, there should be no new transaction triggered. But during unmount we will evict all inodes, which can trigger a new transaction, and triggers warnings on a heavily corrupted fs. [CAUSE] Btrfs allows new transaction even on a read-only fs, this is to allow log replay happen even on read-only mounts, just like what ext4/xfs do. However with rescue mount options, the fs is fully read-only and cannot be remounted read-write, thus in that case we should also reject any new transactions. [FIX] If we find the fs has rescue mount options, we should treat the fs as error, so that no new transaction can be started. Reported-by: Jiaming Zhang Link: https://lore.kernel.org/linux-btrfs/CANypQFYw8Nt8stgbhoycFojOoUmt+BoZ-z8WJOZVxcogDdwm=Q@mail.gmail.com/ Reviewed-by: Boris Burkov Reviewed-by: Johannes Thumshirn Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/disk-io.c | 13 +++++++++++++ fs/btrfs/fs.h | 6 ++++++ 2 files changed, 19 insertions(+) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index adf649ec60beb..d2f9c5be175ea 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3155,6 +3155,15 @@ int btrfs_check_features(struct btrfs_fs_info *fs_info, bool is_rw_mount) return 0; } +static bool fs_is_full_ro(const struct btrfs_fs_info *fs_info) +{ + if (!sb_rdonly(fs_info->sb)) + return false; + if (unlikely(fs_info->mount_opt & BTRFS_MOUNT_FULL_RO_MASK)) + return true; + return false; +} + int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_devices, char *options) { @@ -3298,6 +3307,10 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device if (ret) goto fail_alloc; + /* If the fs has any rescue options, no transaction is allowed. */ + if (fs_is_full_ro(fs_info)) + WRITE_ONCE(fs_info->fs_error, -EROFS); + ret = btrfs_check_features(fs_info, !sb_rdonly(sb)); if (ret < 0) goto fail_alloc; diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h index b8b9ce8921baf..415f867dd1252 100644 --- a/fs/btrfs/fs.h +++ b/fs/btrfs/fs.h @@ -186,6 +186,12 @@ enum { BTRFS_MOUNT_NODISCARD = (1UL << 31), }; +/* These mount options require a full read-only fs, no new transaction is allowed. */ +#define BTRFS_MOUNT_FULL_RO_MASK \ + (BTRFS_MOUNT_NOLOGREPLAY | \ + BTRFS_MOUNT_IGNOREBADROOTS | \ + BTRFS_MOUNT_IGNOREDATACSUMS) + /* * Compat flags that we support. If any incompat flags are set other than the * ones specified below then we will fail to mount -- 2.53.0